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Manage avocado tree growth cycles for productivity gains
... Once start fruiting, all avocado trees show defined and deferent phenological growth patterns (cyclic growths) such as inflorescence emergence, flowering, shoot flush, fruit set, fruits fall, exponential fruit growth, root flush and harvesting. They are among key visible growth patterns depending on existing season (climate), altitude factors and management practices (Whiley et al., 1988;Paull and Duarte, 2011). Avocado planted in different agro ecologies follow different growth patterns of same cycles; in particular area they follow same annual growth cycle due to the specific climate of the area governing tree growth and development. ...
... In addition, an understanding of the phenology elements of avocado is essential for interpreting physiological responses of the crop to environmental factors. Knowledge of the time of root and shoot growth, flowering and fruit set, and the relationships between these events with the seasons growing conditions will allow for application of irrigation, fertilization, and other cultural practices at optimum times (Whiley et al., 1988;Whiley and Wolstenholme, 1990). Thus, understanding developmental phenology for avocado varieties at particular sites ...
... and application of required management practices could greatly enhance a grower's ability to plan corresponding management practices in relation to the events occurring within the tree. These phenological growth and development patterns of avocados were defined in the major avocado growing areas of the world such as California (Salazar-García et al, 1998), South Africa (Whiley, 1994), and Australia (Whiley et al, 1988). Since the geographical locations, seasons and environments of avocado growing regions vary, one should understand these growth events/ patterns for particular areas and particular variety before formulating management practices. ...
Avocado undergoes vegetative and reproductive cycles along the growing season. Each growth cycle has specific timing of recurrent biological event in which different phonological and developmental changes are taken place. Identification of time of each growth stage at particular area for particular variety gives the growers to schedule management practices required for improved productivity and quality. Study was conducted to assess visible phenological growth patterns and describe time-period relationships between phenological growth patterns of matured avocado trees at Melkassa Agricultural Research Center fruit orchard for three years (20192021). Six released avocado varieties grafted on local rootstocks established at the research center fifteen years back were used for the study: which includes Hass, Pinkerton, Bacon, Ettinger, Fuerte and Nabal. The varieties were planted with
planting density of 6 m* 6 m and uniform management practices were applied for all trees. The soil of the orchard is loam soil and furrow irrigated throughout the plantation life. Five sample trees per variety were selected randomly and 20 sample shoots, five from north, south, east and west sides of each sample tree. Sample branches were labelled and bi-weekly observation was made starting the first week of August. The visible growths of avocado varieties such as inflorescence emergence, flower flushing, shoot flushing, fruit set and harvesting periods were assessed throughout the year for three consecutive years. Data were recorded when at least 50% of the experimental fruit trees was in the same stage of development. The result showed that inflorescence emergence and flower flushing of all avocado varieties at Melkassa occurred from September to November due to low temperatures during this period. In addition, the study observed that all avocado varieties produced vegetative
shoots flushing from September up to December. The observation indicated that the harvesting periods of all avocado varieties were concentrated in September and October. The study revealed that all varieties required nearly 11-12 months for fruits to mature and ready for harvesting. In depth future study is required for detail
investigations based on avocado BBCH (Biologische Bundesanstalt, Bundessortenamt Chemische Industrie) scale for all varieties at major production areas of the country. This includes quantification of growths of all variables such as plant height, trunk height, stem diameter, root growth, canopy volume, fruits growth
patterns (trends) and compositions, yield and yield efficiency of the varieties. Further, this study should continue with detail investigations on influences of environmental, weather elements and management practices on the physiological responses on those commercial avocado varieties and local land races of avocado at the major production areas.
... Generally, at low VPD, there is less difference in water vapor concentration between leaf and air, leading to low transpiration rates. Avocado trees respond to increasing VPD by closing their stomata to reduce transpiration in an adverse environmental situation [69,70]. ...
... In addition, Whiley et al. [69] reported that in the flowering stage, the evaporative area increases by up to 90% due to the abundant small avocado flowers with an elevated evaporation ratio, leading to an augmentation of tree transpiration ratio from 13 to 15%. Under these circumstances, the water stress at this phase can provoke flower abortion, fruitlet abscission, and early leaf drop [85]. ...
... In this context, Whiley et al. [69] recommended the irrigation based on tensiometer readings of −40 kPa at 30 cm soil depth during spring, whereas this value could be reduced to −30 kPa during the fruit drop period. The experiment conducted by Vuthapanich et al. [153] found that well irrigated cv. ...
Due to congenital features, avocado (Persea americana Mill.) trees are substantial water users relative to other fruit trees. The current growing deficiency of water resources, especially in arid and semi-arid avocado-producing areas, has led to the demand for more sustainable water-saving measures. The objective of this review was to analyze the role of deficit irrigation as a strategy to face climate change and water scarcity through achieving efficiency, saving water, and maximizing the benefits that could be achieved at the level of the irrigated agricultural system. Particular attention is devoted to studies performed in the subtropical Mediterranean climate, in which irrigated avocado orchards are common. These studies analyzed irrigation demand, deficit irrigation, and determination of water status through physiological parameters, leading to possible sustainable irrigation programs for avocado in the context of water shortage scenarios. Through these insights, we conclude that under the current climatic circumstances with respect to available water resources, avocado farming requires sustainable resilience strategies to reduce irrigation water consumption without affecting the yield and quality of the fruits. Water stress inevitably affects the physiological processes that determine yield. Therefore, an admissible yield loss is required with smaller fruits and water savings made through deficit irrigation strategies. In addition, modern consumers tend to prefer foods based on sustainability, i.e., there is a high demand for socially responsible and environmentally friendly products.
... Figure 3 shows the locations, with the largest amount found on a farm in the southwest, followed northern Antioquia. In the avocado Hass variety, a tree can produce up to 2 million flowers, more than a thousand times the amount of fruit it can bear, but fruit set is only between 0.001 and 0.01% (Whiley et al., 1988;Dixon and Sher, 2002;Can-Alonzo et al., 2005;Cossio-Vargas et al., 2007;Scora et al., 2013). ...
... Avocado trees produce an excessive number of flowers, between 1 and 2 million per tree. However, only one or two fruits of each inflorescence reach maturity (Whiley et al., 1988). In this study, significant differences were found in the number of fallen fruits by location; the municipality of Jardin had 52,926 fallen fruits with less than 0.5 cm, followed by El Peñol with 26,744 fallen fruits (Tab. ...
... This first fruit fall coincided with the report by Teliz and Mora (2015), who found that the avocado has significant fruit fall because of competition between vegetative growth, root growth and fruit development, directly affecting productivity. Whiley et al. (1988) indicated that avocado plants adjust the capacity to nourish fruits by modifying the number through the massive fall of freshly set fruits during the first three to four weeks and again when fruits reach 10 to 40% of their size. It should be noted that fruit fall in avocados can be accentuated by a single or excessive application of nitrogen fertilizers when the fruits reach 2/3 or more of their size. ...
The amount of leaf litter produced by avocado trees cv. Hass is an important potential source of mineral resources, and quantifying its production and nature is crucial to understanding the cycling of nutrients. The main objective of this study was to quantify the production of leaf litter and fallen flowers and small fruits in avocado orchards at eight locations in three producing areas in the Department of Antioquia (west, southwest, and north). The highest leaf litter production occurred in southwest Antioquia, at Jardin (7.6 t ha-1 year-1); the east locations had similar leaf fall (4.03-3.4 t ha-1 year-1). The dry matter produced in the north was very similar in both locations. The dry matter was 2.8 t ha-1 year-1. Higher leaf litter was recorded in all locations during the driest periods. Approximately 80% of the fallen fruits had diameters less than 1 cm. The highest flower production and fall occurred in southwest Antioquia, followed by the northern region.
... Determining the periods of shoot and root flushing and flowering and fruit setting may assist in scheduling fertilization (Lovatt 2001), irrigation (Bárcenas-Ortega et al. 2007), pruning (Menzel & Le Lagadec 2014), pest (Torres et al. 2012) and disease (Ávila-Quezada et al. 2002) control. Improved management practices may also optimize fruit quality and yield (Whiley et al. 1988a, Dixon et al. 2008, Menzel & Le Lagadec 2014. ...
... Several avocado phenological models have been previously developed (Whiley et al. 1988a, Wolstenholme & Whiley 1989, Robinson et al. 2002, Cossio-Vargas et al. 2008, Dixon et al. 2008). In Brazil, two studies have described the vegetative flush, blooming and fruit growth periods for several cultivars, including 'Hass' (Oliveira et al. 2013, Silva et al. 2014). ...
... In São Bento do Sapucaí, in the São Paulo state (Cwb climate, 903 m of altitude), the first shoots emerged by mid-September in 'Hass' and in late September in 'Margarida', under maximum/ minimum temperatures of 20-21 ºC/6-7 ºC (Oliveira et al. 2013). In avocado, the vegetative flush in spring competes with the young fruit for photoassimilates and water, and it is often associated with low yields (Whiley et al. 1988a). ...
Only a few phenological models have been formulated for rain-fed avocados in warm subhumid environments, and none of them have suggested crop management strategies for improving the trees performance in such conditions. The occurrence and intensity of major phenological events were assessed in ‘Hass’ and ‘Margarida’ avocado trees, in order to properly schedule the main crop practices for optimum management of rain-fed orchards in warm subhumid growing environments. Shoot growth, root density, number of open flowers, fruit set and fruit dropping rate were evaluated. For both cultivars, two shoot flushes were observed in September-ctober (spring) and January-February (summer), while a maximum feeder root growth took place in late August, coinciding with flowering. Two other minor root growth flushes occurred after the onset of summer rains. Both cultivars had only one flowering period, followed by an intense fruitlet dropping. A second minor fruit dropping wave occurred in February (midsummer), for both cultivars. By determining the extent of each phenological phase in both avocado cultivars, it is possible to schedule applications of fertilizer, mulch and soil amendments, during the root growth flushes, as well as foliar sprays during shoot flushes, in order to maintain an adequate nutritional and sanitary status. © 2017, Universidade Federal De Goias (UFG). All rights reserved.
... El estudio de la fenología de 'Hass' es importante para la correcta planeación y ejecución de las prácticas de manejo de los huertos, como podas, fertilización, riegos, etc. La fenología es la relación entre el clima y los procesos biológicos periódicos (Whiley et al., 1988). Los árboles frutales muestran diversas fases del desarrollo o fases fenológicas conforme pasan las estaciones del año, por ejemplo: iniciación y diferenciación floral, flujos de crecimiento vegetativo, amarre y caída de fruto, crecimiento y maduración del fruto, crecimiento de raíces, abscisión de hojas, etc. (Wolstenholme y Whiley, 1989). ...
... Existen diagramas fenológicos con diferente grado de complejidad que han sido elaborados para 'Hass' en diversas regiones productoras, como el Sur de Australia (Whiley et al., 1988), Natal, Sudáfrica (Whiley y Wolstenholme, 1990), Quillota, Chile (Gardiazabal y Rosenberg, 1991) California (Arpaia et al., 1994-95) y Nueva Zelanda (Thorp et al., 1998). Estas regiones poseen condiciones climáticas y de cultivo distintas a las de Nayarit, por lo que, el objetivo de este trabajo fue integrar información fenológica registrada en diferentes estudios realizados en Nayarit para describir los ciclos de crecimiento de 'Hass' cultivado sin riego en clima semicálido. ...
... La ocurrencia de un solo flujo de producción de raíces en 'Hass' en Nayarit difiere de lo encontrado en otras regiones, ya que normalmente se observan al menos dos flujos de crecimiento, uno en la primavera y el otro durante el verano u otoño (Arpaia, 1998;Whiley et al., 1988;Sánchez-Pérez et al., 2001). ...
This study was conducted at several periods of time from 2000 to 2005 in two commercial 'Hass' avocado orchards in the municipalities of Tepic and Xalisco, Nayarit, México. The objective was to determine the growth cycles of 'Hass' avocado trees under rainfed conditions. 'Hass' showed two flushes of vegetative growth: winter (greatest intensity) and summer (lowest intensity). The complete floral development process, from closed pointed bud to anthesis, required 11.5 and 7.5 months for winter and summer shoots, respectively. Greatest production of roots occurred in August. "June fruit drop" maximum intensity (45%) was observed during the first summer rains (June). Fruit growth (length), from set (March) to harvest (November), took eight months. Average annual maximum air temperatures fluctuated between 26.8 and 33.4 °C and minimum temperatures were 9.3 to 20.4 °C. Average monthly maximum soil temperatures varied from 20.1 to 24.5 °C throughout the year and the minimum ranged from 18.5 to 23.4 °C. Soil moisture level was ≥85% from the rainy season (June to October) to December; afterwards it decreased, reaching 65% in May.
... In the moist, summer rainfall subtropics, bearing trees are characterized by a spring growth flush that starts during flowering and peaks in early summer. The proportion of terminal and sub-terminal shoots in active growth then reduces to a low level, to be followed by a second (summer and early autumn) growth flush (Whiley et al., 1988b). In climates such as those of southern California (and coastal Israel and Chile), the spring flush may end earlier, allowing an early summer flush and an autumn flush (Chandler, 1958). ...
... sandy soils low in organic matter, in hot, semi-arid areas (see Whiley et al.,Chapter 12, of this volume). Comprehensive surface feeder root (Whiley et al., 1988b) and rhizotron studies (Whiley, 1994) in deep red, high organiccontent krasnozem soils in cool subtropical Queensland have shown considerable feeder root growth as deep as 1 m, and extension of the second (autumn) root growth flush well into winter. Nevertheless, the majority of white, unsuberized feeder roots is found in the top 600 mm of soil, and even shallower in heavy clay soils. ...
... A large crop can be obtained from as few as 200 (small trees at high density) and up to 500 or more mature fruit per tree. In subtropical climates there are two periods of intense abscission, in late spring/ early summer and in mid-summer (Whiley et al., 1988b). Although flowers (2.8-3.4 mm −2 ) and young fruit (50-75 mm −1 ) have few stomates relative to leaves (Blanke and Lovatt, 1993), it has been shown that heavy flowering substantially increases total transpiration (Whiley et al., 1988a). ...
This book is comprised of 15 chapters covering principles and basic understanding in avocado science, technology, best management practices and postharvest aspects. It is aimed at avocado researchers, libraries, teachers and academics, students, advisers, cutting edge growers and industry support personnel. Topics discussed include the history, distribution, uses, taxonomy, botany, genetics, breeding, ecology, reproductive biology, ecophysiology, cultivars and rootstocks, propagation, biotechnology, irrigation and mineral nutrition, crop management, foliar, fruit and soil-borne diseases, insect and mite pests and harvesting, packing, postharvest technology, transport and processing.
... El estudio de la fenología de 'Hass' es importante para la correcta planeación y ejecución de las prácticas de manejo de los huertos, como podas, fertilización, riegos, etc. La fenología es la relación entre el clima y los procesos biológicos periódicos (Whiley et al., 1988). Los árboles frutales muestran diversas fases del desarrollo o fases fenológicas conforme pasan las estaciones del año, por ejemplo: iniciación y diferenciación floral, flujos de crecimiento vegetativo, amarre y caída de fruto, crecimiento y maduración del fruto, crecimiento de raíces, abscisión de hojas, etc. (Wolstenholme y Whiley, 1989). ...
... Existen diagramas fenológicos con diferente grado de complejidad que han sido elaborados para 'Hass' en diversas regiones productoras, como el Sur de Australia (Whiley et al., 1988), Natal, Sudáfrica (Whiley y Wolstenholme, 1990), Quillota, Chile (Gardiazabal y Rosenberg, 1991) California (Arpaia et al., 1994-95) y Nueva Zelanda (Thorp et al., 1998). Estas regiones poseen condiciones climáticas y de cultivo distintas a las de Nayarit, por lo que, el objetivo de este trabajo fue integrar información fenológica registrada en diferentes estudios realizados en Nayarit para describir los ciclos de crecimiento de 'Hass' cultivado sin riego en clima semicálido. ...
... La ocurrencia de un solo flujo de producción de raíces en 'Hass' en Nayarit difiere de lo encontrado en otras regiones, ya que normalmente se observan al menos dos flujos de crecimiento, uno en la primavera y el otro durante el verano u otoño (Arpaia, 1998;Whiley et al., 1988;Sánchez-Pérez et al., 2001). ...
Esta investigación se desarrolló en varios periodos de tiempo del 2000 al 2005, en dos huertos comerciales de aguacate ‘Hass’ en los Municipios de Tepic y Xalisco, Nayarit, México. El objetivo fue determinar los ciclos de crecimiento de árboles de ‘Hass’ cultivados sin riego. El cv. Hass presentó dos flujos de crecimiento vegetativo: invierno (mayor intensidad) y verano (menor intensidad). El proceso completo de desarrollo floral, de yema cerrada a antesis, en brotes del flujo vegetativo de invierno y verano fue de 11.5 meses y 7.5 meses, respectivamente. La máxima producción de raíces ocurrió en agosto. La máxima intensidad (45%) de la “caída de fruto de Junio” ocurrió durante las primeras lluvias de verano (junio). El crecimiento en longitud del fruto, desde el amarre (marzo) hasta cosecha (noviembre), duró ocho meses. Los promedios anuales de temperaturas máximas del aire fluctuaron de 26.8 C a 33.4 C y las mínimas de 9.3 C a 20.4 C. El promedio de las temperaturas máximas mensuales del suelo se mantuvo todo el año entre 20.1C y 24.5 C, y las mínimas entre 18.5 C y 23.4 C. El nivel de humedad del suelo fue 85 % desde la estación lluviosa (junio a octubre) hasta diciembre; posteriormente descendió hasta alcanzar 65% en mayo.
The research was undertaken at several periods of time from 2000 to 2005 in two commercial ‘Hass’ avocado orchards in the municipalities of Tepic and Xalisco, Nayarit, México. The objective was to determine the growth cycles of ‘Hass’ avocado trees under rainfed conditions. ‘Hass’ showed two flushes of vegetative growth: winter (greatest intensity) and summer (lowest intensity). The complete floral development process, from closed and pointed bud to anthesis, required 11.5 and 7.5 months for winter and summer shoots, respectively. Greatest production of roots occurred in august. “June fruit drop” maximum intensity (45%) was observed during the first summer rains (june). Fruit growth (length), from set (march) to harvest (november), used eight months. Annual average of maximum air temperatures fluctuated from 26.8 C to 33.4 C and minimum from 9.3 C to 20.4 C. Monthly average of maximum soil temperatures varied from 20.1C to 24.5 C throughout the year and the minimum ranged from 18.5 C to 23.4 C. Soil moisture level was 85 % from the rainy season (june to october) to december; afterwards it decreased, reaching 65 % in may.
... This pattern depends on species, cultivar, management, and environment. Environmental factors, however, are considered the most important factors that affect tree performance and management strategies (Whiley et al., 1988). ...
... The phases of the phenology cycle of tropical fruit trees are influenced by climatic conditions, mainly temperature and precipitation (Cull, 1986). The effects of climatic and environmental conditions on annual phenological cycles have been studied in several tropical and subtropical fruit crops including avocado (Cull, 1986;Salomon, 1984;Whiley et al., 1988), citrus (Salomon, 1984), mango (Whiley, 1993), and olive (Cimato et al., 1990). Just as the phenology of deciduous temperate trees is mainly determined by seasonal variations in temperature and photoperiod, the phenology of tropical fruit is affected by seasonal variability in water availability (Reich and Borchert, 1984). ...
... Phenological cycles of tropical evergreen trees are less obvious than those of temperate fruit trees. Tropical fruit growers must recognize annual critical growth changes in order to utilize growth cycles as orchard management tools (Whiley et al., 1988). Environment and orchard cultural practices affect vegetative and reproductive development throughout the annual phenological cycle of carambola. ...
... The avocado, like many subtropical fruit tree species (Landsberg 1986), is a large tree which produces a great deal of unproductive wood as structural material, an inefficiency in carbohydrate (CHO) allocation. The vegetative appearance of subtropical fruit crops and the considerable flower and fruit shedding which occurs in spring has led several people to question the effect of N fertilizer on their vegetative-reproductive balance (Whiley et al. 1988;Weinbaum et al. 1992). ...
... In the previous studies with temperate crops, the vegetative-reproductive balance was manipulated by removing fruit. It has been suggested that a reduction in vegetative growth of avocado during the fruit set period will reduce competition for CHO and improve fruit set and yield (Whiley et al. 1988;. A steep decline in CHO reserves occurs during summer and autumn when vegetative flushing occurs and increases over winter during the period of floral development reaching a maximum in spring, just prior to flowering (Scholefield et al. 1985). ...
... The suggestion that N stimulates vegetative growth at the expense of reproductive growth for deciduous crops (Elfing 1988) and avocados (Whiley et al. 1988; is not supported experimentally. To the contrary, where the vigour of peach trees was increased by N fertilizer application, yield increased (Proebstring 1958). ...
This review examines the prospects for manipulating the vegetative-reproductive balance in horticultural crops through nitrogen (N) nutrition. It also examines whether incorrect timing or excessive applications of N stimulate vegetative growth at the expense of reproductive growth. Productivity of horticultural crops is dependent on an adequate N status because photosynthetic capacity is dependent on leaf N content per unit area. Efficient N uptake occurs during periods of active growth and depends on active photosynthesis. Most N in exposed leaves is accumulated as protein and the uptake and conversion to protein requires a carbohydrate (CHO) supply. A feedback mechanism has been proposed from shoots to roots in the control of N uptake, because ammonium and nitrate uptake do not increase at supraoptimal concentrations. Stored CHO and nutrients support actively growing shoots and inflorescences and while vegetative and reproductive meristems compete as sinks, fruit growth depends principally on current photosynthesis. Most of the season's N uptake by deciduous trees occurs during the post-fruit maturity period in late summer and autumn in vegetative growth which is remobilized prior to leaf fall in late autumn into storage. The N is redistributed the following spring to support new season leaf and fruit growth. In sand culture studies conducted with 2-year-old peach and apple trees, an N deficiency which led to inadequate tree N reserves in winter inhibited flowering, fruit set and vegetative growth the following spring. N applied during spring is poorly assimilated. For Prunus spp., 90% of the N contained in the spring vegetative flush is derived from storage, indicating that exogenous N applications at that time are unlikely to influence that season's growth. Vegetable crops which have high growth and N uptake rates compared with tree fruit crops (maximum N uptake rate for tomato 66 kg/ha.week v. peach 1.3 kg/ha.week) rely on exogenous N and current photosynthesis to support growth. In studies where very high N rates were applied to horticultural crops, tree crops were unaffected except in citrus where yield was depressed and tree size was unaffected. The growth and yield of most vegetable crops were depressed at high N rates while at these high N rates, tomato yields were increased while vegetative growth was unaffected. Where a depression in tomato growth occurred at high N rates, it was caused by a salt effect, although chloride at the same osmotic potential depresses growth much more than nitrate. In subtropical fruit and nut crops such as lychee, macadamia and avocado, timing and rate of N were not detrimental to yield. Soil N, tree N and CHO reserves buffer against an external N supply and hence the ability of applied N to manipulate the vegetative-reproductive balance. More work is required to establish the extent and subsequent effect of competition between the vegetative flushes and inflorescence growth for subtropical fruit crops in particular.
... In studies with young, container-grown avocado trees, Whiley and Schaffer (1993) reported that shoot and root sink activity were temporally separated; leaves were the strongest sinks for 14C-photosynt hates during early shoot growth, and the sink strength of roots increased once shoots became quiescent. The asynchronous pattern of shoot and root growth in avocado is illustrated in phenology models developed for avocado (Whiley et al. 1988) which have since been confirmed by the observations of Ploetz et al. (1992) and Whiley and Schaffer (1994). If translocation of both photoassimilates and phosphonate is subject to similar controls, then natural variation (asynchrony) in root vs. shoot growth may well influence distribution patterns of trunk-injected H3P03. ...
... The efficiency of translocation of &Po3 to the roots appears directly related to the sink/source status of the leaves at the time of injection. In our study, shoot phenology measured by dry matter accumulation was similar to that previously reported for avocado (Whiley et al. 1988;Ploetz et al. 1992;Whiley and Schaffer 1994). There were two major periods of shoot growth corresponding to spring and summer. ...
... Trunk injection times are indicated by arrows where 1 = pre-spring shoot growth, 2 = spring shoot maturity, and 3 = summer shoot maturity. Horizontal bars indicate the major periods of root growth defined by Whiley et al. (1988), Ploetz et al. (1992 and Whiley and Schaffer (1994). Data points are mean values from nine treesf s.e. ...
Translocation of phosphonic acid (H3PO3) in cv. Hass avocado trees was studied after trunk injection with 20% H3PO3, formulated as potassium phosphonate, at three stages of tree phenology during the growing season. Initially, translocation was solely acropetal in the xylem, and H3PO3was detected in the leaves 24 h after treatment. Several days after injection, H3PO3concentration in the bark of trunks and in roots increased, indicating basipetal phloem transport of H3PO3from leaves. The rate of accumulation and the final concentration of H3PO3in the roots were directly related to the sink strength of the shoot at the time of injection. For example, trunk injection at the beginning of spring growth flush, when renewal shoots were strong sinks, resulted in low H3PO3root concentrations (<9 8g gfw-1) which peaked about 45 days after treatment. When potassium phosphonate was injected after the transition of spring-grown shoots from sinks to sources, or at summer shoot maturity, root concentrations of H3PO3increased to >25 8g gfw-1 by 30 days after treatment. These results suggest that strategic timing of injections according to phenological events may greatly improve fungicide efficacy when targeting specific organs for protection.
... Mesmo o Brasil apresentando ótimas condições para a produção na cultura do abacate, a ampliação do cultivo é limitada por vários fatores, como a não adoção do adensamento nos pomares comerciais (MENZEL; LAGADEC, 2014) e de manejos agronômicos que favoreçam a produção e qualidade de frutos (PEREIRA, 2015), principalmente por não conseguir manejar a gomose (Phytophthora cinnamomi), e a broca do fruto (Stenoma catenifer) que são respectivamente a principal doença e praga do abacate no Brasil (KOLLER, 2002;CAMPOS, 2006;BRUWER, 2007); ademais dos fatores inerentes a ecofisiologia da planta, como vigor excessivo, baixa fixação de frutos e a dificuldade em controlar a alternância de produção (WHILEY et al., 1988) e o fato da grande maioria dos pomares comerciais serem cultivados sob condições de sequeiro. ...
... A chave para uma produção bem-sucedida é o manejo adequado da cultura (WOLSTENHOLME; WHILEY, 1989;WHILEY et al., 1988) segundo as fases do seu ciclo fenológico. Thorp, Anderson e Camilleri (1995) afirmaram que é necessário o plantio em condições adequadas e a realização de práticas como poda, irrigação, adubação e pulverização, em fases especificas de emissões de fluxos vegetativos e reprodutivos. ...
O abacate é uma fruta tropical com aceitação cada vez maior junto aos consumidores em todo o mundo graças ao seu conteúdo nutricional, às diferentes opções para seu consumo “in natura” e processado e ao seu uso na indústria cosmética. O abacate da var. Hass de origem californiana, conhecido popularmente como avocado, representa uma excelente oportunidade para o setor agrícola brasileiro pela possibilidade de exportação que oferece; tornou-se a variedade mais comercializada. Porém, atualmente, a comercialização do abacate brasileiro em mercados especializados é limitada, devido à heterogeneidade no produto colhido que deriva, em parte, na variabilidade dos materiais cultivados, deficiências no controle fitossanitário da produção primária de abacate e baixos padrões de qualidade. Com o objetivo de constituir uma ferramenta prática de consulta aos produtores, é elaborado este livro que contém indicações básicas sobre o manejo adequado do cultivo do avocado Hass, o que lhes permitirá ser competitivos e ter acesso a mercados especializados. Também esta publicação faz menção às Boas Práticas Agropecuárias (BPA), que se originam na gestão da qualidade para a produção de alimentos “in natura”, as quais foram desenvolvidas para atender o alto grau de sensibilidade do consumidor, sendo imprescindível ter um produto com alta uniformidade de cor, firmeza adequada para consumo, ausência de distúrbios fisiológicos e podridões, e de longa vida de prateleira. Da mesma forma, relacionar exitosamente os efeitos dos fatores de pré-colheita sobre a qualidade pós-colheita corresponde a um dos principais desafios dos produtores, quando se visa exportar o seu fruto para o mercado internacional. Em razão disso, este livro escrito em português pode ser um dos primeiros manuais dedicados ao cultivo do avocado para o Brasil. Ou seja, aquele que decidir cultivar essa planta e conhecê-la em maior profundidade, o livro “Avocado (Persea americana Miller, cv. Hass): Tecnologias de plantio em típicas regiões serranas do Brasil”, será de grande interesse e ajuda para o produtor que necessita pôr em prática as várias tecnologias abordadas no mesmo.
... Knowing the phenology of the plant and the environment in each production zone has enabled the integration of phenological models in Colombia, Spain, and Mexico, and has made technical management more efficient (Rocha-Arroyo, Salazar-García, Bárcenas-Ortega, González-Durán, & Cossio-Vargas, 2011;Alcaraz, Thorp, & Hormaza, 2013;Bernal-Estrada, Vásquez-Gallo, & Cartagena-Valenzuela, 2017). Phenological avocado models have been useful for regulating the nutrient supply according to root growth, controlling Phytophthora cinnamomi (Whiley, Saranah, Cull, & Pegg, 1988;Whiley, Saranah, & Wolstenholme, 1995;Whiley et al., 2013) and managing water (Rocha-Arroyo et al., 2011;Tapia-Vargas, Vidales-Fernández, & Larios-Guzmán, 2015). In the State of Mexico, 'Hass' is the predominant variety (Rubí-Arriaga et al., 2013), but its development in different zones remains unknown. ...
... Conocer la fenología de la planta y el ambiente en cada zona de producción ha permitido integrar modelos fenológicos en Colombia, España y México, y ha hecho el manejo técnico más eficiente (Rocha-Arroyo, Salazar-García, Bárcenas-Ortega, González-Durán, & Cossio-Vargas, 2011;Alcaraz, Thorp, & Hormaza, 2013;Bernal-Estrada, Vásquez-Gallo, & Cartagena-Valenzuela, 2017). Los modelos fenológicos de aguacate han sido útiles para regular el abastecimiento nutrimental acorde con el crecimiento radical, el control de Phytophthora cinnamomi (Whiley, Saranah, Cull, & Pegg, 1988;Whiley, Saranah, & Wolstenholme, 1995;Whiley et al., 2013) y el manejo de agua (Rocha-Arroyo et al., 2011;Tapia-Vargas, Vidales-Fernández, & Larios-Guzmán, 2015). En el Estado de México, la variedad predominante es 'Hass' (Rubí-Arriaga et al., 2013), pero se desconoce cómo se desarrolla en las distintas zonas. ...
... Knowing the phenology of the plant and the environment in each production zone has enabled the integration of phenological models in Colombia, Spain, and Mexico, and has made technical management more efficient (Rocha-Arroyo, Salazar-García, Bárcenas-Ortega, González-Durán, & Cossio-Vargas, 2011;Alcaraz, Thorp, & Hormaza, 2013;Bernal-Estrada, Vásquez-Gallo, & Cartagena-Valenzuela, 2017). Phenological avocado models have been useful for regulating the nutrient supply according to root growth, controlling Phytophthora cinnamomi (Whiley, Saranah, Cull, & Pegg, 1988;Whiley, Saranah, & Wolstenholme, 1995;Whiley et al., 2013) and managing water (Rocha-Arroyo et al., 2011;Tapia-Vargas, Vidales-Fernández, & Larios-Guzmán, 2015). In the State of Mexico, 'Hass' is the predominant variety (Rubí-Arriaga et al., 2013), but its development in different zones remains unknown. ...
... Conocer la fenología de la planta y el ambiente en cada zona de producción ha permitido integrar modelos fenológicos en Colombia, España y México, y ha hecho el manejo técnico más eficiente (Rocha-Arroyo, Salazar-García, Bárcenas-Ortega, González-Durán, & Cossio-Vargas, 2011;Alcaraz, Thorp, & Hormaza, 2013;Bernal-Estrada, Vásquez-Gallo, & Cartagena-Valenzuela, 2017). Los modelos fenológicos de aguacate han sido útiles para regular el abastecimiento nutrimental acorde con el crecimiento radical, el control de Phytophthora cinnamomi (Whiley, Saranah, Cull, & Pegg, 1988;Whiley, Saranah, & Wolstenholme, 1995;Whiley et al., 2013) y el manejo de agua (Rocha-Arroyo et al., 2011;Tapia-Vargas, Vidales-Fernández, & Larios-Guzmán, 2015). En el Estado de México, la variedad predominante es 'Hass' (Rubí-Arriaga et al., 2013), pero se desconoce cómo se desarrolla en las distintas zonas. ...
Avocado is the third most produced crop in the State of Mexico, with 11,296 ha, where the predominant variety is ‘Hass.’ Due to a lack of knowledge about its development in different environments, its agronomic management is highly heterogeneous, since it is based on experiences in other states. The objective of this study was to analyze, describe and quantify the phenological development of ‘Hass’ avocado in three environments in the State of Mexico. The vegetative, flowering, root and fruit development of ‘Hass’ avocado was recorded during the 2011-2012 cycle. Two periods were distinguished for vegetative growth (December-April and October-November), flowering (December-February and August-October), harvest (November-February and August-October) and root growth (April-July and October-December). The vegetative growth (0.40 and 0.06 cm increase in shoot length and diameter, respectively) and root growth (36 and 24 g fresh weight and dry matter, respectively) were lower than fruit growth (70.1 mm increase in diameter) in Coatepec Harinas (temperate with andosol soil and isotherms from 14-18 °C). In contrast, the same growth measurements were higher in the localities with cambisol-luvisol soil and isotherms from 16-20 °C: Ixtapan del Oro (temperate/semi-warm, with 0.69 and 0.12 cm in shoot, and 56 and 48.8 g in root) and Temascaltepec (semi-warm, with 0.78 and 0.23 cm in shoot, and 69.3 and 31.3 g in root), but lower increases in fruit (59.4 and 56.6 mm, respectively). The phenological differences observed among environments will be useful for the technical management of the crop.
... A través del año los árboles frutales presentan diversas fases del desarrollo o fenológicas, tales como flujos de crecimiento vegetativo o de raíces, y de desarrollo floral y del fruto (Wolstenholme y Whiley, 1989). Los ritmos de crecimiento anual varían con el tipo de clima y las condiciones de cultivo, por lo cual se han elaborado diagramas fenológicos para el aguacate (Persea americana Miller) 'Hass' con diferente grado de complejidad en regiones productoras como Australia (Whiley et al., 1988), Sudáfrica (Whiley y Wolstenholme, 1990), Chile (Gardiazabal-Irazábal y Rosenberg, 1991), EUA (Arpaia et al., 1994-95), y Nueva Zelanda (Thorp et al., 1995). En México, la fenología de 'Hass' está descrita para las regiones productoras de Nayarit (Cossio-Vargas et al., 2008) y Michoacán (Rocha-Arroyo et al., 2011a). ...
... Para estos huertos, la altitud es 1556 m y 1428 m, el distanciamiento entre árboles 7x3.5 m y 5x5 m y la edad al inicio INTRODUCTION T hroughout the year, fruit trees present diverse development or phenological phases, such as vegetative or root growth flushes, and of flower and fruit development (Wolstenholme and Whiley, 1989). The rhythms of annual growth vary with the type of climate and the cultivation conditions, so phenological diagrams were elaborated for 'Hass' avocado (Persea americana Miller) with different degree of complexity in production regions like Australia (Whiley et al., 1988), South Africa , Chile (Gardiazabal-Irazábal and Rosenberg, 1991), USA (Arpaia et al., 1994-95), and New Zealand (Thorp et al., 1995). In Mexico, 'Hass' phenology is described for the production regions of Nayarit (Cossio-Vargas et al., 2008) and Michoacán (Rocha-Arroyo et al., 2011a). ...
In the southern area of the state of Jalisco, Mexico, cultivation of 'Méndez' avocado (Persea americana Miller) is important due to its adaptation to the semi-warm climate of the region and because of its early maturation and harvest (summer), in relation to 'Hass' (fall), although the lack of knowledge of its phenology makes the effective management of 'Méndez' orchards difficult. The objective of this study was to document the phenology of 'Méndez' during two production cycles (2014-15 and 2015-16), in two commercial orchards with supplementary irrigation from October to June (annual rain of 728 mm), established in soils of volcanic origin and light texture in southern Jalisco. The maximum temperatures of the soil at 30 cm from the surface were in May (24.5 °C) and the minimum from January to March (15.9 to 14.5 °C). The vegetative flushes (VF) were found in summer (August-September) and winter (February), as well as flowering in summer (September) and winter (February). Flower development (vegetative bud to anthesis) in shoots from the summer and winter VFs lasted 187 and 222 d, respectively. The fruit drop (5 to 6 cm of diameter) was similar in the two flowering seasons (55.4 to 61.8 %). The fruit maturity (≥22.7 % d.m.) happened in July and in September-October for fruits from the summer and winter flowering periods, respectively. There were two flushes of root production and the greatest was in summer (June to August). The maximum and minimum average environmental temperatures of the warmest (April to June) and coldest (January to March) months were 31 and 9 °C, respectively. The results from this study are basic to compare the future changes in the phenology of 'Méndez' avocado.
... Without exception, these relationships were not significant, indicating that the temperature extremes throughout this study did not limit canopy or root growth; correlation coefficients ranged from 0.01 to 0.26. Whiley et al. (1988) described a management model for increasing avocado (Persea americana Miller) productivity and indicated a similar model may be appropriate for lychee. Root growth competes with canopy vegetative and reproductive growth for carbohydrates, and their model focuses on management of growth cycles to balance this competition. ...
... The underlying principle of this phenology model is management of reserve carbohydrate. Carbohydrate reserves generally are at a maximum during late winter when trees are relatively inactive and root growth is limited by low soil temperature (Whiley et al., 1988). ...
'Mauritius' lychee (Litchi chinensis Sonn.) trees were planted in rootobservation chambers in July 1990 to determine the pattern of root and stemextension growth during 12 months. Root and stem lengths were measured atintervals ranging from 7 to 18 days from Aug. 1990 until Aug. 1991. Duringeach period of active canopy growth, up to six stem tips were tagged andmeasured. Root growth was determined by measuring tracings of the extensionof each root in a visible plane of the glass wall of the observationchambers. Stem growth was cyclic, with distinct periods of rapid extensionfollowed by periods with no extension. In contrast, root growth was fairlycontinuous with only three periods of no visible root extension. Meanabsolute extension rates were higher for stems than for roots. There were noconsistent relationships between the timing of root and stem extensiongrowth.
... Marsh, Branson, Davis, Gustafson & Strohman (1978) advised that tensiometer readings should be kept between -15 to -20 kPa at 300 and 600 mm depth and should not be allowed to exceed -40 kPa on a sandy loam soil. Whiley, Saranah, Cull & Pegg (1988) recommended that during spring tensiometer readings should not exceed -30 kPa for a sandy loam soil or -40 kPa for a clay loam soil at a depth of 300 mm within the dripline of the tree. These values should be lowered to -25 kPa and -30 kPa respectively, during the second fruit drop period (December/January). ...
... Several researchers have commented on this subject. Whiley et al., (1988) speculated that the second fruit drop stage of the growth cycle (December/January in Australia), is the most critical period for water management. They summarised their recommendations as follows: Management of water in the orchard during flowering can be critical for fruit-set, whereas during the latter part of spring it is not so critical. ...
The purpose of this paper is to review available literature on avocado irrigation and to identify the most critical factors for optimal irrigation scheduling. It was shown that over irrigation and prolonged over saturated conditions should be avoided at all cost and that avocado trees should be planted on well drained soils, especially under high rainfall conditions. Although a root and irrigation depth of 600 mm is acceptable, it is advisable to determine the root depth for every situation. Knowledge of the water holding capacity of the soil will help to determine the irrigation cycle length. It is recommended that tensiometers be used for irrigation scheduling and that a soil matric potential of -30 kPa at 300 mm depth on a light soil and -50 kPa on a heavy soil is not exceeded. Although the avocado appears to be fairly insensitive to a mild water stress, the critical period where optimal irrigation scheduling is essential, is at fruit-set and the early fruit growth stages. The water requirement of the avocado varies during the season, from relatively low in winter to high in midsummer, decreasing again towards the end of the season.
... In avocado (Persea americana Mill.) tree phenology was first reported in the late 1950's (Chandler 1958;Venning and Lincoln, 1958) with additional contributions to the knowledge base during ensuing years (Kotz6, 1979;Wolstenholme, 1981;Davenport, 1982). However, the first detailed conceptual model was not published until 1988 (Whiley et al., 1988). This model has since been refined with the incorporation of physiological data providing a more in-depth interpretation of tree growth and potential yield limitations. ...
... This method gave a total length (m) of visible white root at the soil-panel interface (0.58 m 2 vertical window area). Reproductive and vegetative phenology data were collected for four seasons at monthly intervals, or more frequently when necessary, using a modified system of Whiley et al. (1988) described by Whiley (1994). ...
A revised and expanded pheno-physiological model has been developed for cv. Hass growing in a cool, humid subtropical climate in south-east Queensland. The model quantifies the seasonal growth activities of reproductive and vegetative components of the tree, details seasonal changes in leaf nitrogen and chlorophyll concentrations, and records changes in the photoassimilation efficiency of leaves from summer through to spring. The pheno-physiological model has assisted in the development of disease prevention strategies and limitations to production have been identified. Studies based on this information have been implemented and successful outcomes achieved. These are discussed in relation to a whole-tree approach to research and development of avocado in subtropical regions.
... This approach has shown to be a reliable index of vegetative and reproductive activity in previous lychee studies and also in other terminally flushing or flowering tree crops, e.g. avocado (Whiley et al., 1988 ) and macadamia (Stephenson et al., 1986b). Data are the means of five trees per orchard. ...
... Lychee panicles are borne on terminal branches and vegetative shoots do not normally emerge until after the fruiting cluster and one or two nodes below the fruiting cluster are removed at harvest. The annual flushing behaviour of lychee is similar to that described in mango (Scholefield et al., 1986), but differs from that in avocado (Whiley et al., 1988 ) and macadamia (Stephenson et al., 1986a,b) where active vegetative growth occurring during spring and/or summer induced fruit and nut drop. ...
The main period of vegetative flushing in high-yielding lychee trees (Litchi chinensis Sonn. cultivars ‘Tai So’, ‘Haak Yip’ and ‘Wai Chee’) in seven orchards in subtropical Australia (latitude 27°S) occurred after harvest from late summer and ceased 4–6 weeks before panicle emergence in May–July. Trees did not flush during winter or spring unless flowering or fruit set failed. There was no evidence of concurrent vegetative and reproductive growth in the same shoot. There was an inverse correlation between the percentage of branches flowering and the percentageof branches flushing vegetatively in the 4–6 weeks preceding panicle emergence. Satisfactory yields were usually obtained when more than 90% of the terminal branches flowered.Flushing did not appear to be affected by temperature and rainfall or leaf nitrogen levels. The interaction of these factors demonstrates the difficultiss in separating the effects of different environental factors on vegetative growth in lychee.
... Avocado growers typically schedule irrigation based on sensors that read in-field soil matric potential, triggering irrigation within the range between −20 and −55 kPa to avoid any detrimental yield effects (Whiley et al. 1988;Du Plessis 1991). However, biopolymers do not release water effectively at these lower tensions, hindering avocado water uptake and increasing stress levels. ...
Under the uncertain scenario of water availability for irrigation, plants are often exposed to drought periods, which can negatively impact their vegetative growth and yield potential. To address this issue, various soil amendments including inorganic, organic, and biological treatments, have been investigated as solutions for mitigating water stress. However, comparative studies of different amendments are lacking. The aim of this study was to assess the efficacy of various soil amendments for alleviating drought stress in avocado trees over two seasons. The study was conducted in a young avocado orchard with sandy loam soil. Different soil amendments, such as zeolite, absorbent biopolymers, mycorrhizae, Ascophyllum nodosum extract, humic acids, and diazotrophic bacteria, were applied either at planting or through fertigation. These treatments were compared to controls with and without water restriction. The water supply was interrupted throughout the growing seasons, and the accumulated water stress during the drought was evaluated. Two and three water restriction were imposed during the first and second season, respectively, on critical phenological stages. Additionally, physical soil properties, vegetative growth, and yield components were assessed. The treatments with the greatest alleviation of water stress were those in which A. nodosum seaweed extract was incorporated, followed by those with humic acid and mycorrhizae. These treatments enhanced soil water retention and stimulated root growth and/or mycorrhization, resulting in a greater volume of soil exploration. Conversely, biopolymer treatment increased water retention but did not increase water availability at the required tension levels for plant extraction, resulting in increased stress. Similarly, although zeolite improved certain soil properties, it did not increase water availability for plants, not alleviating the water stress levels. Moreover, the application of diazotrophic bacteria did not yield beneficial effects on soil or plant health and was ineffective at mitigating water stress in avocado trees. In conclusion, soil amendments that effectively maintain or reduce bulk density, improved soil stability and water availability demonstrated good crop performance even under drought conditions. However, the mitigation of water stress is a complex process influenced by various factors, including root growth, mycorrhization, and other physiological responses.
... El concepto de requerimiento hídrico varía de acuerdo con las etapas de crecimiento fenológico (Whiley et al., 1988). Al respecto, Avilán et al. (2007) mencionan que la ocurrencia de los flujos vegetativos está relacionada con los meses de mayor precipitación. ...
El cultivo de aguacate Hass se ha desarrollado de forma exponencial en varias regiones de Colombia, lo que ha contribuido al incremento de los ingresos de pequeños productores y al aumento considerable del PIB del país. La presente publicación, denominada Modelo productivo para el cultivo del aguacate Hass en Antioquia, constituye un producto de la concertación regional entre productores, asistentes técnicos o extensionistas agropecuarios, comercializadores e investigadores, que integra los resultados de investigación nacional e internacional, con las “prácticas tradicionales sobresalientes” identificadas en las diferentes subregiones productivas. Tiene como objetivo principal unificar criterios y estrategias de manejo sostenible del cultivo, con criterios de calidad y sostenibilidad económica y ambiental, que garantice bienestar social en los territorios. Esta publicación se materializa gracias al apoyo financiero de la Gobernación de Antioquia, a través de su Secretaría de Agricultura y Desarrollo Rural y al esfuerzo colaborativo de varios actores relacionados con la cadena productiva del aguacate Hass destinado al mercado internacional, bajo la moderación y liderazgo del Centro de Investigación La Selva de AGROSAVIA.
... La fenología es la relación entre el clima y los fenómenos biológicos periódicos de un cultivo (Whiley et al., 1988). Los árboles de aguacate muestran diversas fases de desarrollo conforme pasan las estaciones del año, tales como: Iniciación, diferenciación floral, flujos de crecimiento -81 -vegetativo, amarre, caída de fruto, crecimiento y maduración del fruto, de raíces, abscisión de hojas, etc. (Wolstenholme y Whiley, 1999). ...
... In tropical climate flowering trigger out through water deficit spell (Southwick and Davenport, 1986) and high flowering in lemon tree as a result of water stress over the cold stress (Nir et al., 1972;Chaikiatiyyos et al., 1994) while this response is commercially used to induce off-season flowering in lemons (Davies and Albrigo, 1994). Modeling in avocado: Avocado (Persea americana Mill.) tree phenology was first reported in late 1950's (Chandler, 1958;Venning and Lincoln, 1958) with advanced studies by (Wolstenholme, 1981;Davenport, 1982); however, first detailed conceptual model was not published until 1988 (Whiley et al., 1988). A revised and expanded phenolphysiological avocado model was developed in cool, humid subtropical climate of south-east Queensland. ...
... The Queensland fruit fly (Dacus tryoni) seriously damages only Mexican cultivars or Guatemalan × Mexican hybrids in Australia. In Mexico, the avocado weevil (Heilipus lauri) tunnels into the seeds (Whiley, et al., 1988). ...
Avocado (Persea americana L.), also called alligator pear, Fruit of New
World/Butter fruit, belongs to the family Lauraceae. Tree is native to the
Western Hemisphere fromMexico south to the Andean regions. The avocado,
unflatteringly known in the past as alligator pear, midshipman’s butter,
vegetable butter, or sometimes as butter pear, and called by Spanish-speaking
people aguacate, cura, cupandra, or palta; in Portuguese, abacate; in
French, avocatier.
... La fenología, corresponde a las diferentes etapas que permiten el estudio del crecimiento y desarrollo de los órganos vegetativos y productivos de una planta . Estos permiten entender en forma clara el comportamiento de la planta con relación al tiempo, es decir permite un mayor conocimiento sobre el crecimiento y desarrollo de las plantas pasando por sus diferentes etapas (Graber, 1997), así como la relación entre el clima y los fenómenos biológicos periódicos (Whiley et al., 1988). ...
la “Guía para facilitar el aprendizaje en el manejo integrado del cultivo de mora
Rubus glaucus Benth”, está integrada por conocimientos técnicos y metodológicos sobre las competencias
necesarias para el manejo eficiente del cultivo, para cada competencia se formulan los objetivos de
aprendizaje, que guían al desarrollo de los contenidos y ejercicios de aprendizaje.
Esta guía está formada por actividades prácticas utilizadas por facilitadores en el campo de la agricultura,
herramientas que permitirán el aprendizaje, fortalecer los conocimientos y mejorar las destrezas prácticas
en los agricultores.
... In tropical climate flowering trigger out through water deficit spell (Southwick and Davenport, 1986) and high flowering in lemon tree as a result of water stress over the cold stress (Nir et al., 1972;Chaikiatiyyos et al., 1994) while this response is commercially used to induce off-season flowering in lemons (Davies and Albrigo, 1994). Modeling in avocado: Avocado (Persea americana Mill.) tree phenology was first reported in late 1950's (Chandler, 1958;Venning and Lincoln, 1958) with advanced studies by (Wolstenholme, 1981;Davenport, 1982); however, first detailed conceptual model was not published until 1988 (Whiley et al., 1988). A revised and expanded phenolphysiological avocado model was developed in cool, humid subtropical climate of south-east Queensland. ...
... Avocado trees accumulate biomass during growth flushes, which are periods of rapid shoot extension and leaf production that occur one to several times per year (Arpaia et al., 1995;Whiley et al., 1988). The trees in this experiment exhibited two growth flushes during the study. ...
Effect of salinity (1.5, 3.0, 4.5, or 6.0 dS.m(-1)) on growth and physiology of 1-year-old 'Hass' avocado (Persea americana Mill.) trees on one of three rootstocks, 'Thomas', 'Toro Canyon', or 'Duke T, was investigated to determine the relative salinity tolerance of these rootstocks and to determine possible reasons for any observed differences in tolerance. Leaves of trees on 'Thomas' rootstock had the highest-leaf Na+, Cl-,and necrosis compared to trees on the other two rootstocks. Exposure to salinity resulted in decreased growth of shoots on all rootstocks, but was greatest on 'Thomas' and least on 'Duke 7'. The oldest leaves on all rootstocks had the highest proportion of leaf necrosis, whereas younger leaves exhibited almost no necrosis. Salinity reduced net CO, assimilation (A) and chlorophyll concentrations of scion leaves on all rootstocks, but more in older leaves than in younger leaves. Although the effects of salinity on A were greater for trees on 'Thomas' on one measurement date, overall, rootstock differences in A were not significant for any leaf age. Differences in response to salinity among rootstocks were noted primarily in morphological traits such as growth and leaf necrosis, rather than physiological traits such as gas-exchange and water relations. Based on overall growth and physiological response to salinity, trees on 'Thomas' performed poorest, whereas trees on 'Duke 7' exhibited the greatest salt tolerance. The relative tolerance of the various rootstocks appeared to be due primarily to their ability to exclude Na+ and Cl- from the scion.
... The second critical period for irrigation is the rapid fruit growth phase. Effective irrigation management during this time can reduce fruit drop and increase final fruit size (Bower, 1985;Whiley et al., 1988a;Wolstenholme et al., 1990) by preventing tree stress. To ensure maximum fruit size during the rapid growth phase in summer, irrigation intervals should be shortened, however, in autumn when fruit growth is slow there is no advantage to shortening the irrigation intervals (Lahav and Kalmar, 1983). ...
The pome fruit industry in South Africa is a significant contributor to the Gross
Domestic Product of the country, with increasing levels of income generation
and job creation. However, in order to grow in a sustainable manner, and in
parallel to numerous other competing water users, water requirements for the
industry need to be carefully considered, allocated and utilised in the most
efficient ways possible. The importance of accurate observations of actual
orchard water requirements is critical in this regard, not only for improved onfarm
irrigation scheduling accuracy, but also for local and regional water
resource planning and allocation. This study considered only the water
transpired and evaporated by the orchard, and did not account for any
supplementary uses of water during the production season (i.e. it was not a
full water footprint determination as such), however it has illustrated the
differences between so-called “transpirational” water requirements (Gerbens-
Leenes and Nonhebel, 2004) and “evaporational” (ET) water requirements at
orchard scale, and in so-doing has highlighted the beneficial (T) and nonbeneficial
(ET minus T) components of orchard water use. The detailed
transpiration results have also illustrated the strong links between tree
phenology / growth stage and water use.
... Individual avocado fruits require large quantities of carbon because of the high oil content and large seed size of the fruit (Wolstenholme, 1987). Lack of sufficient carbohydrate supply due to inefficient photosynthetic performance may be directly responsible for poor fruit set, high fruit drop, and low fruit yield in avocado (Whiley et al., 1988;Wolstenholme, 1987). Furthermore, it has been theorized that the reproductive and vegetative growth cycles in avocado compete for limited carbon resources, especially before new leaves undergo the transition from carbon sink to carbon source (Wolstenholme, 1990). ...
An understanding of the impact of environmental conditions and cultural practices on avocado leaf photosynthetic performance will not only address the lack of knowledge in this area, but also help growers make decisions about the timing of cultural practices to optimize photosynthetic performance and, in turn, yield. Our work to date has resulted in a better understanding of the basic photosynthetic performance of avocado leaves. New leaves of the spring flush attain a net positive photosynthetic rate approximately 17 days after emergence and reach their maximum photosynthetic capacity 40 to 50 days after emergence. The leaves that developed during the previous season are the primary photosynthetic sources until new leaves begin to contribute to the net carbon gain of the plant, at which point the photosynthetic capacity of older leaves declines. We have found that the hot, dry summer climate of southern California results in high temperature and low humidity stress on avocado leaves, resulting in optimal leaf photosynthesis for a relatively short portion of the day. There is evidence, however, that certain cultivars of avocado may not be affected as severely by these stresses as others. We are currently investigating the use of cultural practices to prolong this period of optimal photosynthesis.
... Avocado trees are very sensitive to waterlogging Whiley and Schaffer 1994;Schaffer and Whiley, 2002). An excess or lack of water during growth limits avocado fruit production and quality, particularly if stress occurs between spring and the beginning of summer (Whiley et al., 1988a;1988b). Therefore, proper irrigation management in avocado orchards is necessary to insure adequate yield and fruit quality (Lahav and Whiley, 2002). ...
Commercial avocado production in Chile has expanded to areas with poorly drained soils presenting low oxygenation over significant periods of time throughout the year. In many of these areas, irrigation management is difficult because plantations are often placed on slopes of hills. Poorly aerated soils combined with irrigation design and management problems can limit avocado fruit production and quality, particularly if hypoxia stress occurs between spring and the beginning of summer. It is well known that avocado trees are very sensitive to waterlogging and the relatively low productivity of this species may be related to root asphyxiation. Therefore, in order to get adequate yield and fruit quality, proper irrigation management and better soil oxygen conditions in avocado orchards are necessary. The objective of this study was to evaluate the effect of the hydrogen peroxide (H 2O 2) injection into the soil as a source of molecular oxygen, on plant water status, net CO 2 assimilation and biomass of avocado trees established in clay loam soil with water content at field capacity. Three-year-old 'Hass' avocado trees were planted outdoors in containers filled with heavy loam clay soil with moisture content kept at field capacity. Plants where divided into 2 treatments, those with H 2O 2 injected into the soil through subsurface drip irrigation and plants in soil with no H 2O 2 added (control). In addition to determining physical soil characteristics, net CO 2 assimilation (A), transpiration (T), stomatal conductance (g s) and shoot and root biomass were determined for plants in each treatment. Injecting H 2O 2 into the soil significantly increased the biomass of the aerial portions of the plant, but had no significant effect on measured A, T or g s. The increased biomass of the aerial portions of plants in treated soil indicates that H 2O 2 injection into heavy loam clay soils may be a useful management tool in poorly aerated soil.
... The well-known Whiley et al. (1988) avocado phenological growth cycle for the humid subtropics of Australia, with two shoot and two root flushes, and a typical "average, target" starch cycle, is shown in Fig. 3 (Whiley and Wolstenholme, 1990). This is the basis for orchard management, with fine-tuning for local conditions, in most of the Australian avocado industry, as well as South Africa and many other countries with similar climates (Whiley, 2002). ...
Alternate bearing (AB) and irregular bearing (IB) present major challenges to growers and marketers of avocados. This problem is common to most tree fruit crops, and varies in intensity, It can manifest countrywide, regionally, on a specific farm and even in the branches of a single tree. AB is typically initiated by an abnormally heavy or light crop in young trees, followed by a light or heavy subsequent crop. This pattern then becomes entrained and difficult to change unless severe climatic events intervene, or drastic management interventions are made. A heavy "on" crop results in reduced vegetative shoot and root flushing, and less carbohydrate (energy reserves) build-up. Seed gibberellins may also reduce flower bud initiation. Fewer flowering and fruiting sites for next season's cropping are formed, and flowering intensity is reduced. Many complex, interacting factors affect AB intensity. A brief discussion is given of remedial measures such as pruning, girdling, growth retardants and management intensification. In future, new cultivars and rootstocks will reduce AB intensity. In the interim, revised growth cycle charts reflecting "on" and "off crop seasons are helpful in managing AB.
... Avocado trees are very sensitive to waterlogging Whiley and Schaffer 1994;Schaffer and Whiley, 2002). An excess or lack of water during growth limits avocado fruit production and quality, particularly if stress occurs between spring and the beginning of summer (Whiley et al., 1988a;1988b). Therefore, proper irrigation management in avocado orchards is necessary to insure adequate yield and fruit quality (Lahav and Whiley, 2002). ...
In Chile, avocado (Persea americana Mill.) orchards are often located in poorly drained, low-oxygen soils, situation which limits fruit production and quality. The objective of this study was to evaluate the effect of injecting soil with hydrogen peroxide (H2O2) as a source of molecular oxygen, on plant water status, net CO2 assimilation, biomass and anatomy of avocado trees set in clay loam soil with water content maintained at field capacity. Three-year-old 'Hass' avocado trees were planted outdoors in containers filled with heavy loam clay soil with moisture content sustained at field capacity. Plants were divided into two treatments, (a) H2O2 injected into the soil through subsurface drip irrigation and (b) soil with no H2O2 added (control). Stem and root vascular anatomical characteristics were determined for plants in each treatment in addition to physical soil characteristics, net CO2 assimilation (A), transpiration (T), stomatal conductance (gs), stem water potential (SWP), shoot and root biomass, water use efficiency (plant biomass per water applied [WUEb]). Injecting H2O2 into the soil significantly increased the biomass of the aerial portions of the plant and WUEb, but had no significant effect on measured A, T, gs, or SWP. Xylem vessel diameter and xylem/phloem ratio tended to be greater for trees in soil injected with H2O2 than for controls. The increased biomass of the aerial portions of plants in treated soil indicates that injecting H2O2 into heavy loam clay soils may be a useful management tool in poorly aerated soil.
... When I was asked in 1988 to review avocado technology towards 2000, I felt fairly comfortable with the 12 year timespan. Furthermore, excellent research was underway, the Whiley et al. (1988) phenological model had just been published, Phytophthora root rot had been brought under control by trunk injections of phosphonate, and there was a general air of optimism in agriculture and especially horticulture. Worldwide, avocado growing had passed from the launch to the growth phase, with little sign of the maturity phase, or the dreaded market saturation when growers wrestle with the consequences of being on the wrong side of the supply and demand equation. ...
The difficult task of predicting and anticipating avocado production in 2020 has been tackled by firstly attempting a vision of the world by 2020. We have started a journey in which some aspects of technology, including I.T. but also plant biology, will show spectacular progress. The nature of agriculture will also change with globalization, the freeing of trade, greater dominance of multiples, more accountability, and seeking of competitive advantages. Value adding and processing will increase in importance. Impacts on avocado growing will be profound. Yields of quality fruit will have to improve dramatically, and the over-production bogey avoided, while keeping costs in check. Strong grower associations are vital.
... In avocado (Persea americana Mill.) trees, increasing carbohydrate partitioning to flowers and fruit provides a challenge for orchard management, as the tree has a natural vegetative bias resulting in a greater allocation of photoassimilates to shoot growth than to reproductive organs (Whiley et al., 1988b;Wolstenholme, 1990;Schaffer and Whiley, 2002). This vegetative bias, coupled with the relatively short leaf longevity (for a subtropical fruit tree species) results in rapid production of short-lived leaves and increased shading within the canopy that reduces the number of well-lit terminal shoots capable of flowering . ...
SUMMARY An important aspect of orchard management is to manipulate and train trees to optimize photo- synthesis within the canopy. Knowledge of the impact of environmental factors, such as light, tem- perature, humidity, flooding, salinity and elevated atmospheric CO2 concentrations on photosyn- thesis of avocado trees provides information that can be applied to canopy management and plant selection for specific environments. This mini-review summarizes the current knowledge of the impact of environmental factors on avocado photosynthesis and its implications for crop manage- ment plant selection.
... The concern about detrimental effects of N fertiliser on the vegetativereproductive balance extends to other subtropical tree fruit crops such as avocado (Whiley et al. 1988;Wolstenholme and Whiley 1990) and macadamia (Stephenson and Gallagher 1989). ...
The effect of timing of nitrogen (N) application as ¹⁵N-enriched ammonium sulfate (50 kg N/ha) on the growth response and N uptake by vegetative and reproductive tissues was investigated in the low-chill peach cv. Flordagem growing on a krasnozem soil at Alstonville. Nitrogen was applied in late August, late September, late October, mid February, and early May. Tree parts were sampled for ¹⁵N at 4 and 8 weeks after application and after fruit harvest in December the following season. After fruit yield was measured, trees were excavated and divided into parts for dry weight and nutrient concentration determinations, and fertiliser N recovery and to estimate tree nutrient removal.
Nitrogen enrichment was detected in all plant parts within 4 weeks of N application, irrespective of timing, and was greatest in rapidly growing tissues such as laterals, leaves, and fruit. The most rapid (P < 0.05) ¹⁵N enrichment in vegetative tissues resulted from September, October, and February N applications and for fruit from a September application. The level of enrichment 4 weeks after fertiliser N application was similar for vegetative and reproductive tissues. The timing of N application in the first season had no effect on fruit yield and vegetative growth the following season.
At tree removal, the recovery of fertiliser N in most tree parts increased (P < 0.05) as fertiliser N application was delayed from October to May the previous season. Maximum contribution of absorbed N to whole tree N was 10–11% for laterals, leaf, and fruit. Data from this study indicate that vegetative and reproductive growth have similar demand for absorbed N, and that uptake of fertiliser N is most rapid when an application precedes a period of rapid growth. Over 2 seasons, recovery of applied fertiliser N was 14.9–18.0% in the tree, confirming that stored N and the soil N pool are the dominant sources of tree N. The recovery of fertiliser N from the May application was 18% even though uptake in all tree parts including roots at 4 weeks after application was very low, indicating that tree fertiliser N uptake occurred when growth resumed after the dormant winter period. The low proportion and recovery of fertiliser N in the tree confirm the lack of immediate influence of applied N to vegetative growth and yield.
Annual crop nutrient removal is a sound basis for fertiliser recommendations, and for the Flordagem orchard (1000 trees/ha), it consisted of fruit plus 70% of laterals (removed at pruning) plus 20% of leaf. Removal in vegetative tissues was relatively low at (kg/ha) 14 N, 1 P, 12 K, 13 Ca, and 2 Mg. The addition of fruit at a yield of 25 t/ha increased total nutrient removal to (kg/ha) 46 N, 5 P, 54 K, 14 Ca, and 5 Mg.
El palto se cultiva en numerosas regiones tropicales y subtropicales del mundo, produciendo 2 millones de toneladas por año. Estudios científicos afirman que es una fruta saludable, por su contenido de nutrientes a diferencia de otras. Las exportaciones de palta han logrado un crecimiento sostenido en los últimos años, manteniéndose el Perú como el tercero en el mundo, después de México y Países Bajos. El trabajo de investigación contribuye a la determinación del régimen de riego del cultivo de palto en el valle río Pampas, determinando el uso consuntivo, necesidades de riego y su programación según la tecnología de aplicación. Se procedió con el planeamiento, revisión de información antecedente, estudio de factores, mediciones in situ y cálculos. Se encontró que la ETo varía de 3.11 a 4.95 mm/día, con valores bajos de mayo a agosto y altos en noviembre y diciembre. Los valores de Kc concordantes al ciclo fenológico, varían de 0.60 a 0.75 en etapa de brotación y de 0.80 a 0.95 en floración y cuajado de frutos, donde consume más agua (setiembre a noviembre) llegando hasta 4.21 mm/día, mientras que de marzo a mayo de 2.12 a 2.18 mm/día; con consumo anual de agua de 1,093 mm/año (10,930 m3/ha/año). Con riego por gravedad, se necesita aplicar entre 5.38 a 11.12 mm/día ó 538 a 111 m3/ha/día; con necesidad de riego total de 22,290 m3/ha/año. Con riego por microaspersión, entre 2.22 a 4.58 mm/día ó 22.2 a 45.8 m3/ha/día; con necesidad de riego total de 9,180 m3/ha/año.
Girdling is extensively applied to promote litchi flowering via the acceleration of bud dormancy and accumulation of carbohydrate in terminal shoots and leaves, but little is known about the response of root growth to girdling treatment during low temperature-mediated floral induction. In this study, litchi plants were girdled before exposure to inductive-cold in the field, and the growth of roots were monitored until floral initiation. The results showed that the length density and growth rate of fine roots increased during cold-dependent floral induction in the entire soil profile, but significantly decreased during flower development. The girdling treatment suppressed the emergence and growth of distal roots but induced that of proximal roots. More fine roots were distributed in shallower soil layers (15–45 cm) where the roots showed more rapid responses to cold and the girdling treatment. Roots reduced starch and sucrose content across the floral induction period and in response to the girdling treatment, which possibly accounted for the suppression of distal root growth. It is suggested that litchi root growth is more sensitive to carbohydrate availability than cold temperatures during floral induction.
This experiment was carried out during the period from April, 20th 2004 to June, 25th 2005 in a plastic house at Al-Shallal nursery in Mosul, to investigate the effects of four planting dates (April, July, October and January) and four IBA concentrations (0, 500, 1000 and 2000) mg.L-1, using talc, on rooting of Carissa geandiflora shoot tip cuttings. A Complete Randomized Design (CRD) was applied including 16 treatments each was replicated three times and each experimental unit consists of 10 cuttings. Data were tested by Duncan multiple test at 5%. Results could be summerized as follows : Planting cuttings in 20th April and 20th July gave best results 95.8% and 97.5% rooting percentage respectively but then declined to 49.2% in October and without rooting in January after 10 weeks from planting date. All IBA treatments caused a significant increase in all rooting parameters, the most effective treatment was 2000 mg.L-1. Using 2000 mg.L-1 in April gave rooting percentage 100%, number of roots/cutting 16.6, average length of roots 12.2 cm, dry root weight 0.35 gm, average cutting length 17.4 cm and number of pear leaves 10.46 pear, with 1.5 shoots/cutting.
Nut trees have strong economic impacts. However, these and other crop trees may use much more water than other row crops. Additionally, the current efficiency of fertilizer use for nut trees is only 50%, and fertilizer prices are increasing. Consequently, efficient irrigation and fertilization strategies are needed, and nut tree growth modeling is an effective tool for developing these strategies. However, there are some limitations of current nut tree growth models. Nut tree growth models fall into two basic categories: mechanistic and functional. Mechanistic models are more valuable to the developer for synthesizing research understanding; however, mechanistic models are more difficult to develop. Functional models are robust and easy to understand and run, but are not necessarily accurate outside the environmental conditions that were used to develop the models. The purposes of the model (research or application) determine which kind of model should be used. A model can be built around object-oriented programming, where objects may be added or subtracted from the model with ease. In the past, tree growth models were written with subroutines to represent objects, but the structure was such that they could not be easily removed because the attributes of the object were not part of the subroutine but were a separate object. Another problem is that traditional models are usually written in FORTRAN or some other computer language not understood by the general scientific community. With increases in computing speed, spreadsheet programs can replace the FORTRAN-based crop simulation models as long as the models are simple in structure. The basic principle of tree growth models to control maximum yield is controversial. Some modeling researchers use carbohydrate reserves in the tree root to control the flowering and then the yield, and this approach is indirectly supported by experimental data. However, there is no direct data to prove this principle. Therefore, direct experiments about the relationship of carbohydrate reserves, flowering, and yield are needed. Much research has examined tree growth under ideal conditions when there is no water or nitrogen stress. However, tree growth models need valid equations for when the trees are under stress. A literature search yields only controlled nitrogen-stressed experiments for nut tree seedlings. Thus, nitrogen- and water-stressed experiments for mature trees are needed. In addition, the two stressors should be tested to determine if they are addictive or multipliable. Accurate tree root depth data are also needed for tree modeling because current models only assume certain values for root depth.
Volume 2 of this revised edition of Tropical Fruits examines the more specialist tropical fruits such as guava, durian, mangosteen, passion fruits and palm fruits. With growing interest in the cultivation, production, study, sales and marketability of these specialist fruits, this is a timely and informative book. Topics like botany, soil and climate requirements, cultivar development, world production and harvesting and postharvest handling are covered in-depth for each crop. This practical and accessible book is an ideal text for Horticulture academics, researchers, extension workers, students, breeders, growers and policy makers.
Monitoring soil water content coupled with phytomonitoring techniques have been shown to be good tools for irrigation management in avocado orchards. There are many well-tested devices for monitoring soil moisture in orchards but options for measuring plant water status are limited. The objective of this study was to determine whether measuring voltage differences between roots and leaves can be used as a technique to measure plant water status related to soil water content. Root and shoot voltage differences were monitored in young 'Hass' avocado trees grafted onto clonal rootstocks grown in containers, and in young seedling 'Mexicola' avocado trees grown hydroponically, both experiments carried out under laboratory conditions. In container-grown 'Hass' avocado trees, root and shoot voltage differences were initially measured for about 2 h to determine steady state conditions. Plants were then exposed to cycles of soil drying and re-watering. In seedling 'Mexicola' trees, electrical signals were measured for at least 75 min in control plants and plants exposed to simulated drought stress. The extracellular electrical potential difference between the base of the trunk and the leaf petiole was continuously monitored after exposing plants to treatments. Results indicated that in 'Hass' avocado trees, a change in soil water content induced by root drying and re-watering was accompanied by a slow change in the electrical signal at the leaf petiole which was greatest after 52 and 32 min for root drying and re-watering, respectively. This was related to a decrease in stomatal conductance (gs) of plants exposed to drought. Also, in hydroponic conditions, significant voltage differences occurred in plants exposed to drought simulated by the addition of polyethylene glycol (PEG 6000) to the hydroponic medium resulting also in a decrease in gs. These results suggest that it may be possible to use voltage differences measurements as a technique for monitoring physiological responses to soil water content.
World avocado production expanded from 2.7 mill. t in 2000 to 3.6 mill. t in 2009. This expansion was largely driven by increasing access to the USA as phytosanitary obstacles were overcome. USA imports of ca. 360,000 t in 2009 have overtaken the European Union (ca. 210,000 t). Increased exports from Mexico, the world's largest producer, have been accompanied by rapid growth of production and export from Chile and Peru, which have overtaken South Africa (40,000 t export, mainly to the EU) and other traditional suppliers. In Africa, Kenya is also a significant exporter to Europe (ca. 12,000 t), but there is scope for expansion if obstacles can be overcome. The main technological problems are relatively low average yield; alternate and irregular bearing; Phytophthora root rot; insufficient proven elite cultivars and rootstocks; uncertainty about best practice management in the variable main environments (humid subtropical, semi-arid winter rainfall coastal areas - respectively mesic/invigorating and stressful/non-invigorating); and postharvest issues. Trends towards higher density planting, containment pruning, bioregulator sprays and integrated management of root rot are well established in the technologically advanced "subtropical" (as opposed to "tropical") industry. Research advances in overcoming longstanding problems, and a trend towards internationalization of research, allow for guarded optimism about the future of arguably "the world's most nutritious fruit".
Mango (Mangifera indica L.) is the single most important tropical/subtropical fruit in the World, with World Production standing at 23.195 million MT in 1997. India produces the most mango with annual production of 12 million MT, followed by China (2.142 million MT), Mexico (1.5 million MT), and Thailand (1.35 million MT). In Asia the largest producers are India, China, Thailand and Pakistan (0.91 million MT), while in Oceania, Australia is the largest producer with 30,000 MT (FAOSTAT Database-1997). The Mango is grown in the tropics and sub-tropics and as a consequence is produced across a large latitude range, under widely varied environments, soils and management conditions. However, this widespread production brings with it a range of special problems or challenges and these are elaborated for the Asia and Pacific region, but many can well be applied to other regions of the World.
Diurnal changes in net carbon dioxide assimilation (A), leaf conductance (gs) and leaf water potential (ψL) were investigated for custard apple (Annona cherimola × Annona squamosa) trees of cultivar 'African Pride' in subtropical Queensland, Australia. Most of the variation in A and gs could be attributed to changes in r.h. (r2>0.69, P<0.05). The addition of other variables besides r.h. into multiple linear regressions analysis added little to explaining the variation in A or gs. Leaf water potential (ψL) was highly responsive to air temperature (AT) (r2 = 0.56, P<0.05). The marked sensitivity of custard apple stomata to low r.h. may be one of the reasons for poor fruit set and size of custard apple fruit under subtropical conditions because of carbohydrate source limitations. The fruit set and early fruit growth of custard apple in the field could be improved by techniques which raise r.h., such as the use of windbreaks and overhead intermittent misting.
Non-astringent persimmon is rapidly expanding as a new fruit crop in warm subtropical regions of the world. Most research and development of this fruit crop has occurred in Japan, where there is a considerable amount of published literature on its performance. Much of this information is not readily accessible to other countries and needs to be interpreted and modified for other climatic regions. This paper reviews reproductive events from floral initiation to the completion of fruit growth. The timing and significance of these events is described in relation to the phenological cycle. Method of improving flowering, reducing fruit drop and altering the fruit maturity period are discussed.
Nut production from pecans, almonds, and pistachios figures heavily in the economies of California, Texas, and New Mexico, as well as several other states, and surface irrigation water supplies have been reduced in low runoff years in the western United States. Water and nitrogen management in tree crops is constrained through lack of information and inability to provide targeted management. The goal of this research was to develop an improved management pecan model to monitor and predict water and nutrient demand and nutrient status in pecan trees, along with the interaction of nutrient and water stress on nut yield. The pecan nut tree model developed by Andales et al. (2006) had a nutrient uptake and allocation and nutrient stress subroutine added to the model to predict the interaction of water and nutrient stress (nitrogen and potassium). The nitrogen submodel presented simulates the interaction of nitrogen transformation, soil temperature, water, and nitrogen uptake to describe nitrate distribution in the root zone of a growing pecan tree for the entire growing season. The nitrogen submodel follows the nitrogen transformation equation developed by Jones and Kiniry (1986) for the CERES-maize model. The nitrogen root uptake submodel follows the approach developed by Yanai (1994), which is a model of solute uptake that accepts root growth, water uptake, and soil solution concentrations as time-varying inputs that interactively link plant and soil processes. The model was tested against a nitrogen–potassium water stress experiment conducted by Smith et al. (1985) in Oklahoma from 1978 to 1983 where the pecan trees received varying rainfall amounts, the only source of water, and four levels of nitrogen application. The measured yield response represented a water nitrogen stress response. The model over-predicted the yield by 42% compared to the measured yield, but the model under-predicted yield by 21% in 1981 with 0 kg/ha of applied N and under-predicted yield by 13% when 224 kg/ha N was applied that year. The current pecan model appears to simulate water stress reasonably well but may overestimate the nitrogen uptake by the pecan trees and underestimate the reduction in yield caused by nitrogen stress. The model also may overestimate yield through lack of an insect damage submodel.
The effect of increasing fruit maturity on fruit base mineral composition, phenolic content and the resultant influence on postharvest fruit quality and ripening physiology of Fuerte avocado, was investigated. Late harvested fruit with increasing maturity had reduced calcium and magnesium concentrations. A reduction in ripening time was associated with a decrease in fruit calcium concentration. The relationship, if any, between fruit potassium concentration and relative maturity was less clear. Total fruit phenolics in creased with increasing fruit maturity, and this was associated with an increase in the incidence of the cold storage browning disorder, mesocarp discolouration. Cold storage had no effect on total fruit phenolic concentration
Phosphonate at 3 concentrations (7.5, 10 and 20%) was injected into the trunks of avocado (Persea americana Mill.) trees showing advanced symptoms of canopy decline caused by phytophthora root rot. All formulations of phosphonate and potassium phosphonate, including the lower rates of 7.5 and 10%, successfully controlled root rot and resulted in improved tree health. The 7.5% phosphonate treatment permitted the formulation of chemically compatible mixtures containing zinc and boron which, when trunk-injected, increased the concentrations of these nutrients in mature summer-grown leaves. Phosphonate formulations containing 17% zinc chelate or 10% zinc nitrate and injected twice during a growing season, at 15 mL/m canopy diameter, increased leaf zinc concentrations above the critical level of 30 mg/kg DM. However, the inclusion of zinc chelate in formulations substantially increased the time of uptake of the injection compared with the formulation containing zinc nitrate. Phosphonate formulations with 0.9% boron, injected twice during a growing season at 15 mL/m canopy diameter, improved leaf boron concentrations, but they failed to reach the critical threshold concentration of 50 mg/kg DM.
Potted lychee trees (cv. Tai so) with mature vegetative flushes were grown under three day/night temperature regimes known to induce floral (18/13°C), intermediate (23/18°C) and vegetative (28/23°C) shoot structures. Root and shoot growth was shown to alternate at all temperatures, with root growth occurring during shoot dormancy and in the initial stages of shoot emergence. As temperature decreased, the rate of root growth decreased and the length of the shoot dormancy period increased. Increasing the period of the endogenous shoot/root growth rhythm was sufficient to induce floral initiation. At all temperatures, shoot dormancy was broken after a similar amount of root growth. This occurred at approximately 3, 6 and 8 weeks for 28/23, 23/18 and 18/13°C, respectively. The concentration of the cytokinin, zeatin riboside, increased in parallel with an increase in root growth rate, reaching a peak in terminal buds just prior to shoot emergence. Application of zeatin riboside to dormant buds resulted in bud-break, but full emergence did not occur. It is proposed that root growth has a strong influence on the period of shoot dormancy, possibly through the initiation of bud-break by zeatin riboside, and can influence emerging shoot structure.
The impact of flower-feeding by Monolepta australis (Jacoby) on fruit-set in avocados was assessed by (1) confinement of beetles on flower panicles to compare fruit-set with that in other insect and non-insect treatments; (2) association of sticky-trap catches of beetles in individual trees with flowering intensity and subsequent production of mature fruit. Fruit-set on panicles with M. australis alone () was equivalent to that when all insects had unrestricted acees (), which contrasted with those in the no insect () and bibionid () treatments. Ultimate fruit production in cv. Fuerte invaded by M. australis ( did not differ significantly from that in a commercial orchard () 20 km away, where this beetle is uncommon. Insecticidal control of M. australis in flowering avocados may be counterproductive by reducing pollination.
The influence of cold storage and increasing fruit maturity on ripening physiology was investigated. Fruits that were cold-stored for 28 days at 5,5°C before ripening, always ripened faster than non-stored fruits of a similar maturity. Non-stored fruit showed a decrease in ripening time with increasing maturity. In cold-stored fruit the relationship between ripening time and maturity was less clear. Cold-stored fruit lost less water during ripening than non-stored fruit of similar maturity, but lost water at a faster rate than non-stored fruit. Increasing maturity reduced the total amount of water lost during ripening. Vascular browning appears to be maturity (time of harvest) related with similar results in both cold-stored and non-stored fruit. Cold storage increased the incidence of mesocarp discolouration which became more acute with increasing fruit maturity
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