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Handbook of Environmental Physiology of Fruit Crops
... Neste âmbito, a intervenção sobre a configuração do pomar e das árvores é fulcral para a sua maximização, constituindo uma área pouco explorada na fruticultura portuguesa. A influência da configuração do pomar e do LAI na radiação intercetada tem sido sobejamente discutida (Jackson & Palmer, 1972;Jackson, 1980;Wertheim et al., 1986;Palmer, 1989;Wagenmakers, 1991;Robinson & Lakso, 1991;Lakso, 1994;Corelli-Grappadelli, 2003). ...
... Os estudos clássicos têm demonstrado que a produtividade das culturas é essencialmente uma função linear da interceção total de energia radiante ao longo do ciclo (Palmer, 1989;Russel et al., 1989;Wagenmakers, 1991;Lakso, 1994;Lakso et al., 1999). Em regiões de climas temperados os "inputs" anuais de radiação solar variam entre 2.3 a 6.0 GJ m -2 , dependendo da latitude, comprimento do dia e nebulosidade, sendo que para um clima com uma receção média anual de radiação solar de 4.0 GJ m -2 o potencial anual de produção de MS para uma vegetação que interceta completamente a radiação durante todo o ano é de cerca de 100 ton ha -1 ano -1 (Russel et al., 1989). ...
... Este facto pode dever-se a uma fraca distribuição da luz em copas excessivamente densas, sugerindo que essa relação deva ser curvilínea quando a interceção de radiação se aproxima dos 100% (Hampson et al., 1997;Sansavini & Musacchi, 2002). Lakso (1994) mostrava que na macieira este ajustamento era linear até 50% da radiação intercetada, enquanto Wagenmakers & Tazelaar (1997), trabalhando com macieiras e pereiras na Holanda, mostraram que este podia acontecer até níveis compreendidos entre 60 a 70%. Referiam ainda que valores superiores podiam resultar em quebras de qualidade e pior formação de gomos florais e valores inferiores em perdas de produtividade. ...
‘Rocha’ pear culture demonstrated to have high yield potencial and when submited to new production models has combined it with the production of high quality fruits. It was demonstrated the need to increase tree density, coupled with changes in training systems to increase light interception. We proposed alternating axes tilt angles, which allow average yields increases of 24.4% and 15.2% in medium and high density orchards respectively.
High density production means adjust technical operations to light microclimate in order to maintain high photosynthetic efficiency inside all the points of the canopy and enhance fruit growth, increasing harvest index. Intensive and precision pruning helped this balance, allowing better light distribuition and stimulating new production organs formation, more efficient and better able to produce quality fruits.
Submodels were calibrated and validated for simulations of development, radiation interception and fruit growth, including in a robust generic model that simulates generic processes of pear ‘Rocha’ development, growth and yield. Modeling helped to clarify interactions between cultural management and conversion and assimilates partitioning, providing important analytical tools and indicators for decision support strategies.
... Neste âmbito, a intervenção sobre a configuração do pomar e das árvores é fulcral para a sua maximização, constituindo uma área pouco explorada na fruticultura portuguesa. A influência da configuração do pomar e do LAI na radiação intercetada tem sido sobejamente discutida (Jackson & Palmer, 1972;Jackson, 1980;Wertheim et al., 1986;Palmer, 1989;Wagenmakers, 1991;Robinson & Lakso, 1991;Lakso, 1994;Corelli-Grappadelli, 2003). ...
... Os estudos clássicos têm demonstrado que a produtividade das culturas é essencialmente uma função linear da interceção total de energia radiante ao longo do ciclo (Palmer, 1989;Russel et al., 1989;Wagenmakers, 1991;Lakso, 1994;Lakso et al., 1999). Em regiões de climas temperados os "inputs" anuais de radiação solar variam entre 2.3 a 6.0 GJ m -2 , dependendo da latitude, comprimento do dia e nebulosidade, sendo que para um clima com uma receção média anual de radiação solar de 4.0 GJ m -2 o potencial anual de produção de MS para uma vegetação que interceta completamente a radiação durante todo o ano é de cerca de 100 ton ha -1 ano -1 (Russel et al., 1989). ...
... Este facto pode dever-se a uma fraca distribuição da luz em copas excessivamente densas, sugerindo que essa relação deva ser curvilínea quando a interceção de radiação se aproxima dos 100% (Hampson et al., 1997;Sansavini & Musacchi, 2002). Lakso (1994) mostrava que na macieira este ajustamento era linear até 50% da radiação intercetada, enquanto Wagenmakers & Tazelaar (1997), trabalhando com macieiras e pereiras na Holanda, mostraram que este podia acontecer até níveis compreendidos entre 60 a 70%. Referiam ainda que valores superiores podiam resultar em quebras de qualidade e pior formação de gomos florais e valores inferiores em perdas de produtividade. ...
‘Rocha’ pear culture demonstrated to have high yield potencial and when submited to new production models has combined it with the production of high quality fruits. It was demonstrated the need to increase tree density, coupled with changes in training systems to increase light interception. We proposed alternating axes tilt angles, which allow average yields increases of 24.4% and 15.2% in medium and high density orchards respectively.
High density production means adjust technical operations to light microclimate in order to maintain high photosynthetic efficiency inside all the points of the canopy and enhance fruit growth, increasing harvest index. Intensive and precision pruning helped this balance, allowing better light distribuition and stimulating new production organs formation, more efficient and better able to produce quality fruits.
Submodels were calibrated and validated for simulations of development, radiation interception and fruit growth, including in a robust generic model that simulates generic processes of pear ‘Rocha’ development, growth and yield. Modeling helped to clarify interactions between cultural management and conversion and assimilates partitioning, providing important analytical tools and indicators for decision support strategies.
... En la primavera, las plantas frutales poseen reservas de carbohidratos y nutrientes, los frutos ven restringido su tamaño por la temperatura, durante el verano las reservas de carbohidratos son limitadas y las temperaturas superan ampliamente los umbrales de desarrollo del fruto. (Lakso, 1994 Giménez 15 La variación en ganancia de carbono no estructural (dn/dt) en el tiempo, depende del flujo de carbono por el pedúnculo (I) y de los fotosintatos refijados por el fruto (P); la pérdida de carbono en el fruto se debe a la respiración del fruto (R) y del incremento en carbono estructural del fruto (G). Para Henton et al. (1999), el término G de la Ec. 1.1.2 ...
... Bajo este concepto la exportación de AIA del fruto está co-regulada por la síntesis de AIA de los brotes y de las hojas . Los factores ambientales como la temperatura y la luz afectan la caída natural de los frutos y flores, son también inhibidores de la exportación de AIA de los Delicious" (Greene, 2006 Desde el punto de vista ecofisiológico solamente con recursos y reguladores (nutrientes, agua, radiación, temperatura) que no arriesguen la supervivencia del árbol, el fruto continuará creciendo y madurando (Lakso, 1994). El sombreado de los árboles completos cuando el fruto posee un diámetro entre 8 a 33 mm provocó una gran caída de los mismos (Byers et al., 1990). ...
... El sombreado de los árboles completos cuando el fruto posee un diámetro entre 8 a 33 mm provocó una gran caída de los mismos (Byers et al., 1990). Tanto el crecimiento de los frutos jóvenes como el cuaje de los mismos dependen fundamentalmente de las hojas de los dardos próximas al fruto (Lakso, 1994). Se ha determinado que existe una relación asintótica entre la exposición a la luz y la retención de los frutos, con una exposición del 25% de luz (75% de sombreado) la retención asciende al 30% de los frutos en cambio con un 80% de exposición se retiene un 70% (Dennis, 2003), en cambio, cuando se sombrean manzanos durante 3 a 5 días se observó un 90% de abscisión, (Kondo & Takahashi, 1987). ...
El tamaño del fruto es una de las características comerciales más importantes
en peras cv. “Williams”. El mismo es determinado por las fases del crecimiento y por
su comportamiento o patrón a lo largo del ciclo productivo. Además del crecimiento,
la carga frutal limita los calibres a recolectar, a mayor carga frutal menores calibres
se obtendrán en cosecha. La regulación de la carga frutal se debe esencialmente a
la abscisión de los frutos.
El mecanismo de abscisión natural es insuficiente para obtener un volumen de
producción y calidad acorde a lo requerido en los mercados. Por ello se realizan
prácticas culturales para regular la cantidad de frutos en la planta y propiciar una
mayor distribución de calibres comerciales. Dicha labor es denominada raleo. El
raleo manual incrementa el costo de la mano de obra, por ello se utilizan hormonas
vegetales sintéticas o biorreguladores como la 6-Benciladenina (BA) que simplifica
esta tarea cultural.
La BA es un biorregulador de probada efectividad con una dosis establecida
como óptima en 150 ppm., aunque todavía no se ha determinado con exactitud el
momento óptimo de aplicación. Esto se debe, a la interacción de los distintos
procesos fisiológicos y climatológicos que intervienen al momento de realizar las
aplicaciones.
El objetivo de la presente tesis fue determinar el patrón de crecimiento y la abscisión
del fruto desde la plena floración hasta la cosecha, que permita ajustar la práctica de
raleo químico en perales cv. “Williams”. Para tal fin se establecieron como objetivos
específicos, determinar el patrón de crecimiento de los frutos con y sin aplicación de
Benciladenina; determinar el período de abscisión de los frutos durante su
crecimiento en la primavera, establecer cuándo se registra el más alto nivel de caída
de frutos, en dicho período y determinar el momento óptimo para la aplicación de
raleadores químicos constituidos por Benciladenina.
Para llevar a cabo dichos objetivos se realizaron distintos experimentos
independientes en una parcela productiva implantada con perales cv “Williams”. Los
ensayos se realizaron durante dos temporadas consecutivas, correspondientes a los
años 2007-2008 y 2008-2009.
En los ensayos de crecimiento se realizó un seguimiento de frutos en 6 plantas
tratadas con BA y 6 plantas testigos. De estos ensayos, se determinó que el
crecimiento del fruto fue afectado por la aplicación de BA solamente en la tasa de
crecimiento y en el calibre de los frutos al momento de cosecha comercial. No se
registraron diferencias significativas al comparar los patrones de crecimiento. Para
ambas temporadas las tasas de crecimiento fueron similares. El momento de
ocurrencia del punto de inflexión del patrón de crecimiento fue en la segunda
temporada de 14 días posteriores al primer ciclo de crecimiento.
En la evaluación de la frecuencia de abscisión a partir del seguimiento de la
caída de frutos en plantas se calculó que la mayor tasa de caída de frutos ocurrió
para el primer y segundo ciclo a los 23 y 27 días después de plena floración (DDPF),
respectivamente. El comienzo de la caída de frutos se observó a los 20 DDPF para
el primer ciclo y a los 8 DDPF para el segundo ciclo. Analizando los patrones de
abscisión de los frutos se observó que la aplicación de BA afectó significativamente
la caída de los frutos.
Finalmente, para determinar el momento oportuno de aplicación de la BA se
realizaron aplicaciones cada 4 días a partir de la caída de pétalos (DDCP) a una
dosis única de 150 ppm y un testigo sin aplicación. Considerando las variables de
raleo y productivas en conjunto se determinaron los momentos de aplicación para la
primera y segunda temporada de análisis, los resultados indicaron el momento
oportuno de aplicación fue 12 DDCP y de entre los 8 y 12 DDCP respectivamente,
dichos momentos corresponden a los 19 DDPF para la primer temporada y a los 11
DDPF para el segundo ciclo.
El momento de aplicación más propicio no fue acorde al momento determinado
como “June Drop”, no obstante en ambas temporadas coincidió con el inicio del
proceso de abscisión.
... Table 2 shows theoretical means, lower and upper limits, and ranges of apple yield for different light interceptions at 10 % increments. Increased apple yield variability at light interception levels > 50 % was previously noted (Lakso, 1994;Wünsche and Lakso, 2000). Light interception above 80-90 % is difficult Fig. 4. Relationship between fruit yield and light interception in apple trees from different studies. ...
... The authors explained how photoinhibition and photorespiration counter dry matter accumulation by either causing damage to the photosystems or triggering a protection mechanism. High variability in yields at light interception > 50 % (Lakso, 1994;Wünsche and Lakso, 2000;Fig. 4) may partially be explained by the fact that low cropping trees produce more vegetative vigour that in turn leads to higher light interception at the expense of yield. ...
The main characteristics of Narrow Orchard Systems (NOS) are (i) narrow canopies, with (ii) multiple closely-spaced upright leaders and (iii) narrow interrows, regardless of tree spacing within the row. In NOS, planting density can be reduced compared with super-high and ultra-high density planting systems on dwarfing rootstocks, utilising a wider range of rootstock vigours coupled to proportional increases in both within-row tree spacing and upright leader number per tree. This paper reviews the development of NOS and results of research carried out on apple, pear, sweet cherry, peach, nectarine, apricot and plum in production regions worldwide. The history of orchard intensification and the evolution of narrow-canopy multileader orchard systems is presented. Implications of NOS for light interception and distribution, yield and fruit quality are discussed. These systems require a solid understanding of crop and cultivar fruiting and vegetative habits, and their interactions with rootstock, environment and management practices. Whilst NOS improve productivity (yield and fruit quality), labour use efficiency and mechanisation, they often require additional labour in the first two years from planting. They are robot-ready systems that will promote transition towards increased digitisation in horticulture. Current developments with new experiments and demonstrations carried out in Australia are discussed. With an increasing body of research supporting the advantages of NOS, this literature review summarises the latest findings and identifies some opportunities for further research and innovation.
... Netting can modify plant water status, light interception, photosynthesis and carbohydrate accumulation in crop plants (Mupambi et al., 2018). The response of the leaves and the canopy to light is the major factor affecting carbohydrate production in apple trees (Lakso, 1994). For a whole canopy, as well as total light, the distribution of light between direct and diffuse components may be important since many leaves may be dependent on diffuse light (Lakso, 1994). ...
... The response of the leaves and the canopy to light is the major factor affecting carbohydrate production in apple trees (Lakso, 1994). For a whole canopy, as well as total light, the distribution of light between direct and diffuse components may be important since many leaves may be dependent on diffuse light (Lakso, 1994). At Girona, the PAR was reduced by 19%-22% by black nets, by 13%-15% by green nets and 6%-11% by white nets. ...
Chemical thinning is a common practice used in apple orchards. It entails an early decrease in fruit tree load, resulting in enhanced fruit size and quality, a reduction or even the complete avoidance of manual thinning, and an increased return bloom. These effects translate into greater economic profitability for the apple grower. A thinning programme can be designed using various active ingredients in single or multiple applications. The efficacy of the programme will be defined by a number of factors, the most important of which are fruit size at the time of application, number of applications, meteorological conditions and dosage used. The main aim of this thesis is to analyse the different factors affecting the thinning efficacy of Brevis®, a commercial chemical thinner, and the subsequent impact on various crop parameters in different apple varieties. These factors include action mode, meteorological conditions, application dosage, fruit size, the effect of using anti-hail netting to reduce solar radiation, the comparative impact of a single or double application, the time interval in double application treatments between the first and second application, and the comparative performance of Brevis® in the apple varieties ‘Gala’ and ‘Fuji’. The tests were performed between 2013 and 2016 at the IRTA experimental stations in Lleida and Mas Badia (Spain) on the apple varieties ‘Gala’, ‘Fuji’ and ‘Pink Lady’. Significant reductions in crop load and yield were observed in all the tests that were conducted for the purpose of evaluating Brevis® thinning efficacy. In addition, fruit colour, size and quality increased as crop load decreased. Brevis® thinning efficacy was demonstrated in studies on ‘Gala’ and ‘Fuji’ varieties for applications made when king fruit diameter ranged between 7.5 mm and 19 mm, with maximum efficacy recorded in the 11.5-14 mm range. Thinning efficacy was also found to be greater in ‘Gala’ than in ‘Fuji’. In the same way, fluorescence values were higher in ‘Fuji’ than in ‘Gala’, which means that the inhibition caused by Brevis® was higher in ‘Gala’ than in ‘Fuji’. The most important meteorological factors affecting Brevis® efficacy were the mean temperature and mean night temperature in the period from 5 days before to 3 days after Brevis® application. A linear relationship was found between Brevis® dosage (applied at rates ranging between 1.1 and 4.4 kg/ha) and all the efficacy parameters of quality (fruit size, colour and weight) and fluorescence evaluated in ‘Gala’ and ‘Fuji’. The pharmacological model based on the biexponential function showed a high degree of fit and the calculated values correlated closely to the real values. The parameters studied in the biexponential function revealed a direct correlation between Brevis® efficacy and photosynthesis inhibition. However, these parameters can presently only be used to characterise Brevis® efficacy of the year in question as it is necessary for the period of inhibition to have finished. In the case of a thinning programme based on two chemical thinner applications made when king fruit are 7.5-13.5 mm in diameter, Brevis® efficacy is defined by the meteorological conditions at the time of each application but is not affected by the time interval between application. The reduction in solar radiation as the result of the use of anti-hail netting did not affect Brevis® thinning efficacy or fluorescence inhibition.
... Netting can modify plant water status, light interception, photosynthesis and carbohydrate accumulation in crop plants (Mupambi et al., 2018). The response of the leaves and the canopy to light is the major factor affecting carbohydrate production in apple trees (Lakso, 1994). For a whole canopy, as well as total light, the distribution of light between direct and diffuse components may be important since many leaves may be dependent on diffuse light (Lakso, 1994). ...
... The response of the leaves and the canopy to light is the major factor affecting carbohydrate production in apple trees (Lakso, 1994). For a whole canopy, as well as total light, the distribution of light between direct and diffuse components may be important since many leaves may be dependent on diffuse light (Lakso, 1994). At Girona, the PAR was reduced by 19%-22% by black nets, by 13%-15% by green nets and 6%-11% by white nets. ...
Hail nets reduce photosynthetically active radiation (PAR) and alter the environment under the netting in apple orchards. Thus, we investigated the effect of nets on the efficacy of metamitron, a short-term photosynthesis inhibitor used for fruit thinning. The objective of this study was to evaluate the effect of the netting and metamitron on thinning efficacy, yield, fruit quality and chlorophyll fluorescence in three apple (Malus domestica Borkh.) cultivars. One or two metamitron applications at different doses or rates were applied the tree under different coloured nets. The reduction of PAR was highest with black nets (19%-22%), followed by green (13%-15%) and white nets (6%-11%). There were no significant differences (P> 0.05) in fruit weight or size with or without nets. Double applications of metamitron increased average fruit fresh weight and reduced the fruit set over four experiments. In contrast, single applications were less effective. In two experiments, thinning was associated with lower yields. However, there was no effect in the other two experiments. The double treatments tended to increase the percentage of the crop with fruit larger than 70 mm in diameter. All thinning strategies showed similar inhibition in fluorescence, with the only observed significant differences between treatments occurring when using a single or double application. The results show that netting does not affect the response to thinning with metamitron.
... This transition transformed traditional low-density planting orchards into modern high-density systems. Because of their smaller root biomass, dwarfing rootstocks are more vulnerable to water stress, soil water deficits and atmospheric demand (Lakso, 1994). Mild to severe uncontrolled water stress during orchard establishments in the first 2-3 years can reduce precocity and productivity, for mature trees, water stress can reduce fruit size (Robinson et al., 2013;Valverdi and Kalcsits, 2021). ...
Instrumentation plays a key role in modern horticulture. Thus, the microtensiomenter, a new plant-based sensor that continuously monitors trunk water potential (Ψtrunk) can help in irrigation management decisions. To compare the response of the Ψtrunk with other continuous tree water status indicators such as the sap flow rate, the difference between canopy and air temperatures, or the variations of the trunk and fruit diameter, all the sensors were installed in 2022 in a commercial orchard of ‘Honeycrisp’ apple trees with M.9 rootstocks in Washinton State (USA). From the daily evolution of the Ψtrunk, five indicators were considered: predawn, midday, minimum, daily mean, and daily range (the difference between the daily maximum and minimum values). The daily range of Ψtrunk was the most linked to the maximum daily shrinkage (MDS; R² = 0.42), the canopy-to-air temperature (Tc-Ta; R² = 0.32), and the sap flow rate (SF; R² = 0.30). On the other hand, the relative fruit growth rate (FRGR) was more related to the minimum Ψtrunk (R² = 0.33) and the daily mean Ψtrunk (R² = 0.32) than to the daily range of Ψtrunk. All indicators derived from Ψtrunk identified changes in tree water status after each irrigation event and had low coefficients of variation and high sensitivity. These results encourage Ψtrunk as a promising candidate for continuous monitoring of tree water status, however, more research is needed to better relate these measures with other widely studied plant-based indicators and identify good combinations of sensors and threshold values.
... Maximum net CO2 assimilation (An) of most C3 species is saturated with a relatively low amount of photosynthetically active radiation (PAR) (600-900 μmol m 2 s -1 PPFD), representing 30%-40% of total sunlight (1500-2000 μmol m 2 s -1 PPFD). Temperature is one of the factors that can influence An; in many deciduous trees, a reduction in An due to temperature increase occurs because of an increased respiration rate (Lakso, 1994). Beppu et al. (2003) showed that An decreased when cherry trees grown under low temperatures were subjected to temperatures above 25 °C, while trees grown at high temperatures reached maximum An at 30 ℃, decreasing to a smaller extent even up to 35 ℃, which demonstrates that there is temperature acclimatization of the photosynthesis of cherry tree leaves. ...
Climate change is increasing sweet cherry (Prunus avium (L.) L.) production under cover systems such as high tunnels, rain covers, and nets. The objective of this review was to provide an overview of the environmental factors and physiological responses involved in cherry production under different types of protective covering systems. The most important environmental factors affected by cover systems are photosynthetically active radiation (PAR), temperature, relative humidity, and wind speed, which in turn affect leaf gas exchange, plant water relations, tree growth, flower development, and fruit quality. The use of covering systems has a positive effect on photosynthesis by increasing the amount of diffused PAR, but a negative effect on the reproductive-vegetative tree balance due to lower total PAR availability. Increases in air temperature by cover systems alter differentially flowering and fruit set, impacting positively the ripening time and cell division of the fruits. Plant water status is improved under cover systems, allowing for greater tolerance to water deficit as well as improved potential fruit cell expansion, with an ensuing positive effect on fruit size, but decreasing fruit firmness due to lower Ca availability fruits. The multiple environmental factors and physiological responses observed in cherry production under cover systems suggest the need to adjust agronomic practices such as pruning, crop load regulation, irrigation, and nutrition according to these specific conditions.
... Potassium does not enter these compounds but contributes to the osmotic regulation, enzymatic activity and the transport process in membranes 15 ,18 . (19) explained that the growth of fruits after flowering depends on processing a large part of the representative materials. (20) indicated the effect of high concentrations of Nitrogen and other nutrients on high dry matter accumulation. ...
This study was carried out in one of the private palm orchards located in the area of the village of Albu Assaf - Al-Dawwar, which is 10 km west of Ramadi city / Anbar Governoaverge, during the 2020-2021 season to study the effect of three levels of fertilizer combinations F0:0 ,F1: 600 g of urea (N 276) + 350 g of triple superphosphate (P2O5 500 ) + 168 g of potassium sulfate (K2O 240), 1200 g urea (552 N) + 700 g triple superphosphate (P2O5 336) + 1000 g potassium sulfate (K2O 480) and three levels of humic acid H0:0, H1:15, H2:30 ml. L-1 and two levels of a combination of biofertilizers, Trichoderma(Trichoderma harzianum) and Mycorrhizal(Glomus mosseae) B0:0, B1:300 ml Trichoderma + 400 g Mycorrhizal, with three replications for each treatment, to increase and improve the production of date palm trees, Khastawi cultiver, The research was carried out as a factorial experiment (2 x 3 x 3) it used the design of randomized complete block, RCBD, where 54 trees of 11 years of age were selected that were homogeneous in terms of growth characteristics as much as possible, Each palm was considered a repeater. The results showed the superiority of the level F2 chemical fertilization in several characteristics, including the percentage of the set fruit, the lowest percentage of fallen, the length and weight of the fruit and its size and total yield, which amounted to 52.431 kg, whereas, the control treatment gave the lowest average for the traits as mentioned earlier. The H2 level of humic acid was superior in the characteristics of the percentage of set fruit, the lowest percentage of fallen, length and weight of the fruit, its size and total yield, which amounted to 58.148. In contrast, the control treatment gave the lowest average for the abovementioned traits. The results also showed the superiority of level B1 of the combination of biofertilizers in the percentage of frozen fruit, falling, fruit length and total yield, which amounted to 51.641 kg. In contrast, the control treatment gave the lowest rate for the abovementioned traits. The binary overlap F2H2 treatment gave the highest rates in the set fruit percentage, length and weight of the fruit, its size and the total yield, which amounted to 59,064 kg, and the lowest percentage of fallen. Also, the bilateral overlap H2B1 treatment gave the highest rates in the set fruit percentage and fruit length and the lowest percentage of fall. The same treatment with the B0 treatment appeared to outperform in the weight and size of the fruit and the total yield, which amounted to 58.915 kg compared to the control treatment that gave a lower average., the bilateral overlap F2B1 treatment gave the highest rates in the characteristics of fruit length and weight, as well as the triple overlap F2H2B1 treatment, gave the highest averages in the characteristics of the set fruit percentage and the lowest percentage of fallen and weight of the fruit and the total yield, which amounted to 59.648 kg compared to the control treatment that gave a lower average for the mentioned traits where the response was significant for the type is Khastawi in terms of increasing the yield and its components. Keywords: Date palm; chemical fertilization; NPK; bioFertilization; Humic acid; Khastawi.
... Similarly, high temperatures can cause direct damage to fruit, reduce fruit quality (Racsko & Schrader, 2012) impair photosynthesis, and reduce fruit numbers and growth (Lakso, 1994(Lakso, , 2011. ...
Temperate perennial fruit and nut trees play varying roles in world food diversity-providing edible oils and micronutrient, energy, and protein dense foods. In addition, perennials reuse significant amounts of biomass each year providing a unique resilience. But they also have a unique sensitivity to seasonal temperatures, requiring a period of dormancy for successful growing season production. This paper takes a global view of five temperate tree fruit crops-apples, cherries, almonds, olives, and grapes-and assesses the effects of future temperature changes on thermal suitability. It uses climate data from five earth system models for two CMIP6 climate scenarios and temperature-related indices of stress to indicate potential future areas where crops cannot be grown and highlight potential new suitable regions. The loss of currently suitable areas and new additions in new locations varies by scenario. In the southern hemisphere (SH), end-century (2081-2100) suitable areas under the SSP 5-8.5 scenario decline by more than 40% compared to a recent historical period (1991-2010). In the northern hemisphere (NH) suitability increases by 20% to almost 60%. With SSP1-2.6, however, the changes are much smaller with SH area declining by about 25% and NH increasing by about 10%. The results suggest substantial restructuring of global production for these crops. Essentially, climate change shifts temperature-suitable locations toward higher latitudes. In the SH, most of the historically suitable areas were already at the southern end of the landmass limiting opportunities for adaptation. If breeding efforts can bring chilling requirements for the major cultivars closer to that currently seen in some cultivars, suitable areas at the end of the century are greater, but higher summer temperatures offset the extent. The high value of fruit crops provides adaptation opportunities such as cultivar selection, canopy cooling using sprinklers, shade netting, and precision irrigation.
... Cultivar, clone, training system, planting density, fruit quality and price condition orchard viability (Sansavini & Musacchi, 2002;Robinson et al., 2007;Bravin et al., 2009;Leão de Sousa & De Melo-Abreu, 2015;Lordan et al., 2019;Sanchéz et al., 2020), so they must be all considered in a rigorous and responsible way. In the absence of stresses (drought, nutritional or other), productivity (dry matter production) is positively related with intercepted radiation (Lakso & Robinson, 1997;Sansavini & Musacchi, 2002), although these relationship does not remain linear with very high intercepted levels, due to the weak distribution of the radiation in excessively dense canopies (Lakso, 1994;Wagenmakers & Tazelaar, 1997;Sousa, 2013). At the orchard scale, light interception is affected by planting density, row orientation, tree structure and planting design (Robinson, 2011;Yang et al., 2016) and, at the tree scale, by the intrinsic architectural pattern of a cultivar, training and pruning (Buler & Mika, 2009;Sousa, 2013;Da Silva et al., 2014;Lordan et al., 2019). ...
Portuguese apple orchards located in the central west region, registered as ‘Maçã de Alcobaça’ protected geographical indication (EC 1107/96), have grown under managing practices according to the principles of precision and integrated production (DGADR, 2011). However, without a stabilized model regarding planting densities. Four orchards of Malus × domestica Borkh ‘Gala Schniga’, grafted onto ‘M.9’ rootstock, with 1,481 (4.5×1.5 m – orchard O1), 3,704 (3.0×0.9 m – O2), 3,861 (3.7×0.7 m – O3) and 4,762 (3.5×0.6 m – O4) trees ha‑1, planted in 2004 (O1), 2015 (O3 and O4) and 2016 (O2), were studied to compare light interception and distribution, photosynthesis, stomatal conductance, intrinsic and instantaneous water use efficiency (WUE), specific leaf area (SLA), reflectance parameters, yield, fruit distribution per position and harvest. Orchards O4 and O2 intercepted more light at solar noon, with maximum intercepted fractions near 0.50 and 0.45, respectively. The lowest canopy volume (8,781 m3 ha‑1) of O3 was reflected on a maximum intercepted fraction similar to O1 at solar noon (below 0.35). Leaves from O1 and O3 showed the highest photosynthetic rates and stomatal conductance in outside leaves at 1,500 and 150 µmol m‑2 s‑1. Leaves from O4 showed the best intrinsic and instantaneous WUE, SLA at the beginning of the season, normalized difference vegetation index (NDVI), maximum quantum yield of the PSII photochemistry, and performance index (PIabs). Orchard O4 had the highest productivity (113 t ha‑1). Average fruit weight and amount of fruits from the first harvest were also higher in O4 and O2 due to more light exposed surface area. On the contrary, O1 had a higher fruit number per tree and smaller fruit weight, although high productivity. This work pretends to clarify the most appropriate range of tree densities to use in modern orchards, benefits, and special care in high density orchards management.
... Photosynthetically active radiation (PAR) in the chamber was maintained at 1700 mmol·m -2 ·s -1 . Light saturation of A (photosynthesis) for pecan is reached between a PAR of 1500 to 1700 mmol·m -2 ·s -1 (Anderson, 1994;Lombardini et al., 2009). Reference CO 2 concentration was kept at 410 mmol·mol -1 , near the global mean atmospheric concentration (U.S. National Oceanic and Atmospheric Administration, 2021). ...
Analysis of composite pecan leaf samples typically used to determine need for nutrient applications does not account for variability among trees in the sampled area. To account for this unmeasured variability, pecan orchard block nutrient standards are greater than actual single tree nutrient requirements. In 2018 and 2019, we measured variability in a pecan orchard block by evaluating nutrient status of all trees in a study area consisting of two cultivars (Wichita and Western) grafted on open-pollinated ‘Ideal’ seedlings. Foliar zinc (Zn) coefficient of variation ( cv ) ranged from 0.186 to 0.255 within individual cultivars and years but was as high as 0.30 when combining cultivars within a year. The ‘Western’ cultivar had higher foliar Zn concentrations than ‘Wichita’, but Zn concentrations were not consistently associated with other leaf nutrient levels, soil Zn status, or other soil properties. Using observed foliar Zn variability, we determined that it is necessary to sample 35 trees for a composite sample to achieve a relative margin of error of 10% and 95% confidence level in a pecan orchard block with more than 1000 trees. We developed field scale foliar Zn recommendations based on individual tree research that indicates a minimum acceptable leaf Zn concentration of ≈15 mg·kg –1 is needed to maintain optimal photosynthetic function in Zn chelate fertigated pecan trees. Assuming a Zn cv of 0.30 and a composite sample comprised of leaves from 35 trees, the minimum acceptable orchard block Zn level to ensure that less than 5% of trees had suboptimal levels of Zn was 27.6 mg·kg –1 . An orchard block Zn level below 23.4 mg·kg –1 indicates that more than 5% of trees in the block had suboptimal foliar Zn concentrations.
... Concorde and Packham's Triumph pear varieties have very similar fruiting characteristics. Increasing the leaf to fruit ratio and thus increasing the size of the source relative to the sink is offered as an explanation for the improved fruit size (Lakso et al., 1994;Wünsche and Lakso, 2000). ...
Pear as a fruit species forms various categories of fruit-bearing branches during its life cycle. Depending on how many years it takes to form a young fruiting wood of pear cultivar from its meristem, there can be an annual, biennial, or perennial organogenesis cycle, which in the first place depends on cultivar’s genotype, the rootstock on which the cultivar is grafted, the applied agricultural techniques in nursery and other conditions. Knowledge of the individual pear cultivars organogenesis cycle is the basis for planning regular and stable yields. In order to determine the structure of a fruiting wood for an individual pear cultivar, it is necessary to make analyses on individual increment categories; what is developing from those increments in the following year. The morphological characteristics of annual increments are analysed (spurs, stems, and long shoots) of Packham’s Triumph pear cultivar, as well as the morphological characteristics of each category’s annual increment bourse-over-bourse, all with statistically significant difference between studied factors and factorial levels. Peckham’s Triumph had higher average length of long shoots in both examining years 2011 (53.63) and 2012 (45.33) and William's cultivar had the shorter ones.
... Photosynthetically active radiation (PAR) in the chamber was maintained at 1700 mmolÁm -2 Ás -1 . Light saturation of P n for pecan is reached between a PAR level of 1500 to 1700 mmolÁm -2 Ás -1 (Anderson, 1994;Lombardini et al., 2009). The reference carbon dioxide (CO 2 ) concentration was kept at 400 mmolÁmol -1 , near the global mean atmospheric concentration (U.S. ...
Many growers fertigating their orchards with zinc–ethylenediaminetetraacetic acid (Zn-EDTA) are still using supplemental zinc foliar sprays because of a lack of confidence that soil-applied Zn-EDTA is supplying enough Zn to the trees. A field study was conducted in a pecan orchard located near San Simon, AZ, on 8-year-old ‘Wichita’ trees growing in an alkaline, calcareous Vekol loam soil to evaluate the effectiveness of supplemental foliar Zn sprays. All trees were fertigated with 6.0 kg⋅ha –1 Zn in the form of Zn-EDTA in 2018 and 11.0 kg⋅ha –1 Zn in 2019 and did not exhibit visible signs of Zn deficiency. Foliar treatments of 3.75 mL⋅L –1 urea–ammonium nitrate (UAN), 3.6 g⋅L –1 zinc sulfate monohydrate (ZnSO 4 ·H 2 O), 3.6 g⋅L –1 ZnSO 4 ·H 2 O with 3.75 mL⋅L –1 UAN, 11 mL⋅L –1 Zn-EDTA, and water alone were applied to individual fruiting shoot terminals of trees on two dates each in 2018 and 2019. Treatments were sprayed directly onto the leaves of the selected terminals. Zn-EDTA was included as a foliar treatment in 2019 only. Leaf photosynthesis was measured to determine the impact of leaf Zn concentrations on plant function. Midday stem water potential (MDSWP) was measured to verify that water stress was not limiting photosynthesis. Both measurements were taken about 2 to 4 weeks after the application of foliar treatments. MDSWP measurements indicated a lack of water stress and therefore no effect on photosynthesis. Leaf samples collected from untreated branches indicated that the average foliar Zn concentration of untreated leaves was 21.3 mg⋅kg –1 in 2018 and 15.7 mg⋅kg –1 in 2019. No differences were observed in photosynthesis rates of treated branches. No additional benefit to leaf photosynthetic function or appearance was observed from spraying Zn on foliage of trees fertigated with Zn-EDTA.
... In broccoli, the use of biostimulants increased stomatal conductance and the photosynthetic rate [35]. Increased photosynthesis was associated with increased stomatal conductance as is usually the case [36][37][38]. However, despite higher stomatal conductance, intercellular CO2 concentration (Ci) was lower, suggesting that the biostimulant enhanced photosynthesis directly and not indirectly via increased stomatal aperture (otherwise Ci would have been higher). ...
Experiments were carried out in 2018 and 2019 to evaluate the effects of a biostimulant of animal origin, with a hormone-like action, on the growth and physiology of young olive trees. The biostimulant, consisting of a complex of natural amino acids (glycine, proline, and hydroxyproline, etc.), was applied by fertigation to both potted (one-year-old) and field-grown (2 years after transplanting) young olive trees. The control consisted of trees treated with an amount of urea nitrogen equal to the total nitrogen supplied with the biostimulant. Potted trees treated with the biostimulant showed greater growth than the control soon after treatment and up to the end of the vegetative season. Generally, this was associated with higher leaf photosynthetic rates and stomatal conductance. At the end of the experiment, all tree parts (roots, stem, shoots, and leaves) of the treated trees had greater biomass than the control. The trunks of field-grown trees treated with the biostimulant had greater growth with respect to the control. Overall, the results indicate the possibility of using the biostimulant based on complexes of natural amino acids to promote the growth of young olive trees.
... Internal flesh breakdown in mangoes is a physiological disorder manifested by pulp premature, uneven ripening [5]. There is still no consensus regarding its origin, although this disorder has been associated with nutritional imbalances, particularly related to high nitrogen levels and low calcium contents in mango pulps [6]. Some external indications -e.g., intense yellow pigmentation in mango peel -may be observed, but at this stage the pulp has already developed dark orange color, fermented odor, and aqueous texture. ...
The advent of new compact, bench-top, inexpensive and more user-friendly low-field nuclear magnetic resonance spectrometers in the last decade opens new opportunities for new non-destructive and non-invasive analytical methods to study physical-chemical properties of the internal parts of fruits. Correlations of the internal chemical environment with NMR relaxometry signals is an important parameter for food quality control, however, differently from controlled processed food, internal fruits environment has not always a straight correlation with relaxometry signals. In this paper we demonstrate that Time Domain-NMR signals combined with chemometrics analysis are a powerful tool for studies and industrial control of the internal quality of Palmer mangoes, providing tools to evaluate the fruit ripeness and internal flesh breakdown, which are highly difficult to be detected in intact fruits by other analytical methods. Results shows that combining transverse relaxation time distribution spectra with Principal Component Analysis it is possible to classify three groups: unripe mangoes, ripe mangoes, and ripe mangoes with physiological defects.
... Passion flowers include more than 500 described species and are distributed in tropical and sub-tropical areas around the world (Vanderplank 2000). Some species of this genus as Passiflora edulis f. flavicarpa Deneger (yellow passion fruit) and Passiflora edulis f. edulis Sims (purple passion fruit) are economically important worldwide (Martin & Nakasone 1994). Whereas, species as Passiflora ligularis Juss (sweet granadilla) and Passiflora quadrangularis L. (giant granadilla) are cultivated mainly in the Andean regions (Kluge 1998). ...
Several species of the genus Anastrepha Schiner are associated to different hosts and have a great economic importance in fruit crops of the Neotropical region. Ripe and unripe fruits of six passion flowers species were sampled in Oxapampa during 2016 and 2018. Larvae of Anastrepha pseudoparallela Loew (Diptera: Tephritidae) were detected infesting fruits of Passiflora ambigua Hemsl and Passiflora quadrangularis L. For the first time, this fruit fly species is recorded attacking fruits of passion flowers in Peru.
... As an example, in some studies with reduced stomatal conductance owed to extreme heat exposure, grapevines recovered within a few days [16,19,20]. Furthermore, some varieties are more heat-tolerant than others [55,56], and several acclimatization processes have been identified for extreme temperatures [25,49,57]. In the present study, a single variety (cv. ...
Extreme heat events or heatwaves can be particularly harmful to grapevines, posing a major challenge to winegrowers in Europe. The present study is focused on the application of the crop model STICS to assess the potential impacts of heatwaves over some of the most renowned winemaking regions in Europe. For this purpose, STICS was applied to grapevines, using high-resolution weather, soil and terrain datasets from 1986 to 2015. To assess the impact of heatwaves, the weather dataset was artificially modified, generating periods with anomalously high temperatures (+5 °C), at specific onset dates and with specific episode durations (from five to nine days). The model was then run with this modified weather dataset, and the results were compared to the original unmodified runs. The results show that heatwaves can have a very strong impact on grapevine yields. However, these impacts strongly depend on the onset dates and duration of the heatwaves. The highest negative impacts may result in a decrease in the yield by up to −35% in some regions. The results show that regions with a peak vulnerability on 1 August will be more negatively impacted than other regions. Furthermore, the geographical representation of yield reduction hints at a latitudinal gradient in the heatwave impact, indicating stronger reductions in the cooler regions of Central Europe than in the warmer regions of Southern Europe. Despite some uncertainties inherent to the current modelling assessment, the present study highlights the negative impacts of heatwaves on viticultural yields in Europe, which is critical information for stakeholders within the winemaking sector for planning suitable adaptation measures.
... This leads to some researchers opting for development of growth stage specific models [22]. However, having to develop separate models for each phenological stage is cumbersome since phenology in fruit orchards is highly influenced by environmental factors, such as temperature and relief [23,24]. Therefore, demanding field observations to determine phenological stage or advanced and performant models which predict the phenological stage are required [25]. ...
Early and precise spatio-temporal monitoring of tree vitality is key for steering management decisions in pome fruit orchards. Spaceborne remote sensing instruments face a tradeoff between spatial and spectral resolution, while manned aircraft sensor-platform systems are very expensive. In order to address the shortcomings of these platforms, this study investigates the potential of Remotely Piloted Aircraft Systems (RPAS) to facilitate rapid, low cost, and flexible chlorophyll monitoring. Due to the complexity of orchard scenery a robust chlorophyll retrieval model on RPAS level has not yet been developed. In this study, specific focus therefore lies on evaluating the sensitivity of retrieval models to confounding factors. For this study, multispectral and hyperspectral imagery was collected over pome fruit orchards. Sensitivities of both univariate and multivariate retrieval models were demonstrated under different species, phenology, shade, and illumination scenes. Results illustrate that multivariate models have a significantly higher accuracy than univariate models as the former provide accuracies for the canopy chlorophyll content retrieval of R2 = 0.80 and Relative Root Mean Square Error (RRMSE) = 12% for the hyperspectral sensor. Random forest regression on multispectral imagery (R2 > 0.9 for May, June, July, and August, and R2 = 0.5 for October) and hyperspectral imagery (0.6 < R2 < 0.9) led to satisfactory high and consistent accuracies for all months.
... Thus, there is a great gap between the average yield harvested and the potential yield that cashew crop is capable of producing under optimum growth conditions (Lakshmipathi et al., 2014). The vegetative and reproductive growth of trees depends on assimilate production which is controlled by tree architecture and leaf functions, both modulated by environmental interactions (Lakso, 1994). ...
Introduction - The high economic potentials of cashew (Anacardium occidentale L.) as a trade commodity has nothwithstanding been hampered by the universal low yield of the crop, a major production challenge that requires an urgent and drastic solution. Various research attempts to provide "High Tech" innovative approaches to increase production and productivity are yet to have meaningful impact. Nonetheless, traditional and cultural methods of improving and stabilizing yields have evolved through the years and would need standardization. Materials and methods - This paper reviews the important research gaps observed in the production practices, assesses the various biotic and abiotic factors that could contribute meaningfully to the immediate and future cashew production and productivity, and highlights important plant features to harness as potentials to further optimize crop development, crop management and economic output. Results and discussion - Different landraces of differing nut grades have been adopted for different ecological zones and these possess differing characteristics of crop growth, seed sizes, quality, and yields. Improving cashew growth and yields should commence at nursery stage for the selection of vigorous plants, use of dynamic population adjustment methods, control mechanisms for flowering, sex ratio adjustment and fruit set/retention, adoption of soil amendment methods for different soil types, incorporation of cropping system approaches to control weeds, and irrigation techniques for dry areas, and introduction of high grade varieties into production systems that will impact on the value chain, are those cultural practices that need appraisal. Conclusion - Optimizing cashew management practices can improve the economic, nutritional and industrial performances of this underutilized crop. Adoption of improved production practices will result in an increase in crop yield, accruable foreign exchange, and improved livelihood of growers, improvement in consumer healthy eating, and industrial evolution from increased production of processed nuts and overall higher output along the production value chain.
... While for other angiosperms, the cell division ceases followed by cell growth [6]. During development, one of the main characteristics of avocado is the large accumulation of oil fraction that is used as harvest and quality indexes, which can be up to 9-15% of oil in fresh weight, levels that are dependent on maturity stage and growing conditions in 'Hass' avocado [7][8][9][10]. Additionally, the mesocarp also accumulates high nutrient levels, which includes 6% of carbohydrates, 2% of proteins and vitamins E, C, B2, B12, B1, K and D [6,11]. ...
Background
Avocado (Persea americana Mill.) is a basal angiosperm from the Lauraceae family. This species has a diploid genome with an approximated size of ~ 920 Mbp and produces a climacteric, fleshy and oily fruit. The flowering and fruit set are particularly prolonged processes, lasting between one to three months, generating important differences in physiological ages of the fruit within the same tree. So far there is no detailed genomic information regarding this species, being the cultivar ‘Hass’ especially important for avocado growers worldwide. With the aim to explore the fruit avocado transcriptome and to identify candidate biomarkers to monitore fruit development, we carried out an RNA-Seq approach during 4 stages of ‘Hass’ fruit development: 150 days after fruit set (DAFS), 240 DAFS, 300 DAFS (harvest) and 390 DAFS (late-harvest).
Results
The ‘Hass’ de novo transcriptome contains 62,203 contigs (x̅=988 bp, N50 = 1050 bp). We found approximately an 85 and 99% of complete ultra-conserved genes in eukaryote and plantae database using BUSCO (Benchmarking Universal Single-Copy Orthologs) and CEGMA (Core Eukaryotic Gene Mapping Approach), respectively. Annotation was performed with BLASTx, resulting in a 58% of annotated contigs (90% of differentially expressed genes were annotated). Differentially expressed genes analysis (DEG; with False Discovery Rate ≤ 0.01) found 8672 genes considering all developmental stages. From this analysis, genes were clustered according to their expression pattern and 1209 genes show correlation with the four developmental stages.
Conclusions
Candidate genes are proposed as possible biomarkers for monitoring the development of the ‘Hass’ avocado fruit associated with lipid metabolism, ethylene signaling pathway, auxin signaling pathway, and components of the cell wall.
... Thus, there is a great gap between the average yield harvested and the potential yield that cashew crop is capable of producing under optimum growth conditions (Lakshmipathi et al., 2014). The vegetative and reproductive growth of trees depends on assimilate production which is controlled by tree architecture and leaf functions, both modulated by environmental interactions (Lakso, 1994). ...
... Light interception was below 20% for both tree shapes at the 2nd leaf, and increased to 70% and 60%, for V and conic tree shapes, respectively, at the 7th leaf. These observations coincide with previous studies that reported more light interception for V shaped trees when compared with conic shapes (Lakso, 1994;Robinson, 1997;Robinson and Lakso, 1989). Also similar to other studies (Palmer et al., 1992;Tustin et al., 1998), light interception was affected by planting density. ...
While the adoption of high-density apple orchards during the last decades has resulted in a significant improvement in yield and fruit quality, there is great disparity of opinion on the optimum density or the optimum tree shape. A 2-ha replicated field trial was planted in 1997 at the New York State Agricultural Experiment Station in Geneva, New York and continued through 2016, with 4 apple cultivars (‘Empire’, ‘Fuji’, ‘Gala’, and ‘McIntosh’), where we compared 8 tree planting densities (598, 840, 1026, 1283, 1655, 2243, 3262, and 5382 trees/ha), and two tree shapes (conic and V). At the lowest 2 densities, trees were planted on M.7 rootstock (598 trees/ha) and M.26 rootstock (840 trees/ha). At all of the higher tree densities, trees were planted on M.9. After 20 years, there was a strong negative correlation of tree planting density and trunk cross sectional area for all the cultivars and training systems, with the exception of ‘McIntosh’ in a V tree shape where no clear differences were observed. A different pattern for each cultivar was observed with respect to yield and planting density. High-density plantings were more appropriate for ‘Fuji’ and ‘Gala’, where conic tree shapes were better than V shapes. On the other hand, with ‘Empire’ and ‘McIntosh’ high planting density was not as beneficial. The highest yields from ‘McIntosh’ were realized at less than 3000 trees/ha with V tree shapes, or ∼3500 trees/ha with conic tree shapes. Planting density significantly affected firmness, soluble solids, fruit color, and fruit size. Light interception for each density and shape was measured only with ‘Empire’. Planting density had a strong positive effect on light interception. There were no significant differences in interception between tree shapes through the 4th leaf, however, after that more light was intercepted by the V shaped trees. Cumulative yield was a linear function of light energy intercepted by the canopy. While V tree shapes had more light interception, conic shapes seemed to have a better efficiency converting intercepted energy into yield. Planting density improved light interception, but decreased tree partitioning because of the need for more pruning leading to unbalanced trees. Tall Spindle at high planting density seemed to be the best option for cultivars with similar bearing habits such as ‘Fuji’ and ‘Gala’.
... It is not unreasonable, however, to expect similar P n :temperature thresholds between apple and pear because Pyrus communis L. and the major species hybridized to develop M. ·domestica Borkh. have similar centers of origin ( Westwood, 1993), nearly equivalent photosynthetic light response behavior ( Einhorn et al., 2012;Lakso, 1994), and early-season fruit growth and development patterns ( Westwood, 1993). Based on data from apple and the previous assumptions, maximum daytime temperatures during Expt. 2 of 25 to 32 °C and nighttime temperatures between 5 and 9 dfa (i.e., >15 °C) would have reduced available CHO because of increased respiratory costs. ...
Postbloom thinning of ‘Bartlett’ pears (Pyrus communis L.) is required to produce fruit of commercially acceptable size. In the Pacific Northwestern United States, low temperatures during early stages of pear fruitlet development often limit the efficacy of commercial thinning compounds. Hand thinning, therefore, remains the standard crop load management practice. Chemical thinning protocols are necessary to reduce the cost and dependence on hand labor. The plant hormone abscisic acid (ABA) was evaluated over multiple years in several ‘Bartlett’ pear orchards. ABA was applied to whole canopies at variable rates (50–500 ppm) when fruit diameter was generally between 10 and 12 mm. In three of four trials, ABA thinned in a dose-dependent manner. The relative degree of thinning for a given dose, however, was inconsistent among trials. Trees treated with ABA had a higher proportion of blank and single-fruited spurs than the control. Net photosynthesis (Pn) of single leaves was reduced 75% to 90% within one day of ABA application but gradually returned to ≈80% of control levels within 7 days and fully recovered by ≈14 days. Slightly greater and longer lasting Pn inhibition occurred with increasing ABA dose. Fruit weight and return bloom generally increased with increasing ABA rate. Fruit quality, when measured, was unaffected by ABA treatments. Inconsistent thinning response with ABA may be attributed to environmental factors, biological factors, or both. © 2017, American Society for Horticultural Science. All rights reserved.
... As we look for improved productivity of orchards to face future challenges linked to increasing population and decreasing resource availability, the physiology of tree light interception and utilization has much to offer. Whilst for the last 50 years research has shown the strong link between light interception and orchard productivity (Lakso, 1994), commercial orchards are still widely lacking in their capacity to intercept light in sufficient amounts. This is why, according to Tustin (pers. ...
... Differences between scions may also depend on the leaf area. Lakso (1994) pointed out, hydraulic conductivity of apple root systems can change in relation to the apparent evaporative demand of the top. Rootstock resistance of G.41 was significantly lower than for M.9 (p = 0.0036). ...
New highly productive apple rootstocks resistant to fire blight and crown rot can improve orchard profitability. However, some of the most promising rootstocks appear to have weak or brittle graft unions that are susceptible to breakage in the nursery and in the field. Flexural strength of graft unions may be related to the amount of vascular connections between graft partners, and poor vascular connections may cause increased hydraulic resistance. We sought to determine if transpiration rate and hydraulic resistance were correlated with graft union strength by comparing Geneva® 41 with the strong graft-forming Malling 9 selection NIC™ 29. The primary goal of this study was to compare weak and strong graft unions between similarly vigorous rootstocks by measuring whole-tree transpiration, as well as hydraulic resistance using the pressure chamber method. The effects of rootstock and grafting method on xylem hormone concentrations were also compared. There was no correlation between graft union strength and whole tree transpiration rate or leaf area-specific transpiration rate. The hydraulic resistance of the weaker forming rootstock was not significantly different than the strong graft union rootstock and was more closely correlated with overall size of the root system. However, hydraulic resistance of the scion and graft union were small relative to root system resistance, making it difficult to detect differences in graft union resistance among scion-rootstock combinations. Conversely, we observed differences in the hormone profile of xylem exudate among rootstock genotypes and among graft types.
... In apples the stomatal behaviour of the leaves appears to be correlated with photosynthetic rate (Lakso, 1994). Several factors are known to control stomatal conductance, such as light, soil water potential, internal CO 2 concentration as well as sink strength in trees. ...
... 2, time clusters were created as a blocking factor and PAR-in was adjusted between replications on each measurement date to account for the variability of ambient PAR measurement. Lombardini et al. (2009) and Anderson (1994) reported light saturation for pecan P n at 1500-1700 mmol · m -2 · s -1 . Average PAR in Expt. 1 was 1986 mmol · m -2 · s -1 and in Expt. 2 was 1821 mmol · m -2 · s -1 . ...
Southwestern U.S. pecan [Carya illinoinensis (Wangenh.) K. Koch] orchard soils are typically alkaline and calcareous, making micronutrients such as manganese (Mn) poorly available for root uptake. Manganese is essential to the light reactions of photosynthesis (Pn), but the level of leaf Mn for optimum Pn in pecan is unknown. Our objective was to characterize the relationships of foliar Mn fertilizer applications and leaf Mn nutrition with Pn over a broad range of leaf Mn concentrations. Two experiments were conducted from 2011 to 2012 (Expt. 1) and in 2013 (Expt. 2) in immature, nonbearing ‘Pawnee’ and ‘Western’ pecan orchards near Las Cruces, NM. To create differential leaf tissue Mn concentrations, four Mn spray concentrations were applied foliarly: 0.00, 0.34, 0.68, and 1.3 g Mn/L (Control, Low, Medium, and High, respectively). In Expt. 2, we added a higher Mn concentration (2.7 g Mn/L). Repeated measurements of leaf Pn were made beginning 1 week following a Mn application using aportablePn system. Across treatments in both studies, final leaf Mn concentrations ranged from 21 to 1488 µg·g⁻¹. Leaves treated with 0.68 g Mn/L had higher Pn than the other treatments in each experiment. In 2013, Pn rates of the leaves treated with 0.68 g Mn/L increased 7.1% and 10.4% over the Control for ‘Pawnee’ and ‘Western’, respectively. Our data confirm an association between leaf tissue Mn and Pn; the leaf tissue Mn concentration at which Pn rates are optimized in immature pecan trees was estimated to be 151.64 (±17.3SE) µg·g⁻¹ Mn. © 2017, American Society for Horticultural Science. All rights reserved.
... -1 in early summer to about 8 µmol.m -2 .s -1 at harvest time [12][13][14]. ...
... The decrease in RWC is a result of high salt concentration of the external solution, which caused osmotic stress and dehydration at cellular level (Chartzoulakis 2005). Bongi and Palliotti (1994) reported that a reduction in RWC caused a reduction in P N . Cultivars which can limit the accumulation of harmful elements and maintain a positive water balance in their tissues are more tolerant to salt. ...
The effect of salinity on some morpho-physiological characteristics in lisianthus cultivars was investigated. Cultivars namely, Blue Picotee (C1), Champagne (C2), Lime Green (C3), and Pure White (C4), were subjected to salt stress (0–60 mM NaCl) in a sand culture and their responses were measured. Our results showed that as a salinity level increased, growth parameters, relative water content, photosynthetic pigments, and gas-exchange characteristics decreased in all cultivars, while root fresh mass, root/shoot length ratio, electrolyte leakage, and a malondialdehyde content increased. However, the changes were less pronounced in C3 and C4 compared to C1 and C2. The regression analysis of the relationship between salinity levels and seedling height or root/shoot length ratio defined two groups with different slope coefficients: C1 and C2 as salt-sensitive cultivars and C3 and C4 as salt-tolerant cultivars. Shoot dry mass and leaf area tolerance indices were less affected by salinity in C3 and C4 compared to those in C1 and C2. Further, C3 and C4 showed higher photosynthetic rates, greater stomatal conductances, and accumulated greater K⁺ and Ca²⁺ contents and K⁺/Na⁺ ratios in roots and shoots compared to those in C1 and C2. The results suggests that C3 and C4 could be recommended as resistant cultivars due to maintaining higher growth, water balance, leaf gas exchange, ion compartmentalization, and lower lipid peroxidation in response to salinity compared to C1 and C2.
... Out of the 400 known species of Passiflora, about 50 or 60 bear edible fruits. The majority of these species are unknown outside their center of origin (Martin and Nakasone, 1994). The name " Passion fruit " is not derived from any aphrodisiac quality of the fruit but was named, reportedly, by a Spanish Catholic missionary who saw the flower, the symbolism of the passion of Christ where " Passus " means " suffering " and " Flos " means " flower " . ...
... La mayoría de ellas tienen su origen en la región tropical y subtropical de Suramérica (Cunha, 1996); de las especies conocidas, alrededor de 60 producen frutos comestibles. En el ámbito mundial se destacan por su importancia económica las especies Passiflora edulis f. flavicarpa Degener (maracuyá), Passiflora edulis f. edulis Sims (gulupa) y Passiflora alata Curtis (Martin & Nakasone, 1994). ...
En el proyecto ICA-Asohofrucol (TR 1305) se pudo determinar que actualmente se registran 17 especies del género Dasiops Rondani asociadas a pasifloras cultivadas en Colombia, 5 de ellas de importancia económica en cultivos de curuba, maracuyá, granadilla y gulupa (Figura. 1). También se estableció que existe una asociación de dos especies del género Dasiops Rondani para cada una de las pasifloras cultivadas, una
especie que afecta el botón floral y otra que afecta el fruto.
... respiration demand (GR) and organ carbon concentration were estimated from the literature, using mainly Lakso (1994) and Walton et al.(1999). Parameters related to the part of reserve that can be used by each entity at each time step (Rm) were peach values. ...
Background and aims:
Plant growth depends on carbon availability and allocation among organs. QualiTree has been designed to simulate carbon allocation and partitioning in the peach tree (Prunus persica), whereas MappleT is dedicated to the simulation of apple tree (Malus × domestica) architecture. The objective of this study was to couple both models and adapt QualiTree to apple trees to simulate organ growth traits and their within-tree variability.
Methods:
MappleT was used to generate architectures corresponding to the 'Fuji' cultivar, accounting for the variability within and among individuals. These architectures were input into QualiTree to simulate shoot and fruit growth during a growth cycle. We modified QualiTree to account for the observed shoot polymorphism in apple trees, i.e. different classes (long, medium and short) that were characterized by different growth function parameters. Model outputs were compared with observed 3D tree geometries, considering shoot and final fruit size and growth dynamics.
Key results:
The modelling approach connecting MappleT and QualiTree was appropriate to the simulation of growth and architectural characteristics at the tree scale (plant leaf area, shoot number and types, fruit weight at harvest). At the shoot scale, mean fruit weight and its variability within trees was accurately simulated, whereas the model tended to overestimate individual shoot leaf area and underestimate its variability for each shoot type. Varying the parameter related to the intensity of carbon exchange between shoots revealed that behaviour intermediate between shoot autonomy and a common assimilate pool was required to properly simulate within-tree fruit growth variability. Moreover, the model correctly dealt with the crop load effect on organ growth.
Conclusions:
This study provides understanding of the integration of shoot ontogenetic properties, carbon supply and transport between entities for simulating organ growth in trees. Further improvements regarding the integration of retroaction loops between carbon allocation and the resulting plant architecture are expected to allow multi-year simulations.
... Another hypothesis is that A max and g s are co-regulated under water stress [111][112]. While g s is, at times, correlated with VPD l [113], an increasing body of literature suggests that g s depends on leaf water status [72 -74; 84], possibly leaf or turgor pressure potentials [85][86]. Thus, while both water status and VPD l affect g s , the mechanisms of such responses are not clear. ...
The genus Juglans consists of four sections. Three of these, Rhysocaryon (black walnuts native to the Americas), Cardiocaryon (Japanese, Manchurian and Chinese walnuts, including selections known as heartnuts) and Trachycaryon (the butternut of eastern North America), exhibit thick shells and non-dehiscent hulls [234]. The fourth section, Juglans, is comprised of a single species, Juglans regia L., distinguished by a dehiscent hull which separates from the shell at maturity [234]. J. regia, the Persian walnut, is native to central Asia and grows as a wild or semi-cultivated tree in a wide area from south-eastern Europe and the Caucasus to Turkey and Iran, through southern portions of the former Soviet Union into China and the eastern Himalayas. It has been cultivated for its nut crop for at least several thousand years and was probably introduced into European commerce and agriculture by the ancient Greeks. It was prized by the Romans as Jovis glans and was utilized in medieval Europe as an herbal medicine, particularly for brain and scalp ailments. Since its introduction into North America it has commonly been referred to as the English walnut to distinguish it from the American black walnut while the correct name is Persian walnut [15; 217].
... The profitability of orchard depends upon the efficient absorption and utilization of light. Of various environmental factors, solar radiation should be considered first, as a source of energy that drives the biological production of dry matter and ultimately fruit yield (Lakso, 1994). The light interception is determined by the amount and arrangement of leaves, fruits and branches with in the tree canopy, tree shape and size, spacing, row orientation and angular distribution of light from the sun (Palmer, 1981). ...
The world is currently experiencing a faster rate of warming than ever before, resulting in climate change that affects natural vegetation and ecosystems. Changing phenological aspects and both the quantity and quality of global fruit production are affecting farmers’ incomes and food security. Fruit and nut species may survive in the wintertime in their native environments due to dormancy. Climate change also affects winter chilling, thus reducing fruit production and quality since most temperate fruit and nut species require exposure to chilling conditions for their proper development. Various strategies, including cultivar selection, defoliation, microclimatic modulation, color shedding, and usage of dormancy-triggering drugs, have been explored to bypass dormancy limitations. Rising temperatures accelerate fruit tree maturity, leading to earlier harvests. Higher temperatures and CO2 levels produce fruits and vegetables with higher ascorbic acid and phenols. Climate change shortens the vegetative and reproductive phases. Higher temperatures reduce the vegetative phase of most fruit crops, thus shortening their blooming period. Changes in the blooming seasons might introduce new insect pests. Global warming and unpredictable moisture levels will affect future food production despite increased carbon dioxide levels. Carbon dioxide has a smaller impact on most substances as opposed to temperature. Faced with these kinds of challenges to world fruit production, mitigation and adaptation strategies relating to strategic scientific evaluation should be developed.
Longe vão os tempos em que a discussão
sobre diferentes modelos de pomar vai
ocupando profissionais, académicos e
curiosos. De um lado, a ciência, reforçada
sucessivamente pelo conhecimento
proporcionado pelas novas tecnologias.
Do outro, o fundamentalismo toldado
por mitos e preconceitos, muitas vezes
de conversa fácil e tendenciosa, distante
da ciência, do mercado e incapaz de se
libertar de uma cultura ancestral. Neste
artigo procuraremos explicar a razão pela
qual a fruticultura evoluiu no sentido da
alta densidade e o porquê deste modelo ter
reforçado a eficiência e a sustentabilidade
da produção nacional.
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.
In 2018, 23.2 Mt of pears were produced in the world across 1.3 million hectares (ha) of cultivated land. This review analyzes different training systems and management styles that have been adopted worldwide, emphasizing the European pear's economic and environmental sustainability for the Mediterranean area of cultivation. Despite a reduced number of cultivars utilized around the world, pear presents a plethora of innovative training systems. In Europe, dwarfing rootstocks have led to reduced planting distances and a subsequent increase in planting density. Still, the economic sustainability of these systems is now questionable. Many of the quince rootstocks have made it possible to considerably reduce the size of the tree and introduce the concept of continuous row planting, with the management of orchards from the ground (i.e., pedestrian orchard). The planting distance must be chosen according to the soil fertility, the vigor of the grafting combination, and the training system. The planting distance dramatically affects the pruning and the management of soil, fertilization, and irrigation. The reduction of tree size also lowers the volume of spray necessary when applying pesticides. The variability in yield worldwide results from the interaction amongst cultivar/rootstock/training system/climate/management.
The crop water stress index (CWSI) has shown to be a good indicator of water status in fruit trees. Conventional CWSI measured over solar noon is widely used to monitor plant water status. This study compared the theoretical CWSI averaged over morning hours, CWSI mo , and over solar noon hours, CWSI md , of apple trees. This study also assessed their sensitivity to the changes in soil water status (soil water deficit [SWD, %] and soil water potential [SWP, kPa]) at different root zone depths. Four different types of commercial and experimental apple orchards with different characteristics growing under semi‐arid conditions in Washington State, United States, were chosen to assess CWSI mo against CWSI md sensitivity to soil water status. In some of these locations, soil water status ranged from fully watered to severely stressed (low water deficit to high water deficit). Ground‐based thermal and microclimate measurements were recorded continuously at 10‐s intervals and acquired for the 15‐min average on a daily basis throughout the study period. The linear relationship between SWD and CWSI mo at the effective root zone depth (average of 0–150 mm and 0–460 mm) resulted in a slightly higher correlation ( R ² = 0.42–0.64, p < .001) compared to the traditional CWSI md ( R ² = 0.32–0.60, p < 0.001). The correlation between CWSI mo and SWP ( R ² = 0.38–0.69, p < 0.001) was found to be larger than the correlation between CWSI mo and SWD, while SWP was less correlated with CWSI md ( R ² = 0.33–0.55, p < 0.001). Interestingly, a better relationship between soil water status and both CWSI mo and CWSI md was observed using a nadir view orientation thermal measurement. The CWSI mo showed higher sensitivity to SWP than SWD.
Exogenous application of abscisic acid (ABA) can cause fruit abscission. ABA indirectly reduces carbon assimilation via stomatal closure, but may also induce abscission directly through hormone action. Variable thinning of pear suggests an effect of light environment on ABA efficacy. We tested the hypothesis that combinations of ABA and shade will be additive in inducing fruit abscission if they affect different physiological processes. A two-way factorial design was used to evaluate ABA (0, 125 ppm) and shading (0, 44, 77%) on gas exchange and fruit set of 10-year-old ‘Bartlett’ pear trees on OH × F 97 rootstock. Within 6 h from the application of ABA (applied at petal fall), entire canopies of treated and non-treated trees were shaded for 15 days. Single-leaf stomatal conductance (gs) was controlled solely by ABA, whereas photosynthesis (Pn) was regulated by ABA and shade. Under increasing shade, however, Pn inhibition was not increased by ABA. Internal CO2 of leaves was consistently highest for 77% shade, indicating non-stomatal effects. Fruit set was significantly reduced by both ABA and shade, but a significant interaction suggested that ABA played a negligible role in abscission as shading increased. The data suggest that ABA and shading inhibited Pn by different mechanisms; shading limited light reactions and ABA reduced CO2 supply. When 125 ppm ABA was combined with high levels of shading, shading placed greater limits on Pn. Had ABA elicited a direct hormonal response to induce fruit abscission, an additive effect of ABA and shade would have been observed. Based on these data, the major role of ABA on pear thinning may be carbohydrate deficit.
The study analyzes the effect of associating four legumes (Crotalaria spectabilis, Cajanus cajan, Vigna unguiculata and Crotalaria longirostrata) in two spatial arrangements during two mango production cycles on the reproductive biology and productivity of ‘Ataulfo’ mango in the state of Chiapas, Mexico. Variables were measured from July 2011 to April 2013. Legume associations increased the number of floral panicles during the two cycles studied. The Crotalaria spectabilis treatment retained 510 floral panicles versus 359 in the control. Cajanus cajan showed a highly significant masculine/hermaphroditic flower ratio of 79/21 percent. Highest yields were obtained in the Crotalaria spectabilis and Crotalaria longirostrata associations (924 and 1388 kg ha-1 respectively). It is concluded that differences in reproductive variable values and productivity in mango favouring legume scenarios, were due to microclimatic changes and lower temperature fluctuations induced, to the incorporation of nitrogen by the legume rhizobia, to soil humidity and to the incorporation of organic matter.
The study analyzes the effect of associating four legumes (Crotalaria spectabilis, Cajanus cajan, Vigna unguiculata and Crotalaria longirostrata) in two spatial arrangements during two mango production cycles on the reproductive biology and productivity of ‘Ataulfo’ mango in the state of Chiapas, Mexico. Variables were measured from July 2011 to April 2013. Legume associations increased the number of floral panicles during the two cycles studied. The Crotalaria spectabilis treatment retained 510 floral panicles versus 359 in the control. Cajanus cajan showed a highly significant masculine/hermaphroditic flower ratio of 79/21 percent. Highest yields were obtained in the Crotalaria spectabilis and Crotalaria longirostrata associations (924 and 1388 kg ha-1 respectively). It is concluded that differences in reproductive variable values and productivity in mango favouring legume scenarios, were due to microclimatic changes and lower temperature fluctuations induced, to the incorporation of nitrogen by the legume rhizobia, to soil humidity and to the incorporation of organic matter.
Key words: Mangifera caesia Jack ex Wall, Legume, Association, Ecophysiology, Climate change, Productivity
The study analyzes the effect of associating four legumes (Crotalaria spectabilis, Cajanus cajan, Vigna unguiculata and Crotalaria longirostrata) in two spatial arrangements during two mango production cycles on the reproductive biology and productivity of ‘Ataulfo’ mango in the state of Chiapas, Mexico. Variables were measured from July 2011 to April 2013. Legume associations increased the number of floral panicles during the two cycles studied. The Crotalaria spectabilis treatment retained 510 floral panicles versus 359 in the control. Cajanus cajan showed a highly significant masculine/hermaphroditic flower ratio of 79/21 percent. Highest yields were obtained in the Crotalaria spectabilis and Crotalaria longirostrata associations (924 and 1388 kg ha-1 respectively). It is concluded that differences in reproductive variable values and productivity in mango favouring legume scenarios, were due to microclimatic changes and lower temperature fluctuations induced, to the incorporation of nitrogen by the legume rhizobia, to soil humidity and to the incorporation of organic matter.
Key words: Mangifera caesia Jack ex Wall, Legume, Association, Ecophysiology, Climate change, Productivity
In many perennial fruit trees, flowering in the year following a year with heavy fruit load can be quite limited. This biennial cycle of fruiting, termed alternate bearing, was described 170 years ago in apple (Malus domestica). Apple inflorescences are mainly found on short branches (spurs). Bourse shoots (BS) develop from the leaf axils of the spur. BS apices may terminate ~100 days after flowering, with formation of next year's inflorescences. We sought to determine how developing fruit on the spur prevent the adjacent BS apex from forming an inflorescence. The presence of adjacent fruit correlated with reaccumulation of transcript encoding a potential flowering inhibitor, MdTFL1-2, in BS apices prior to inflorescence initiation. BS apices without adjacent fruit that did not flower due to late fruitlet removal, neighboring fruit on the tree, or leaf removal, also reaccumulated MdTFL1-2 transcript. Fruit load and gibberellin (GA) application had similar effects on the expression of MdTFL1-2 and genes involved in GA biosynthesis and metabolism. Some apple cultivars are less prone to alternate bearing. We show that the response of a BS apex to different numbers of adjacent fruit differs among cultivars in both MdTFL1-2 accumulation and return flowering. These results provide a working model for the further study of alternate bearing, and help clarify the need for cultivar-specific approaches to reach stable fruit production. This article is protected by copyright. All rights reserved.
The crop-environment interaction in horticultural crops is receiving increased attention in the context of changing climatic conditions. Environmental stresses can cause morpho-anatomical, physiological and biochemical changes in crops, resulting in a strong profit reduction. A clear understanding of environmental factors and their interaction with physiological processes is extremely important for improving horticultural practices. Drought, excess moisture, salinity and heat stress are amongst the most important environmental factors influencing crop growth, development and yield processes. A comprehensive understanding of the impact of these stress factors will be critical in evaluating the impact of climate change and climate variability on horticultural crop production. Environmental stresses influence an array of processes including physiology, growth, development, yield and quality of crop. A clear understanding of environmental factors and their interaction with physiological processes is extremely important for improving horticultural practices. This review presents the most recent findings about the effects of the main abiotic environmental factors (water, temperature, salinity) on whole plant physiology of horticultural crops.
With the increasing effect of global warming, olive growing is facing very severe conditions. In Tunisia, the rainfall deficit reached in some areas more than 50% of the normal amount and the temperature rose considerably. The present study was conducted in order to understand the behavior of the olive trees to these changes. We found considerable morpho-structural leaf differences among the cultivars. Based on the study of leaf structure, „Dahbia‟ leaves showed the highest value of ratio (palisade/spongy parenchyma). So, this cultivar enhanced its sclerophylly by building parenchyma tissues. Also, „Besbessi‟ showed the lowest total lamina with high value of leaf stomatal resistance. In fact, to cope with the environmental stress conditions and water scarcity, olive cultivars used different strategy to overcome the surrounding circumstances. „Fougi‟ showed the lowest relative water content when „Lucques‟ exhibited good protection against water loss through the lowest values of water saturation deficit associated to the low values of stomatal resistance and leaf water potential. Concerning the chlorophyll fluorescence, the maximum quantum yield as the ratio Fv/Fm revealed that, for all studied cultivars, the functional integrity of photosystem II was not affected. The results obtained indicated good plasticity of olive leaves to cope with stress. The leaf mechanisms employed are very various (morpho-structural and eco-physiological) and differ from cultivar to another.
The effects of cloches and plastic soil mulch were evaluated on the fruit development period and fruit quality of the low-chill peach cv. Flordaprince in subtropical Australia. The fruit development period was not shortened cloche or plastic soil mulch treatments. However, mean total fruit weight per tree was significantly increased 23.8% and individual fruit weight 35.8% when paclobutrazol and cloche were combined. In contrast, for non-paclobutrazol treated trees under cloche, yield was reduced 8.5% due to excessive vegetative growth caused higher temperatures under cloche. Cloche, alone, significantly reduced fruit colour 38% but Brix was not significantly affected treatments.
The aim of this study was to investigate the roles of spur characteristics and carbon partitioning in regulating cultivar differences in fruit size of two late-maturing japanese pear cultivars, 'Atago' and 'Shinkou'. The study of spur characteristics showed that the two cultivars displayed different patterns in leaf development, flower characteristics, fruit growth, and shoot type. In contrast to 'Atago' with dramatically larger fruit, 'Shinkou' is a heavily spurred cultivar with a higher total leaf area and leaf number per spur early in fruit growth, less vegetative shoots, and smaller fruit but larger core. No significant differences were obtained in specific leaf weight, leaf thickness, chlorophyll content, and net photosynthesis of mature leaves, and seed number per fruit between the two cultivars. The results of trace experiment with 13C revealed that on a spur basis, there were no significant differences in the amount of 13C assimilate produced by spur leaves on each labeling date except at 190 days after anthesis, however, there were highly significant differences in the amount of 13C allocated to fruit between cultivars. Moreover, a higher amount of 13C assimilates was allocated to 'Atago' flesh (or fruit) than that in 'Shinkou'. Analysis of relative sink strength (RSS) indicates that the sink strength of fruit was dominant over those of other organs in the spur measured in both cultivars except at the early stage of fruit growth. 'Atago' exhibited a greater RSS of fruit and lower losses of 13C for respiration and export than 'Shinkou'. These results suggest that the movement of photosynthates into the fruit was determined by sink strength of the fruit rather than the source strength in the two cultivars.
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