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Nitrogen Requirements for Vegetative Growth, Flowering, Seed Production, and Ramet Growth of Paphiopedilum armeniacum (Orchid)
Abstract
Paphiopedilum armeniacum S. C. Chen et F. Y. Liu is endemic to China and has great ornamental value. Little is known about its nutrient requirement for growth and reproduction after deflasking (transplantation of seedlings from culture vessels to pots) We studied the effects of adding nitrogen (N) (0, 105, 210, and 420mg·L-1) on the vegetative growth and reproduction of P. armeniacum. N enrichment improved leaf area and lengthened the leaf lifespan during the vegetative stage. The effects of N application on flower size were minor. The intermediate N level of 210 mg·L-1 (MN) increased the seed capsule weight, seed germination rate, and improved the growth of seedlings that developed from seeds of MN-treated plants. N fertilizer exerted little influence on ramet emergence and ramet number per plant, but a low N concentration of 105 mg·L-1 promoted the leaf number and leaf area of ramets. Appropriate N levels for P. armeniacum in production and cultivation should be determined according to different production objectives.
... Research related to mineral fertilisation in orchids is scarce, but orchids are considered to have nutritional requirements like other species (Ichinose et al., 2018;Biswas et al., 2021). Thus, nitrogen nutrition is an essential practice for orchid cultivation and can help growers to produce orchids more efficiently (Zong-min et al., 2012). But growers generally use mineral nutrition based on other agricultural crops, without considering the specific nutritional needs of each species (Costa et al., 2024). ...
... Wang (2007) showed that Phalaenopsis Taisuco Kochdian plants treated with 200 mg L 1 of N and P, but with low doses of K (50 and 100 mg L 1 ) in substrate with only pine bark, advanced their flowering, approximately by 15 days, compared to plants grown with moss. Themselves, Zong-min et al. (2012) reported that Paphiopedilum armeniacum with a high dose of N (420 mg L 1 ) decreased the time to flowering by five days compared to the lower dose (105 mg L 1 ), and 8 days when no N was applied. Satari et al. (2022) observed no difference in time to first flower opening of Phalaenopsis, with application of various NPK formulations (19-6-20, 12-12-36, 20-20-20), where the range of days to anthesis was 278 to 282 days. ...
Objective: To analyze features of time to flowering of orchids and some strategies for its control in cultivation for ornamental purposes. Design/methodology/approach: Information from various authors and our own data is shown, in relation to the management of flowering time of ornamental orchids, based on treatments of environmental effects, plant growth regulators (PGRs) and nutrition. Findings/conclusions: It is possible to reduce the flowering time of orchids by environmental modifications, mainly temperature and photoperiod. This can also be achieved by nutritional management, mainly macro-nutritional, and through organic nutrition and PGRs. However, much more information is needed, especially for native orchid species with ornamental potential.
... Although the effects of nitrogen on orchid growth under cultivation conditions have been confirmed by some studies, the demand for that nutrient is relatively low (Mou et al., 2012;Wang and Chang, 2017). Within a certain range, increasing the nitrogen concentration can promote vegetative growth, and increase the number of flowers produced by genera such as Phalaenopsis, Cattleya, and Dendrobium. ...
... When abundant nitrogen is available, this orchid is propagated primarily by seeds. However, asexual reproduction dominates when nitrogen supply is limited (Mou et al., 2012). Therefore, these reports demonstrate that the effect of nitrogen on orchid growth varies by species and developmental stage. ...
The Orchidaceae is a diverse and wide spread family of flowering plants that are of great value in ornamental, medical, conservation, and evolutionary research. The broad diversity in morphology, growth form, life history, and habitat mean that the members of Orchidaceae exhibit various physiological properties. Epiphytic orchids are often characterized by succulent leaves with thick cell walls, cuticles, and sunken stomata, whereas terrestrial orchids possess rhizomes, corms, or tubers. Most orchids have a long juvenile period, slow growth rate, and low photosynthetic capacity. This reduced photosynthetic potential can be largely explained by CO2 diffusional conductance and leaf internal structure. The amount of light required for plant survival depends upon nutritional mode, growth form, and habitat. Most orchids can adapt to their light environments through morphological and physiological adjustments but are sensitive to sudden changes in irradiance. Orchids that originate from warm regions are susceptible to chilling temperatures, whereas alpine members are vulnerable to high temperatures. For epiphytic orchids, rapid water uptake by the velamen radicum, water storage in their pseudobulbs and leaves, slow water loss, and Crassulacean Acid Metabolism contribute to plant-water balance and tolerance to drought stress. The presence of the velamen radicum and mycorrhizal fungi may compensate for the lack of root hairs, helping with quick absorbance of nutrients from the atmosphere. Under cultivation conditions, the form and concentration of nitrogen affect orchid growth and flowering. However, the limitations of nitrogen and phosphorous on epiphytic orchids in the wild, which require these plants to depend on mycorrhizal fungi for nutrients throughout the entire life cycle, are not clearly understood. Because they lack endosperm, seed germination depends upon obtaining nutrients via mycorrhizal fungi. Adult plants of some autotrophic orchids also gain carbon, nitrogen, phosphorus, and other elements from their mycorrhizal partners. Future studies should examine the mechanisms that determine slow growth and flower induction, the physiological causes of variations in flowering behavior and floral lifespan, the effects of nutrients and atmospheric-nitrogen deposition, and practical applications of mycorrhizal fungi in orchid cultivation. © 2018 Kunming Institute of Botany, Chinese Academy of Sciences
... While there are studies on the use of mineral fertilizers in orchid nutrition (Bichsel & Starman, 2008;Wang, 2000;Wang, 1996;Zong-min, Ning, Shu-yun, & Hong, 2012), there are few specific ones and the application form of many others is unknown. Among the advantages of the efficient use of fertilizers are the stimulation of vegetative growth, the increase of precocity in flowering and the promotion of the symbiotic relationship with mycorrhizal fungi (Espinosa-Moreno, Gaytán-Acuña, Becerril-Román, Contreras, & Trejo-López, 2000). ...
... Si bien existen estudios sobre el uso de los fertilizantes minerales en la nutrición de orquídeas (Bichsel & Starman, 2008;Wang, 2000;Wang, 1996;Zong-min, Ning, Shu-yun, & Hong, 2012), hay pocos específicos y se desconoce la forma de aplicación de muchos otros. Entre las ventajas del uso eficiente de los fertilizantes se encuentran la estimulación del crecimiento vegetativo, el aumento de la precocidad en la floración y la promoción de la relación simbiótica con hongos micorrízicos (Espinosa-Moreno, Gaytán-Acuña, Becerril-Román, Contreras, & Trejo-López, 2000). ...
The use of biofertilizers in orchid growing can be an alternative to reduce the environmental impact of traditional inorganic fertilization. The aim of this research was to evaluate the effect of mineral fertilization and biofertilization on some physiological parameters of Laelia anceps Lindl. subsp. anceps seedlings in vegetative stage. Three fertilization treatments were evaluated: 1) mineral fertilization (MF), 2) biofertilization (BFERT) and 3) mineral fertilization + biofertilization (MF + BFERT). The concentration and content of chlorophylls, and the concentration of amino acids and total soluble proteins were measured. No treatment affected the concentration of chlorophylls in leaves. In general, the MF and BFERT treatments significantly increased the concentration of chlorophylls a, b and total in pseudobulbs, and their content in leaves and pseudobulbs. The concentration of amino acids in pseudobulbs was higher with MF, while the concentration of proteins in leaves was greater with MF + BFERT. Biofertilization promoted positive responses in the physiological parameters evaluated in comparison with mineral fertilization; therefore, it is considered to have potential for use in the species evaluated in this study.
... Nitrogen is one of the main structural elements of plants and plays an important role in the vegetative and reproductive growth. Zong-min et al. (2012), stated that this element represents 2% of the dry matter of the plants and is a component of proteins, nucleic acids, coenzymes and numerous secondary metabolites (Miller and Cramer, 2004), its failure reduces plant growth and leaf area with the consequent decrease in the rate of photosynthesis. Proper management of N in horticultural plants leads to obtain high-quality flowers, fruits and seeds. ...
... Su insuficiencia reduce el crecimiento de la planta y del área foliar con la consecuente disminución en la tasa fotosintética. El manejo adecuado del N en las plantas hortícolas conduce a obtener alta calidad de flores, frutos y semillas (Zong-min et al., 2012). ...
México es el cuarto productor de mango (Mangifera indica L.) en el mundo. El cultivar Ataulfo tiene importancia comercial por presentar mayor vida en anaquel que la de otros cultivares; pero presenta la desventaja de producir frutos sin semilla que carecen de valor para la exportación. Para determinar si aplicaciones de boro al suelo pueden disminuir la formación de frutos sin semilla y mejorar el estado nutrimental del árbol, se hicieron aplicaciones al suelo de boro (Solubor) de 25, 50 y 100 g de B por árbol, a los tres meses después de la cosecha, en una huerta de ocho años de edad en Tepic, Nayarit. Se evaluó el porcentaje de frutos sin semilla, la concentración nutrimental en hojas, inf lorescencias y frutos. El análisis nutrimental foliar antes de la aplicación de los tratamientos indicó que los árboles presentaron deficiencia de nitrógeno. Las dosis de 50 y 100 g de B, disminuyeron en 45 y 35%, respectivamente, el número de frutos sin semilla y mejoraron la concentración de Ca y B en la planta, así como la de B en brotes con inf lorescencia y de hojas al final del desarrollo del fruto. Las inflorescencias concentraron N, P, K y Mg. El Ca y B se concentraron en las hojas. La semilla acumuló más N, P, K, Ca y Mg que la pulpa con epidermis. Los frutos con semilla superaron a los sin semilla en la concentración de N, P y Mg, en tanto que éstos últimos concentraron más Ca.
... Nitrogen is one of the main structural elements of plants and plays an important role in the vegetative and reproductive growth. Zong-min et al. (2012), stated that this element represents 2% of the dry matter of the plants and is a component of proteins, nucleic acids, coenzymes and numerous secondary metabolites (Miller and Cramer, 2004), its failure reduces plant growth and leaf area with the consequent decrease in the rate of photosynthesis. Proper management of N in horticultural plants leads to obtain high-quality flowers, fruits and seeds. ...
... Su insuficiencia reduce el crecimiento de la planta y del área foliar con la consecuente disminución en la tasa fotosintética. El manejo adecuado del N en las plantas hortícolas conduce a obtener alta calidad de flores, frutos y semillas (Zong-min et al., 2012). ...
Mexico is the fourth largest producer of mango (Mangifera indica L.) in the world. The Ataulfo cultivar has commercial importance because of its larger shelf life compared to other cultivars; but it has the disadvantage of producing seedless fruits that have no value for export. In order to determine whether the application of boron to soil can reduce the formation of seedless fruit and, improve the nutritional status of the tree, soil applications of boron were made (Solubor) 25, 50 and 100 g of B per tree, after three months after harvest in an orchard eight years old in Tepic, Nayarit. The percentage of seedless fruit, the nutrient concentration in leaves, inflorescences and fruits were evaluated. The nutritional analysis foliar before application of said treatments trees presented nitrogen deficiency. Doses of 50 and 100 g of B decreased by 45 and 35%, respectively, the number of seedless fruit and improved concentration of Ca and B on the plant, and that of B in shoots with inflorescences and leaves at the end of fruit development. The inflorescences concentrated N, P, K and Mg. Ca and B were concentrated in the leaves. The seeds accumulated more N, P, K, Ca and Mg than the pulp with epidermis. The fruit with seeds outscored the seedless in the concentration of N, P and Mg, while the latter concentrated more Ca.
... Additionally, the growth environment significantly impacts nitrogen-use efficiency, which varies greatly under different soil types, nitrogen levels, and climatic conditions [69]. Nitrogen uptake and utilization can be affected by different soil nutrients as well as rhizosphere microbial species in the same plant in different habitats [70]. The results of the present study showed that heterogeneous habitats could have an effect on nitrogen-use efficiency. ...
Paphiopedilum micranthum, an IUCN Red List species, is discontinuously distributed in the karst limestone mountain of southwest China and exhibits ecological specialization, typically through lithophytic and terrestrial ecotypes. Whether the distribution of rhizosphere bacteria and fungi in these different habitats is random or reflects soil preferences requires further investigation. A total of 73 samples from the core distribution areas in China, representing all habitats in two sites, were analyzed for soil differences by comparing edaphic properties and microbial community structure based on high-throughput sequencing of bacterial 16S rRNA genes and fungal ITS region sequences, alongside soil physiochemical data. The results showed no significant differences in microbial community richness and diversity across the heterogeneous habitats. However, significant differences in taxa were observed across various habitats. Dominant bacterial phyla included Actinobacteriota, Proteobacteria and Acidobacteriota, with dominant genera such as Crossiella, Pseudonocardia, 67-14, Mycobacterium and RB41. The primary fungal phyla were Basidiomycota and Ascomycota, featuring prominent genera such as Phlegmacium, Archaeorhizomyces, Trechispora, and Lepiota. There were 16 bacterial genera and 13 fungal genera associated with nitrogen transformation and fixation. Alkali-hydrolyzed nitrogen (AN) was identified as a main driver of soil bacterial and fungal community variation. Based on an analysis of soil physicochemical properties, ammonium nitrogen content was consistently higher than nitrate nitrogen across different habitats. Furthermore, across all heterogeneous habitats, P. micranthum showed no significant differences in nitrate nitrogen, ammonium nitrogen, or their ratio. The nitrogen-use efficiency of P. micranthum ranged from 7.73% to 9.87%, with the highest efficiency observed in the terrestrial habitat of Shedu. These results suggest that P. micranthum prefers habitats rich in organic matter and nitrogen, showing a preference for ammonium nitrogen uptake in natural conditions. Heterogeneous habitats affect plant nitrogen-use efficiency as well as changes in microbial community composition.
... The levels of nutrients to be offered may vary according to the production objective. According to Zong-Min, Ning, Shu-Yun and Hong (2012), N enrichment results in increased leaf area and leaf length during vegetative state, however, it has little effect on the size of flowers in Paphiopedilum. In seed production, the use of intermediate levels of N provides an increase in capsule weight and seed germination rate, in addition to improving seedling development. ...
The Orchidaceae family stands out when it comes to the commercialization of pot flowers, this is due to their flowers being widely attractive and have variability of colors, size and shapes according to the species; this results in plants with high relevance to the economy in the floriculture sector. The goal of this study was to elucidate questions about the effect of micronutrients on initial growth, the influence of electrical conductivity and frequency of fertilizer application, and the efficiency of organic fertilization with castor bean cake, on the growth and nutrition of Brassia verrucosa Lindley orchid. Studies with mineral fertilization involving nitrogen (N), phosphorus (P) and potassium (K) in Cattleya and Phalaenopsis seedlings allowed to obserevar that the N increment increased the number of flowers in Cattleya, while P and K did not affect this variable. The salinity of irrigation water also has an effect on growth and flowering. The electrical conductivity, the sources of fertilizers, their interaction with the substrate, the balance between the nutrients, the quantities and frequencies to be used, in addition to the different phenological requirements and characteristics intrinsic to the species, are important aspects to be considered in fertirigation.
... Nitrogen is one of the essential minerals for chlorophyll and protoplasm formation [23]. Zong-min et al., [24] indicated that nutrient availability particularly nitrogen determines plant vegetative development and yield. ...
A field experiment was conducted at the Research and Production Station of the National Research Center in Nubaria District, Beheira Governorate, Egypt, during the 2020 /2021 to study the effect of organic (Poultry Manure) and inorganic fertilizers (Potassium Nitrate) on sunflower growth parameters under water stress conditions. The soil application of Poultry manure (0, 2, 4, 6 ton fed-1) occupied the main plots and potassium nitrate treatments applied as a foliar spray at the rates (0, 1, 2 and 3%) randomly distributed in the sub-plots. Results showed that the increase in poultry manure rates was accompanied by significant increase in chlorophyll content, relative water content and total leaf Area. Data indicated that the maximum values of the proline content were registered for the control treatment and the minimum values recorded with the application of 6-ton poultry manure fed-1 combined with 3.0% KNO3 foliar spray under sufficient and deficit irrigation treatments. Results indicated that increasing poultry manure rates was associated with significant increase of sunflower plant height, head weight, head diameter, 100 seed weight and grain yield of sunflower. Results indicated that the highest values of growth and yield parameters of sunflower were attained by application of 6.0 ton fed-1 poultry manure with a foliar spray KNO3 at a rate of 3.0% under water stress condition.
... In other words, the nutrient content of the soil composition: chicken manure: oil palm empty fruit bunches fertilizer contains sufficient nutrient elements to form leaves. The availability of nutrients, particularly nitrogen affects plant vegetative growth and crop yields (Zong-Min et al., 2012). An increase in the number of leaves corresponds to that in leaf area. ...
Spinach was a vegetable that was rich in nutrients and has many health benefits. The high level of public consumption of spinach plants in line with population growth, it was necessary to increase production by using organic fertilizers. This research aimed to determine the effects of the composition of the growing media among soil, chicken manure, and oil palm empty fruit bunches fertilizer on the growth and yield of spinach. The research used a completely randomized design (CRD) with 6 treatments repeated three times and each treatment unit consisted of 5 plants so that the total number of all plants was 90 plants. The results of the analysis of diversity showed that the treatment of chicken manure and oil palm empty fruit bunches fertilizer had a very significant effect on the plant height, leaf area, plant fresh weight, crown fresh weight, root fresh weight and plant dry weight. The provision of chicken manure and oil palm empty fruit bunches fertilizer had a significant effect on the number of leaves, but had no significant effect on the level of greenness of the leaves and the root shoot ratio. The results of the study showed that the soil treatment: chicken manure: oil palm empty fruit bunches fertilizer (1:2:2) provided the best results on the variables of plant height, number of leaves, leaf area, plant fresh weight, crown fresh weight, root fresh weight, and plant dry weight. The soil composition : chicken manure : oil palm empty fruit bunches fertilizer (1:2:2) was the best combination of planting media for the spinach growth and yield. Spinach cultivation using the composition of soil planting media, chicken manure, oil palm empty fruit bunches (1:2:2) could increase crop yields.
... In addition, compared with Peters®, the NK1+BO combination increased mean Clf A (5.85 versus 7.33 mg g -1 ) and Crt (4.78 versus 5.81 mg g -1 ) content. In Paphiopedilum arminiacum, increase in nitrogen concentrations in fertigation increased the Clf A+B content (Zong-Min et al., 2012). Likewise, Maass, Céspedes and Cárdenas (2020) observed that the fertilization of Petroselinum crispum with the highest concentrations of bokashi increased shoot dry mass and chlorophyll content. ...
Potted flower production is an important floricultural activity. However, there have been few studies on the fertilization management of orchids. Fertigation with urea and potassium chloride is feasible, but little information is available regarding the interaction of these fertilizers with other sources of nutrients. Thus, the present study evaluated the effects of application of bokashi and a simple superphosphate and their interactions with fertigation on the growth and nutrition of hybrid Cattleya. Seedlings of Laeliocattleya Drumbeat × Laeliocattleya Gold Digger hybrid were submitted to two ferti-irrigation levels (absent and present) using urea and potassium chloride as nitrogen and potassium sources, respectively. As complementary fertilization, bokashi and superphosphate were applied singly and in combination. A commercial fertilizer (Peters®) was used as an additional control. Fertigation increased plant height; leaf area; number, length, and diameter of pseudobulbs; dry mass of leaves, pseudobulbs, and roots; and content of chlorophyll, carotenoid, and nitrogen. The application of bokashi resulted in dry mass gain in all plant organs. The combination of fertigation and bokashi was superior to the commercial fertilizer in terms of increased leaf area, chlorophyll A content, carotenoid content, and dry mass.
... Substrate management and nitrogen (N) fertilization in ornamental orchids are key factors determining the success of orchid production systems (Zong-min et al., 2012). However, the mechanisms of nutrient uptake in wild epiphytic orchids are not entirely known, while the effects of the form and concentration of N on growth and flowering of orchids are poorly understood (Zhang et al., 2018). ...
The effects of three fertilization methods (FM) using the Peters Professional® 30N-10P-10K water soluble fertilizer were analyzed: fertilization in irrigation water (FIW), foliar fertilization (FF), and their combination (FIW + FF), as well as two substrate particle sizes (SuPS): larger particle size (LPS) and smaller particle size (SPS), on the growth and macronutrient status of Laelia anceps subsp. anceps (Orchidaceae). A 3 × 2 factorial experiment was established. Aerial and root growth, dry weight and concentration of macronutrients N, P, K, Ca, and Mg in leaves, pseudobulbs, and roots were all evaluated. The interaction of the study factors resulted in a greater number of leaves, while by simple effects, greater leaf area, number of pseudobulbs, root volume, and dry matter of leaves and roots were obtained, when FIW and LPS were used. With FF, greater growth in root volume was observed. There were no differences in the concentration of N in the growth organs analyzed, but due to the interaction of factors, a higher concentration of P, K, Mg, and S was observed in roots, mainly with FIW + FF and SPS; although for P, there was a higher concentration in FIW and LPS. In the case of SPS, the concentrations of K and S were higher in leaves, and in pseudobulbs P, K, Ca, Mg, and S were higher. The results showed that there are positive effects on plant growth when FIW and LPS are used, while higher concentrations of nutrients in leaves, pseudobulbs and mainly in roots are observed when using SPS.
... Nitrogen is one of the essential minerals for chlorophyll and protoplasm formation [28,29], and its deficiency can cause yellowing of leaves and stunted growth of plants [30]. Reports of Cambui et al. [31] and Zongmin et al. [32] indicated that nutrient availability particularly nitrogen determines plant vegetative development and yield. Hence, the better sunflower morphological growth in plots supplied with organic fertilizers could be linked directly to nutrient availability. ...
Utilization of adequate fertilizer rate enhances soil physical and chemical properties, minimizes soil nutrient imbalance, and promotes better crop growth and development. The study investigated the influence of varying rates of chicken manure and NPK fertilizers as it affected growth, nutrient uptake, seed yield, and oil yield of sunflower on nutrient-limiting soil. Field experiments were carried out during 2014 and 2015 planting seasons for both main and residual studies. There were eight treatments comprising four rates of chicken manure (5, 10, 15, and 20 t·ha ⁻¹ ), three rates of NPK (30, 60, and 90 kg·N·ha ⁻¹ ), and control. The experiment was laid out in a randomized complete block design with three replicates. Growth, yield, dry matter and proximate, nutrient uptake concentration, and oil content were determined following standard procedures. Data were analyzed using ANOVA, and means were compared with the Duncan multiple range test (DMRT) at p≤0.05 . Performance of sunflower was superior on the field fertilized with 10 t·ha ⁻¹ chicken manure which was comparable to 90 kg·N·ha ⁻¹ NPK fertilizer. Sunflower seed yield and oil quality were superior in plots supplied with 10 t·ha ⁻¹ chicken manure which was comparable to 60 kg·N·ha ⁻¹ NPK. Growth, yield, dry matter, and proximate content were least in the unfertilized plots.
... MD2 plants during red bud stage [11]. Nitrogen plays a very important role in growth, reproduction, and maintenance of the photosynthetic capacity of plants [30,31]. However, N content in plants has also been linked in reducing the concentration of anthocyanin in berries and soluble solids in grape juice, due to the increase in vegetative growth [32]. ...
Vermicompost is an organic waste produced from earthworms that can enhance the soil condition and is rich with essential plant nutrients, thus increasing produce quality and shelf life. In this study, a one-year field trial was conducted to elucidate the effects of vermicompost supplementation on the composition of bioactive compounds and antioxidant activities of pineapple (Ananas comosus var. MD2) fruits, compared to control and application of chemical fertilizer. Based on the results, pineapple fruits produced from plants supplemented with chemical fertilizer showed the strongest radical scavenging properties against 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), followed by vermicompost and control plants. Application of chemical fertilizer and vermicompost also produced fruits with a very high content of chlorophylls and β-carotene compared to control plants. However, the amounts of bioactive compounds present in fruits produced with chemical fertilizer are higher than in fruits produced with vermicompost. Total phenolics content and Ferric Reducing Antioxidant Power (FRAP) reducing power were lowest in fruit extracts produced from pineapple plants supplemented with vermicompost. These results suggested that vermicompost cannot completely replace chemical fertilizer for the production of fruits with a high content of phytoconstituents but could be used as an additional supplement to reduce environmental pollution and ensure agricultural sustainability.
... Uma das principais razões nos ganhos da parte aérea é atribuída a expansão e desenvolvimento das folhas, possivelmente estimulado pelo fornecimento dos nutrientes, principalmente de N, que resultou em plantas mais altas e consequentemente refletiu no acúmulo de massa seca. Zong-min et al. (2012) relataram que a aplicação de N em Paphiopedilum armeniacum, resultou em incrementos da área e comprimento foliar. Para Dendrobium nobile, o aumento da concentração de N em solução, de 0 para 100 mg L -1 , houve um incremento de 76% em altura (BICHSEL et al., 2008). ...
Fertilization through nutrient solution is commonly used in commercial production of potted flowers, being employed soluble NPK formulations. However, most commercial formulations available in the market have high costs and the use of agricultural fertilizers can be an economically viable alternative. The objective of this study was to evaluate the effectiveness of agricultural fertilizers applied as nutrient solutions, in replacement of commercial formulations, on initial growth of Cattleya labiata. C. labiata seedlings in vitro propagated were grown in a greenhouse with controlled temperature, 27 ± 2° C, and retaining 50% brightness. Polypropylene pots were used with 0.415 L capacity, containing a mixture of pine bark and charcoal (1:1, v:v) as substrate. Altogether were used 4 treatments: without fertilization (control); Peters® - NPK 20 20 20 (3.0 g L -1 ); NPK - urea (1.3 g L -1 ), superphosphate (3.3 g L -1 ) and potassium chloride (1.0 g L -1 ); NK - urea (1.3 g L -1 ) and potassium chloride (1.0 g L -1 ). The nutrient solutions were applied 50 ml per pot every two weeks, according to the treatments. Were evaluated phytometric characteristics, pH and electrical conductivity of the substrate beyond the levels and accumulation of macronutrients. The experimental design was completely randomized with 12 replications, being considered each pot with two plants as an experimental unit. The parameters were submitted to ANOVA and Tukey’s test at 5% probability. Regarding phytometric parameters no significant differences were observed between the treatments that received fertilization, which are superior to the control in height and dry mass of shoots. The more accumulated nutrients were K>Ca>N, in the treatments that received fertilization. The use of urea, superphosphate and potassium chloride, applied in nutrient
solution, have potential to replace the commercial formulations in the initial growth of native orchid Cattleya labiata.
A condutividade elétrica e frequência de aplicação na fertirrigação de orquídeas, não estão estabelecidas. O objetivo foi avaliar a influência da condutividade elétrica e das frequências de aplicação de fertilizantes, no crescimento e nutrição de Brassia verrucosa. Mudas de Brassia verrucosa foram cultivadas por 18 meses. As fertilizações tiveram como fonte de nitrogênio (N), fósforo (P) e potássio (K): ureia, cloreto de potássio e fosfato monoamônico diluídos em três concentrações: C1 (0,5:0,5:0,5; g L-1), C2 (1:1:1; g L-1) e C3 (2:2:2; g L-1). As condutividades elétricas apresentaram 1,25, 2,5 e 4,7 mS cm-1, respectivamente. Foram adotadas três frequências de aplicação: mensal (F1), quinzenal (F2) e semanal (F3). Plantas somente irrigadas foram o controle. O delineamento foi inteiramente casualizado com 10 repetições, em esquema fatorial 3x3+1. Os parâmetros fotométricos e teores de macronutrientes na parte aérea, foram submetidos a ANOVA e teste Tukey a 5% de significância. A condutividade das soluções resultou em maiores incrementos sobre as variáveis fitométricas. Aumento da condutividade elétrica promoveu incrementos no crescimento da Brassia verrucosa, bem como aumentos nos teores de N, P e K. A condutividade C3 (4,7 mS cm-1) aliada a frequências de aplicação quinzenais (F2) ou semanais (F3), resultaram no aumento de brotações.
Background
Paphiopedilum armeniacum ( P. armeniacum ), an ornamental plant native to China, is known for its distinctive yellow blossoms. However, the mechanisms underlying P. armeniacum flower coloration remain unclear.
Methods
We selected P. armeniacum samples from different flowering stages and conducted rigorous physicochemical analyses. The specimens were differentiated based on their chemical properties, specifically their solubilities in polar solvents. This key step enabled us to identify the main metabolite of flower color development of P. armeniacum , and to complete the identification by High-performance liquid chromatography (HPLC) based on the results. Additionally, we employed a combined approach, integrating both third-generation full-length transcriptome sequencing and second-generation high-throughput transcriptome sequencing, to comprehensively explore the molecular components involved.
Results
We combined physical and chemical analysis with transcriptome sequencing to reveal that carotenoid is the main pigment of P. armeniacum flower color. Extraction colorimetric method and HPLC were used to explore the characteristics of carotenoid accumulation during flowering. We identified 28 differentially expressed carotenoid biosynthesis genes throughout the flowering process, validated their expression through fluorescence quantification, and discovered 19 potential positive regulators involved in carotenoid synthesis. Among these candidates, three RCP2 genes showed a strong potential for governing the PDS and ZDS gene families. In summary, our study elucidates the fundamental mechanisms governing carotenoid synthesis during P. armeniacum flowering, enhancing our understanding of this process and providing a foundation for future research on the molecular mechanisms driving P. armeniacum flowering.
A falta de estudos que indiquem as necessidades nutricionais de muitas orquídeas resulta na realização de práticas de adubação embasadas em experiências práticas e que não necessariamente atendem às demandas nutricionais de todas as espécies. O objetivo deste trabalho foi avaliar a influência da adubação mineral e orgânica e suas respectivas combinações no desenvolvimento da orquídea Cattlianthe ‘Chocolate drop’. As mudas desse híbrido foram obtidas por clonagem in vitro, e cultivadas em condição de casa de vegetação, utilizando potes plásticos com capacidade de 1 L contendo como substrato uma mistura de casca de pinus e carvão (4v:3v). Os tratamentos avaliados foram: sem adubação (testemunha), fertirrigação com fertilizante mineral ultra solúvel (FMU), mistura de torta de mamona e farinha de ossos (TM+FO), bokashi (BOK), FMU + mistura de torta de mamona e farinha de ossos [FMU+(TM+FO)], FMU + bokashi (FMU+BOK), mistura de torta de mamona e farinha de ossos + bokashi [(TM+FO)+BOK], FMU + mistura de torta de mamona e farinha de ossos + bokashi [FMU+(TM+FO)+BOK]. Após oito meses do início das adubações foram avaliados o desenvolvimento da parte aérea e o acúmulo de nutrientes. O tratamento FMU+BOK foi significativamente superior ao tratamento sem adubação, com incrementos aproximados de 54, 42, 33 e 78% da massa seca da parte aérea, comprimento da parte aérea, comprimento médio radicular e área foliar, respectivamente. A combinação entre adubação mineral e orgânica favoreceu o desenvolvimento de plantas do híbrido de
Cattlianthe ‘Chocolate drop’.
The malting barley (Hordeum vulgare L.) industry is oft en challenged by the availability of sufficient volume and quality to meet demand. Our objective was to evaluate the effects of agronomic practices on grain uniformity, protein concentration, yield, and yield components. Field experiments were conducted from 2005 to 2008 at eight rain-fed locations in western Canada. The effects of two seeding rates (200 and 400 seeds m(-2)) and five N (0, 30, 60, 90, and 120 kg ha(-1)) rates on two two-row barley cultivars ('AC Metcalfe' and 'CDC Copeland') were determined. Each experiment was conducted for 3 yr at each location (24 environments). CDC Copeland displayed some advantages over AC Metcalfe including higher grain yield, lower protein and more uniform kernels. For both cultivars, kernel weight, and plumpness were lower at the higher seeding rate; protein was also lower, maturity was earlier and kernels were more uniform. With increasing N rate, barley yield, kernel weight, and tillers plant(-1) increased, but days to seed maturity and protein concentration also increased, and kernel plumpness and seed uniformity decreased. The increase in protein was less pronounced with CDC Copeland suggesting that there may be less risk with this cultivar of unacceptable protein levels at relatively high N rates. At many environments barley plant stand decreased while lodging increased with increasing N rates. To improve the likelihood that barley will be acceptable for malting growers should select low-protein varieties, seed at relatively high rates and limit N application.
We examined changes in nitrogen content of the first leaves in relation to growth and nitrogen status of sunflower (Helianthus annuus L.) plants that were raised hydroponically at two irradiance levels (high and low light, HL and LL) and at two nitrogen concentrations
(high and low nitrogen, HN and LN). Initial increases in total dry mass and total nitrogen of the whole plant were faster
in HL-plants than in LL-plants irrespective of nitrogen supply, but in LN-plants the increase in total nitrogen was soon blunted.
When plants grown under the same irradiance were compared, nitrogen content of the first leaves (leaf N) decreased faster
in LN-plants than in HN-plants, while for the plants grown at the same nitrogen concentrations, it decreased faster in HL-plants
than in LL-plants. Since these changes in leaf N were not explained solely by the changes in plant dry mass or plant nitrogen,
we introduced an index, ‘nitrogen deficit (ND*)’, to quantify nitrogen deficit of the whole plant. ND* was expressed as ND*(t)=[Nmax–N(t)]×DM(t), where Nmax and N(t) were nitrogen contents in the young, expanding leaves that had just unfolded to expand, at the initial stage with
sufficient nitrogen and at time t, respectively, and DM(t), plant dry mass at t. The decrease in leaf N was expressed as a
liner function of ND* irrespective of the growth conditions, which indicates validity of this index. Limitation of the use of ND*, and mechanisms by which leaves sense nitrogen demand are also discussed.
Field experiments were conducted from 1995 to 1997, to determine the best cutting management schedule and optimum level of fertiliser nitrogen for enhanced seed production of Setaria sphacelata cv. Nandi. These experiments were conducted under rainfed conditions at Jhansi, India. The treatments, consisting of 3 cutting regimes (clipped, cut and uncut) and 4 levels of nitrogen (0, 40, 80 and 120 kg/ha), were allo- cated factorially in a randomised block design with 3 replicates. The highest seed yield (52.9 kg/ha) was recorded from uncut crop, which was significantly (P
Stinging nettle (Urtica dioica) is a herbaceous, dioecious perennial that is widely distributed around the world, reproduces both sexually and asexually, and is characterized by rapid growth. This work was aimed at evaluating the effects of plant maturity, shoot reproduction and sex on the growth of leaves and shoots.
Growth rates of apical shoots, together with foliar levels of phytohormones (cytokinins, auxins, absicisic acid, jasmonic acid and salicylic acid) and other indicators of leaf physiology (water contents, photosynthetic pigments, alpha-tocopherol and F(v)/F(m) ratios) were measured in juvenile and mature plants, with a distinction made between reproductive and non-reproductive shoots in both males and females. Vegetative growth rates were not only evaluated in field-grown plants, but also in cuttings obtained from these plants. All measurements were performed during an active vegetative growth phase in autumn, a few months after mature plants reproduced during spring and summer.
Vegetative growth rates in mature plants were drastically reduced compared with juvenile ones (48 % and 78 % for number of leaves and leaf biomass produced per day, respectively), which was associated with a loss of photosynthetic pigments (up to 24 % and 48 % for chlorophylls and carotenoids, respectively) and increases of alpha-tocopherol (up to 2.7-fold), while endogenous levels of phytohormones did not differ between mature and juvenile plants. Reductions in vegetative growth were particularly evident in reproductive shoots of mature plants, and occurred similarly in both males and females.
It is concluded that (a) plant maturity reduces vegetative growth in U. dioica, (b) effects of plant maturity are evident both in reproductive and non-reproductive shoots, but particularly in the former, and (c) these changes occur similarly in both male and female plants.
Soil nutrient availability directly enhances vegetative growth, flowering, and fruiting in alpine ecosystems. However, the impacts of nutrient addition on pollinator visitation, which could affect seed output indirectly, are unknown. In a nutrient addition experiment, we tested the hypothesis that seed output in the insect-pollinated, self-incompatible shrub, Chuquiraga oppositifolia (Asteraceae) of the Andes of central Chile, is enhanced by soil nitrogen (N) availability. We aimed to monitor total shrub floral display, size of flower heads (capitula), pollinator visitation patterns, and seed output during three growing seasons on control and N addition shrubs. N addition did not augment floral display, size of capitula, pollinator visitation, or seed output during the first growing season. Seed mass and viability were 25-40% lower in fertilised shrubs. During the second growing season only 33% of the N addition shrubs flowered compared to 71% of controls, and a significant (50%) enhancement in vegetative growth occurred in fertilised shrubs. During the third growing season, floral display in N addition shrubs was more than double that of controls, received more than twice the number of insect pollinator visits, and seed output was three- to four-fold higher compared to controls. A significant (50%) enhancement in vegetative growth again occurred in N addition shrubs. Results of this study strongly suggest that soil N availability produces strong positive bottom-up effects on the reproductive output of the alpine shrub C. oppositifolia. Despite taking considerably longer to be manifest in comparison to the previously reported top-down indirect negative effects of lizard predators in the same study system, our results suggest that both bottom-up and top-down forces are important in controlling the reproductive output of an alpine shrub.
We found inconsistencies in the commonly used data for chlorophyll analysis in 80% acetone. Recently developed extinction coefficients for chlorophyll b in N,N-dimethylformamide (DMF) based on values from 80% acetone are low as a result of these inconsistencies. We determined extinction coefficients of chlorophyll a (Chl a) and chlorophyll b (Chl b) in DMF for wavelengths of 618 to 665 nanometers. The simultaneous equations necessary for quantifying Chl a, Chl b, or total Chl in DMF in the absence of other chlorophyllous pigments are: Chl a = 12.70A(664.5) - 2.79A(647); Chl b = 20.70 A(647) - 4.62A(664.5); total Chl = 17.90A(647) + 8.08A(664.5), where A = absorbance in 1.00 centimeter cuvettes and Chl = milligrams per liter.N,N-Dimethylformamide is a very convenient solvent for Chl extraction since it is effective on intact plant parts and Chl is quite stable in DMF. There was no difference in the amount of Chl extracted when plant tissue was stored for 1 or 3 days at three temperatures, with or without solvent added.
Plants with limited resources adjust partitioning among growth, survival, and reproduction. We tested the effects of water and nutrient amendments on seed production, size, and quality in Sarcobatus vermiculatus (greasewood) to assess the magnitude and importance of changes in reproductive partitioning. In addition, we assessed interactions among the environment of seed-producing plants (adult plant scale), seed size, and seedling microenvironment (seedling scale) on successful seedling establishment. Interactions of these factors determine the scale of resource heterogeneity that affects seedling establishment in deserts. Both total number of seeds produced per plant and seed quality (weight and germination) increased significantly in the enriched treatment in a 3-year field experiment. Seedling length 3 days after germination and seed N concentration, other measures of seed quality, were higher for seed from both irrigated and enriched plants than for seed from control plants. Field S. vermiculatus seed production and quality can be substantially increased with irrigation and nutrient enrichment at the adult plant scale and this allows management of seed availability for restoration. However, based on a greenhouse study, seedling environment, not the environment of the seed-producing plant or seed size, was the most important factor affecting seedling germination, survival, and growth. Thus it appears that production of more seed may be more important than improved seed quality, because higher quality seed did not compensate for a low-resource seedling environment. For both natural establishment and restoration this suggests that heterogeneity at the scale of seedling microsites, perhaps combined with fertilization of adult shrubs (or multi-plant patches), would produce the greatest benefit for establishing seedlings in the field.
Experiments were conducted to determine how nitrogen (N), phosphorus (P), and potassium (K) rate and fertilizer termination time affect the growth and flowering of a Dendrobium nobile Lindl. hybrid, Dendrobium cv Red Emperor 'Prince'. Nitrogen, P, and K were tested in separate experiments as a factorial combination of five rates and three termination dates (1 Sept., 1 Oct., and 1 Nov. 2005). Nitrogen and K rates were 0, 50, 100, 200, and 400 mg·L -1. Phosphorus rates were 0, 25, 50, 100, and 200 mg·L -1. Levels of the nutrients not being tested were held constant. For all nutrients, ending fertilization on 1 Sept. resulted in greater or similar pseudobulb thickness compared with ending fertilization on 1 Oct. or 1 Nov. Pseudobulbs grew taller as the N rate increased, peaking at 100 and 200 mg·L-1. There were interactions between the N rate and fertilizer termination time on all reproductive characteristics. For all fertilizer termination times, flower number increased once N was applied. When ended on 1 Nov., 200 and 400 mg·L-1 N caused a delay to reach anthesis. All P rates resulted in taller plants with equally more nodes when compared with 0 mg·L-1. As the K rate increased from 0 to 100 mg·L-1, plant height increased, with no further increase at higher rates. The number of leaves remaining increased as N and K rates increased up to 200 mg·L-1. Total flower number and flowering node number increased as the K rate increased to 100 mg·L-1 (terminated on 1 Sept.) or 50 mg·L-1 (terminated on 1 Oct. or 1 Nov.). In the fourth experiment, only N was ended at four termination times, whereas all other nutrients continued to be supplied until flowering. Control plants received all fertilizer elements until flowering. The duration of N application did not affect vegetative or flowering characteristics. No aerial shoots were observed as a result of prolonged application of N at all rates. In summary, 100 mg·L-1 N, 25 mg·L-1 P, and 100 mg·L-1 K are recommended for optimal vegetative growth and reproductive development of Dendrobium cv Red Emperor 'Prince'.
Bare-root seedling plants of a white-flowered Phalaenopsis hybrid [P. arnabilis (L.) Blume × P. Mount Kaala `Elegance'] were grown in five potting media under three fertility levels (0.25, 0.5, and 1.0 g·liter ⁻¹ ) from a 20N-8.6P-16.6K soluble fertilizer applied at every irrigation. The five media included 1) 1 perlite:1 Metro Mix 250:1 charcoal (by volume); 2)2 perlite:2 composted pine bark:1 vermiculite; 3) composted pine bark; 4) 3 perlite:3 Metro Mix 250:1 charcoal; and 5) 1 perlite:1 rockwool. During the first flowering season, plants in the 1 perlite: 1 Metro Mix 250:1 charcoal medium had slightly fewer but larger flowers and thicker stalks (section of the inflorescence between the base and oldest flower) than those in the 1 perlite:1 rockwool medium. Medium had no effect on stalk length. Two media (3 perlite: 3 Metro Mix 250: 1 charcoal and 1 perlite: 1 rockwool) resulted in root systems that were inferior to those in the others. Fertilizer level had no effect on bloom date or flower size. Regardless of medium, increasing the fertility from 0.25 to 1.0 g·liter ⁻¹ increased flower count, stalk diameter and length, and leaf production following flowering. During the second flowering season, media had limited effect on plant performance. Increased fertility promoted earlier inflorescence emergence and blooming. Higher fertilizer rates also caused a linear increase in the number of flowers and inflorescences per plant, and in stalk diameter, total leaf count, and leaf size.
Nitrogen was supplied at variable rates and timing by drip irrigation to pot-grown sour cherries (Prunus cerasus) for two seasons. In the third season, the trees were planted in the field and fertigated identically. Shoot and wood growth, bud and flower development, fruit set, yield and fruit size were measured. The nitrogen content of the leaves was measured at the time of nutrient supply changes, showing a decline in the early and late part of the season. Generally, change in nitrogen supply was reflected in leaf nitrogen values, with a diminishing effect as the season progressed. A high nitrogen spring supply and a good whole-season and August supply increased shoot growth in some cases. Blossom density, the number of flowers per bud and per tree, fruit set, yield and leaf development on branches were lower when nitrogen availability was high in the late part of the previous season. Consequently it is recommended that good availability of nitrogen is ensured during spring and early summer (May–June) only, which would also reduce the risk of nitrogen leaching during autumn and winter.
Effects of macroelement concentrations on growth, flowering, and nutrient absorption in mericlone seedlings of an Odontoglossum hybrid (Odontioda Lovely Morning `Sayaka') were studied in sphagnum moss culture. Concentrations of N, P, and K in irrigation were varied independently between 0 and 2 times control. Leaf number and area varied little, but leaf color became pale with declining N level. Bulb diameter became smaller with lower N levels. The number of roots also smaller in low N levels. Root length shortened at 0 N and P. Lower N levels also resulted in shorter and thinner stalk, fewer flowers, and advanced flowering date. Flowers became narrow with low K levels.
We have compared the ability of shadegrown clones of Solamum dulcamara L. from shade and sun habitats to acclimate to bright light, as a function of nitrogen nutrition before and after transfer to bright light. Leaves of S. dulcamara grown in the shade with 0.6 mM NO 3 (-) have similar photosynthetic properties as leaves of plants grown with 12.0 mM NO 3 (-) . When transferred to bright light for 1-2 d the leaves of these plants show substantial photoinhibition which is characterized by about 50% decrease in apparent quantum yield and a reduction in the rate of photosynthesis in air at light saturation. Photoinhibition of leaf photosynthesis is associated with reduction in the variable component of low-temperature fluorescence emission, and with loss of in-vitro electron transport, especially of photosystem II-dependent processes.We find no evidence for ecotypic differentiation in the potential for photosynthetic acclimation among shade and sun clones of S. dulcamara, or of differentiation with respect to nitrogen requirements for acclimation. Recovery from photoinhibition and subsequent acclimation of photosynthesis to bright light only occurs in leaves of plants provided with 12.0 mM NO 3 (-) . In these, apparent quantum yield is fully restored after 14 d, and photosynthetic acclimation is shown by an increase in light-saturated photosynthesis in air, of light-and CO2-saturated photosynthesis, and of the initial slope of the CO2-response curve. The latter changes are highly correlated with changes in ribulose-bisphosphate-carboxylase activity in vitro. Plants supplied with 0.6 mM NO 3 (-) show incomplete recovery of apparent quantum yield after 14 d, but CO2-dependent leaf photosynthetic parameters return to control levels.
Barley (Hordeum vulgare L.) and tomato Lycopersicon esculentum Mill.) were grown hydroponically and examined 2, 5, and 10 d after being deprived of nitrogen (N) supply. Leaf elongation rate declined in both species in response to N stress before there was any reduction in rate of dryweight accumulation. Changes in water transport to the shoot could not explain reduced leaf elongation in tomato because leaf water content and water potential were unaffected by N stress at the time leaf elongation began to decline. Tomato maintained its shoot water status in N-stressed plants, despite reduced water absorption per gram root, because the decline in root hydraulic conductance with N stress was matched by a decline in stomatal conductance. In barley the decline in leaf elongation coincided with a small (8%) decline in water content per unit area of young leaves; this decline occurred because root hydraulic conductance was reduced more strongly by N stress than was stomatal conductance. Nitrogen stress caused a rapid decline in tissue NO
3-pools and in NO
3-flux to the xylem, particularly in tomato which had smaller tissue NO
3-reserves. Even in barley, tissue NO
3-reserves were too small and were mobilized too slowly (60% in 2 d) to support maximal growth for more than a few hours. Organic N mobilized from old leaves provided an additional N source to support continued growth of N-stressed plants. Abscisic acid (ABA) levels increased in leaves of both species within 2 d in response to N stress. Addition of ABA to roots caused an increase in volume of xylem exudate but had no effect upon NO
3-flux to the xylem. After leaf-elongation rate had been reduced by N stress, photosynthesis declined in both barley and tomato. This decline was associated with increased leaf ABA content, reduced stomatal conductance and a decrease in organic N content. We suggest that N stress reduces growth by several mechanisms operating on different time scales: (1) increased leaf ABA content causing reduced cell-wall extensibility and leaf elongation and (2) a more gradual decline in photosynthesis caused by ABA-induced stomatal closure and by a decrease in leaf organic N.
バーク植えのオドンチオダの生育と開花に好適な施肥量を明らかにするために，2年間にわたって生育と開花に対する窒素，リン酸，カリ施肥の影響について検討した．窒素施肥は成長中のカレントシュート（CS）の乾物重の増加，葉面積の拡大および小花数の増加をもたらし，その効果は2年目で顕著になった．Nの最適施肥水準は緩効性肥料として560 mg／鉢／年と判断された．生育と開花が最も促進されたCSの最終葉の窒素含有率は1.86％であった．CSの最終葉の葉緑素濃度（SPAD）と窒素含有率との間には高い相関関係（r = 0.854）があり，最終葉のSPAD値から葉の窒素含有率を予測することが可能であった．生育と開花に対するリン酸とカリの影響はほとんどなく，リン酸とカリは緩効性肥料としてそれぞれ240 mg／鉢／年と280 mg／鉢／年程度の施肥量で十分であった．
: Availability of nitrogen almost always limits plant growth. Therefore, efficient use of nitrogen is essential for the plants. In upright plants, especially when they form dense plant stands, old, lower leaves are shaded by young, upper leaves. Nitrogenous compounds in such shaded leaves are degraded and re-allocated to the developing young, upper leaves. These processes raise efficiency of nitrogen use in photosynthetic production of the plant. For this to occur in the most effective way, leaves would need to sense their photosynthetic status in a plant and increase, maintain or decrease their photosynthetic capacity accordingly. Hypotheses that explain how a leaf can sense its photosynthetic status in the plant are reviewed. They include systems involving phytochrome, sugar-sensing, or cytokinin. Our experimental results with Helianthus annuus and Phaseolus vulgaris plants, which were subject to various shading treatments, are examined in the light of these hypotheses. Our experimental results favoured the sugar-sensing hypothesis: A leaf can sense demand of other plant parts for photosynthates produced by it and nitrogen abundance or deficiency by monitoring its sugar concentration. Problems that are to be challenged in the near future are also pointed out.
Senescence was induced in leaves of Arabidopsis thaliana by transferring rosettes from a nutrient-sufficient medium to water. A visible gradient of yellowing along the shoot axis became apparent within 5 d. Leaves were grouped into four age-classes, representing fully green (nodes 17-20) through about one-third (nodes 13-16) and one-half (9-12) to more than 80% yellow (5-8). The decrease in chlorophyll and carotenoid content with increasing tissue senescence was accompanied by a loss of total protein and of specific polypeptides identified by electrophoresis and Western blotting. Heterogeneity in the rates at which photosynthetic proteins decreased during senescence could be related to differences in susceptibility to proteolysis conferred by location (soluble proteins are more labile than membrane components) and association with stabilizing components such as pigments. The abundance of senescence-related mRNAs was determined by Northern analysis using heterologous DNA probes and also cDNAs isolated from Arabidopsis by differential library screening. Expression of the plastid gene psbA increased until the most extreme stage of senescence, in contrast to the pattern of the protein it encodes, D1, which was almost undetectable in ail but mature green tissue. Transcripts corresponding to two senescence-enhanced cDNAs from Brassica napus, LSC54 and LSC94, were strongly up-regulated in senescing Arabidopsis leaves. Two Arabidopsis cDNAs, LdeVA8 and LdeVA32, detected mRNAs of increasing abundance up to mid-senescence and decreasing thereafter. Another homologous clone, LdeVA43, hybridized with a transcript showing some enhancement in early senescence. Partial base sequences of LdeVA8 and LdeVA32 revealed homologies with genes encoding a metallothionein-like protein and catalase, respectively. LSC54 also encodes a putative metallothionein. The possible significance of the patterns of gene expression in senescing rosette leaves of A. thaliana is discussed.
Photon yields of oxygen evolution at saturating CO2 were determined for 44 species of vascular plants, representing widely diverse taxa, habitats, life forms and growth conditions. The photonyield values on the basis of absorbed light (fa) were remarkably constant among plants possessing the same pathway of photosynthetic CO2 fixation, provided the plants had not been subjected to environmental stress. The mean fa value ±SE for 37 C3 species was 0.106±0.001 O2·photon-1. The five C4 species exhibited lower photon yields and greater variation than the C3 species (fa=0.0692±0.004). The fa values for the two Crassulaceanacid-metabolism species were similar to those of C3 species. Leaf chlorophyll content had little influence on fa over the range found in normal, healthy leaves. Chlorophyll fluorescence characteristics at 77 K were determined for the same leaves as used for the photon-yield measurements. Considerable variation in fluorescence emission both at 692 nm and at 734 nm, was found 1) among the different species; 2) between the upper and lower surfaces of the same leaves; and 3) between sun and shade leaves of the same species. By contrast, the ratio of variable to maximum fluorescence emission at 692 nm (Fv/FM, 692) remained remarkably constant (The mean value for the C3 species was 0.832±0.004). High-light treatments of shade leaves resulted in a reduction in both fa and the Fv/FM, 692 ratio. The extent of the reductions increased with time of exposure to bright light. A linear relationship was obtained when fa was plotted against Fv/FM, 692. The results show that determinations of the photon yield of O2 evolution and the Fv/FM, 692 ratio can serve as excellent quantitative measures of photoinhibition of overall photosynthetic energy-conversion system and of photochemistry of photosystem II, respectively. This is especially valuable in field work where it is often impossible to obtain appropriate controls.
The aim of this work was to examine whether carbohydrates are involved in signalling N deficiency through source:sink imbalance. Photosynthetic metabolism in tobacco was studied over 8 d during the withdrawal of N from previously N-sufficient plants in which the source:sink ratio was manipulated by shading leaves on some of the plants. In N-sufficient plants over this time-scale, there was a small decline in photosynthetic rate, Rubisco protein and amino acid content, with a larger decrease in carbohydrate content. Withdrawal of N from the growing medium induced a large decrease in the rate of photosynthesis (35% reduction after 8 d under the growing conditions, with a reduction also apparent at high and low measuring CO2), which was caused by a large decrease in the amount of Rubisco protein (62% after 8 d) and Rubisco activity. Higher amounts of hexoses preceded the loss of photosynthetic activity and sucrose and starch accumulation. Reduction of the source:sink ratio by shading prevented the loss of photosynthetic activity and the increase in hexoses and other carbohydrates. These data indicate that the reduction of photosynthesis that accompanies N deficiency in intact plants has the characteristics of sugar repression of photosynthesis observed in model systems, but that the accumulation of hexose prior to the decline in photosynthesis is small. The possibility that sugar repression of photosynthesis under physiological conditions depends more crucially on the C:N status of leaves than the carbohydrate status alone is discussed.
The epiphytic habitat is assumed to be nutrient deficient, although this generally held notion is based almost completely on circumstantial evidence (Zotz & Hietz 2001). Most studies on the nutrient relations of vascular epiphytes focus on nitrogen (Bergstrom & Tweedie 1998, Hietz & Wanek 2003, Stewart et al . 1995). Although nitrogen plays a key role in limiting plant growth worldwide, there is an on-going discussion whether nitrogen or rather phosphorus are more limiting in many tropical forests (Grubb 1989, Harrington et al . 2001, Vitousek & Howarth 1991). To identify which nutritional factor is most limiting for plant growth, nutrient ratios have been proposed as a very useful tool (Koerselman & Meuleman 1996). These authors stated that N:P ratios exceeding 16 are indicative of P limitation, while an N:P ratio <14 suggests N limitation. Some reports of such ratios in the epiphyte literature indicate that phosphorus may indeed be limiting for epiphytes in tropical forests. For example, the N:P ratio of two field-grown bromeliads ( Tillandsia circinnata and T. usneoides ) decreased dramatically from 23.6 and 40.4, respectively, to 3.6 and 3.4, respectively, when fertilized with both N and P in the laboratory (Benzing & Renfrow 1974a). On the other hand, however, the average N:P ratios of mature leaves of 41 epiphyte species compiled from a number of papers did not appear particularly high (12.1±10.5, cf. Zotz & Hietz 2001).
Adventitious shoots formed from nodal sections of floral-stalks of Phalaenopsis Pink Leopard Petra that had been propagated on Hyponex medium with 6-benzyladenine (BA). After subculturing adventitious shoots on Vacin-Went medium with BA, more than 70% of the shoots formed floral buds, and 10% of the floral buds flowered in 9-month-old shoots. Floral buds were not formed on the adventitious shoots cultured on Vacin-Went medium lacking BA. A high concentration of total nitrogen inhibited the development of floral buds, and low-temperature treatments failed to induce the formation of floral buds in vitro.
The ratio of variable fluorescence to maximal fluorescence (F
v/F
m) was measured during a night and day cycle in five different macroalgae growing in the littoral zone at the Swedish west
coast; the green algae Ulva lactuca, Cladophora sp. and Enteromorpha flexousa, the red alga Ceramium nodulosum and the brown alga Fucus vesiculosus. All the green algae and C. nodulosum showed both diurnal fluctuations in F
v/F
m during days of high light intensities and a significant negative correlation between F
v/F
m and photon irradiance (PI). An attempt has been made to improve calculations of macroalgal net growth based on carbon fixation
(αnet) considering this diurnal change in F
v/F
m. By assuming that the negative linear correlation between F
v/F
m and the maximum quantum yield for photosynthesis (Φ) is proportional to that between F
v/F
m and αnet, it was possible to include the daily variation of αnet due to photoinhibition. To compensate for the variation of F
v/F
m, a representative value for each day was obtained by weighting all values of F
v/F
m over the diurnal period in relation to total PI. For all algal species there was a fairly good agreement between this representative
value and the F
v/F
m value measured around noon. As the daily representative F
v/F
m value showed a negative linear correlation with the daily mean PI, it was possible to correct αnet for differences of daily mean PI.
The effects of nitrogen deficiency on CO2 assimilation, carbohydrate content and biomass were studied in two olive (Olea europaea L.) cultivars (‘Meski’ and ‘Koroneiki’). One-year-old plants were grown in pots and subjected to four nitrogen levels for 58 days.Nitrogen-deficient plants had significant lower leaf nitrogen and chlorophyll a contents. They also showed a significant reduction in their photosynthetic capacity. A tolerance difference between cultivars was observed: ‘Meski’ proved to be more efficient in maintaining CO2 assimilation rates than ‘Koroneiki’ under nitrogen deficiency, which was reflected by increased photosynthetic nitrogen use efficiency. Accumulation of carbohydrates, especially starch, mannitol, sucrose and glucose, was observed in nitrogen-deficient leaves. This indicates that both the high carbohydrate and the low nitrogen content inhibit photosynthesis in nitrogen-deprived olive plants. Total biomass was strongly reduced (mainly caused by a decrease in leaf dry weight) under nitrogen deficiency for both cultivars, but root:shoot ratio was hardly affected. Elongation of fine roots was enhanced in ‘Koroneiki’ under severe nitrogen-deprivation.
One of six water-soluble fertilizers, 10N-13.1P-16.6K, 15N-4.4P-24.9K, 15N-8.7P-20.8K, 20N-2.2P15.8K, 20N-4.4P-16.6K, and 20N-8.7P-16.6K (10-30-20, 15-10-30, 15-20-25, 20-5-19, 20-10-20, and 20-20-20 in N-P2O5-K2O, respectively), was applied to young seedlings of Phalaenopsis Tam Butterfly at concentrations of 200 or 100 mg N l−1. After seven months, leaf span, leaf size, total leaf area, and shoot and root fresh weight were not different among various fertilizers within either concentration. However, plants had a wider leaf spread, produced more and larger leaves, and had greater total leaf areas in response to the higher fertilizer concentration, regardless of which fertilizer was used. The different fertilizers had a small but significant effect on leaf number. The 10N-13.1P-16.6K fertilizer caused a lower medium pH than the others. Medium fertigated with the 10N-13.1P-16.6K or 15N-8.7P-20.8K fertilizer always had higher EC than that receiving the 20N-8.7P-16.6K fertilizer. In a second experiment, the same fertilizers at the 200 mg N l−1 concentration were used on mature plants in late August, with either municipal water (EC = 1.4 dS m−1) or water from a reverse osmosis system (RO, EC = 0.03 dS m−1). Regardless of which fertilizer was used, flowering date, flower size and number, as well as plant width were unaffected. The 10N-13.1P-16.6K fertilizer resulted in 12% more leaves than 20N-8.7P-16.6K by May the following year. Plants fertigated with RO water had slightly larger flowers and longer leaves.
Insufficient nitrogen (N) and phosphorus (P) frequently limit primary production. Although most nutrient studies on vascular epiphytes have focused on N uptake, circumstantial evidence suggests that P rather than N is the most limiting element for growth in this plant group. We directly tested this by subjecting a total of 162 small individuals of three bromeliad species (Guzmania monostachia, Tillandsia elongata, Werauhia sanguinolenta) to three N and three P levels using a full-factorial experimental design, and determined relative growth rates (RGR) and nutrient acquisition over a period of 11 weeks. Both N and P supply had a significant effect on RGR, but only tissue P concentrations were correlated with growth. Uptake rates of N and P, in contrast, were not correlated with RGR. Increased nutrient supply led to an up to sevenfold increase in tissue P concentration compared to natural conditions, while concentrations of N hardly changed or even decreased. All treatment combinations, even at the lowest experimental P supply, led to decreased N:P ratios. We conclude that P is at least as limiting as N for vegetative function under natural conditions in these epiphytic bromeliads. This conclusion is in line with the general notion of the prevalence of P limitation for the functioning of terrestrial vegetation in the tropics.
Coffee is native to shady environments but often grows better and produces higher yields without shade, though at the expense of high fertilization inputs, particularly nitrogen (N). Potted plants were grown under full sunlight and shade (50%) conditions and were fertilized with nutrient solutions containing either 0 or 23 mM N. Measurements were made in southeastern Brazil during winter conditions, when relatively low night temperatures and high diurnal insolation are common. Overall, the net carbon assimilation rate was quite low, which was associated with diffusive, rather than biochemical, constraints. N deficiency led to decreases in the concentrations of chlorophylls (Chl) and total carotenoids as well as in the Chl/N ratio. These conditions also led to qualitative changes in the carotenoid composition, e.g., increased antheraxanthin (A) and zeaxanthin (Z) pools on a Chl basis, particularly at high light, which was linked to increased thermal dissipation of absorbed light. The variable-to-maximum fluorescence ratio at predawn decreased with increasing A+Z pools and decreased linearly with decreasing N. We showed that this ratio was inadequate for assessing photoinhibition under N limitation. Expressed per unit mass, the activities of superoxide dismutase and glutathione reductase were not altered with the treatments. In contrast, ascorbate peroxidase activity was lower in low N plants, particularly under shade, whereas catalase activity was lower in shaded plants than in sun-grown plants, regardless of the N level. Glutamine synthetase activity was greater in sun-grown plants than in shaded individuals at a given N level and decreased with decreasing N application. Our results suggest that the photoprotective and antioxidant capacity per amount of photons absorbed was up-regulated by a low N supply; nevertheless, this capacity, regardless of the light conditions, was not enough to prevent oxidative damage, as judged from the increases in the H(2)O(2) and malondialdehyde concentrations and electrolyte leakage. We demonstrated that N fertilization could adequately protect the coffee plants against photodamage independently of the anticipated positive effects of N on the photosynthetic capacity.
The costs of reproduction in plants
- Obeso,
Obeso, J.R. 2002. The costs of reproduction in
plants. New Phytol. 155:321-348.
A preliminary report on the population size, ecology, and conservation status of some Paphiopedilum species (Orchidaceae) in southwest China
- Z H Tsi
- Y B Lou
- P J Cribb
- N Mcgough
- S Gloria
- C Lawrence
Tsi, Z.H., Y.B. Lou, P.J. Cribb, N. McGough, S.
Gloria, and C. Lawrence. 1999. A preliminary
report on the population size, ecology, and
conservation status of some Paphiopedilum
species (Orchidaceae) in southwest China.
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Effects of N and P concentration on growth and flowering of the Phalaenopsis orchid
- Wang,
Wang, Y.T. 2003. Effects of N and P concentration
on growth and flowering of the Phalaenopsis
orchid. HortScience 38:746-747.
A preliminary report on the population size, ecology, and conservation status of some Paphiopedilum species (Orchidaceae) in southwest China
- Tsi,