Carbohydrate production and transport in cotton cultivars grown under boron deficiency

An adequate supply of boron (B) is required for the optimal growth and development of cotton (Gossypium hirsutum L.) plants, but the low phloem mobility of B limits the possibilities of correcting B deficiency. There are indications that different cotton cultivars could have different responses to B deficiency. The differences in responses of cotton cultivars to B regarding photoassimilate production and transport were studied in a greenhouse experiment with nutrient solution. Treatments consisted of three cotton cultivars (FMT 701, DP 604BG and FMX 993) and five concentrations of B (0.0, 2.5, 5.0, 10.0 and 20.0 µmol L−1). Sampling began at the phenological stage B1 (first square) and continued for four weeks. The leaf area and the number of reproductive branches and structures decreased due to B deficiency. A higher level of abortion of reproductive structures was observed under B deficiency. Boron deficiency increased the internal CO2 concentration but decreased the transpiration rate, stomatal conductance and photosynthesis. Despite the decrease in photosynthesis, nonstructural carbohydrates accumulated in the leaves due to decreased export to bolls in B-deficient plants. The response to B deficiency is similar among cotton cultivars, which shows that the variability for this trait is low even for cultivars with different genetic backgrounds

Respostas fisiológicas à aplicação de reguladores vegetais e nutrientes em videira ‘crimson seedless'

The present study aimed to evaluate the effect of foliar application of auxin (Ax), cytokinin (CK) and gibberellin (GA) mixture, isolated or combined with the cobalt (Co) and molybdenum (Mo) mixture, in 'Crimson Seedless' grapevine, analyzing their effects on photosynthetic activity duration, metabolism and development of the plant, as well as increase production and fruit quality. The experiments were conducted in Juazeiro - BA, Brazil, in a randomized block design with four treatments, six blocks, with four plants each. Treatments were: T1 - Control; T2 - CK+Ax+GA 1.8L ha-1, T3 - CK+Ax+GA 1.8L ha-1 + Co+Mo 1.0L ha-1, and T4 - CK+Ax+GA 1.8L h-1 + Co+Mo 1.5L h-1. The treatments applications were carried out in three phases: inflorescence primordial stage, when berries were with 6 to 8 mm in diameter and berries elongation. In the first experiment, the photosynthetic activity duration was assessed by evaluating gas exchanges in leaves that were marked soon after sprouting, until the end of the cycle. In the second experiment, were evaluated gas exchanges, antioxidant enzymes activities, levels of carbohydrates and chlorophyll at 3, 5, 7, 14 and 21 days after the 1st application, at 1, 3 and 5 days after 2nd application and at 1, 3 , 5, 7 , 14, 21 and 28 days after the 3rd application (DAA). Thus, plants maintained their photosynthetic activity during the whole cycle, until the end of evaluations, for 133 days after sprouting leaves. However, it was observed that the application of plant growth regulators and nutrients anticipating the moment when the leaves reached the maximum absorption rate of CO2, indicating that these treatments have optimized the photosynthetic process. At the same time, rates of CO2 assimilation and carboxylation efficiency began to show greater efficiency after 14 DAA, as well as higher levels of chlorophylls, carotenoids and sugar concentrations, as in the 1st far as ...O presente trabalho objetivou avaliar o efeito da aplicação foliar da mistura de auxina (Ax), citocinina (CK) e giberelina (GA), isolada ou combinada com a mistura de nutrientes, cobalto (Co) e molibdênio (Mo), em videira ‘Crimson Seedless’, buscando analisar seus efeitos na duração da atividade fotossintética das folhas e no metabolismo e desenvolvimento da planta, bem como no aumento da produção e qualidade de frutos. Os experimentos foram desenvolvidos no município de Juazeiro – BA, Brasil, em blocos casualizados, com quatro tratamentos e seis blocos. Os tratamentos foram: T1 - Testemunha; T2 - CK+Ax+GA 1,8L ha-1; T3 - CK+Ax+GA 1,8L ha-1 + Co+Mo 1,0L ha-1; e T4 - CK+Ax+GA 1,8L ha-1 + Co+Mo 1,5L ha-1. As aplicações foram realizadas em três fases: primórdio de inflorescência, bagas chumbinho, e alongamento de bagas. No primeiro experimento, avaliou-se a duração da atividade fotossintética das folhas, através de avaliações nas trocas gasosas em folhas marcadas logo após a brotação, até o final do ciclo. No segundo experimento, foram avaliadas as trocas gasosas, atividades de enzimas antioxidantes, teores de carboidratos e clorofilas aos 3, 5, 7, 14 e 21 dias após a 1ª aplicação; aos 1, 3 e 5 dias após a 2ª aplicação e aos 1, 3, 5, 7, 14, 21 e 28 dias após a 3ª aplicação (DAA). Assim, as plantas mantiveram a atividade fotossintética durante todo o ciclo, até o final das avaliações, aos 133 dias após a brotação das folhas. Entretanto, observou-se que a aplicação de reguladores vegetais e nutrientes antecipou o momento em que as folhas atingiram a taxa de assimilação de CO2 máxima, indicando que esses tratamentos otimizaram o processo fotossintético. Ao mesmo tempo, as taxas de assimilação de CO2 e eficiência de carboxilação começaram a apresentar maior eficiência após 14 DAA, assim como maiores teores de clorofilas, carotenoides e ..

Efeitos fisiológicos de fungicidas no desenvolvimento de plantas de pepino japonês enxertadas e não enxertadas, cultivadas em ambiente protegido

As estrobilurinas são fungicidas com efeitos fisiológicos positivos no rendimento das culturas, devido ao aumento da fotossíntese líquida e melhor balanço hormonal. O boscalida complementa a ação desses fungicidas, seja aplicado alternadamente, seja aplicado em conjunto. E, assim como as estrobilurinas, é um fungicida sistêmico que funciona preventivamente inibindo a germinação de esporos, e possui pouco efeito curativo; portanto, a aplicação preventiva desses produtos traz como benefícios, além de proteger a planta, o de incrementar a produção através de seus benefícios fisiológicos. O presente trabalho teve como objetivo avaliar o efeito da aplicação de piraclostrobina, azoxistrobina e boscalida em pepino japonês (Cucumis sativus L.) enxertado e não enxertado, em condições de ambiente protegido, visando a seus efeitos fisiológicos no metabolismo e desenvolvimento da planta, bem como no aumento da produção e qualidade dos frutos. O experimento foi conduzido em área experimental da Faculdade de Ciências Agronômicas da Universidade Estadual Paulista, Campus de Botucatu-SP em ambiente protegido. O delineamento experimental foi inteiramente casualisado, fatorial 2 x 5, sendo plantas de pepino enxertadas e plantas não enxertadas e 5 tratamentos com fungicidas: testemunha, azoxistrobina 60g ha-1, boscalid 50g ha-1, piraclostrobina 50 g ha-1, boscalid (100g ha-1) + piraclostrobina (50 g ha-1), aplicados 18 dias após o transplante a intervalos de 7 dias, via foliar. O efeito dos tratamentos foi avaliado através das observações das seguintes características: produção de frutos e massa média do fruto, trocas gasosas, índice de clorofila nas folhas e atividade das enzimas peroxidase, superóxido dismutase, catalase e nitrato redutase. Em função dos resultados obtidos, conclui-se que os fungicidas testados apresentam efeitos fisiológicos positivos nas plantas...Strobilurins are fungicides of positive physiological effects on crop yield due to increased net photosynthesis and improved hormone balance. Boscalid complements the action of these fungicides, applied alternately or together. And, as the strobilurins, is a systemic fungicide that works preemptively inhibiting germination of spores, and has little curative effect; therefore the preventive application of these products protect the plant and increases production through its physiological benefits. This experiment aimed to evaluate the effect of applying pyraclostrobin, azoxystrobin and boscalid in japanese cucumber (Cucumis sativus L.) grafted and non-grafted, in greenhouse conditions, aiming to their physiological effects on metabolism and plant development, as well as increased production and fruit quality. The study was conducted in an experimental area which belongs to the School of Agronomical Sciences (FCA), São Paulo State University (UNESP), Campus Botucatu, in greenhouse conditions. Experimental design was completely randomized, 2 x 5 factorial arrangement, including grafted cucumber plants and non-grafted plants and 5 fungicide treatments: control, azoxystrobin 60g ha-1, boscalid 50g ha-1, pyraclostrobin 50 g ha-1, boscalid (100g ha-1) + pyraclostrobin (50 g ha-1), sprayed 18 days after transplant (DAT) at 7-day intervals into leaves. The effect of the treatments was evaluated through observations of the following: fruit production and fruit weight, gas exchanges, leaf chlorophyll content and activity of peroxidase, superoxide dismutase, catalase and nitrate reductase. Based on these results, we conclude that the tested fungicides have positive physiological effects on Japanese cucumber plants grafted and non-grafted, and these effects were more evident in grafted plants, in which all fungicides increased yield, nitrate reductase activity (in early development) also antioxidative... (Complete abstract click electronic access below)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP