Ecofisiologia de mangueiras‘Tommy Atkins’submetidas a diferentes regimes hídricos e disponibilidade de luz

Abstract

Resumo: A interação entre o déficit hídrico e o mau aproveitamento de radiação luminosa pelas plantas pode ocasionar redução nas trocas gasosas e, consequentemente, diminuir o seu crescimento e sua produção. Em mangueira 'Tommy Atkins', os estudos sobre essa interação são escassos. Diante do exposto, objetivouse avaliar variáveis ecofisiológicas em folhas de mangueiras 'Tommy Atkins' submetidas a variações de luminosidade e de regime hídrico na copa, em diferentes horários. Os dados foram analisados em delineamento inteiramente casualizado, arranjado em parcela subsubdividida 3x3x4, com três repetições. Os regimes hídricos comporam as parcelas, posições da folha na copa, as subparcelas e horários de avaliação, as subsubparcelas. As variáveis de assimilação líquida do carbono (A), condutância estomática ao vapor de água (gs), transpiração (E), temperatura foliar (Tf) e temperatura do ar (Ta), bem como déficit de pressão de vapor do ar (VPD) foram medidas em sistema aberto, sob luz artificial e concentração de CO 2 ambiente, por meio do IRGA. Os resultados indicaram que a interação entre o regime hídrico, posições da folha na copa e horários de avaliação interferem na ecofisiologia de mangueira 'Tommy Atkins'. As folhas posicionadas no centro da copa (com menor luminosidade) apresentam reduzida capacidade produtiva, comparativamente às demais. As plantas cultivadas em regime hídrico de 50% apresentam maior eficiência de uso da água, especialmente durante o período de condições ambientais mais adversas (09:00 às 13:00 horas).O eficiente manejo das condições hídricas e das posições das folhas na copa afetam positivamente as trocas gasosas e, consequentemente, seu crescimento e sua produção.Palavras-chave: Arquitetura da planta. Eficiência de uso da água. Estresse hídrico. Mangifera indica. Abstract:The interaction between water deficit and the poor use of light radiation by plants can result in a reduction in gas exchange with a consequent reduction in growth and production. In the 'Tommy Atkins' mango, studies of this interaction are rare. Given the above, the aim was to evaluate ecophysiological variables in leaves of the 'Tommy Atkins' mango subjected to varying conditions of lighting and water regime in the canopy, at different times and under semi-arid conditions. The data were analysed in a completely randomised design, arranged in 3x3x4 split lots, with three replications. The first, second and third lots were represented by the water regime, position in the canopy and time of evaluation respectively. The variables for net carbon assimilation (A), stomatal conductance to water vapour (gs), transpiration (E), leaf temperature (Tf), air temperature (Ta) and vapour pressure deficit (VPD) were all measured in an open system, under artificial light and ambient CO 2 concentrations, using the IRGA. The results showed that the interaction between water regime, position in the canopy and time of evaluation affect ecophysiology in the 'Tommy Atkins' mango. Leaves in the centre of the canopy (with less light) show reduc...

Gas exchange and post-harvest quality of ‘Kent’ mango subjected to controlled water deficit in semi-arid region

“…Regarding production, there was interaction between phenological stages and production cycles (Figure 3). The first production cycle showed higher temperatures, resulting in higher gas exchange and higher photosynthetic production than the second cycle, which resulted in higher fruit production, as also observed in 'Tommy' mango by Almeida et al (2015). According to Taiz et al (2017), the increase in stomatal conductance may lead to a higher CO 2 influx in leaf In the first cycle, the highest production of 'Kent' mango was estimated at 44.6 and 48.4 kg plant -1 for the irrigation depths of 83.37 and 72.76% ETc, in the F2 and F3 stages, respectively.…”

Spatial Variability of Ecophysiological and Production Components in Irrigated Noble Garlic

“…Among these, vapor pressure deficit is the most relevant. According to Almeida et al (2015), vapor pressure deficit can portray crop water stress, as well as plasticity in water use. In this sense, points with higher garlic yields coincided with those with lower VpdL, whose greatest trends were to the north of the map (Figure 4).…”

Biostimulant alleviates abiotic stress of mango grown in semiarid environment

“…Considering the initial characterization of the plants (Start), the leaf soluble carbohydrates concentration before the treatment application was slightly higher than the concentrations obtained after the application of the treatments, a fact that may be linked to the imposition of water stress during this period. Almeida et al (2015) reported that one of the water stress effects on plants is the lower vegetative growth, promoting the accumulation of reserves.…”

“…According to Almeida et al (2015), plants under water stress tend to reduce photoassimilate production and consume the accumulated amount but, on the other hand, when water is adequately supplied there is signaling for ordinary metabolism and, consequently, photoassimilate accumulation. For the last evaluation date, T5 had a higher average carbohydrate concentration, but without significant difference from the other treatments (Figure 3).…”