Transpiração e temperatura foliar da cana-de-açúcar sob diferentes valores de potencial matricial

Abstract

RESUMO:O objetivo deste trabalho foi avaliar a variação diurna da transpiração e da temperatura foliar da cana-de-açúcar, cv. RB867515, sob diferentes potenciais matriciais de água no substrato de cultivo e as condições meteorológicas em ambiente protegido. O efeito do estresse hídrico na transpiração e temperatura foliar foi determinado a partir da suspensão da irrigação, quando foram realizadas três campanhas de medições, iniciadas aos 122; 150 e 185 dias após o plantio (DAP) até que o potencial matricial de água no substrato (Ψ) alcançasse 1.500 kPa, aproximadamente. Sob ausência de estresse hídrico (Ψ>50 kPa), a transpiração das plantas atingiu o valor máximo entre 10 e 13 h, próximo de 60; 70 e 100 g planta -1 h -1 para 122; 150 e 185 DAP, respectivamente. Sob condições de estresse hídrico severo (Ψ<1.100 kPa), houve redução na transpiração diária de aproximadamente 73%, comparativamente às medições realizadas sem estresse e sob condições meteorológicas similares. Em condições de ausência de estresse hídrico e de céu nublado, o valor médio da diferença entre a temperatura foliar e a temperatura do ar foi de 2,9 °C. Em contraste, sob condições de estresse hídrico severo e valores elevados de radiação solar global, a temperatura foliar chegou a ser 6,6 ºC superior à temperatura do ar. PALAVRAS-CHAVE:Saccharum officinarum, evapotranspiração, termometria a infravermelho, estresse hídrico, irrigação. TRANSPIRATION AND LEAF TEMPERATURE OF SUGARCANE UNDER DIFFERENT MATRIC POTENTIAL VALUESABSTRACT: The objective of this study was to evaluate the diurnal behaviour of transpiration and leaf temperature of sugarcane (cv. RB867515) under different water matrix potential in the cultivation substrate and greenhouse meteorological conditions. The water stress effect on transpiration and leaf temperature was determined after irrigation suspension, when three measurement campaigns were initiated at 122; 150 and 185 days after planting (DAP) until the matrix water potential in the substrate (Ψ) reached -1,500 kPa, approximately. Under the absence of water stress (Ψ > -50 kPa), plant transpiration reached the maximum value between 10:00 AM and 13:00 PM, near to 60; 70 e 100 g plant -1 h -1 , for 122; 150 and 185 DAP, respectively. Under severe water stress (Ψ < -1,100 kPa), there was daily transpiration reduction of approximately 73%, compared to measurements performed without water stress and under similar meteorological conditions. Under the absence of water stress and overcast sky conditions, the average value of the difference between leaf temperature and air temperature was -2.9 °C. In contrast, under severe water stress and high values of global solar radiation, the leaf temperature was found to be 6.6 °C above the air temperature.

Arugula production as a function of irrigation depths and potassium fertilization

“…Trentin et al (2011) observed that leaf temperature is closely associated with the process of transpiration. As it increases, there is a reduction in leaf temperature due to the dissipation of energy in the form of latent heat.…”

Growth of sugarcane (Sacharum ssp L.) in different production scenarios exhibitions and slopes

“…A cana-de-açúcar (Saccharum spp L.) destaca-se como uma das principais culturas de interesse econômico para o Brasil, fornecendo matéria-prima para a produção de açúcar, etanol e energia (TRENTIN et al, 2011) e pela eficiência na produção de biocombustíveis. Com destaque para o estado de São Paulo, tendo a maior área e a maior produção no país, 5,4 milhões de hectares e mais de 400 milhões de toneladas, respectivamente (AGRIANUAL, 2015).…”

Alterations on the Evapotranspiration of Sugarcane Cultivars Under Distinct Salinity Levels Applied in the Fertigation

“…When the mentioned variables have higher values, as observed at 97 and 105 DAP, favorable conditions are established for intensification of the crop evapotranspiration Trentin et al 2011). In the specific case of these days, the values of Tair, VPDair and Rg were generally higher in the period between 11 a.m. and 2 p.m.…”

“…In addition, there are few researches carried out to evaluate the effect of salinity on sugarcane evapotranspiration. Trentin et al (2011) evaluated the effect of water stress on RB867515 cultivar at 125 DAP, verifying reductions in plant transpiration in relation to non-stress treatment, of 28.1 and 63.3% for the matrix potentials around -474 and -1272 kPa, respectively. The value of 28.1% is very close to the average reduction of 29% in ETcd, verified for the four cultivars in the this experiment, corresponding to the salinity increase from 3 to 9 dS m -1 , the last value being estimated through the equations shown in Figure 3.…”

“…The 3 dS m -1 value of the nutrient solution used in the cultivation of sugarcane was based on the studies of Trentin et al (2011), Boehringer et al (2013 and Batista et al (2015), and the amounts of NaCl in studies carried out with the aim of evaluating the effect of salinity on sugarcane growth (Plaut et al, 2000;Patade et al, 2011;Willadino et al, 2011;Simões et al, 2016). The EC monitoring was performed manually with a portable conductivity meter (CDH-42 model, Omega, Stamford, CT, USA).…”