INFLUÊNCIA DA IRRIGAÇÃO SUPLEMENTAR COM ÁGUAS RESIDUÁRIAS SOBRE AS TROCAS GASOSAS FOLIARES DO ALGODOEIRO

Abstract

The use of wastewater in irrigation has grown as a supplement to circumvent water scarcity. However, little is known about the responses of cultures to its application. Thus, the objective was to evaluate the impacts of supplementary irrigation with treated wastewater on the gas exchange of cotton (Gossypium hirsutum L), simulating water scenarios considered normal, drought and severe drought, in the presence and absence of NPK. The experiment was carried out in the municipality of Russas - CE, in an area next to the stabilization pond of CAGECE - Companhia de Agua e Esgoto do Estado do Ceará, in DBC, in the subdivided plot scheme, with four blocks. The plots were water scenarios (normal, drought and severe drought); the subplot was supplementation or not with wastewater treated in the simulated summer days; the sub-installment was the application or not of NPK. The cultivar used was BR 433. At 25 days after sowing, photosynthesis, transpiration, internal CO2 concentration and leaf temperature were analyzed. The drought and severe drought scenarios had little impact on the cotton leaf gas exchange. However, supplementary irrigation reduced leaf temperature and attenuated the effects of the drought scenario on photosynthesis, regardless of whether or not NPK was applied.