Crescimento inicial de cultivares de girassol submetidas à deficiência hídrica

Abstract

The global demand for fossil fuels resulted from the increased demand for energy coupled with the imminent risk of the depletion of non-renewable fuel sources has led researchers to consider environmentally and economically viable alternatives. An option to overcome this crisis consists on using plant-derived fuels produced from oilseeds. In this scenario, the sunflower is one of the five main oil-producing species in the world given its advantageous characteristics from the agricultural and economic perspective. However, the success of this crop depends on several biotic and abiotic factors. Among the biotic factors, water deficit is one of the most limiting factors in agriculture. Therefore, the objective of this study was to evaluate the growth performance of two sunflower cultivars, Hélio 250 and Hélio 251, submitted to different levels of soil water availability. The experiment was conducted in a greenhouse with treatments consisting of 100% soil water retention capacity (WRC) and two levels of lower water availability, representing 75% and 50% of WRC. The most limiting treatment was that of 50% WRC. We observed lower values for the variables MS C, MS R , AF, AL, chlorophyll content, A, gs, Ψ, and TRA in the H250 cultivar in the treatment with lower water availability (WRC of 50%). For cultivar H251, in addition to the variables abovementioned, the WRC of 50% also affected the MS F , DC, and E. Cultivars H250 and H251 showed similar response patterns among all variables analyzed in the water restriction treatments (WRC of 75% and 50%), apart from Ψ at noon. Although it is considered a species of broad edaphoclimatic adaptability with potential for cultivation in drier areas, the sunflower cultivars evaluated were susceptible to drought and are not indicated for cultivation under a WRC of 50%.