Phenotyping of sweet sorghum for tolerance to hydric stress through morphological characteristics

Abstract

This study was conducted to identify the sweet sorghum cultivars presenting higher tolerance to drought as well as to phenotypically discriminate the root morphological characteristics of those genotypes for environments with water deficit.The cultivars (Rio, Ramada, BRS 501 andBRS 506) were subjected to two treatments (Environments). The first one was an environment named unrestricted water (AI) -37.5 kPa, and the second one, with hydric restriction, named restricted water (AR) with a matrix pressure lower than the with CPA treatment, that is, -375kPa. The difference between the ideal weight of the treatment and the weight observed in the vase, before being irrigated, when compared with an identical vase used in the treatments without the plant, provided an evapotranspiration of the cultivar during the period. The roots were analyzed by the WinRhizo system, in order to obtain the following characteristics under study: length, volume, superficial area, projected area and root diameter. For all characteristicsunder evaluation, the variance analysis showed no interaction (P> 0.05) between genotype and environment. Separately, no variations were observed (P> 0.05) in the genotypes and environments evaluated for the characteristics under study, except the root diameter. Thus ,it was observed that the diameter of the roots were higher (P <0.05) when the plants were submitted to higher drought stress conditions (AIR). Findings indicate that the cultivars did not present significantly different characteristics in the contrasting environments, which probably occurred because they are very tolerant to the imposed stress, the phenological stage under evaluation study was too initial, or the stress had low intensity to generate different activities in the cultivars..