Aspectos fisiológicos e bioquímicos de genótipos de girassol sob estresse por alumínio

Abstract

Acids soils comprise approximately 50% of arable land the world and potentially usable for the food production. The presence of toxic Al is a major problem limiting the development of crops in these regions. This study aimed to identify from 25 sunflower genotypes, tolerant and sensitive ones to Al, with a view to identifying physiological and/or biochemical parameters that can serve as indicators of sunflower tolerance to this stress. The results in the selection of genotypes showed that Catissol, 11-26 EXP, OH and H-860 H-358 were the most tolerant and IAC-Uruguay, AG 960, EXP 44-49, IAC Iarama, BRS-G27, 887 and EXP H-251 more sensitive compared between themselves. They also found that the levels of N and K in leaves and roots and P content in leaves did not correlate with tolerance. In contrast, the maintenance of P content in roots of stressed plants, seems to play an important role in Al tolerance in sunflower, suggesting its use as a physiological marker for the selection of Al tolerance in this species. The Catissol variety (tolerant) and IAC-Uruguay (sensitive) were used for assess the physiological and biochemical responses to aluminium stress to over time. The data showed reduction in the percentage of membrane integrity, relative water content and pigments in IAC-Uruguay variety, in contrast to Catissol variety. The results of soluble carbohydrates, amino acids and free proline in both varieties suggest that accumulate of these solutes, mainly in the roots of Catissol, may play an important role in stress tolerance of the girassol to Al3+.