Resistência diferencial ao estresse salino entre porta-enxertos de videira (Vitis vinifera L.) associada à seletividade K+/Na+ e eficiência fotossintética

Abstract

Soil salinity is one of the most important environmental stresses for agriculture worldwide, especially in the semiarid region, reducing the productivity of numerous plant species. Therefore, a precise regulation of the response to salt stress represents a key step for plant adaptation and survival. The vine is one of the most widespread crops worldwide. Little is known about the physiological processes involved in the selective absorption between K+ and Na+ ions associated with the exclusion and partition of Na+ and Cl- ions and the interaction of these mechanisms in grapevines under salinity, which can be a differential in tolerance for this crop. The present study aimed to elucidate the resistance mechanisms between two contrasting genotypes of vine rootstock, IAC 313 and Paulsen 1103, under salinity, through three experiments. In experiment I, the relationship between K+/Na+ selectivity in rootstocks and photosynthetic disorders was studied, allowing to show whether genotypes with better ionic homeostasis under salinity have physiological mechanisms to protect the processes involved with the assimilation of CO2. Experiment II was carried out in a complementary way to the results of the first study, where the objective was to characterize the differential affinity in K+ absorption in the absence of Na+ between the two grapevine rootstocks. Experiment III was carried out with the objective of evaluating the effect of the external increase of K+ in avoiding excessive Na+ absorption under salinity. The results show that the differential contrast in tolerance between the two vine rootstocks is associated with selective ion absorption between K+ and Na+ combined with the exclusion and partition mechanism of toxic ions Na+ and Cl- resulting in a better tolerance to salinity.