Screening of some sunflower hybrids for drought tolerance under laboratory conditions

Helianthus annuus L. is one of the most important crops in the world, widely cultivated for its edible seeds and highquality oil with a wide range of application in human consumption, oleochemical, pharmaceutical and cosmetics industries and also for biodiesel production. In the environment with changing climatic conditions the global agricultural production (including sunflower seeds) suffers considerable decrease due to the negative impact of abiotic factors such as heat, drought, salinity etc. Therefore, one of the main objectives of the breeders is to obtain drought tolerant varieties, which can express their full yield potential inclusively under drastic water deficiency. Though sunflower is considered drought-tolerant crop, it is very sensitive to water deficit at the stage of germination, seedling and flowering. In this context, the aim of this study was to evaluate drought tolerance potential in some new sunflower experimental hybrids at germination and early seedling growth stages under laboratory conditions using PEG-6000. Two levels of osmotic stress (induced by PEG concentrations 10 and 20%) were created and the reaction of genotypes was evaluated against a control. Germination rate (GR), germination stress tolerance index (GSI), plant height stress index (PHSI), root length stress index (RLSI) and dry matter stress index (DMSI) were used to determine the genotypic response to water stress. Drought stress affected the germination rate and seedling traits in all samples, indicating significant differences among genotypes and PEG concentrations. Plant height and seedling fresh weight are the most affected, such as a significant reduction of these parameters was observed in all sunflower genotypes. In contrast, an increase in RLSI was observed in the majority of tested sunflower hybrids. The hybrids HM1, HM11, HM14, HM17 and HM20 created by Moldavian Company AMG-Agroselect Comert and H5, H9 and H17 belonged from NARDI Fundulea, Romania performed well among evaluated sunflower genotypes, indicating a greater tolerance in terms of germination rate, shoot and root development, as well as dry plants weight at both levels of water stress. The genotypes with best performance could be recommended for breeding program and cultivation in areas with water deficiency during the germination and early seedling growth stages