Evaluation of reaction of sunflower (Helianthus annuus L.) genotypes in terms of yield and yield components under water stress conditions

The present study was carried out to identify sunflower tolerant genotypes at Research Station of Dryland Agricultural Research Institute (Sararood) in Kermanshah. The experiment was carried out in the form of a lattice square design. In this study, 64 sunflower genotypes with 8x8 arrangements were compared in two conditions of non-stress and applying water stress (irrigation cut off at flowering stage). The results showed that between genotypes as well as water stress treatment levels, there was no significant difference in number of heads per area. For head diameter in water stress conditions, in 27 genotypes head diameter was more than 11.4 cm and in 16 genotypes, head diameter did not reach even 10 cm. In non-stress conditions, Sil-96 genotype was shown the highest number of seeds per head by producing more than 842 seeds per head. However, 12 other genotypes were placed in a statistical group with this genotype. By applying water stress in 11 genotypes (including the Sil-96), the number of seeds per head was more than 630 and in 16 genotypes, the number of seeds per head was less than 400. In terms of weight of 1000 seeds, there was no significant difference between sunflower genotypes in both conditions of non-stress and water stress application. But by comparing two conditions of stress and non-stress, it was found that water stress caused a significant reduction in the weight of 1000 seeds in amount of 8.62%. Sil-96 genotype showed the highest seed yield in both stress and non-stress conditions. Although in each of the conditions of the water treatment, were placed into a statistical group with four other genotypes. Also, Sil-96 genotype had the highest stress tolerance index. Therefore, it seems that this genotype is recommended for cultivation in both stress and non-stress conditions.