Studies on genotypic variability and seed dormancy in sunflower genotypes (Helianthus annuus L.)

Seed dormancy is a major drawback and causes a great problem in efficient seed production of sunflower for which great efforts have been made to develop techniques in breaking seed dormancy of sunflower. Studies have indicated that sunflower genotypes showed a large variability in dormancy. Few nearly non-dormant genotypes have been identified which may be incorporated in breeding programme for inducing this non-dormancy trait. Different hours of hydro-priming (15 and 20 h) have been adopted to determine their effects in breaking dormancy. It has been assessed that 15 h priming improved germination percentage and higher seedling vigour than that at 20 h priming period. This priming period is considered as a novel technique to break dormancy and to improve seedling vigour in sunflower. Fifteen hours priming period gave significant increase in germination percentage compared to the control. In another study, the same sunflower hybrid grown/obtained from different sources showed variability in dormancy, where 15 h priming improved germination significantly in most of the sources except few cases. This indicates that climatic conditions prevailing in different regions have great impact on seed dormancy in sunflower. It is assumed that the priming could have made some biochemical changes in the seed leading to the breaking of seed dormancy and enhancing seed germination and vigour in sunflower.