Genetic analysis of yield and its components in sunflower lines under normal and drought stress conditions

Turn to occurrence of drought stress in recently years, it asks for attention drought stress conditions has to be considered in plant breeding programs also combining ability determination of inbred lines derived from plant breeding programs. It could be useful to determine drought stress tolerant genetic materials. Production of hybrid cultivars due to high yield, uniformity in maturity and agronomic characteristics and resistance to disease has been popular among plant breeders. Identifying suitable parent lines for production hybrid cultivars under drought stress conditions is very important. For this it has to be identified inbred lines with high general combining ability and then Identifying lines with specific combining ability for important agronomic traits under both normal and drought stress conditions.
In order to production new sunflower hybrids and evaluated of general and specific combining ability of some sunflower inbred and restorer lines, in first year of this project 4 inbred lines and 3 restorers (this materials are belonged to oilseed department, seed and plant improved institute) has been selected for crossing. In second years, 12 derived hybrids along with Farokh and SHF-81-90 as checks were evaluated using RCBD design with 3 replications under normal and drought stress conditions. Under normal conditions irrigations has been occurred as usual so that plants did not encountered to drought stress in non vegetative or reproductive stages and under drought stress conditions irrigation has been deleted from flowering stage. Some important agronomic traits such as days to maturity, plant height, head diameter were recorded based on Schneiter and Miller, 1981 instruction. Grain yield was accented using harvesting two rows of each plot with one plant deleted from head and end of each plot. Seed oil content was measured using NIR instrument model DA7200.
Combined variance analysis showed that drought stress had significant effect on all traits exception seeds per head. The most reduction due to drought stress belonged to seed yield and 1000 seed weight and the least reduction belonged to seed oil content percent. Variance analysis of combining ability showed that effects of CMS and restorer lines (general combining ability) were statistically significant for most traits under normal and drought stress conditions. Results showed that restorer lines had more portion than it in CMS lines for genetic variation. Significant effects for CMS and restorer lines in addition to their interaction effect showed that most evaluated traits were controlled by both additive and dominant gene effects.