Effects of seasonal variation on seed yield and oil content in sunflower.

To investigate the seasonal variation effects on seed yield and oil content in sunflower, 73 genotypes were grown at Punjab Agricultural University, Ludhiana during Spring and Rablioffseason, 2005. Spring crop was planted in March while Rabi crop was planted in October. Results showed reduction in seed yield as well as oil content in Rabi crop as compared to those of Spring crop. However, the reduction in seed yield was more as compared to the reduction in oil content which shows that seed setting is adversely affected by the low temperature prevailing during reproductive period, while the oil production in the tissue is not affected to that extent. The different genotypes responded differently to the environmental variation. Only one genotype i.e. GP2-670-3-2 revealed stable performance for both the characters over the environments and also it remained unaffected by the frost effect during Rabi season. A few genotypes viz. GP2-661-2-5, GP2-622-6-2, GP2-132-4-3, GP2-120-4-1, GP2-2104-2-3 showing mild reduction in oil content from spring season to winter season were identified for use in further breeding programme.