English

Abstract

Drought is one of the most damaging environmental stresses, which decreases the achene yield of sunflower (Helianthus annuus L.). The objectives of our experimentations were to determine the type of gene action in sunflower under drought stress, for the identification of the lines with higher achene yield for purpose of developing hybrid with higher achene yield. Thirty-two single cross hybrids from 12 inbred lines were developed through line × tester mating design through crossing 8 drought tolerant inbred lines with 4 drought susceptible lines. The evaluation experiment was performed under an alpha (0,1) lattice incomplete block design with three replications. The achene yield related traits like DF, DM, PH, NL/P, HD, SG, AY/P and TAW were evaluated under normal irrigation and drought stress conditions. Values of degree of dominance greater than one indicating that traits were under the control of dominant genetic effect. Based on GCA effects, L1 proved good combiner for early flowering, maturity and short stature; while L6 was a good combiner for NL/P, HD and AY/P while L8 for HD, SG, AY/P and TAW under drought stress condition. Based on SCA effects, Hybrid 20 was found a good SCA combiner for early flowering, early maturity, short stature, higher HD, AY/P and TAW under normal as well as drought stress conditions. It was suggested form our study that the lines L1, L6 and L8 can be further used to develop drought tolerant hybrids for higher yield and L5 × L12 (Hy 20) was proposed for general cultivation in irrigated as well as rainfed areas of Pakistan.