YIELD STABILITY OF SUNFLOWER HYBRIDS AND VARIETIES IN DIFFERENT SOWING DATES IN THE VALLE DEL MAYO, SONORA

Abstract

The present study was performed in the Mayo Valley, Sonora, Mexico. lts objctive was to evaluare the yield stabil ity of four sunflower (Helianthus annuus L.) hybrids (Sun Hi 338, IS-241, IS-893 and Saffola) and two varieties (Cernianka and Peredovik) at six planting dates from November 20, 1980 to March 10, 1981. Results indicated that: 1) Yield decreased as planting dates were delayed; 2) Sunflower hybrids had the highest yields in the first planting date (Nov. 20) while the varieties were the best yielders in the second planting date (Dec. 10); 3) All cultivars had regression coefficients statistically equal to one; however, the varieties tended to perform better under unfavorable environments and the hybrids performed better under favorable environments; 4) Excluding the hybrid IS-241, all other genotypes were inconsistent (S 2d _¡>0); 5) All genotypes showed different behaviour through planting dates; 6) In general, after the fourth planting date yields were greatly reduced; and 7) With the exception of protein content, the magnitude of other phenotypic characters was reduced as planting date was delayed.