Breeding Potentials of Noncultivated Cottons. IV. Location and Parental Effects on Agronomic Characters and Fiber Properties in Hybrids1

Abstract

We studied the inheritance of six agronomic characters and five fiber properties in Ft hybrids between two cultivars and eight primitive race stocks of cotton, Gossypium hirsutum L., in 1975 and between the same two cultivars and four other race stocks in 1976. Plants were grown at Phoenix, Ariz., where insecticides were applied as needed for control of pink bollworm, Pectinophora gossypiella (Saunders), and at Tempe, Ariz., where no insecticides were applied. Location effects were significantfor most characters both years. Location ✕ race‐stock interactions were also significant for several characters. Usually, however, hybrid arrays that ranked first at one location also ranked first or second at the other location, thus suggesting that inconsistencies in performance occurred in other arrays. The Tempe location, therefore, was usually as suitable as the Phoenix location, revealing superior hybrid performance in spite of heavy pink bollworm pressure. One exception was bolls/plant in 1976, where the highest ranked array at Phoenix was the lowest ranked array at Tempe. Genetic variability in hybrids was attributed mostly to differences in race stocks, but cultivars contributed variability in a few characters. In 1975, significant race‐stock effects coupled with the absence of cultivar ✕ race‐stock interactions indicated the presence of adequate amounts of additive genetic variability. In 1976, however, five of 11 characters showed significant cultivar ✕ race‐stock interactions, indicating that these race stocks may be more refractory. Individual heterotic combinations also indicated the presence of nonadditive genetic variability. F1 vs. parental cultivar “favorable” heterosis was shown in a number of combinations but did not consistently appear in the same combinations at both locations.