Yield, flowering, and leaf area index of okra-leaf and normal-leaf cotton isolines

Cotton (Gossypium hirsutum L.) with alternative leaf morphologies, such as the cleft-shaped okra-leaf types, offers production advantages such as earlier maturity. However, okra-leaf types have not been commercially viable in the USA. The objectives of this study were to test okra-leaf types in genetic backgrounds varying in maturity and region of adaptation and to provide growth data that might explain yield differences, Four to seven pairs of selected cotton okra- and normal-leaf isolines (and check cultivars) were grown in the field in one 2-yr (Exp, A) and two l-yr experiments (Exp, B and C) from 1994 to 1996 near Stoneville, MS, in row spacings of 76 and 102 cm. In Exp. A, average lint yields of okra-leaf isolines were greater overall than normal-leaf lines (847 vs. 749 kg ha(-1)), but in Exp. C, the opposite was true (1020 kg ha(-1) for okra- vs. 1130 kg ha(-1) for normal-leaf types). No yield difference was found between leaf types in Exp. B, Yields of okra-leaf lines were either equal to or less than those of recently released high-yielding commercial types whose okra-leaf isolines are not yet available. Okra-leaf types were usually 1 to 4 d earlier in maturity than their normal-leaf counterparts, possibly contributing to their overall yield advantage in Exp, A. When only okra-leaf isolines were considered, Tamcot HQ95 ranked first or second highest for yield and was the earliest to mature in all three tests. In general, the row-spacing effect and interactions with row spacing were not significant. The results indicate that the okra-leaf trait should be considered for producing future cultivars.