Genetic analysis of earliness in upland cotton (Gossypium hirsutum L.).: I.: Morphological and phenological variables

Inheritance and interrelationships of morphological and phenological components of earliness were evaluated in a diallel analysis involving seven early-maturing parents and a standard cultivar. This study was initiated in 1993 by making all possible crosses, without reciprocals, among the eight parents. Field evaluation of the eight parental genotypes and the 28 F-1 was made in 1994 in a randomized complete block design with four replications. Of 13 earliness components studied, all but days to first square, vertical flowering interval, boil maturation period, and production rate index showed significant additive genetic variance. Heritability estimates ranged from 0.02 for production rate index to 0.39 for days to first open bell. Correlation analysis showed generally that the lower the node to the first fruiting branch and the shorter the plant, the earlier was the onset of squaring, flowering, and boil opening.