Combining ability, heritability, and genotypic correlations for lint yield and fiber quality of Upland cotton in delayed planting

- Combining ability and heritability for yield traits in cotton changed between delayed planting and normal planting.
- Genotypic correlations changed between delayed planting and normal planting.
- There is a need for testing parents under environments of delayed planting in order to maintain yield in delayed planting of cotton.

Delayed planting is a necessary practice in Upland cotton (Gossypium hirsutum L.) production when double cropping cotton with small grain crops. All current cultivars used for delayed planting were selected under environments of normal planting. The information about genetic values of parents in delayed planting will help determine if it is necessary for testing parents under environments of delayed planting before their use in development of cultivars for the delayed planting system. General combining ability (GCA), specific combining ability (SCA), broad sense heritability, and genetic correlation were compared between two treatments of planting date, the normal planting (mid-April to early May) and delayed planting (late May). Ten F2 hybrid populations derived from a half diallel crossing design and their five parents were planted in 2012 and 2013 with four replicates each year. GCA effects for lint yield and two yield components of boll no. and seeds per boll were different between delayed planting and normal planting. Both direction changes of SCA effects for yield components were observed between treatments of planting date. However, effects of SCA × year were not significant in delayed planting. Reductions in broad sense heritability of yield traits were observed in the delayed planting (0.01-0.25) compared with that of the normal planting (0.10-0.88). Combining ability effects and heritability for fiber properties were similar between treatments of planting date. Genotypic correlation between lint yield and fiber strength became more negative, −0.83, in delayed planting compared with −0.34 in normal planting. The change of genotypic correlations between lint yield and fiber quality in the delayed planting implies an increase of complexity for interrelationships among fiber traits in the double cropped cotton. Overall, the results should inform cotton breeders the need of testing parents for lint yield under environments of delayed planting.