|Wu, Jixiang -|
Submitted to: Euphytica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 2, 2012
Publication Date: May 22, 2012
Citation: Zeng, L., Wu, J. 2012. Germplasm for genetic improvement of lint yield in Upland cotton genetic analysis of lint yield with yield components. Euphytica. 187:247-261. Interpretive Summary: Gains in cotton lint yield per acre and fiber quality have been low in recent years. Improvement of lint yield in cotton is critical for growers to maintain profitability. Yield is a complex trait and is affected by environmental conditions. Breeders often select for yield components (number of bolls per plant, weight per boll, weight per seed, amount of lint per seed, and number of seed per boll) which can be more effective than direct selection for increased lint yield. Identification of good lines to transmit superior traits for yield and yield components to progenies can help breeders select for high yielding cultivars using these lines as parents in breeding. Crosses were made between cultivars and wild germplasm lines in order to introduce desirable genes from this germplasm into cultivars for improving lint yield. Two wild germplasm lines, SP156 and SP205, had desirable combinations between lint yield and yield components including lint percentage, boll number, boll weight, and seed weight. These two lines were identified as good parents to transmit superior traits in yield components when crossed with other cultivars. Thus, these two lines can be used as parents in breeding for development of both pure lines and hybrids.
Technical Abstract: Determination of genetic effects for lint yield and yield components in cotton (Gossypium hirsutum L.) germplasm is critical for its utilization in breeding programs. This study was designed to apply the conditional approach and an additive and dominant (AD) model to analyze genetic effects and genetic relationships for lint yield and yield components. Forty-eight F2 hybrids derived from crosses between four extant Upland cotton cultivars and breeding lines as female parents and 12 exotic germplasm lines as male parents were evaluated at two locations in 2008 and 2009. Conditional and unconditional variance components were estimated by the mixed linear model based conditional approach. In F2 hybrids, boll number contributed the most variation to lint yield based on path coefficient analysis. Lint yield and yield components were mainly controlled by genotypic effects, i.e. additive variance and dominance variance (>66% of total phenotypic variation). Lint percentage and lint per seed had the highest proportions of additive variance component to the total phenotypic variances. SP156 and SP205 had positive additive effects for lint yield and yield components and were also parents of the most hybrids with positive predicted dominant effects. Therefore, these two lines are good combiners for development of both pure lines and hybrids. Positive additive contribution effects to lint yield from lint percentage, boll number, boll weight, and seed weight were detected in different parents. Adding seed weight to boll number and lint percentage increased additive contribution effects to lint yield from these two components relative to the contribution effects from either boll number or lint percentage alone. Results in this study suggest that boll number, lint percentage, and seed weight should be balanced in pure line development.