Author
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Zeng, Linghe |
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Pettigrew, William |
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Submitted to: Field Crops Research
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 10/7/2014 Publication Date: 2/1/2015 Citation: Zeng, L., Pettigrew, W.T. 2015. Combining ability, heritability, and genotypic correlations for lint yield and fiber quality of Upland cotton in delayed planting. Field Crops Research. 171:176-183. Interpretive Summary: The small grain crop, wheat, has become one of major biofuel crops and its acreage in Delta region has increased dramatically in recent years. How to utilize the empty land after harvest of wheat has become imminent. Growing cotton after wheat can be an effective approach to increase land use efficiency and promote profit for cotton growers. Planting of cotton has to be delayed in this practice to allow planting after wheat is harvested. Currently, there are some small acreages of cotton planted after wheat in Delta region. The acreage is expected to increase in future. One of the problems is that the current cotton cultivars used in this practice were all developed for the normal planting system. Whether is it necessary to develop cotton cultivars that can be used for the delayed planting system? This study was designed to analyze genetic values in ten genetic populations in order to answer this question. If the genetic values were influenced by environments of the delayed planting, it would suggest a necessity to develop cotton cultivars for the delayed planting system. The populations and their parents were planted at an early date (normal) and a late date (delayed) in 2012 and 2013, respectively. Although genetic values in the genetic populations changed under the environments of delayed planting, the changes were marginal. Because the success of this management option depends on the cost and profit, we suggest that the current cotton cultivars can be directly used for small acreages of delayed planting. Technical Abstract: 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 of genetic values in parents under environments of delayed planting will help determine if it is necessary to test 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 (early April to late April) 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 of some parents for lint yield and two yield components of boll no. and seeds per boll were different between treatments of delayed planting and normal planting. Change of SCA effects for yield components were observed in delayed planting. 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 quality were similar between treatments of planting date. Genotypic correlation between lint yield and fiber strength became more negative, -0.83, in the delayed planting compared with -0.34 in the 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 delayed planting system. Overall, the results should inform cotton breeders the necessity for testing parents for lint yield under environments of delayed planting. |
