|Dever, Jane -|
|Zhang, Jinfa -|
|Glass, Kathryn -|
|Jones, Andrea -|
|Myers, Gerald -|
|Bourland, Fred -|
Submitted to: Journal of Cotton Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 11, 2013
Publication Date: April 1, 2014
Citation: Zeng, L., Campbell, B.T., Dever, J.K., Zhang, J., Glass, K.M., Jones, A.S., Myers, G.O., Meredith Jr, W.R., Bourland, F.M. 2014. Genotype by environment interaction effects on lint yield of cotton cultivars across major regions in the U.S. Cotton Belt. Journal of Cotton Science. 18:75-84. Interpretive Summary: Environment is an important factor affecting yield of cultivars. Cotton cultivars with high instability in agronomic performance across environments could perform well in one environment and poorly in another environment and this would affect success in breeding for improving yield. Therefore, evaluation of cultivars for performance stability at multiple locations and in different years is critical for maintaining profitability for cotton growers. However, cost would be high with extensive increase of test locations and test years. Identification of similarity among test locations and group the similar test locations can help reasonably arrange test locations and reduce the cost. In this study, data were obtained from Regional High Quality tests (RHQ) conducted as part of the USDA-Agricultural Research Service National Cotton Variety Tests between 2003 and 2009; RHQ is a program to test cotton cultivars at different locations in the U.S. Cotton Belt annually and select cultivars with good yield and desirable fiber quality. In this study, the data of RHQ were analyzed for environmental effects on lint yield of different cultivars in order to identify cultivars with wide adaptation to different environments. Results indicate environments were different across locations and years for lint yield. The test locations of Lubbock, TX and Las Cruces, NM were distinct from other test locations distributed in the other regions in the Cotton Belt. These results suggest that the number of test sites in the Plains and the Western regions should be increased while the test sites in the other regions of the Cotton Belt can be reduced in order to improve success in breeding for cultivars with high stability and reduce cost in tests.
Technical Abstract: Analysis of genotype (G) by environment (E) interactions and their influence on performance of cotton (Gossypium hirsutum L.) cultivars can help cotton breeders improve performance stability of cultivars across environments. Data from multi-locations trials of the Regional High Quality Tests (RHQ) conducted as part of the USDA-ARS National Cotton Variety Tests during 2003 and 2009 were used to analyze G x E and relationships among test locations for megaenvironments. The trials were located in the Western, the Plains, the Central, the Delta, and the Eastern regions of the U.S. Cotton Belt. Strong genotypic effects for lint yield relative to the interactions of genotype by environment were observed consistently during all trial years. Effects of genotype x location for lint yield were either larger or comparable to the effects of genotype x year. The relationships among test locations were analyzed in GGE biplot and no clear megaenvironments were identified among test locations across years. This result indicated highly unpredictable environmental factors across locations and years in the Cotton Belt. Nevertheless, the locations of Las Cruces, NM in the Western and Lubbock, TX in the Plains test regions were identified distinct from the test locations in the other areas. It was hypothesized that the environments in the U.S. Cotton Belt belonged to one megaenvironment with the areas in the Western and the Plains as a sub-region. The daily minimum temperature was identified significantly correlated to environment scores of the first principal component axis with r values -0.41 and -0.30 for the early and late growing seasons, respectively. This result suggests that genetic improvement of cotton cultivars for tolerance to low temperature during the early and late growing season could increase yield stability.