Location: Crop Genetics ResearchTitle: Genotypic and environmental effects on cottonseed oil, nitrogen, and gossypol contents in eighteen years Regional High Quality tests
|Campbell, Benjamin - Todd|
|Dever, Jane - Texas A&M University|
|Zhang, Jinfa - New Mexico State University|
|Jones, Andrea - University Of Missouri|
|Raper, Tyson - University Of Tennessee|
|Hague, Steve - Texas A&M University|
|Smith, Wayne - Texas A&M University|
|Myers, Gerald - Louisana State University|
|Bourland, Fred - University Of Arkansas|
Submitted to: Euphytica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/22/2015
Publication Date: 7/31/2015
Citation: Zeng, L., Campbell, B.T., Bechere, E., Dever, J.K., Zhang, J., Jones, A., Raper, T.B., Hague, S., Smith, W., Myers, G.O., Bourland, F. 2015. Genotypic and environmental effects on cottonseed oil, nitrogen, and gossypol contents in eighteen years Regional High Quality tests. Euphytica. 206:815-824.
Interpretive Summary: Oil and protein contents are important cottonseed compositions which can be extracted and utilized in dairy cattle feeding, frying food for human consumption, and biofuel. Cottonseed also contains glands producing gossypol, a chemical to be toxic to cattle. These compositions are critical for utilization of cottonseed as secondary products to promote profit of cotton growers. Therefore, cotton cultivars have to be improved with increase of oil and protein contents and decrease of gossypol content in cottonseed. Environment is an important factor for performance of cotton cultivars and could affect cottonseed compositions. In this study, data were obtained from National Cotton Variety Trials (NCVT) conducted during 1996 and 2013; NCVT is a program to test cotton cultivars at different locations in US Cotton Belt annually. The data of the 18 years NCVT tests were analyzed for environmental effects on oil, protein, and gossypol contents in cottonseed of different cultivars. Results showed that cottonseed compositions were affected by environments. It was concluded that cotton cultivars must be tested at multiple locations for improvement of oil, protein, and gossypol contents.
Technical Abstract: Determination of environmental influence on seed traits is critical for genetic improvement of seed quality in Upland cotton (Gossypium hirsutum L.). The objective of this study was to analyze the relative contribution of environment and genotype (G) for seed oil, nitrogen (N), and gossypol contents using historical data from the Regional High Quality (RHQ) tests conducted from 1996 through 2013. The 18-year tests of RHQ were divided into six three-year cycles with an average of about 20 genotypes and 7 to 10 testing locations (loc) in each cycle. Variance components of oil, N, and gossypol contents were estimated in each cycle and expressed as percentages of the total variance. Highly significant G × loc effects were identified for all seed quality traits in each cycle. For oil content, variance estimates of G to the total variance ranged from 20 to 57% in different cycles. For N content, loc was the main source of variance with variance estimates of loc to the total variance ranging from 44 to 73 % in different cycles. In most cycles, loc and G were the main source of variance for free-gossypol content. For most seed quality traits, there was not a clear trend of changes among breeding cycles for the variance estimates of G to the total variance. Broad-sense heritability for oil content, N content, and free-gossypol ranged from 0.79 to 0.96, 0.65 to 0.86, and 0.28 to 0.93, respectively. Highly significant G × loc interactions indicate that multiple location trials for testing seed quality traits are necessary. However, heritability estimates for these seed traits indicate stability across environments as well as the potential for genetic improvement. Significant reduction in seed index was observed in half of the breeding cycles with a range of 10.4 to 9.52 within cycles. Correlation between seed index and oil content was positive with r values ranging from 0.23 to 0.77 in different cycles.