Identifier

etd-02132008-102450

Degree

Doctor of Philosophy (PhD)

Department

Plant, Environmental Management and Soil Sciences

Document Type

Dissertation

Abstract

Cotton (Gossypium spp.), the most important textile fiber crop in the United States (US), is cultivated in 17 states across the southern US. and a very important agricultural commodity for several states. The use of hybrids in the US has been limited due to seed cost production. The objective of this study was to investigate a novel method for the production of F2 cotton hybrids using honey bees as pollinators and Roundup Ready® gene as selection trait. This research was conducted during three years (2005-2007) in Louisiana. Crosses between non-transgenic and transgenic varieties were made in 2005 to obtain F1 cottonseeds using honey bees. In 2006, F2 cottonseed was obtained. In 2007, F1, F2, and parents were field tested using a randomized complete block design with 3 replications in two locations. Data analysis was conducted using the SAS PROC MIXED procedure with estimates of means generated using least square means (LS means). Results indicate that all crosses exhibited heterosis in the F1 hybrid populations relative to the best parent. The crosses LA1110023/PHY410R and ARKRM24-12-04/PHY410R exhibited a higher degree of heterosis for yield averaging 33.1% and 20.6%, respectively, across locations. Yield heterosis in the F2 population was of 20.9% and 19.5%, respectively, and statistically different from the best parent. The ARK9506-40-05/PHY410R cross had yield heterosis averaging 15.6% in the F1 population and 13.5% in the F2 population; however, these were not significantly different from the best parent. The lack of significant yield heterosis might be attributed to experimental error and suggests the need for further field testing. Fiber quality descriptors from the six crosses, did not have a significant heterosis in the F2 population relative to the best parent. In summary, the use of herbicide resistant varieties as males and Roundup Ready® gene as selection trait, conventional varieties as females and honey bees as pollinators, has proven to be a viable method for developing F2 hybrid varieties. Further variety testing will be required to determine the best combination of parents. Promotion of this technology among seed companies is required for the development of better and improved cotton varieties as F2 hybrids.

Date

2008

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Gerald O. Myers

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