Evaluation of drought tolerance for Atlas fescue,perennial ryegrass,and their progeny

Primitive cottons (Gossypium spp.) represent resources for genetic improvement. Most primitive accessions are photoperiod sensitive; they do not flower under the long days of the U.S. cotton belt. Molecular markers were used to locate quantitative trait loci (QTLs) for node of first fruiting branch (NFB), a trait closely related to flowering time in cotton. An F₂ population consisted of 251 plants from the cross of a day neutral cultivar Deltapine 61, and a photoperiod sensitive accession Texas 701, were used in this study. Segregation in the population revealed the complex characteristics of NFB. Interval mapping and multiple QTL mapping were used to determine QTLs contributing to NFB. Three significant QTLs were mapped to chromosome 16, 21, and 25; two suggestive QTLs were mapped to chromosome 15 and 16. Four markers associated with these QTLs accounted for 33% of the variation in NFB by single and multiple-marker regression analyses. Two pairs of epistasis interaction between markers were detected. Our results suggested that at least three chromosomes contain factors associated with flowering time for this population with epistasis interactions between chromosomes. This research represent the first flowering time QTL mapping in cotton. Makers associated with flowering time may have the potential to facilitate day neutral conversion of accessions. Contribution of USDA-ARS in cooperation with the Mississippi Agric. and Forestry Exp. Stn. Journal paper J-11131 of Mississippi Agric. and Forestry Exp. Stn. Mention of trademark, proprietary product, or vendor does not constitute a guarantee or warranty of the product by USDA, ARS and does not imply its approval to the exclusion of other products or vendors that may also be suitable.