Screening and Evaluation of Upland Cotton Race Stocks and Elite Lines for Photoperiod Response and Flowering Time

Elite cotton cultivars with desirable flowering time and broad genetic diversity can significantly improve overall agricultural productivity. Perennial primitive accessions of cotton have been described as an important source of useful genetic variability for cotton genetic improvement. Race stocks and elite lines along with the controls were planted in mid May of years 2010 and 2011 at Clayton, NC.  Eighteen TAMCOT varieties were evaluated for the earliness per se and determinate growth habit. Earliness was determined by counting the node of first fruiting branch and determinate growth habit was recorded by counting the number of bolls formed after August 1^st of each year. Race stocks were evaluated for earliness per se and photoperiod response by planting in two replicates. Results on the phenotypic variation for flowering time per se and photoperiod response in the above lines of cotton will be presented.