Variation in Growth Patterns Among Cotton Cultivars Using Nodes-Above-White-Flower

N. Benson and E. Vories


 
ABSTRACT

Profitable cotton production is often limited by delayed maturity, especially in northernareas of the Cotton Belt. This study was conducted to define growth patterns associated with the maturity of contrasting cotton cultivars using recently developed plant monitoring techniques.

Four short-season cultivars and two full-season cultivars were evaluated in three irrigated and one non-irrigated test in 1989, 1990., and 1991. Growth patterns, for each cultivar, were determined by plotting the number of nodes abov@e the uppermost first position white flower (NAWF) against days after planting (DAP). By regressing NAWF by DAP, accumulative early season growth and maturity were calculated by determining NAWF at 60 DAP and days to NAWF = 5, respectively. Finally, a computer-based management system, COTMAN, which integrated NAWF data with historical weather, was used to estimate optimum date of defoliation, i.e. maturity. Within each test, cultivars capable of attaining maturity within a specified probability level were defined as having a Type I growth pattern, while cultivars unable to attain maturity were defined as having a Type II growth pattern.

Growth patterns in 1989 and 1990 typified the Type I shape. Two forms of Type II-shaped patterns were apparent in 1991, one caused by early season stress and a second caused by excess vegetative growth. The shapes of growth patterns across cultivars were similar within each test with fullseason cultivars consistently having more NAWF than short-season cultivars. In tests having a Type I-shaped growth pattern, variation in maturity among cultivars (indicated by "days to NAWF = 511) could be detected at first flower (indicated by "NAWF at 60 days"). Differences in maturity of cultivars generally were not detected when Type II-shaped patterns occurred. COTMAN defined as Type II both the Type II-shaped patterns and late-maturing Type I-shaped patterns. Late-maturing, Type I-shaped patterns were mainly due to delayed planting date; and occurred more frequently in northern than southern locations and, more frequently in full-season than short-season cultivars. These data indicate that growth patterns can be accurately assessed and analyzed using NAWF parameters and COTMAN. Also, the influence of environment and cultural factors can overwhelm the genetic differences in maturity.



Reprinted from 1995 Proceedings Beltwide Cotton Conference pg. 524
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998