Effects of Premature Defoliation and Plant Kill on Germination of Cottonseed1

Abstract

AbstractPerformance data on cottonseed (Gossypium hirsutum L.) harvested from plants following premature defoliation and premature plant kill are limited. The objective of this study was to determine the effects of premature defoliation following adverse weather, hand defoliation, and premature plant kill (plants cut off at the soil line and dried rapidly in the greenhouse) at different dates in the fall on germination of cottonseed. The seed were stored for several weeks in the laboratory at about 30% relative humidity and 21 C before they were germinated at alternating 20 to 30 C and at a constant 18 C. Means for germination percentage, germination rate index (GRI), and coefficient of velocity of germination (CVG) were separated by Duncan's multiple range test. Reduced germination and GRI were obtained with seed harvest from plants that set fruiting following late season irrigation, premature defoliation following low temperatures, leaf removal by hand, and prematurely killed in September. Premature plant kill in October increased germination when compared to 50 and 100% leaf removal by hand and the check (no leaves removed). Germination was similar for seed harvested from plants with 50% leaf removal and the check. Removal of all leaves had the most adverse effect on the performance of cottonseed. The lowest CVG was obtained from plants left intact in the field. Seed from a determinant cultivar appeared to be affected less than seed from an indeterminant one.