SEED DEVELOPMENTAL PROBLEMS AND SEED ROT IN SOUTH CAROLINA

摘要

Seed developmental problems have occurred in many cotton fields in South Carolina during the past three seasons. Five replicated field experiments were conducted at the Pee Dee Research & Education Center during the 2001 growing season. Experimentswere designed to determine the impact of the environment, varieties, and management practices on seed abnormalities, as well as the relationships between seed problems, stink bug feeding, and other new cotton disorders. Experiments revealed seed developmental problems occurred in all varieties examined. This list of varieties included a conventional variety released in the early 1920's (Dixie Triumph), conventional varieties adapted to S.C. and developed at the Pee Dee Station during the 1970's (SC 1, PD 1, PD 2, PD 2164), conventional varieties not adapted to the Southeastern U.S. (Maxxa, Sphinx, Tamcot SP21), conventional varieties currently grown in S.C. (DPL 5690 and ST 474), and transgenic varieties currently grown in S.C. (DPL 655BR and PM 1218BR). The only cultivar which appeared to be consistently more susceptible than the other varieties to seed abnormalities was Maxxa, a variety which is grown primarily in the Western U.S. Few seed developmental problems were found in bolls younger than three weeks of age. Seed rot symptoms appeared to increase as boll age increased. High levels of seed abnormalities during boll development were generally associated with increased problems with hardlock cotton at maturity and problems with mechanical picking at harvest. The occurrence of seed abnormalities and seed rot symptoms was unaffected by the various management inputs applied during the growing season such as: increasing the boll load per plant (Low plant population), decreasing the boll load per plant (early fruit removal with Prep), applying plant growth regulators (Messenger or PixPlus), increasing the potassium rate by 100 lbs/A, increasing the boron rate by 0.5 lb/A, reducing the nitrogen rate from 90 lbs/A to 40 lbs/A.