Field Trial And Agronomic Performance Of Antibiotics In Naturally-colored Cotton Against Key Leaf Damaging Pests

摘要

Laboratory tests were conducted to acquire the antibiotic effect of white and naturally-colored cotton varieties/lines, AP_2, PM_1 and PM_4 compared to the control, SR60, using fresh leaves fed to the 3rd instar Helicoverpa armigera larvae. There were no significant differences found in the developmental times and weights of the bollworm larvae and pupae fed on the leaves of the different cotton varieties/ lines except for the percentage of adult abnormalities in PM_1 and PM_4. The leaf damage by the leafhoppers was undertaken in a greenhouse using adult and nymph leafhoppers released in a screen cage containing one month-old cotton plants of each variety/line grown in pots. After 14 days, the results revealed that AP_2 had the lowest score for hopperbum rating (3.5). Cotton variety trials in sprayed and unsprayed plots were conducted during 2006 and 2007 at two locations, the Field Crop Research Center at Nakhon Ratchasima and a farmer's field at Thongpapoom, Kanchanaburi. The mean annual number of key pests and the annual yield of each variety/line at each location were compared and the average agronomic performance of each variety/ line was HVI analyzed. At Nakhon Ratchasima, leafhoppers were more abundant than aphids and whiteflies in both 2006 and 2007. There was a significant difference in the mean leafhopper numbers for AP_2 and PM_4 between both plots during the two years, while for PM_1 there was a significant difference in 2007 only. Seed weights of SR_(60) and PM_1 differed between the sprayed and unsprayed plots in 2006. At Tongpapoom, Kanchanaburi, both SR_(60) and PM_4 in 2006, and PM_4 again in 2007 had significantly different amounts of leafhopper between the sprayed and unsprayed plots. The yield of SR_(60) in the sprayed plot significantly differed from the unsprayed plots in 2006. Agronomic performance of each cotton fiber found only micronaire range in PM_1 from Thongpapoom and the fiber lengths of SR_(60), AP_2 and PM_1 grown at Nakhon Ratchasima to be designated as premium. At Tongpapoom, the AP_2 fiber length fell in the base range. The percent lint of AP_2 was the highest at Nakhon Ratchasima, while PM_4 had the lowest value for this parameter at both locations.