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Title: Differential tolerance of Hawaiian sugarcane varieties to diuron, 3-(3,4-dichlorophenyl)-1, 1-dimethylurea 
Author: Osgood, R. V (Robert V.), 1941
Date: 1969
Publisher: [Honolulu]
Abstract: Hawaiian sugarcane varieties, which are interspecific hybrids within the genus Saccharum, were found to differ substantially in their tolerance to diuron, 3-(3,4-dichlorophenyl)- 1,1-dimethylurea, and ametryne, 2-(ethylamino)-4- (isopropylamino)-6-(methylthio)-s-triazine. Metabolism, uptake and distribution of diuron were studied as possible mechanisms of the differential varietal response. In a field experiment diuron and ametryne were applied at 9 lb./acre (4 lb./acre pre-emergence + 5 lb./acre post-emergence) to three varieties of sugarcane which were reported to be either susceptible (H 53-263), intermediately susceptible (H 57-5174), or tolerant (H 50-7209) to herbicides. Using growth in height and diameter as criteria of phytotoxicity, variety H 53-263 was found to be susceptible to both diuron and ametryne, while varieties H 50-7209 and H 57-5174 were found to be tolerant. Tillering was reduced in all varieties; however, reduction was greatest in variety H 53-263. In nutrient solution the concentrations of diuron which brought about a 50% reduction in the fresh weight of variety H 53-263 and H 50-7209 were 0.35 and 1.6 ppm, respectively. Monomethyldiuron, a diuron metabolite, was found to be about 2.5 times less toxic to H 53-263 than diuron. Diuron-14c was found to be degraded in both the resistant variety, H 50-7209, and the susceptible variety, H 53-263. The primary metabolites were monomethyldiuron, 1-(3,4dichlorophenyl)- 3-methylurea, and demethylated diuron, 3,4-dichlorophenylurea. Degradation of diuron was more extensive in the resistant variety, H 50-7209, than in the susceptible variety H 53-263. In an uptake and translocation study, both the tolerant and susceptible varieties removed approximately 8~ of; carbonyl-labeled diuron from nutrient solution within 9 days after treatment. The distribution of radioactivity 14 days after treatment was almost identical in both varieties when calculated on a total activity basis: however, when the distribution data were calculated on the basis of activity per unit of dry weight, there was a greater concentration of radioactivity in the younger leaves of the susceptible variety H 53-263, than in the resistant variety, H 50-7209. Conversely, there was a greater concentration of radioactivity in the roots of H 50-7209 than in H 53-263. The differential varietal response to diuron exhibited by varieties H 53-263 and H 50-7209 is believed to be at least partially explained by differential metabolism and translocation.
Description: Typescript. Thesis (Ph. D.)--University of Hawaii, 1969. Bibliography: leaves 57-58. xii, 75 l illus
Rights: All UHM dissertations and theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission from the copyright owner.
Keywords: Herbicides -- Toxicology, Sugarcane -- Varieties

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