RESPONSE OF THE COTTON PLANT TO MALEIC HYDRAZIDE

Abstract

SINCE MALEIC HYDRAZIDE (1,2-dihydropyridazine-3,6-dione) has been reported to inhibit the growth of numerous plants while having no apparent effect on others (Crafts, 1949; Currier and Crafts, 1950; Naylor and Davis, 1949; Schoene and Hoffman, 1949; U. S. Rubber Company, 1949), the feasibility of its use as a selective herbicide becomes evident. In that the hormone type weed-killers such as 2,4-dichlorophenoxyacetic acid and its derivatives are extremely injurious to cotton (Ergle and Dunlap, 1949), any new selective herbicides are of particular interest in the Cotton Belt. Crafts (1949) has stated that very promising results have been obtained in preliminary greenhouse experiments using maleic hydrazide for the control of weeds in cotton, particularly the control of numerous grasses. There are also some data in the literature indicating that cotton is not as susceptible to injury by maleic hydrazide as are some plants that may appear as weeds in the cotton field (Currier and Crafts, 1950; U. S. Rubber Company, 1949). This experiment, therefore, was designed to determine the effect of relatively high concentrations of maleic hydrazide on the growth and chemical composition of young cotton plants. The maleic hydrazide used in this experiment was supplied as the diethanolamine salt by the Naugatuck Chemical Division, U. S. Rubber Company, Naugatuck, Connecticut. METHODS.-Cotton, variety Stoneville 2B TPSA, was planted outside on June 18, in 2-gal. glazed jars filled with Lufkin fine sandy loam. The jars were thinned to a uniform stand of one plant per jar after 15 days. When the plants were 35 days old and had produced seven to eight true leaves, segregation was made into three groups. One lot was sprayed with 5 ml. per plant of an aqueous solution containing an equivalent of 2400 p. p. m. of maleic hydrazide, the second with 5 ml. per plant of 4800 p. p. m. of maleic hydrazide and the third remained untreated. These series will be hereafter designated as 2400, 4800, and control, respectively. Each of the maleic hydrazide solutions contained 2 ml. of Grasselli spreader per liter. Care was taken in each of the spray treatments that all parts of the plants were covered and that none of the solution was lost by run-off. At noon of the twenty-sixth day after application of the maleic hydrazide, the sixth and seventh leaves of all the above series were harvested for histological examination and chemical analysis. Histological material was taken from corresponding areas on