M B, CHETTIY PATIL, HOLALAGOUD2019-10-282019-10-281997No. of references 105http://krishikosh.egranth.ac.in/handle/1/5810133163"Field experiments were conducted on the naturally grown Eupatorium at the Farm Forestry Department, University of Agricultural Sciences, Dharwad during 1995 and 1996 to find out the allelopathic effect of crop and weed extracts on growth, development and reproductive efficiency of Eupatorium and the effect of additives to increase the efficacy of herbicides. The first experiment consisted of twenty nine treatment combinations having leaf and root extracts of two crop species (Paddy and Sunflower) and five weed species (Lantana, Marigold, Cassia, Parthenium and Clerodendron) both at 5 and 10% concentrations. The treatments were imposed by preparing aqueous extracts of crop and weed extracts before the full bloom stage (approximately 90 days old seedlings). The second experiment consisted of thirteen treatment combinations comprising different concentrations of 2,4-D and Glyphosate (2000, 3000 and 4000 ppm) along with the additives urea, KN03 and Ammonium sulphate at 1 % concentration. The treatments were imposed at 60 days old plants.Results revealed that with an increase in the concentration of extracts, there was a decrease in photosynthetic rate, transpiration rate, chlorophyll content, sugar content, stomatal resistance, leaf temperature and relative water content. However, there was a significant increase in the total free phenols due to the application of extracts. It was further observed that the effect was more with leaf extracts than with the root extracts. Among different species, parthenium followed by clerodendron and lantana were more effective in bringing a desirable change for controlling growth and development of Eupatorium as compared to other crop and weed extracts.In the second experiment, relative water content was found to be least in Glyphosate in combination with Ammonium Sulphate and higher concentrations of Glyphosate and 2,4-D alone. Photosynthetic rate and stomatal conductance decreased with an increase in the concentration of herbicides with the combination of additives. Decrease in various biochemical parameters like chlorophyll a, chlorophyll b and total chlorophyll was noticed with an increase in the concentration of herbicides and in combination with additives. Among them, the extent of decrease was more in Glyphosate+Ammonium sulphate, 2,4-D + Ammonium sulphate and higher concentrations of Glyphosate and 2,4-D alone. "ennullThesis