Studies on the influence of foliar nutrient sprays on the root exudation pattern in four crop plants

Studies conducted to examine the exudation pattern of amino acids and sugars in four crop plants, viz sorghum, sunnhemp, ragi, and tomato indicated that in all, 17 known amino acids and 4 sugars were exuded and that the number and nature of the exuded amino acids and sugars differed with the plant species and with the age of plant. Glutamic and aspartic acids were found to be present in the exudates of all the plant species at all stages of plant growth examined. The quantities of amino acids and sugars differed with plant species and the maximum quantity of the chemicals was exuded during the early stages of plant growth. Glutamic acid among amino acids, and glucose among sugars, were always present in higher concentrations than the others, in the exudates in all the four crop plants. Foliar application of nitrogen in the form of NaNO3 and phosphorus as Na2HPO4, was found to alter the exudation pattern of amino acids and sugars and such influence differed in different plant species. There was a general increase in the total concentration of amino acids and a decrease in sugar content in the exudates after treatment of the foliage with N, while a decrease in the amino acid content and increase in total sugars with P-treatment was observed