Abstract
L-Tryptophan (L-TRP), a physiological precursor of Auxin, significantly affected the maize crop growth and dry matter accumulation in a laboratory experiment. The trial was conducted using completely randomized design (CRD). Four concentrations of L-TRP, 0.0025, 0.025, 0.25 and 2.5 mg kg-1 of soil were applied as soil drench along with a control. L-Tryptophan enhanced the leaf area plant-1 , shoot length and shoot dry matter. L-Tryptophan did not increase the number of leaves per plant at first harvest but it increased the leaves at second, third, fourth and fifth harvests. At the start, crop growth rate (CGR) and relative growth rate (RGR) increased with a slower pace with L-TRP from 0.0025 to 0.25 mg kg-1 but these increased swiftly from 0.25 to 2.5 mg kg-1 . Soil drenching @ 2.5 mg kg-1 of L-TRP produced maximum reflective effects on cell expansion, leaf area and shoot dry matter. At final harvest, L-TRP @ 2.5 mg kg-1 of soil caused 86.93 % increase in shoot dry matter over control. The associations of shoot dry matter with leaf area per plant, CGR and RGR were significant and linear.
