Greenhouse experiments showed that the preemergence herbicide fluchloralin ušed at recommended level inhibited the activities of nitiite reductase, net photosynthetic rate and DCPIP photoreduction but did not cause appreciable reduction in nitráte reductase activity. Prolonged treatment of groundnut cv. TMV-2 with fluchloralin resulted in accumulation of nitrite in leaves whereas statistically significant changes were not found in leaf crude protein and chlorophyll contents and growth of plants during different stages of growth.
Partitioning of current photosynthates towards primary metabolites and its simultaneous incorporation in leaf alkaloids was investigated in developing leaves of medicinally important Catharanthus roseus. Of the total 14CO2 assimilated, the leaves at positions 1-6 fixed 8, 22, 25, 19, 13, and 8 %, respectively, and stem 3 %. Leaf fresh mass, chlorophyll content, and CO2 exchange rate increased up to the third leaf. The total alkaloid content was highest in young actively growing leaves, which declined with age. Total 14C fixed and its content in ethanol soluble fraction increased up to the third leaf and then declined. The 14C content in primary metabolites such as sugars and organic acids was also highest in the 3rd leaf. The utilization of 14C assimilates into alkaloids was maximum in youngest leaf which declined with leaf age. Hence the capacity to synthesize alkaloids was highest in young growing leaves and metabolites from photosynthetic pathway were most efficiently utilized and incorporated into alkaloid biosynthetic pathway by young growing leaves. and N. K. Srivastava ... [et al.].