L-tryptophan, an auxin precursor, is crucial for the regulation and coordination of many metabolic and physiological processes of plants. It was hypothesized that exogenous application of L-tryptophan may help in reducing time to onset of flowering and floral bud drop. This pot experiment was conducted to evaluate the effect of soil and foliar applied L-tryptophan on the phenology, growth and gas exchange and yield of okra. L-tryptophan was delivered as soil application (0, 20, 40 and 80 mg kg-1) or foliar spray (0, 5, 10 and 20 mg L-1) each at seedling emergence, flower initiation and fruiting. Both soil and foliar applied L-tryptophan significantly improved all growth, physiological and yield parameters of okra. Soil and foliar application of L-tryptophan at 40 mg kg-1 and 10 mg L-1, respectively were the most effective. Foliar application of L-tryptophan at 10 mg L-1 increased the plant height, internodal distance and fruit yield per treatment up to 49, 79 and 96%, respectively, while its soil application at 40 mg kg-1 increased these parameters by 58, 94 and 47%, respectively over control. Soil and foliar application at these levels also reduced time to onset of flowering (15 and 14%) and floral bud drop (92 and 85%). Both soil and foliar applied L-tryptophan improved the physiological parameters. chlorophyll content and photosynthetic rate. These findings may imply that both soil and foliar application of L-tryptophan (40 mg kg-1 and 10 mg L-1, respectively) could be used to reduce early floral bud drop and to increase the growth and yield of okra.
|Number of pages||9|
|Journal||Soil and Environment|
|Publication status||Published - 27 May 2016|