Inhibitory Effect of Aqueous Extracts of Tree-legumes on Germination and Seedling Growth of Food Legume, Green Gram (Vigna radiata L.).

Background: Green gram (Vigna radiata), the third most important pulse crop, is grown in tank-fed, command areas after the harvest of paddy. In such areas, legume trees like Delonix regia and Peltophorum pterocarpum are commonly found and tree parts often fell in watercourses and were flown to crop fields along with irrigation water. Hence, it is necessary to study whether any allelopathic effect is present in these parts of trees which may affect the growth and development of green gram grown in farmland crops. Methods: Collected different tree parts viz., bark, leaf and fresh flower, a matured pod of Delonix regia and Peltophorum pterocarpum, cleaned and soaked distilled water at weight/volume ratio of 1:10 for 24 hrs. Aqueous extracts were filtered and tested for inhibition of green gram. Pot culture experiments were conducted with 10 treatments and four replications. Germination (%), shoot length (cm), root length (cm), fresh weight (mg), dry weight (mg), seedling vigour index-I and vigour index-II in green gram were recorded and the magnitude of inhibition versus simulation in bioassay was compared through response index. Result: Among the plant parts, Delonix regia flower and Peltophorum pterocarpum matured pods suppressed germination (45.00 and 60.00%), shoot length (13.87 and 13.39 cm), root length (4.27 and 10.49 cm), seedling vigour index-I (624.15 and 803.40) and seedling vigour index-II (960.75 and 948.00) respectively in green gram. This might due to presence of inhibitory chemicals in flowers of Delonix regia and matured pods of Peltophorum pterocarpum compared to other plant parts of trees. [ABSTRACT FROM AUTHOR]