Allelopathic Effects of Litchi chinensis on Mung bean and Soybean in Agroforestry System

Abstract

Background: A pot experiment was conducted to demonstrate the allelopathic effect of the litchi tree (Litchi chinensis) on two crops such as mung bean (Vigna radiata) and soybean (Glycine max). The experiment was conducted at the Agroforestry Research field of Hajee Mohammad Danesh Science and Technology University, Dinajpur, Bangladesh. Five treatments were applied in this experiment, and they are: T1 (topsoil at the base of litchi trees), T2 (soil in the root zone of litchi trees), T3 (soil mulched with dry litchi leaves), T4 (soil irrigated with aqueous litchi leaf extract) and T5 (control, i.e., fresh garden soil). A factorial randomized complete block (RCBD) design with four replicates was used in this experiment. There were 40 pots in total.
 Results: The results of the study showed that all treatments in the experiment inhibited the germination and growth of both mung beans and soybeans compared to controls. The germination inhibition and growth parameters of mung bean and soybean varied according to soil collected from different plant parts and root zone locations of different trees. The allelopathic effect of litchi trees was in the following order: T3 (soil mulched with dry leaves) > T4 (soil irrigated with aqueous leaf extract) > T1 (topsoil at the base of the tree) > T2 (tree root zoon soil) > T5 (control).
 Conclusions: Litchi leaves have a stronger allelopathic effect than litchi ground or root zone soil. Again, dried leaves have stronger allelopathic effects than green (fresh) leaves. Therefore, regular washing of dried leaves is very important for litchi-based agroforestry systems. On the other hand, between the two crops, soybeans were more suppressed than mung beans.