ALLELOPATHIC EFFECTS OF Albizia lebbeck, Leucaenea leucocephala, Melia azedarach AND Litchi chinensis ON AGRICULTURAL CROPS

Abstract

A pot experiment was conducted at the Agroforestry Farm, Hajee Mohammad Danesh Science and Technology University during May 2009 to July 2009 to observe the allelopathic effects of Albizia lebbeck, Leucaena leucocephala, Melia azedarach and Litchi chinensis on two agricultural crops viz: mungbean and soybean. There were four experiments and each experiment had five treatments viz: T; (top soil); T, (root zone soil); T3 (soil mulched with dry leaf); Ty (soil watered with aqueous leaf extract); T; (control/fresh garden soil). The experiments were laid out in the Randomized Complete Block Design (RCBD) with four replications. The results of the present studies revealed that inhibition of germination and growth parameters of mungbean and soybean were varied according to different parts of plants and soil from different place. Incase of Albizia lebbeck the allelopathic effects of the treatments were as the following order: T, (soil watered with aqueous leaf extract) > T (root zone soil) >T; (soil mulched with dry leaf>T, (top soil)>T, (control / fresh garden soil); For Leucaena leucocephala: T, (soil watered with aqueous leaf extract)>T, (top soil)>T; (soil mulched with dry leaf) >T; (control / fresh garden soil) >T, (root zone soil ); For Melia azedarach: T> (root zone soil) >T3 (soil mulched dry leaf) >T, (soil watered with aqueous leaf extract >T; (top soil > T; control / fresh garden soil; For Litchi chinensis:T3 (soil mulched with dry leaf)>T, (soil watered with aqueous leaf extracts)>T, (top soil)>T2 (root zone soil)>T; (control/fresh garden soil). Among the four tree species Leucaena leucocephala has little stimulatory effects on mungbean and soybean. In agroforestry system, Leucaena leucochephala is a better choice as compared to the other tree species like Albizia lebbeck, Melia azedarach and Litchi chinensis. Although, Melia azedarach is well-known for its biological activities in many countries, the inhibitory effects were also observed. However, the allelopathic effects of the trees on the tested crops were as the following the order: Litchi chinensis > Albizia lebbeck> Melia azedarach> Leucaena leucocephala. Among the different parts of the trees, fresh leaf extracts had more inhibitory effects as compared to the other parts of trees like root and dry leaf.