Azadirachta indica and Citrullus colocynthis extracts increase defense response of wounded Ricinus communis and improve its growth

Abstract

The interactive effects of mechanical wounding with or without crude extracts of neem ( Azadirachta indica ) and bitter apple ( Citrullus colocynthis , CCT) supplementation on growth, chlorophyll, carotenoids, soluble sugars (SS), soluble proteins (SP) and total free amino acids (TAA) in Ricinus communis plants were studied. In responses to mechanical wounding Ricinus plants produced more soluble sugars and soluble proteins. On the other hand, chlorophyll a, cartenoids and total free amino acids contents as well as dry mass production declined upon wounding. Neem and CCT crude extracts application, whether independently or in combination, counteracted in various degrees the deleterious effects of wounding stress on growth. Crude extracts increased SS, SP as well as Chl and cartenoids contents and improved wounded plants growth. The effect of single factors (wounding, neem and CCT extract) could be modified or reverse by the interaction between these factors when used in combination (eg. total amino acids, Chl a and carotenoids). The results clearly indicate that CCT and neem crude extracts supplementation might be beneficial in attenuating the harmful effects of mechanical wounding stress on plant growth.