Use of non-conventional chemicals as an alternative approach to protect chickpea (Cicer arietinum) from Sclerotinia stem rot

Four non-conventional chemicals, viz., zinc sulphate (ZS), oxalic acid (OA), sodium malonate (SM) and sodium selenite (SS), were applied as foliar sprays to chickpea (Cicer arietinum) and the plants were subsequently challenged against Sclerotinia sclerotiorum, the causal agent of stem rot in chickpea. All the chemicals reduced mortality of chickpea from S. sclerotiokum infection. Among them, ZS at 10(-3) rmuol gave the best result as only 13.6% mortality was recorded after 28 d compared to 100% in the control. High performance liquid chromatographic analysis of treated chickpea leaves revealed activation of shikimic acid as well as phenyl propanoid pathways and synthesis of several phenolic compounds increased specially after application of OA, ZS and SM. Individual treatment of the chemicals showed better results than their combinations as plant mortality was reduced and accumulation of phenolics increased in their individual treatments. A positive correlation was observed between induction of phenolic compounds and survival of the plants. In vitro assay of the four chemicals showed only SS to be antifungal. The protection of plants by ZS, OA and SM is possibly because of induction of resistance in the host against S. sclerotiorum. (c) 2006 Elsevier Ltd. All rights reserved.