Allelopathic interference of wheat crop root exudates on germination, seedling growth and leaf chlorophyll attributes of purslane and annual ryegrass

Common purslane (Portulaca oleracea) and annual ryegrass (Lolium rigidum) are important infesting weeds of field crops. Furthermore, prospects of herbicide resistance also demands considering alternative options such as the use of allelopathic crops for weed management. Wheat is an important allelopathic crop and present research was conducted to evaluate the allelopathic prospects of four wheat varieties on P. oleracea and L. rigidum in a laboratory-based germination and seedling growth bioassays. The Equal-Compartment-Agar (ECA) method was used to check the allelopathic effects of wheat genotypes while the interference in weed leaf chlorophyll pigments was measured by HPLC. Germination, radicle length and weed biomass were reduced following co-growth of weeds with wheat genotypes for 10-days. Wheat root exudates reduced the seedling growth of L. rigidum but it varies from 29% to 60%, depending on the wheat genotype, e.g. ‘Ursita’ showed a stronger allelopathic potential than ‘Glosa’ to inhibit the germination and radicle length of L. rigidum. Wheat also caused damage to xanthophyll pigments in weed leaves. The reduction of chlorophyll pigments was more prominent in L. rigidum than P. oleracea. The results conclude that wheat genotypes are allelopathic in nature and can be an alternate option to control L. rigidum and P. oleracea. However, wheat varieties differ considerably in their allelopathic potential and their performance should be checked against weeds under the natural field conditions.