Testing the role of allelochemicals in different wheat cultivars to sustainably manage weeds

BACKGROUND

Selecting wheat varieties with allelopathic potential or high competitiveness against weeds is a sustainable solution for organic farming to eliminate the use of synthetic herbicides. Wheat is one of the most economically important crops. This study focuses on screening the allelopathic or competitive potential of four wheat cultivars, Maurizio, NS 40S, Adesso and Element, on two weeds of interest due to acquired herbicide resistance, Portulaca oleracea and Lolium rigidum, through germination and growth bioassays and the identification and quantification of benzoxazinoids (BXZs) and polyphenols (phenolic acids and flavonoids).

RESULTS

The different cultivars showed different abilities to manage surrounding weeds and different capacity to exude or accumulate specialized metabolites in the presence of those weeds. Furthermore, each cultivar behaved differently depending on the weed present in the medium. The most efficient cultivar to control the tested monocot and dicot weeds was Maurizio, as it effectively controlled germination and growth of L. rigidum and P. oleracea while exuding large amounts of benzoxazinones through the roots, especially the hydroxamic acids 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one and dihydroxy-2H-1,4-benzoxaxin-3(4H)-one. By contrast, NS 40S, Adesso and Element showed the potential to control the growth of just one of the two weeds through allelopathy or competition.

CONCLUSION

This study reveals that Maurizio is the most promising wheat cultivar for sustainable weed control, and that the screening of crop varieties with allelopathic potential, which results in the displacement of synthetic herbicides, is an immediate solution in ecological and sustainable agriculture. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Weed pressure determines the chemical profile of wheat (Triticum aestivum L.) and its allelochemicals potential

BACKGROUND

Common purslane (Portulaca oleracea) and annual ryegrass (Lolium rigidum) are important infesting weeds of field crops. Herbicides are mostly used for weed suppression, while their environmental toxicity and resistance in weeds against them demand considering alternative options, such as the use of allelopathic crops for weed management. Wheat is an important allelopathic crop and present research focused on the identification and quantification of benzoxazinoids (BXZs) and polyphenols (phenolic acids and flavonoids) of the wheat accession 'Ursita' and to screen its allelopathic impact on P. oleracea and Lolium rigidum through equal-compartment-agar (ECA) method.

RESULTS

Weed germination, radicle length, biomass and photosynthetic pigments were altered following co-growth of weeds with Ursita for 10-day. Root exudates from Ursita reduced (29-60%) the seedling growth and photosynthetic pigments of Lolium rigidum depending on co-culture conditions of planting density. Weed pressure caused significant increase in the production of phenolic acids (vanillic, ferulic, syringic and p-coumaric acids) and root exudation of BXZs, in particular benzoxazolin-2-one (BOA), 2-hydroxy-7-methoxy-1,4-benzoxazin-3-one (HMBOA), 2-hydroxy-1,4-benzoxazin3-one (HBOA) and 2,4-dihydroxy-1,4-benzoxazin-3-one (DIBOA) in wheat tissues (shoots, roots) and exudate in root rhizosphere agar medium in response to co-cultivation with Lolium rigidum and P. oleracea, depending on weed/crop density.

CONCLUSION

The work revealed that Ursita is allelopathic in nature and can be used in breeding programs to enhance its allelopathic activity. Meanwhile, there are opportunities to explore allelopathic effect of wheat cultivars to control P. oleracea and Lolium rigidum under field conditions. © 2022 Society of Chemical Industry.