Abstract
The productivity of important grain crops wheat, rice and maize is adversely affected by various biotic and abiotic stresses. Weeds and phytopathogens are the major biotic stresses involved in biomass reduction and yield losses of these cereal crops. Various weeds compete with crop plants for natural resources viz. light, moisture, nutrients and space, and cause yield losses to agricultural produce. Weeds also increase harvesting costs and reduce quality of the farm produce. Weed management strategies include crop rotation, mechanical weeding or treatment with different herbicides. Although, sprays of different herbicides control various destructive weeds but their excessive use is environmentally unsafe and uneconomic. Indiscriminate use of these agrochemicals for weed control has resulted into considerable pollution of soil, groundwater and atmosphere. Therefore, effective biological weed management is an attractive approach for achieving the increased crop production to meet the food demands of the escalating global population. Many bacteria and fungi have been identified from the plant rhizospheres, which suppress the growth of weeds. The production of indole acetic acid, aminolevulinic acid, toxins and hydrogen cyanide has been correlated with the growth suppression of various weeds. Interestingly, inoculation with bioherbicides results in creation of biased rhizosphere leading to resource partitioning of nutrients towards growth stimulation of crop plants. Thus, inoculation of plants with bioherbicides has been found to increase germination percentage, seedling vigor, root and shoot growth, seed weight and increased grain, fodder and fruit yields. These environment-friendly biocontrol strategies for management of weeds are highly compatible with the sustainable agriculture.
Highlights
Weeds adversely affect the production of the world's most important food and cash crops
The results suggested that indole acetic acid (IAA) production by strain
The cyclic tetrapeptide phytotoxin tentoxin produced by Alternaria alternata caused phytotoxic damage to both monocot and dicot weeds species and showed the potential to be used as bioherbicide (Saxena, 2014)
Summary
Weeds adversely affect the production of the world's most important food and cash crops. P. minor is another troublesome weed of wheat in India, Pakistan, USA, Canada, Africa, Australia, France, Iran and Mexico It may cause 25-80% reduction in wheat yield (Chhokar et al, 2009). & Dinoor, 2000; Mohan Babu et al, 2003; Adetunji et al, 2019) These rhizosphere bacteria colonize the root surface of weed seedlings and suppress the growth of weed plants by reducing weed density, biomass and its seed production (Kremer & Kennedy, 1996). Inoculation of soil with deleterious microorganisms (biocontrol agents) may suppress weed growth by production of hydrogen cyanide (Zeller et al, 2007). These rhizosphere microorganisms could be exploited for development of bioherbicides as ecofriendly technology for management of weeds in sustainable agriculture. In-depth understanding of mechanisms and factors involved in crop-weed competitive interactions is required to develop cost-effective and sustainable weed management strategies (Swanton et al, 2015; Adetunji et al, 2019)
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