Differential suppression of rice weeds by allelopathic plant aqueous extracts

Abstract

-Herbicidal potential of different plant aqueous extracts was evaluated against early seedling growth of rice weeds in pot studies. Plant aqueous extracts of sorghum (Sorghum bicolor), sunflower (Helianthus annuus), brassica (Brassica compestris), mulberry (Morris alba), eucalyptus (Eucalyptus camaldunensis), and winter cherry (Withania somnifera) at a spray volume of 18 L ha -1 each at the 2-4 leaf stage of rice weeds viz horse purslane (Trianthema portulacastrum) [broad-leaf], jungle rice (Echinochloa colona), and E. crus-galli (barnyard grass) [grasses] and purple nut sedge (Cyperus rotundus) and rice flat sedge (C. iria) [sedges]. The results showed significant interactive effects between plant aqueous extracts and the tested weed species for seedling growth attributes depicting that allelopathic inhibition was speciesspecific. Shoot and root length, lateral plant spread, biomass accumulation, and leaf chlorophyll contents in test species were all reduced by different extracts. The study suggested the suppressive potential of allelopathic plant aqueous extracts against rice weeds, and offered promise for their usefulness as a tool for weed management under field conditions. Keywords: allelopathy, aqueous extracts, seedling growth, weeds, inhibition.RESUMO -O potencial herbicida dos extratos aquosos de diferentes plantas foi avaliado por meio do crescimento inicial de plântulas de plantas daninhas do arroz em bioensaios. Extratos aquosos de folhas de sorgo (Sorghum bicolor), girassol (Helianthus annuus), brássicas (Brassica compestris), amoreira (Morris alba), eucalipto (Eucalyptus camaldulensis) e cereja-de-inverno (Withania somnifera) foram aplicados num volume de calda de 18 L ha -1 , na fase de 2-4 folhas, sobre as seguintes espécies de plantas daninhas do arroz: beldroega-cavalo (Trianthema portulacastrum) [folhas largas]; arroz-selva (Echinochloa colona) e capim (E. cruss-galli)[gramíneas]; e tiririca-roxa (Cyperus rotundus) e tiririca-arroz-plana (C. iria) [ciperáceas]. Os resultados mostraram efeitos significativos na interação entre os extratos aquosos das plantas testadas e as diferentes espécies de plantas daninhas no que diz respeito ao crescimento das plântulas, o que demonstra que a inibição alelopática foi específica. O efeito dos diferentes extratos nas espécies estudadas manifestou-se na redução do comprimento das raízes, na propagação lateral/vegetativa das plantas, na acumulação de biomassa foliar e no teor de clorofila. O estudo sugere o potencial inibitório dos extratos aquosos de plantas alelopáticas no controle de plantas daninhas do arroz e salienta a possibilidade de seu uso como ferramenta para manejo dessas plantas em campo.Palavras-chave: alelopatia, extratos aquosos, crescimento das plântulas, inibição de plantas daninhas.

Bio-Economic and Qualitative Impact of Reduced Herbicide use in Direct Seeded Fine Rice Through Multipurpose Tree Water Extracts

“…In our preliminary studies, water extracts of these trees were found to inhibit rice weed growth (Khaliq et al, 2012). However, the suppressive effects of tank mixing these extracts have not yet been documented against weeds of direct seeded rice fields.…”

In vitro allelopathic effect of aqueous extracts of sugarcane on germination parameters of wheat

“…Knowledge about allelopathic nature of preceding crops may be helpful in modifying cultivation pattern of wheat with other crops. During the last few years, allelopathic activities of several plants and agricultural crops including wheat have been rigorously worked out (Khaliq et al, 2013;Muhammad and Majeed, 2014). Sampietro and Vattuone (2006) observed root elongation of some selected weeds and crops at lower concentrations while declined root growth at higher concentration of aqueous extracts of sugarcane straw.…”

Seasonal variation in allelopathic potential of the leaves of Copaifera langsdorffii Desf.

“…For example, the application of leaf extracts from Sorghum bicolor, Helianthus annuus, Eucalyptus camaldulensis, Brassica campestris, Morus alba, and Withania somnifera to invasive plant species in rice crops reduced root length (Khaliq et al 2013). Almeida et al (2008) found that extracts from Leonurus sibiricus leaves a ected the germination and root growth of Cucumis sativus; however, a greater e ect was seen on root growth than on germination.…”