Toxic action of aqueous wheat straw extract on horse e purslane

Abstract

-The toxic action of aqueous wheat (Triticum aestivum) straw extracts was investigated on germination, early seedling growth, some biochemical attributes and the antioxidant enzymes of horse purslane (Trianthema portulacastrum). Aqueous extracts of wheat straw were prepared by soaking the wheat straw in distilled water in 1:10 w/v ratio and diluted to obtain the concentrations of 0, 25, 50, 75 and 100%. These were used as pre and post emergence in laboratory and screen house trials. Wheat aqueous extracts exhibited phytotoxicity to horse purslane by inhibiting and delaying its germination and suppressing seedling growth. Wheat phytotoxins in its aqueous extracts suppressed the chlorophyll content and soluble protein, and enhanced soluble phenolics and the activity of antioxidant enzymes as catalase, peroxidase and superoxide dismutase in the seedlings of horse purslane compared with the control. Such inhibitory activity is believed to originate from exposure to wheat phytotoxins that are present in its aqueous straw extract. The suppressive effects of wheat straw need to be investigated further under field conditions. Keywords: phytotoxins, germination, seedling growth, phenolics, antioxidants.RESUMO -A ação tóxica de extratos aquosos da palha de trigo (Triticum aestivum) foi investigada na germinação, no crescimento inicial da plântula, em alguns atributos bioquímicos e nas enzimas antioxidantes de beldroegas-cavalo (Thianthema portulacastrum). Extratos aquosos de palha de trigo foram preparados pela imersão deste em água destilada na proporção de 01:10 m/v e diluidos para obtenção de cinco concentrações (0, 25, 50, 75 e 100%). Estes foram usados como pré e pós-emergência em ensaios de laboratório e casa de vegetação. Os extratos aquosos de trigo exibiram toxicidade às beldroegas-cavalo, inibindo e retardando a sua germinação e suprimindo o crescimento das plântulas. Toxinas no extrato aquoso de trigo suprimiram o teor de clorofila e proteína solúvel, aumentaram os fenóis solúveis e a atividade de enzimas antioxidantes como catalase, peroxidase e superóxido dismutase em plântulas de beldroega-cavalo comparado ao controle. Acreditase que essa atividade inibitória origina-se da exposição das beldroegas-cavalo às toxinas presentes no extrato aquoso de palha de trigo. Efeitos supressivos da palha de trigo precisam ser investigados em condições de campo.Palavras-chave: palha de trigo, toxinas, germinação, crescimento das plântulas, fenólicos antioxidantes.

Phytotoxic Activity of Parthenium Against Wheat and Canola Differ With Plant Parts and Bioassays Techniques

“…Phenolic compounds are reported to decrease leaf expansion, chlorophyll content, photosynthesis and electron transport (Colpas et al, 2003;Norman et al, 2004). Phytochemical-mediated reduction in seedling photosynthetic pigments primarily due to phenolic acids has also been reported by Khaliq et al (2012). Our results have revealed that whole plant and leaf extracts were more suppressive than root extract to both test species at all concentrations.…”

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

“…The increase in dry biomass of wheat seedlings treated with root and stem peel extract in the current study may probably be due to increase in photosynthetic rate and greater accumulation of photoassimilate in the shoot, increase in thickness and length of seminal root, decrease in proline content and greater potassium ion uptake induced by allelopathic extracts of S. officinale; as in earlier studies some authors argued that botanical extracts could have positive influence on these phenomena thus stimulating biomass of the receptor plant (Rizvi and Rizvi, 1992;Gatti et al, 2010;Ibrahim et al, 2013). Similarly, reduced biomass, seminal root and shoot length under leaf extract suggests the presence of phenolic and growth inhibitory compounds in leaves of sugarcane and these reductions may be regarded as a result of induced oxidative damage and activation of cellular anti-oxidant systems which in turn changed permeability patterns of cell membrane, irregularities in mineral and ion uptake and the activation of stress enzymes (Oracz et al, 2007;Khaliq et al, 2012).…”

Allelopathy of aqueous Pachyrhizus erosus L. extracts on Euphorbia heterophylla and Bidens pilosa

“…A relationship between secondary metabolism substances and chlorophyll content has been noted. Khaliq et al (2012) observed that plants treated with wheat straw extracts presented proportionally decreased chlorophyll content, in relation to increased metabolic substances. Reducing chlorophyll content interferes with light energy uptake, and leads to inhibitory action on plant metabolism, such as cell growth, multiplication and maintenance (Carmo et al 2007).…”

“…Conclui-se que os extratos preparados com P. erosus possuem efeito alelopático nas espécies avaliadas. other species during different developmental periods (Khaliq et al 2012). For example, the germination percentage of Lycopersicum esculentum was shown to decrease over 80 %, when applying a dry Duranta repens extract, while the extract prepared with the fruits of this species reduced the same variable by only 20 % (Tur et al 2010).…”