Studies On Germination Ecology, Phytotoxic Effects And Control Of Rhynchosia Capitata (roth) Dc In Mungbean

Hafiz Haider, Ali (2013) Studies On Germination Ecology, Phytotoxic Effects And Control Of Rhynchosia Capitata (roth) Dc In Mungbean. Doctoral thesis, University Of Agriculture, Faisalabad Session.

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Abstract

Studies on dormancy, ecology, phytotoxic effects, competition and chemical control of Rhynchosia capitata (Roth) DC in mungbean (Vigna radiata (L.) Wilczek) were investigated in the laboratory experiments at Department of Agronomy, University of Agriculture, Faisalabad and under farmer’s field conditions.In laboratory experiments different treatments for breaking dormancy of R. capitata seeds were evaluated. Seeds were soaked in thiourea, KNO3, HCl, HNO3 and H2SO4 as well as scarified mechanically (sand paper).Results indicated that seeds of R. capitata show signs of physical dormancy that is mainly because of impermeability of their coat. Mechanical scarification, acid scarification (soaking of seeds in H2SO4 for 60 and 80 and in HCl for 12 and 15 h) were very effective in breaking dormancy and promoting germination. Seed soaking in HNO3 for 1 to 5 days showed little effect, while, various concentrations of thiourea and KNO3 were ineffective in breaking seed dormancy of R. capitata. Germination response of R. capitata to environmental factors such as temperature, salt stress, drought stress, pH, light and seeding depth were also studied. Germination increased as the temperature increased from 25oC and considerably reduced at 45oC.Germination of R.capitata seeds was not influenced by presence or absence of light. Increase in salt stress, moisture stress and seed burial depth significantly decreased the seed germination of R. capitata. Seeds of R. capitata had ability to germinate over a wide range of pH (5-10).In seed burial trial, maximum seedling emergence of 93 % was recorded at 2 cm depth, and seedlings failed to emerge from a depth of 12 cm.In third laboratory experiment, allelopathic influence of R. capitata on germination and seedling growth of mungbean along with detection of the phytotoxic materials liable for this action were studied.Aqueous extracts of root, shoot, leaf, fruit and whole plant (5%) adversely affected germination and seedling growth of mungbean, but higher inhibition was seen with R. capitata leaf water extract.A linear decrease in the germination characteristics of mungbean was observed with the decrease in the concentration of leaf extract from 5% to 1%.ssThe soil incorporated residues (1-4% w/w) of R. capitata stimulated the development of root and hypocotyl at low concentrations and inhibited their development at elevated concentrations.Rhynchosia capitata soil incorporated residues (4% w/w) significantly reduced the seedling vigour index of mungbean in addition to its significant effect on total germination.A noteworthy amount of water soluble phenolic acids were found in extracts of different plant parts of R. capitata.Total phenolic acids were greater in leaf extract compared to that of stem, fruit or root extracts.Two phenolic acids, vanillic acid and 4-(hydroxymethyl) benzoic acid were found in R. capitata leaf extract.Effect of different weed crop competition periods i.e. full season competition, weed crop competition for 3, 4, 5, 6, 7 weeks and zero competition were studied under field conditions on mungbean. The results showed that full season weed competition produced highest weed fresh and dry weight, maximum NPK contents (%) and NPK uptake, highest Fe, Mn, Na, Zn, Ca, Cu and Mg contents and micronutrients uptake by R. capitata in both the years of study.The maximum plant height, number of pods per plant, grain number per pod and 1000-grain weight of mungbean was recorded in weed free plots. Increase in competition period decreased above parameters of mungbean significantly. Increase in R. capitata competition period decreased the mungbean grain yield significantly. In 2011, the weed-free plots gave the highest grain yield of 1688.6 kg ha-1 followed by competition 3 weeks after planting with 1582.0 kg ha-1 of seed yield.The full season R. capitata competition decreased the grain yield to 869.3 kg ha-1.Similar trend was also observed during 2012. In second field experiment, the efficacy of herbicides namely pendimethalin + prometryn @ 875 g, 700 g and 525 g a.i ha-1, Smetolachlor @ 1440 g a.i ha-1 and pendimethalin @ 825 g a.i ha-1 in controlling R. capitata was evaluated. All doses of the herbicides suppressed the dry biomass of R. capitata from 60 to 78% in 2010 and 2011. Pendimethalin+prometryn @ 875g a.i. ha-1, recorded (74% in 2010 and 78% in 2011) maximum reduction in total weed dry weight. Among herbicide treatments, maximum grain yield was recorded with pendimethalin+prometryn @ 875 g a.i. ha-1 in both the years.Pendimethalin + prometryn @ 875 g a.i. ha-1 proved best treatments for effective control of R. capitata in mungbean and to get maximum economic benefits

Item Type: Thesis (Doctoral)
Uncontrolled Keywords: Control, Capitata, Studies, Mungbean, Ecology, Rhynchosia, Studies, Effects, Germination
Subjects: S Agriculture > S Agriculture (General)
Depositing User: Muhammad Khan Khan
Date Deposited: 01 Sep 2016 06:20
Last Modified: 01 Sep 2016 06:20
URI: http://eprints.hec.gov.pk/id/eprint/690

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