Please use this identifier to cite or link to this item: http://prr.hec.gov.pk/jspui/handle/123456789/2246
Title: Evaluation of allelopathic potential of some indigenous wheat (Triticum aestivum L.) genotypes
Authors: MAHMOOD, KHALID
Keywords: Applied Sciences
Agriculture & related technologies
Agronomy
Issue Date: 2013
Publisher: UNIVERSITY OF AGRICULTURE FAISALABAD, PAKISTAN
Abstract: The studies were carried out for the evaluation of allelopathic potential of some indigenous wheat (Triticum aestivum L.) genotypes. The objectives were to screen and rank 35 indigenous wheat genotypes for their allelopathic potential for weed management, and to evaluate the comparative methods of using allelopathic material. The studies were carried out at Agronomic Research area, University of Agriculture Faisalabad during the Rabi 2008- 2009 and 2009-10. Soil belongs to the Lyallpur Soil Series (Aridisol-fine-silty, mixed, hyperthermic Ustalfic, Haplargid in USDA classification, and Haplic Yermosols in FAO’s classification scheme). The pH of saturated soil paste and electrical conductivity of the saturation extract were 7.8 and 0.80 dS m-1, respectively. The soil was sandy clay loam. A series of experiments were conducted to establish allelopathic potential of wheat genotypes under controlled (laboratory and green house) and field conditions. In laboratory bioassays, allelopathic potential was evaluated against five test species, viz. garden cress (Lepedeium sativum L), canary grass (Phalaris minor Retz), wild oat (Avena fatua L), horse purslane (Trianthema portulacastrum L) and purple nutsedge (Cyperus rotundus L) by using straw aqueous extracts of 35 wheat genotypes. A control without straw aqueous extract (only distilled water) was maintained for comparison. In pot experiments, the residual allelopathic effect of wheat rhizosphere soil was evaluated against horse purslane and purple nutsedge, two noxious weeds of summer crops following wheat in rotation. Wheat-infested rhizosphere soil from 15 cm collar from all wheat plots was collected and used in pots for evaluating its allelopathic potential. Soil in control pots was taken from a previously fallow plot of same field. A series of bioassays were carried out wherein straw aqueous extracts of wheat genotypes were foliar applied at 2-4 leaf stage of test species. Control pots were sprayed with distal water. In another set of experiments, straw of wheat genotypes was applied either as surface mulch or soil incorporated to explore its inhibitory activity against early growth of five test species as named earlier. Control pots received no straw. Root exudates of wheat genotypes were also evaluated using double pot technique against garden cress. Separate set of experiments were designed and executed for each test species in each case. Allelopathic potential was evaluated on the basis of germination count, root and shoot growth parameters. Both lab and pot experiments were conducted using completely randomized design with three replications and repeated in time. In two-year field experiments, 35 wheat genotypes were sown in 23 cm spaced rows in a randomized complete block design with three replicates using a net plot size of 5 m x 1.61 m. Plot without wheat plantation (fallow plots) were maintained as control. Data on weed density and dry weight were recorded for each wheat genotype. Straw of these field grown wheat genotypes was collected at physiological maturity and used to prepare aqueous extracts and/or used as mulch in respective bioassays as outlined above. During 2nd year, a separate field experiment was carried out wherein wheat genotypes were sown as described for previous field experiment but straw aqueous extract of that specific genotype was foliar applied (55.5 ml L-1 of water) to respective plots at 30 DAS. Volume of spray (320 L ha-1) was calibrated using water. Data on weed density and dry weight were recorded for each wheat genotype. Straw aqueous extracts of most of tested wheat genotypes demonstrated strong inhibition of germination of all selected weeds over control. Wheat genotypes V6007, V6111, V6034, V7189, Chanab 2000, Uqab 2000, Bakhar 2002, V4611, AS 2000, Pak 81, and Rohtas 90 inhibited the germination of wild oat (82%, 71%, 71%, 69%, 69%, 69%, 69%, 65%, 62%, 45%, and 41%) respectively, and it also expressed strong inhibition of seedling growth of all other selected weeds that was associated with high tissue concentration of total phenolics in these wheat genotypes. Wheat genotypes (Shafaq 2006, Inqlab 91, Barani 83, Punjab 96, Kohistan 97, Sandal 73, Fareed 2006, V6018 and V6016) characterized as having lower concentration of total phenolics and hence, expressed weak suppression of tested weed species as evaluated on the basis of seedling dry weights. Surface mulch of wheat straw was less inhibitory as compared to straw incorporation and straw aqueous extracts. In field studies, weed density and dry weight (individual and total) as recorded at different intervals varied significantly amongst wheat genotypes. Wheat genotypes significantly suppressed the density and dry weight of associated weeds over control (fallow plot). Maximum reduction in total weeds density at 55 DAS was observed for wheat genotype V6007 (84%) followed by Bakhar 2002 (84%), Chanab 2000 (82%), Uqab 2000 (81%), V7189 (78%), V4611 (77%), V6034 (76%), Pak 81 (76%), V6111 (74%), AS 2000 (74%) and Rohtas 90 (74%). Maximum suppression in total weeds dry weight at 55 DAS was recorded in wheat genotype V6007 (97%) followed by Chanab 2000 (95%), Bakhar 2002 (94%), Uqab 2000 (92%), V7189 (91%), V4611 (90%), V6034 (90%), V6111 (89%), Pak 81 (88%), AS 2000 (88%), and Barani 83 (88%). Negative correlation was observed between total phenolics in straw of different wheat genotypes and weed density and dry weight. A highly pronounced variation was observed among wheat genotypes for their allelopathic potential and the inhibitory potential was positively associated with total phenolics in these genotypes.
URI:  http://prr.hec.gov.pk/jspui/handle/123456789//2246
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