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Studies into Bio-Ecological Interference of Cleavers (Galium Aparine L) in Weat (Triticum Aestivum L)

Ahsan, Aziz (2009) Studies into Bio-Ecological Interference of Cleavers (Galium Aparine L) in Weat (Triticum Aestivum L). PhD thesis, University of Agriculture, Faisalabad .

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Abstract

Investigations regarding Galium aparine interference in wheat were made in two different experiments in the Research Laboratory and at the Agronomic Research Area, Department of Agronomy, University of Agriculture, Faisalabad, Pakistan during the year 2005/06 and 2006/07. In lab experiments aqueous extracts obtained from roots, stem, leaves and fruit of cleavers (G. aparine) harvested at maturity, and soil taken from a G. aparine infested field were used to determine their allelopathic effects on germination and seedling growth of wheat (Triticum aestivum L.) at 15oC and 20oC. Maximum time taken for 50% germination and mean germination was recorded for stem and fruit extracts. Time taken for 50% germination and reduction in germination index was maximum at 20oC whereas maximum mean germination time was recorded at 15oC. Reduction in root and shoot length, and biomass of wheat seedlings due to different extracts over control was 34.0 to 67.9%, 10.4 to 61.6% and 16.5 to 38.0%, respectively. Maximum reduction in root and shoot length, their dry weights and seedling biomass of wheat was caused by fruit extract of G. aparine. Root extract showed 32.4% increase in shoot dry weight and 11.4% in seedling biomass of wheat over control. Soil beneath G. aparine plants significantly reduced the shoot length, dry weight and seedling biomass but increased root dry weight of wheat seedlings. Field trials conducted to measure the competitive effects of five G. aparine density levels (0,18,36,54 and 72 plants m-2) on the productivity of wheat planted under three sowing time regimes demonstrated that wheat grain yield loss varied between 4 to 32% with weed density ranging from 18 to 72 plants m-2 in each year. Maximum grain yield of 5480 and 5395 kg ha-1 was obtained in 2005/06 and 2006/07, respectively from G. aparine free wheat and G. aparine density of 18 plants m-2 did not cause significant yield reduction over control in our conditions. The wheat growth and yield determinants like number of spike bearing tillers, spikelets per spike, grains per spike, 1000-grain weight, grain yield and NPK concentration were significantly reduced by increasing G. aparine density. Sowing of wheat on 7th Nov. proved to be helpful in reducing wheat grain yield loss from G. aparine infestation. Galium aparine per plant dry weight and seed production which are important elements of weed population dynamics were suppressed with delayed sowing and increasing G. aparine densities in the presence of crop while its NPK concentration did not differ significantly. Response surface analysis indicated that G. aparine density around 40 plants m-2 is most crucial as it results in maximum G. aparine per plant dry weight and seed production. It also explained that with increase in weed density and delay in sowing after mid November there will be a subsequent decrease in wheat grain yield. Analysis of maximum ridge estimate of response surface depicted that maximum grain yield (5780 kg ha-1) could be achieved at derived sowing date values of 7th to 12th November while maintaining a G. aparine density of 0 to 3 plants m-2 on a sandy loam soil with less than 1% organic matter. On the basis of these findings we can propose that soil incorporated plant residues of this weed will have broader ecological implications on the growth of a succeeding crop and wheat should be planted in early November to get bumper yields and the option of herbicides to control G. aparine at its density beyond 18 plants m-2 should be exploited.

Item Type:Thesis (PhD)
Uncontrolled Keywords:Galium aparine interference, Triticum aestivum L, Germination
Subjects:Agriculture & Veterinary Sciences(a) > Agriculture(a1)
ID Code:2772
Deposited By:Mr. Javed Memon
Deposited On:07 Jan 2010 12:02
Last Modified:07 Jan 2010 12:02

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