Pak. J. Weed Sci. Res. 10(1-2):11-16, 2004

Weed Management Strategies In Wheat

 (Triticum aestivum L.)
Muhammad Arif, Inayat Ullah Awan, and Haji Himayat Ullah Khan^[1]

Abstract

An experiment to study the impact of integrated weed management strategies in wheat crop was conducted at the Agronomic Research Area of the Faculty of Agriculture, Gomal University, D. I. Khan, Pakistan, during 2001-02. Four post-emergence herbicides in comparison with kasola hoeing, weed free for full season and weedy check were evaluated. 2,4-D Ester and Buctril M40EC @1.25 L ha^-1 each were applied alone and in combination with Puma Super 75EW @ L ha^-1. One, two and three hoeings with kasola were done after first, second and third irrigation, respectively. The data revealed that the application of herbicides and Kasola hoeings significantly affected the fresh and dry weed biomass (g m^-2), number of tillers m^-2, spike length (cm), number of spikelets spike^-1, number of grains spike^-1 and grain yield (t ha^-1). Weed free crop for full season produced the highest grain yield (7.08 t ha^-1). Among herbicides, the mixture of Buctril-M40EC and Puma Super 75EW produced the maximum grain yield (5.60 t ha^-1), whereas three hoeings with kasola gave the highest grain yield (5.21 t ha^-1) among the kasola hoed treatments.

Key words:  Wheat, weed control methods, chemical and mechanical control, integrated weed management.

Introduction

Wheat (Triticum aestivum L.) is the basic component of human diet. It is the most widely grown cereal grain crop in the world, except in the rice-eating regions of Asia. Wheat products are the principal cereal foods of an overwhelming majority of the world inhabitants. It is staple food of the people of Pakistan and it is the backbone of the country’s economy.

In Pakistan, it ranks first among the cereal crops and occupies about 66% of the annual food cropped area (Anonymous, 1996). A decrease in wheat production severely affects the economy of Pakistan and adds into the miseries of the inhabitants. A better progress has been made in increasing per hectare yield of wheat in the country during the last few years. The bumper wheat harvests of 1999-2000 and 2000-2001 have changed the nation’s status from wheat importing to an exporting country. But, still Pakistan harvests lower yield per unit area as compared to advanced wheat growing countries. Besides other factors for lower yield, lack of proper weed control is the most important one. Weeds stress the cultivated crop through interference and by providing habitat for other harmful organisms. Weeds not only reduce the yield of crops but also deteriorate the quality of farm produce by contaminating the seed thereby reducing its market value. They compete with cultivated crops for space, solar radiation, water, soil nutrients and carbon dioxide.

The annual losses to wheat crop due to weed infestation in Pakistan and N.W.F.P amount to Rs.28 billions and Rs.2 billions, respectively (Pervaiz and Quazi, 1992). These enormous losses warrant an efficient control of weeds for lucrative economic returns. The control of weeds from the crop field is, therefore, very essential for obtaining good crop and high economic returns.

Now weed technology has entered a scientific phase and even though chemical weed control is important, however, now integrated weed management is emphasized and desired. The use of chemicals is usually easy, time saving, highly effective and most economical approach to weed control. However, it is environmentally less safe as  mechanical, cultural and biological methods of weed control.

The combination of chemical and other weed control methods in the form of integrated weed management package is recommended for the sustainability of production and environment. Rao (1983) observed that a combination of chemical, cultural and hand weed control methods was more effective in controlling weeds than their isolated applications. While, Jarwar et al. (1999) observed that chemical weed control method is very effective along with cultural method of weed control. Enough work on integrated weed management in N.W.F.P has not been published, hence the present studies were initiated to determine the integrated impact of weed management on the wheat crop production with the following objectives.

1.                   To determine the impact of different weed management strategies on wheat yield.

2.                   To determine the economic benefit obtained from the use of different weed control methods.

Materials and Methods

An experiment to study the effect of integrated weed management on wheat crop was carried out at the Agronomic Research Area of the Faculty of Agriculture, Gomal University, Dera Ismail Khan, Pakistan, during 2001-02. The experiment was laid out in Randomized Complete Block Design (RCBD) with nine treatments (Table-1) and three replications. The net plot size was kept at 4x2 m². Wheat variety Dera-98 was sown on 31st October, 2001 on a well prepared seedbed with a single row hand drill in the rows 30 cm apart. Seeding rate was 120 kg ha^-1. The field was fertilized with urea and TSP (Triple Super Phosphate) at the rate of 120 kg N and 75 kg P₂O₅ ha^-1, respectively. The full dose of phosphorous and half dose of nitrogen were applied as a basal dose at the time of seedbed preparation and the rest of the nitrogen was applied with first irrigation. All other cultural practices were uniform for all treatments. The crop was harvested on 15th April and threshed manually.

The following data were recorded during the course of studies.

1.                    Fresh weed biomass per treatment (g m^–2)

2.                    Dry weed biomass per treatment (g m^–2)

3.                    Plant height (cm)

4.                    Number of tillers (m^-2)

5.                    Spike length (cm)

6.                    Number of spikelets spike^-1

7.                    Number of grains spike^-1

8.                    1000-grain weight (g)

9.                    Grain yield (t ha^-1)

Statistical Analysis

The data recorded were analyzed statistically by using the analysis of variance techniques (Steel and Torrie, 1980). Duncan’s Multiple Range Test (Duncan, 1955) was used to compare the differences among treatment means. 

Table 1.Detail of treatments in the experiment

Results And Discussion

Weed infestation in wheat is a serious problem causing considerable reduction in wheat yield. Herbicides and hand weeding are commonly used to limit weed population. The results of the study as affected by different treatments are presented as under:

Fresh weed biomass (g m^–2)

Major broad leaved weeds in the field were Convolvulus arvensis (field bind weed), Chenopodium album (common lambsquarters), Medicago denticulata (common medic), Melilotus indica (indian sweet clover), Rumex dentatus (prickly dock) and Anagallis arvensis (pimpernel). Among grasses, Avena fatua (wild oats) and Phalaris minor (canary grass) were dominant in the experimental area. Data on the fresh weed biomass (g m^–2) of wheat are given in Table–2. The results indicated significant differences for the said parameter. Weedy control plots gave the highest biomass of fresh weeds (69.49 g). Among various herbicides, Buctril-M40 EC treated plot had (8.10 g) of fresh weed biomass higher than 6.6 g of weed free all the season. These findings were in conformity with those of Awan et al (1990), Shahid (1994) and Tunio et al., 2004, who reported that herbicides and hand weeding significantly reduced weed density and weed biomass m^–2.

Dry weed biomass (g m^–2)

Data on dry weed biomass indicated that dry weed biomass was markedly affected by different weed management treatments. The highest dry weed biomass (10.56 g ha^-1) was recorded in weedy check plot, whereas the lowest dry weed biomass (0.62 g m^-2) was observed in (weed free plot for all season). Among herbicides, maximum dry weed biomass (3.72 g m^-2) was recorded in (2,4-D + Puma Super 75EW treated plot), while least dry weed biomass (1.89 g m^-2) was produced by Buctril-M treated plot. Among kasola hoeings, three hoeings gave lowest dry weed biomass (1.49 g m^-2) [Table-2].

Plant height (cm)

Data on plant height at maturity (Table-2) revealed that plant height was significantly affected by different herbicides application and hand weedings. The maximum plant height was recorded in weedy control plot (99.06 cm), followed by weed free the entire season plot (96.79 cm), three hoeings (96.6 cm) and Buctril-M treated plot (96.49 cm). The minimum plant height was produced by 2,4-D+Puma Super treated plot (85.35 cm). Among various herbicides, maximum plant height (96.49 cm) was produced by Buctril-M 40 EC. Kasola hoed plots remained at par with each other.

Number of tillers (m^–2)

The data on the number of tillers m^–2 (Table-2) indicated that all herbicides and weedings with kasola caused more tillers than control. Weed free for full season plot had maximum number of tillers m^–2 (504.66), while the minimum tillers (389.66) were observed in weedy control plot. Among herbicidal treatments, Buctril-M 40EC + Puma Super 75EW treated plot has maximum number of tiller m^–2 (454.33). While kasola hoed plots remained at par with each other. These results are similar to Veleva (1982) who reported increased tillering with the application of herbicides.

Spike length (cm)

The results on spike length (cm) of wheat indicated that all herbicides and kasola weedings produced higher spike length than weedy control plot. Maximum spike length (11.477 cm) was recorded in weed free plot all the season. The minimum spike length (9.120 cm) was found in (weedy control plot). Among various herbicides, the mixture of Buctril-M40EC + Puma Super 75EW gave maximum spike length (11.477 cm). In case of kasola hoeings, the maximum spike length was recorded in single hoed plots (11.08 cm). These findings are in accordance with Jalis and Noor (1980).

Number of spikelets spike^-1

The data on number of spikelets per spike indicated that minimum numbers of spikelets per spike were obtained in weedy control plot (15.94) was significantly different from other treatments. The maximum numbers of spikelets per spike (17.57) were recorded in weed free plot all the season, followed by one hand weeding and Buctril-M + Puma Super treated plot with 17.10 and 17.01 spikelets per spike, respectively (Table-2). The results were in conformity with the findings of Khan et al (1999).

Number of grains spike^-1

Number of grains spike^-1 is an important yield component. Its data are given in Table–2. Maximum number of grains (58.87) were recorded in Buctril-M + Puma Super treated plot closely followed by 2, 4-D + Puma Super treated plot (58.81) and weed free crop all the season with 58.23 and  grains per spike^-1, respectively. The minimum grains per spike were found in weedy control plot (51.45). Among various herbicides, the combination of Buctril-M 40EC + Puma Super 75EW produced highest number of grains per spike^-1 (58.87). Among kasola hoeings three hoeings produced highest number of grains per spike (57.92). Shahid (1994) and Khan et al., (1999) also reported similar results.

Grain yield (t ha^–1)

Grain yield data are given in Table-2. The statistical analysis and comparison of treatment means showed that all the treatments caused significantly higher grain yield than weedy check. The maximum grain yield of (7.08 t ha^–1) was produced by weed free plot while the minimum grain yield (2.59 t ha^–1) was recorded in weedy control plot. Among various herbicides, the plots treated with the combination of Buctril-M40EC and Puma Super 75EW produced maximum grain yield (5.60 t ha^–1). In Kasola hoed plots,     3 hoeings gave maximum grain yield (5.21 t ha^–1). These findings are similar to Awan et al., (1990) and Tunio et al., 2004.

Table 2. Effect of integrated weed management on the yield and yield components of wheat

* Means followed by different letters are significantly different at 5% level of probability.

References Cited

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