Agrotechnology

Effect of Weed Control Methods on the Yield of Wheat

Md. Mohaiminul Islam, Mahfuza Begum, Md. Abdus Salam and Md. Azizur Rahman^* Department of Agronomy, Bangladesh Agricultural University, Mymensingh, Bangladesh
^*Correspondence: Md. Azizur Rahman, Department of Agronomy, Bangladesh Agricultural University, Mymensingh, Bangladesh, Email:

Received: 14-Sep-2022, Manuscript No. AGT-22-18002; Editor assigned: 19-Sep-2022, Pre QC No. AGT-22-18002 (PQ); Reviewed: 03-Oct-2022, QC No. AGT-22-18002; Revised: 17-Jan-2023, Manuscript No. AGT-22-18002 (R); Published: 27-Jan-2023, DOI: 10.35248/2168-9881.23.12.309

Introduction

Wheat (Triticum aestivum L.) is the second important cereal crop next to in Bangladesh. From nutritional point of view, wheat is superior to rice for its higher protein content. Wheat grain is rich in food value containing 12% protein, 1.72% fat, 69.60% carbohydrate and 27.20% minerals. Almost 50% of the total cropped area is occupied by wheat. During 2015-16, the area under wheat cultivation was 10.26 lac acre, with a production of 13.11 lac m tons. It occupies 4% of total cropped area and 11% of the area cropped in Rabi season, contributing 7% to the total output of cereal food, this indicates that wheat cultivation may solve food problem to a considerable extent and save huge foreign currency of the country as well. But the average yield of wheat in Bangladesh is not still satisfactory. The low yield of wheat in Bangladesh is attributable to a number of reasons; viz. unavailability of quality seed, lack of using proper plant densities, late planting, poor field management, climatic hazards, intensive cropping and non-replishment of soil nutrients, inadequate fertilizer use, irregular irrigation and infestation of weeds as well as diseases and insects. But among all the factors weeds cause more loses to agriculture than all pests. There are innumerable reports on negative effects of weeds on crop plants. Thus cause huge yield losses. Weed infestation may reduce yield by 45.5 to 63.9%, in wheat while reduced up to 92% by competition from ryegrass, 17-62% due to wild oat. Wheat yield severely reduced due to broad spectrum weed flora in different areas of Bangladesh. Number of weed species in wheat field varied country to country and up to 45 weed species have been reported in Pakistan, 33 in Iran, 90 in India and 73 in Bangladesh. Moreover, weeds serve as alternate hosts to insects, nematodes and pathogenic fungi such as common broad leaved weeds for Fusarium, wild grasses and grassy weeds for wheat streak mosaic virus and its vector and wheat curl mite. So we can say that weeds are one of the major constraints of wheat production and weed control is the key factor in increasing yield. Weed control has been observed as one of the most important practice in crop production because good weed control will ensure maximum yield and high quality of farm produce.

But farmers in Bangladesh usually are reluctant to control weeds in wheat although there are reports of considerable yield increase in wheat due to weed control. Farmers, however, control weeds in wheat fields through traditional method i.e. hand weeding which is laborious, time consuming and expensive. Herbicidal weed control methods offer an advantage to save labor and money, as a result, regarded as cost effective that’s why chemical weed control has already become popular in Bangladesh. A report published by Shah and Habibullah, revealed that chemical weed control was proved to control weeds effectively, thus produce higher grain yield of wheat than hand weeding. But herbicide use till now is concentrated in rice cultivation. However, use of herbicides in wheat cultivation has also been gaining attention in recent years. But information regarding efficacy of herbicides on weed control and yield performance of wheat is still scanty under Bangladesh context. Under the above circumstances, the present study was conducted with the following objectives:

• To see the effect of selected herbicides on weed infestation behavior in wheat field.

• To evaluate the effect of herbicides weed control as well as on yield performance of wheat.

• To evaluate the economics of the weed control practices.

Materials and Methods

The experiment was carried out at the agronomy field laboratory, Bangladesh agricultural university, mymensingh during the period from November 2017 to March 2018 to study the effect of herbicides on weed control and yield of wheat. The details of the materials used and methodologies followed during the experiment are presented in this chapter.

Description of the experimental site

The experimental field is situated at the southern part of the BAU Farm at 24°75’N latitude and 90°50’E longitude at an elevation of 18 m above the sea level. It belongs to the old Brahmaputra floodplain agro-ecological zone AEZ-9. The experimental field was medium high land with salty clay loam soil texture having pH value of 6.8. The experimental site belongs to non-calcareous dark grey floodplain soil. The experimental area situated under subtropical climate, characterized by high temperature, high humidity and heavy rainfall with occasional gusty winds during April-September (kharif season) and scanty rainfall associated with moderately low temperature but plenty of sunshine during October to March (Rabi season) [1].

Experimental treatment

The experiment consisted of the following treatments:

• Unweeded (T).

• Hand weeding at 25 DAS (T).

• Hand weeding at 40 DAS (T).

• Hand weeding at 25 and 40 DAS (T).

• Panida 33EC-2.5 Lha as pre emergence herbicide at 2 DBS (T).

• Panida 33EC-2.5 Lha as pre emergence herbicide at 2 DBS +hand weeding at 40 DAS (T).

• Affinity 50.75WP-1.5 kgha as post emergence herbicide at 12 DAS (T).

• Affinity 50.75WP-1.5 kgha as post emergence herbicide at 12 DAS+hand weeding at 40 DAS (T).

• Panida 33EC-2.5 Lha as pre emergence herbicide at 2 DBS +affinity 50.75WP-1.5 kgha as post emergence herbicide at 12 DAS (T).

• Panida 33EC-2.5 Lha as pre emergence herbicide at 2 DBS +affinity 50.75WP-1.5 kgha as post emergence herbicide at 12 DAS+hand weeding at 40 DAS (T).

• Weed free (T).

***DBS: Days before Sowing (Table 1).

Table 1: Description of herbicides.

Description of weed control treatment

Weeds were allowed to grow in that treatment up to crop harvest. Weeding was not done at all. Hand weeding was done at 25 Days after Sowing (DAS) and another two hand weeding was done at 40 DAS, and 25 and 40 DAS with the help of locally used hand implement like niri. Chemical weed control was done by two herbicides with recommended doses including pre emergence and post emergence herbicide. Panida 33EC (Pendemithalin) as pre emergence herbicide and Affinity 50.75 WP (Carphentrazone ethyl) as post emergence herbicide. Pre emergence herbicide was applied at five days before sowing and post emergence herbicide was applied at 10-12 days after sowing, respectively, as per treatments [2].

Description of the variety (BARI Gom-26)

The variety is relatively shorter in height (92 cm-105 cm). Number of tiller plant^-1 is five to six, leaf broad, recurved and deep green in colour. In younger stage tiller is intermediate, plant deep green, a lot of hair present in upper culm node. The flag leaf is broad and erect, medium wax coating is present in panicle, stem and leaf sheath. Panicle initiation time is 60-63 days, spike medium, grain/spike 45 to 50, grain white, glossy and large size. 1000 grain weight is 48 g-52 g. Crop duration time is 104-110 days. Average yield is 3500-4500 kg ha^-1.

Experimental design

The experiment was laid out in Randomized Complete Block Design (RCBD) with four replications. The treatments were randomly assigned in each replication. The unit plot size was 4.0 m × 2.5 m. The total number of plots in the experiment was 44. Block to block and plot to plot distance were 1.0 m and 0.75 m, respectively.

Crop husbandry

At first the experimental field was opened with a tractor drawn harrow on 10 November 2017. Later on, the land was ploughed and cross ploughed three times by a country plough followed by laddering to obtain the desirable tilth. The corners and levels of the experimental field were trimmed by spade and visible larger clods were broken into small pieces by wooden hammer. The whole experimental land was divided into the unit plots maintaining the desired spacing. The unit plot was spaded one day before seed sowing and basal dose of fertilizer was incorporated thoroughly.

The plots were fertilized with urea, Triple Super Phosphate (TSP), muriate of Potash (MoP) gypsum and boric acid at the rate of 220, 180, 50, 120 and 6 kg ha^-1, respectively. The whole amount of TSP, MoP, gypsum, boric acid and one third of urea were applied just before final land preparation. The rest amount of urea was applied in two equal splits at 20 and 40 DAS. BARI Gom-26 was the variety of wheat which was supplied by agronomy farm laboratory, Bangladesh agricultural university. Seeds were sown on 29 November 2017 in the line at the rate of 120 kg seed ha^-1. The seeds were covered with soil. Care was taken to avoid bird damage. Weeding was done according to treatment specification. A light irrigation was done at 55 DAS when there was scarcity of moisture in the field. Since no infestation of disease and insect was observed in the plots, no plant protection measure was taken.

Data collection

Five plants were selected randomly from each plot before harvest. The following growth and yield contributing characters were recorded.

Weed parameter

• Weed density (no. m^-2).

• Weed dry weight (g m^-2).

• Importance value of weed (%).

• Weed control efficiency (%).

Yield contributing plant characters

• Plant height (cm).

• Number of total tiller hill^-1.

• Number of effective tillers hill^-1.

• Number of non-effective tiller hill^-1.

• Spike length (cm).

• Number of spikelets spike^-1.

• Number of unfilled grain spike^-1.

• Number of filled grain spike-1.

• 1000 grain weight (g).

• Grain yield t ha^-1.

• Stover yield t ha^-1.

Procedure of collecting data

Data on density of weeds were collected from each plot of wheat field by using 0.25 m^-2 quadrate as per method described by Cruz, et al. The quadrate was placed twice at random in each plot, kept for taking data on weed density at 50 DAS and at harvest. In each plot all weeds inside the quadrate were counted species wise and their average values were converted to number m^-2. After counting the weeds in each quadrate, the weeds were uprooted and separated species wise. Weeds were washed and dried at first in the sun and thereafter, in an electrical oven for 72 hours maintaining of a constant temperature of 65°C. After drying, the weight of each species was taken by an electrical balance. The average oven dry weight of each weed species was expressed in gm^-2. After taking all weights, the importance value of weed was calculated [3].

Importance value of weed can be calculated through the formula:

I.V.W (%)=(Dry weight of individual weed species)/(Dry weight of all the weed species ) × 100

Weed Control Efficiency (WCE) was calculated using the following formula developed by Sawant and Jadhav:

Where,

WCE=Weed Control Efficiency

DWC=Dry weight of weeds in weedy check (control)

DWT=Dry weight of weeds in each treatment

The extent of weed control by different weed control treatments and susceptibility of different weed species were graded on the basis of weed control efficiency by the following scale as suggested by Mian and Gaffer (Table 2).

Table 2: Different weed species were graded on the basis of weed control efficiency.

The crop of each plot was harvested from 1 m² of the central area with sickle at full maturity on 20 March 2018. Just before harvesting five hills excluding the border plants and the harvest area of each plot were selected at random and uprooted for collecting data on yield components. The harvested crops from each plot were bundled separately, tagged properly and brought to the threshing floor [4].

After harvesting, crop of each plot was dried separately. After threshing, cleaning and drying of grains, bulk was made plot wise. Then the grain and stover weights of each plot were recorded. Sample plants were processed in the similar way

A brief outline of the data recording procedure has been given below: Height of the plant was measured from five randomly selected mature plants from each plot. The measurement was taken prior to harvest from the ground level to the tip of the upper most spikelets of the spike and their average values were calculated for each unit plot.

Wheat growth and yield parameters

Numbers of total tillers of each sample was counted and mean values were recorded.

Tillers with ears were considered for counting the number of effective tillers hill^-1.

The tillers with no ear were counted as non-effective tillers. The number of spikelets per spike of each sample was counted from the five selected samples of each plot and their average value was calculated.

Length of the spike was measured randomly from the five selected sample of each plot and their average value was calculated.

Number of filled grains per spike was counted from the five selected sample of each plot and the average number was recorded.

Number of unfilled grains per spike was counted from the five selected sample of each plot and the average number was recorded.

One thousand clean dried grains were counted from the seed stock obtained from the each plot and weighted by using electrical balance for determining 1000 grain weight.

Grain obtained from 1 m² of each unit plot was sun dried and weighted carefully for recording the grain yield. Grain yield was recorded at 14% moisture content and grain yield was finally converted into ton per hectare [5].

Stover obtained from 1 m² of each unit plot was sun dried and weighted carefully for recording the stover yield. Stover yield was finally converted to ton per hectare^-1. Biological yield refers to the total dry matter accumulation of a plant system. Improved harvest index represents increased physiological capacity to mobilize photosynthates and translocate them into organs having economic yield.

The harvest index was calculated by the following formula:

Harvest index (%)=Grain yield/Biological yield × 100.

Statistical analysis

Data on yield and yield parameters were compiled, tabulated and analyzed statistically using the analysis of variance technique. Analysis of variance was done and mean differences were adjusted by Duncan’s New Multiple Range Test (DMRT). Comparison of the means was done by using Least Significance Difference (LSD) at 5% probability.

Economic analysis

The cost of individual head of expenditure was recorded and partial budget analysis was done. The budget consists of the following heads:

Variable cost: All non-material and material costs constituted the variable cost.

Overhead cost: The cost is indirectly related to crop production that is called overhead cost.

Gross return: Gross return was computed by adding market values of grain and straw yield.

Net income: Net income was calculated by using the following formula:

Net income=Gross return-Variable cost

BCR (Benefit Cost Ratio): Benefit cost ratio was calculated by using the following formula:

Results and Discussion

Results obtained from the present study have been presented in Tables 1 to 2. The results of the study regarding the effect of weed control methods on weed density, weed dry weight, weed control efficiency, plant height, total number of tillers plant^-1, number of effective tillers hill^-1, number of non-effective tillers hill^-1, number of spikelets spike^-1, spike length (cm), number of filled grains spike^-1, number of unfilled grains spike^-1, 1000 seed weight (g), grain yield tha^-1, stover yield tha^-1, and harvest index (%) of BARI released wheat variety BARI Gom-26 are presented and discussed in this chapter [6].

Floristic composition of weeds

A total of 18 weed species belonging to 13 families infested the experimental crops of which three from Poaceae, two from each of the family solanaceae, commeliaceae, amaranthaceae and one from each of the family Cyperaceae, Chenopodiaceae, Brassicaceae, Apiaceae, Convolvulaceae, Polygonaceae, Fabaceae, Scrophulriaceae, Portulaceae and annual outnumbered the perennial. Local name, english name, scientific name, family, morphological type, life cycle of those weeds of the experimental plot have been presented in Table 1. Results showed that 12 species Cyperus rotundus, physalis heterophylla, Solanum torvum, Cynodon dactylon, Echinochola colonum, Chenopodium album, Raphanus raphanistrum, Ipomoea acquatica, Polygonum tuberosum, Cyanotis axillaris, Lindemia spp, Alternathera philoxeroides were present at 50 DAS and at harvest. But others six species were not present in all the growing season. Dacus carota and Vicia hirsuta were present only at 50 DAS not at harvest and Digitaria sanguinalis, Portulacea oleracea, Amaranthus viridi and Commelina diffusa appeared at harvest [7].

Infested weed species with their importance value at 50 DAS and harvest

A total of 14 weed species was observed at 50 DAS in the experimental field. At 50 DAS five most important weed species were Polygonum hydropiper>Chenopodium album>Cyperus rotundus>Dacus carota>Echinochola colonum were the dominant weed in T₁, T₃, T₄, T₅, T₇, T₈, T₁₀, T₀. In case of T₂ and T₉ treatment, the rank and order of five most dominant weed species was differed and Ipomoea acquatica was found instead of Dacus carota. In T₆ treatment Cynodon dactylon was found instead of Echinochola colonum.

At harvest 16 weed species was observed of which the five most important weed species were Polygonum hydropiper>Chenopodium album>Cyperus rotundus>Cynodon dactylon>Amaranthus viridis were the dominant weed species in T₁, T₂, T₃, T₄, T₅, T₇, T₈, T₁₀ and T0. The rank and order of five most dominant weed species was differed in T₆ and T₉ treatment. In T₆ and T₉ treatment Cynodon dactylon is relpaced by Echinochola colonum. Kabir conducted an experiment at the agronomy field laboratory, Bangladesh agricultural university; reported that Cynodon dactylon, Polygonum hydropiper, Cyperus rotundus, Digitaria sanguinalis, Physalis heterophylla, were the most important weed species in wheat.

Weed density

Weed density (m^-2) was significantly influenced by weed control practices. At 50 DAS the highest weed population was found from unweeded treatment followed by T₆ (affinity 50.75WP as post emergence herbicide), T₁ (hand weeding at 25 DAS), T₄ (Panida 33EC) and T₈ (Panida 33EC+affinity 50.75WP). The lowest weed population was found in T₉ (Panida 33EC+affinity 50.75+hand weeding at 40 DAS) which was statistically identical with T₂, T₃, and T₅ treatments when hand weeding at 40 DAS was included.

At harvest the highest weed population was found from unweeded condition followed by T₁ (hand weeding at 25 DAS) and T₆ (affinity 50.75) treatments. Lowest weed population was found in T₁₀ (weed free) treatment and second lowest population density was found in T₉ (Panida 33EC+affinity 50.75+hand weeding at 40 DAS treatment). Similar research finding was also reported by Rekha, et al. who opined that weed density was lower in all weed control practices compared to the unweeded control plot.

Weed dry weight

Weed dry weight at different days after sowing was significantly influenced at 1% level of significance due to different weed control treatments. At 50 DAS the highest weed dry weight was found in unweeded condition followed by T₄ (Panida 33EC), T₁ (Hand weeding at 25 DAS). Similar to the weed density the lowest dry weight of weed was recorded in T₉ (Panida 33EC pre emergence herbicide+affinity 50.75+hand weeding at 40 DAS) treatment.

At harvest the highest weed dry weight was found in unweeded condition followed by T₆ (affinity 50.75), T₄ (Panida 33EC) treatments. Lowest weed dry weight was found in T₁₀ (weed free) condition followed by T₉ (Panida 33EC+affinity 50.75+hand weeding at 40 DAS) treatment.

Shobnom mustari conducted an experiment, she found that weed density increase gradually until harvest irrespective of herbicidal treatment. Weed density varied significantly due to different weed control treatments. The highest weed density was found in unweeded control treatment and lowest weed density was found in weed free treatment at harvest. Among the entire herbicidal treated plot the highest weed density was found in pendimethalin treated plot at harvest, while the least was observed in the treatment receiving pendimethalin along with one hand weeding. Weed dry weight was significantly affected by herbicide. Among the herbicidal treatments, (Carfentrazoneethyl+ Isoproteuron) contributed to the highest dry weight; while the lowest dry weight was contributed by the treatment receiving carfentrazone-ethyl and one hand weeding.

Tesfay Amare conducted an experiment and found that the effects weed management practices on weeds density were significant. Among the weed management practices the minimum weeds density was recorded in hand weeding followed by isoproturon at 1.50 kgha^-1 and 1.25 kgha^-1 while the maximum total weed density was in weedy check. The effect of weed management practices on weed dry weight was significant. The lowest weed dry weight was recorded in hand weeded plots but it did not differ significantly with isoproturon at 1.50 kgha^-1 whereas the highest weed dry weight was recorded in weedy check.

Weed control efficiency (%)

The grading of weed control efficiency varied with different weed control practices. It is important to mention here that the treatments which included T₂, T₃, T₅, T₇,T₉ and hand weeding at 40 DAS gave the best result as “excellent control” (96.09-100%). Pre-emergence followed by post emergence herbicides T8 gave the good control (74.73%). The three other treatments T₁,T₄,T₆, which were hand weeding at 25 DAS and single application of pre-emergence or post emergence herbicide produced fair control (52.14-65.50%).

At harvest, herbicide either the weed free condition and the effect of both pre emergence followed by post emergence herbicide along with hand weeding like T₉ (Panida 33EC as pre emergence+affinity 50.75WP as post emergence herbicide+hand weeding gave good control (85.26-88.25%) and T₃,T₅,T₇ (affinity 50.75WP+hand weeding at 40 DAS ), T₈ (affinity 50.75+hand weeding), T₉ (Panida 33EC+affinity 50.75) gave fair control (40-69%) in which two hand weeding or one hand weeding along with pre or post emergence herbicide or combination of both pre followed by post emergence herbicides were used. On the other hand, T₁, T₂, T₄, T6 gave poor control (20-39%) in which one single application of hand weeding and either pre emergence or post emergence herbicide.

From the result it is showed that weed control efficiency at harvest was lower than the weed control efficiency at 50 DAS. This is because herbicides used singly or in combination gradually lost their control efficiency over weed. Besides this new weeds emerged throughout the growing season. In case of T₉ manual weeding practice was used along with herbicidal application, both pre and post emergence herbicide which produced good control compared to other treatment. Found the similar result concluding the highest weed control efficiency of chemicals with manual hand weeding.

In agronomic crop production systems, the seed bank in the soil is the primary source of new infestations of annual weeds each year and represents the majority of weed pests. Herbicides are very effective at reducing weed populations and at the same time the number of seeds added to the soil seed bank. From the experiment it is revealed that single application of both pre and post emergence herbicide produce more weed at harvest resulting more seed store in soil than combine application of pre emergence herbicide followed by post emergence herbicide along with hand weeding. conducted an experiment and results revealed that Atrazine (0.75 kg/ha pre emergence) followed by 2,4-D (1.00 kgha^-1 post emergence) at 30 DAS recorded significant reduction in weed seed bank and gave an excellent control of weeds followed by mechanical weeding. Significantly lower weed population, weed dry weight, weed index and higher Weed Control Efficiency (WCE) was noticed in weed free check and Atrazine (0.75 kgha^-1 pre emergence) followed by 2,4-D (1.00 kgha^-1 post emergence) during the different growth stages of crop. Therefore, it can be said that besides herbicidal application manual weeding is required for effective weed control.

Yield and yield contributing characters of wheat

Plant height: Plant height was significantly influenced at 1% level of significance due to different weed control treatments. It was found that the highest plant height (107.0 cm) was observed in T₉ (Panida 33EC+affinity 50.75WP+hand weeding at 40 DAS) which was identical to T₁₀ (weed free). The lowest plant height (99.40 cm) was recorded in T₀ treatments which was identical to T₁ (hand weeding at 25 DAS). Pammy conducted an experiment in agronomy field laboratory to see the effect of herbicide on wheat and observed that plant height of wheat was reduced due to competition of weeds. She found that the highest plant height was observed in the treatment where Panida 33EC as pre emergence+U-46 D fluid as post emergence+hand weeding and lowest one in unweeded condition.

Number of total tillers hill^-1: Total number of tillers hill^-1 was significantly influenced at 1% level of significance due to different weed control treatments. The highest number of tillers hill-1 (7.53) was observed in T₁₀ (weed free) which was statistically identical to T₉ (Panida 33EC+affinity 50.75WP +hand weeding at 40 DAS). The lowest number of tillers hill^-1 (5.76) was observed at no weeding (T₀) treatment which was identical to T₁,T₂ treatments. Pammy reported that different weed management treatments reduced weed population and thereby decreased weed crop competition during entire growth stage. Thus increases tillers and other yield attributes. She found that the highest number of tillers hill^-1 was observed in the treatment where Panida 33EC as pre emergence+U-46 D Fluid as post emergence and hand weeding at 40 DAS were applied.

Number of effective tillers hill^-1: There was significant effect on number of effective tillers hill-1 due to weed control treatment at 1% level of significance. Similar to total tiller hill^-1 the highest number of effective tillers hill^-1 (6.950) was produced from the treatment T₁₀ (weed free) which was statistically identical to T₉ (Panida 33EC+affinity 50.75WP+hand weeding at 40 DAS). The lowest number of effective tillers hill^-1 (5.28) was observed from no weeding treatment which was identical to T₁,T₂,T₄ and T₆ treatments. Among this four treatments responsible for lowest number of effective tillers first two treatments were included single hand weeding and second two were included single application of herbicide, either pre emergence or post emergence. Similar result was reported by Nahar as weed infestation decrease the no. of effective tillers hill^-1. Other weed control treatments produced intermediate result thereby decreased weed crop competition during entire growth stage.

Number of non-effective tillers hill^-1: The effect of weed control treatment on the number of non-effective tillers hill^-1 was nonsignificant.

Spike length: The length of spike was influenced significantly by different weed control treatment. The longest spike (17.00 cm) was recorded from treatment T₉ (Panida 33EC followed by affinity 50.75 WP+hand weeding at 40 DAS) which was statistically similar to T₈ and T₁₀ and the shortest spike (13.71 cm) was recorded from no weeding treatment. The similar result was also found by Karim and Mamun and Okafor who reported that spike length was reduced due to competitive stress of weeds.

Number of spikelets spike^-1: The effect of weed control treatment on the number of spikelets spike^-1 was significant. The number of spikelets spike^-1 was different as different weed control treatments ranged from 14.16 to 17.66. The highest number of spikelets spike^-1 (17.66) was observed in T₁₀ treatment (weed free) which was statistically similar to T₉ and crop weed competition was higher in unweeded plot and hence lowest number of spikelets spike^-1 (14.16) was produced. Pammy observed that observed that pre emergence herbicide Panida 33EC followed by post emergence U-46 D fluid+hand weeding at 40 DAS gave highest number of spikelets. The lowest spikelets spike^-1 (14.16) was obtained by unweeded control treatment. Other weed control treatment produced intermediate result.

Number of unfilled grains spike^-1: The analysis of variance indicates that the effect of weeding treatments on the unfilled grains spike^-1 was significant. The lowest (1.21) unfilled grains spike^-1 were recorded from the treatment T₉ (pre emergence herbicide Panida 33EC+affinity 50.75WP+hand weeding at 40 DAS) which was statistically similar with T₁₀. The highest number of unfilled grains spike^-1 (2.35) was recorded in no weeding treatments. Pammy reported that the unfilled grains spike^-1 decreased with the increasing frequency of weeding treatments. She found that he lowest unfilled grains spike^-1 was recorded from the treatment where pre emergence herbicide Panida 33EC+U-46 D fluid as post emergence herbicide+hand weeding at 40 DAS was applied.

Number of filled grains spike^-1: The effect of weed control treatment on the number of filled grains spike^-1 was observed due to weed control treatment at 1% level of significance. Significantly, the highest filled grains spike^-1 (49.52) was produced by the treatment T₁₀ (weed free) followed by T₉ (pre emergence herbicide Panida 33EC+ affinity 50.75WP+hand weeding at 40 DAS) which is statistically similar with T₃,T₅,T₇ and T₈ treatments. The lowest number (40.29) of filled grains spike-1 was recorded T0 (unweeded) weeding treatment. T₁,T₂,T₃,T₄,T₅ produced intermediate result. Similar result observed by Yadav as weed control practices increased number of filled grains spike^-1.

1000 grain weight: The effect of weed control treatment on the number of non-effective tillers hill^-1 was non-significant.

Grain yield: The weed control treatment had significant effect on grain yield at 1% level of significance. The highest grain yield (5.113 tha^-1) was obtained from the treatment (T₁₀) (weed free) followed by T₉ (pre emergence herbicide Panida 33EC+ affinity 50.75WP+hand weeding at 40 DAS). Both pre emergence followed by post emergence herbicidal treatment showed moderate grain yield. The lowest grain yield (2.49 tha^-1) was obtained from unweededy treatment higher grain yield in treatment T₁₀ might be resulted from higher no. of effective tiller hill^-1, no. of spikelet spike^-1 and no. of filled grain spike^-1. Pammy conducted an experiment to see herbicidal effect on wheat and found that highest yield (5 tha^-1) obtained from the treatment where Panida 33EC as pre emergence herbicide+U-46 fluid as post emergence herbicide+hand weeding at 40 DAS were practiced.

Stover yield: Different weed control treatments in regard to stover yield manifested significant difference at 1% level of significance. The maximum stover yield (5.58 tha^-1) was produced under the treatment T₁₀ (weed free) which was statistically identical to T₈ (Panida 33EC+affinity 50.75WP). Second highest stover yield produced by T₉ similar with T₅. The lowest stover yield (2.52 tha^-1) was produced by no weed control treatment. Rahman, Mamun and Salim and Singh and Singh also observed reduction in stover yield in wheat due to weed competition, respectively by 31.90%, 31.74%, 44.10%.

Biological yield: Weed control treatment had significant effect on the biological yield. The highest (10.48) biological yield was obtained from the treatment T₁₀ (weed free) followed by T₉ treatment. The lowest biological yield (5.09) was obtained from no weeding treatment. Salek observed that weed management practices showed the highest biological yield compared with unweeded condition.

Harvest index (%): Weed control treatment had significant effect on the harvest index. Similar trend of stover yield was observed in harvest index (%). The highest (50.06%) harvest index was obtained from the treatment T₂ (hand weeding at 40 DAS). The lowest harvest index (36.96%) was obtained from no weeding treatment. Salek observed that weed management practices showed the highest harvest index compared with unweeded condition.

Percent yield loss in wheat over weed control

Percent yield loss varied with different weed control practices is given. The highest yield loss 51.30% was recorded under treatment in T₀ (unweeded). The lowest yield loss 4.16% was recorded in T₉ (Panida 33EC+affinity 50.75WP+hand weeding at 40 DAS).

Economics of treatments

Net returns: There were eleven weed control treatments in the experiment to evaluate their cost of production, economic performance and return of BARI Gom-26. Among the eleven treatments, T₀ was unweeded treatment and another ten were weed control treatments. In case of control, there was no involvement of cost for weed control.

It is obvious from the data that net returns from wheat influenced to a great extent by different weed control treatments. The treatment T₉ (Panida 33EC+affinity 50.75+hand weeding at 40 DAS) provided the highest net return of 62420 tkha^-1, that excelled rest of the treatments. The other treatment such as T₈ (Panida 33EC+affinity 50.75WP), T₁₀ (weed free), T₁ (hand weeding 25 DAS), T₇ (affinity 50.75+hand weeding at 40 DAS, T₆ (affinity 50.75WP), T₄ (Panida 33EC), T₂ (hand weeding at 40 DAS), T₃ (hand weeding at 25 and 40 DAS) and unweeded condition (T₀) provided additional net returns of taka 49570, 32730, 31995, 28180, 27875, 23179, 20520, 17835, 10920, 9590 ha^-1 respectively.

In case of B: C ratio all the treatments evaluated for weed control in wheat was calculated. The highest B: C ratio of 1.67 was recorded with the treatment T₉ (Panida 33EC+affinity 50.75+hand weeding at 40 DAS) followed by T₈,T₁,T₇,T₅,T₁₀,T₆,T₃,T₄,T₂ and T₀ with the B: C values 1.59,1.41,1.36,1.31,1.30,1.25,1.23,1.21,1.20,1.14 respectively.

From this experiment, it can be concluded that application of Panida 33EC+affinity 50.75+hand weeding at 40 DAS is the best treatment in terms of economic returns and B: C ratio for controlling weeds and having considerable yield increase in wheat [8].

Conclusion

The unit plot size was 4.0 m × 2.5 m. The total number of plots in the experiment was 44. Block to block and plot to plot distance were 1.0 m and 0.75 m, respectively. The plots were fertilized with urea, Triple Super Phosphate (TSP), Muriate of Potash (MoP) gypsum and boric acid at the rate of 220, 180, 50, 120 and 6 kgha^-1, respectively. The whole amount of TSP, MoP, gypsum, boric acid and one third of urea were applied just before final land preparation. The rest amount of urea was applied at 24 days after sowing and lag vegetative phase (50 days after sowing). Seeds were sown on 29 November 2017 in the line at the rate of 120 kg seed ha-1. Harvesting was done at 20 march, 2018.

The weeds were counted using a plant quadrate 0.5 m-0.50 m size and the data of total weed density (number m^-2), total dry weight (gm^-2) was recorded at 50 DAS and at harvest. Five plants were selected randomly from each plot at maturity for recording data on yield and related parameters.

The plant characters such as plant height, Number of total tillers hill^-1, number of effective tillers hill^-1, number of spikelets spike^-1, number filled grains spike^-1, grain yield, stover yield were recorded. The data were analyzed statistically and means were compared by Duncan’s multiple range test.

Weed density and dry weight were significantly influenced by the weed control treatments. At 50 DAS the highest weed population was found from T₀ (unweeded) treatment and lowest weed population was found in T₉ (Panida 33EC+affinity 50.75+hand weeding at 40 DAS). At harvest the highest weed population was found from (T₀) unweeded condition and lowest weed population was found in T₁₀ (weed free) treatment. At 50 DAS the highest weed dry weight was found in T₀ (unweeded) condition. Similar to the weed density the lowest dry weight of weed was recorded in T₉ (Panida 33EC pre emergence herbicide +affinity 50.75+hand weeding at 40 DAS) treatment. At harvest the highest weed dry weight was found in T₀ (unweeded) condition and lowest weed dry weight was found in T₁₀ (weed free) treatment.

All crop characters were significantly influenced by the weed control treatment. The treatment T₁₀ (weed free) produced the highest plant height, number of total tillers hill^-1, number of effective tillers hill^-1, number of spikelets spike^-1, number filled grains spike^-1, grain yield, stover yield followed by the T₉ treatment (Panida 33EC pre emergence herbicide+affinity 50.75+hand weeding at 40 DAS). In the T₉ treatment plant height, number of total tillers hill^-1, number of effective tillers hill^-1, number of spikelets spike^-1, number filled grains spike^-1, grain yield, stover yield 107, 7.48, 6.945, 17.31, 46.67, 4.90 and 5.25 respectively.

After economic analysis the highest B: C ratio was found in treatment T₉ (Panida 33EC pre emergence herbicide+affinity 50.75+hand weeding at 40 DAS). It means farmers become more benefited through applying this treatment. It may be concluded that application of Panida 33EC+affinity 50.75WP +hand weeding at 40 DAS could be used as the best weed control practice in wheat cv. BARI gom-26.

References

1. Amare T, Sharma JJ, Zewdie K. Effect of weed control methods on weeds and wheat (Triticum aestivum L.) yield. World J Agric Res. 2014;2(3):124-128.

   [Crossref][Googlescholar][Indexed]

2. Amare T. Effect of weed management methods on weeds and wheat (Triticum aestivum L.) yield. Afr J Agric Res. 2014;9:1914-1920.

   [Crossref][Googlescholar][Indexed]

3. Nadeem MA, Tanveer A, Ali A, Ayub M, Tahir M. Effect of weed control practice and irrigation levels on weeds and yield of wheat (Triticum aestivum). Indian J Agron. 2007;52(1):60-63.

   [Googlescholar]

4. Nath CP, Das TK, Rana KS, Bhattacharyya R, Pathak H, Paul S, et al. Weed and nitrogen management effects on weed infestation and crop productivity of wheat mungbean sequence in conventional and conservation tillage practices. Agric Res. 2017;6:33-46.

   [Crossref][Googlescholar][Indexed]

5. Antralina M, Istina IN, Simarmata T. Effect of difference weed control methods to yield of lowland rice in the SOBARI. Procedia Food Sci. 2015;3:323-329.

   [Crossref][Googlescholar][Indexed]

6. Jehangir IA, Hussain A, Sofi N, Wani S, Ali OM, Abdel Latef AA, et al. Crop establishment methods and weed management practices affect grain yield and weed dynamics in temperate rice. Agron. 2021;11(11):2137.

   [Crossref][Googlescholar][Indexed]

7. Khaliq A, Shakeel M, Matloob A, Hussain S, Tanveer A, Murtaza G. Influence of tillage and weed control practices on growth and yield of wheat. Philipp J Crop Sci. 2013;38(3).

   [Googlescholar]

8. Chhokar RS, Sharma RK, Sharma I. Weed management strategies in wheat-A review. J Wheat Res. 2012;4(2):1-21.

   [Googlescholar]