Effect of pre and post emergence application of herbicides on growth and yield of Dolichos bean

Introduction

Dolichos bean (Dolichos lablab L.) is an important vegetable legume cultivated for its tender green pods. The crop is valued for its nutritional importance Fresh green pods contain about 86.1% moisture, 3.8% protein, 6.7% carbohydrates, 0.75% fat, 0.9% minerals, and vitamin A in contrast, mature dry seeds provide 23% protein, 62.5 g carbohydrates, and around 340 calories per 100 g of edible portion (Tindall, 1983) [1] . and its contribution to farm income. However, weed infestation is one of the major constraints affecting the productivity of dolichos bean. Weeds compete with the crop for essential resources such as nutrients, moisture, light and space, particularly during the early stages of crop growth. Manual weeding is effective in reducing weed competition, but repeated hand weeding is labour-intensive and increases the cost of cultivation. Herbicides can provide timely and effective weed suppression and may reduce the dependence on manual labour. However, the effectiveness of a herbicide depends on the weed spectrum, time of application, dose and crop tolerance. Therefore, identification of an effective and crop-safe herbicide is important for improving crop growth and productivity. The present investigation was therefore undertaken with the objective to identify a suitable herbicide for better growth and yield of dolichos bean and to study relative performance of different herbicides in weed control.

Materials and Method

Experimental site

The experiment was conducted during the Kharif season of 2025-26 at the Instructional Farm, Department of Vegetable Science, Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola, Maharashtra. The study was conducted on dolichos bean cv. Konkan Bhushan. The experimental findings covered weed infestation, crop growth, yield attributes, pod yield.

Experimental design and treatments

The experiment was laid out in a Randomized Block Design with three replications and eight treatments. The experimental plot measured 3.15 × 1.80 m and crop spacing was 45 × 30 cm. The treatments consisted of six herbicidal treatments, farmers' practice and a weedy check. Weedy Check

Observations recorded

Observations were recorded on monocot, dicot and total weeds, weed dry matter, weed control efficiency, weed index, plant height, number of leaves per plant, number of branches per plant, pod characters and pod yield B:C ratio.

Weed flora

The major weed flora identified in the experimental field included Cynodon dactylon, Cyperus rotundus, Echinochloa colona, Dactyloctenium aegyptium, Eleusine indica, Parthenium hysterophorus, Euphorbia hirta, Amaranthus viridis, Chenopodium album, Portulaca oleracea and Celosia argentea. √ 𝑋 + 0.5)

Results and Discussion

Influenced of herbicides on monocot weeds

The data in respect of monocot weed count recorded at harvest are presented in table 1 revealed that, the monocot weed population significantly minimum monocot weeds (9.18) were counted in the treatment T 7 -Farmer practice of 3 HW and found to be par with T 2 -RM Pendimethalin 30% + Imazethapyr 2% EC @ 860 g a.i./ha fb 1 HW at 35 DAS as PE (20.98), while significantly the maximum monocot weeds were counted in the treatment T 8 -Weedy check (201.04). Monocot weeds difficult to control because they are perennial species with deep rhizomes and tuberous roots that regenerate even after herbicide application. This underground reserve system makes them tolerant to most pre-emergence and post-emergence herbicides, leading to poor suppression in dolichos bean. However, Pendimethalin 30% + Imazethapyr 2% EC gives better result to control against monocot weeds. Similar findings was reported by Rao et al. (2005) [2] in cowpea, Patil and Jadhav (2014) [3] in cluster bean.

Influenced of herbicides on dicot weeds

The data in respect of dicot weed count recorded at harvest are presented in table 1 revealed that, the dicot weed population significantly minimum dicot weeds (6.97) were counted in the treatment T 7 -Farmer practice of 3 HW and found to be at par with the treatment T 2 -RM Pendimethalin 30% + Imazethapyr 2% EC @ 860 g a.i./ha fb 1 HW at 35 DAS as PE (12.53). However, significantly the maximum dicot weeds were counted in the treatment T 8 -Weedy check (103.14). Similar findings were earlier recorded by Meena et al. (2020) [4] in cluster bean, Maurya et al. (2016) [5] in pea, Manjunath and Hosmath (2016) [6] in soyabean.

Influenced of herbicides on total weeds

The data in respect of total weed count recorded at harvest are presented in table 1 revealed that, the total weed population, significantly minimum total weed population (16.15) was recorded in the treatment T 7 -Farmer practice of 3 HW which was found to be at par with treatment T 2 -RM Pendimethalin 30% + Imazethapyr 2% EC @ 860 g a.i./ha fb 1 HW at 35 DAS as PE (33.51) and followed by the treatments T 6 -RM Imazethapyr 35% + Imazamox 35% WG @ 100 g a.i./ha fb 1 HW at 35 DAS as PoE (59.06) and T 3 -RM Diclosulam 0.9% + Pendimethalin 35% SE @897.5 g a.i/ha as PE fb 1 HW at 35 DAS (66.05). However, significantly the maximum total weed population was recorded in the treatment T 8 -Weedy check (304.18). Similar findings reported by Subbalaxmi et al. (2021) [7] in mungbean, Jhadhav et al. (2025) [8] in soyabean.

Influenced of herbicides on dry matter of weeds

The data in respect of dry matter of weeds is recorded at harvest are presented in table 1 revealed that the, significantly the lowest weed dry matter was recorded in T 7 -Farmers' practice (HW at 20,40,60 DAS) (30.24 g/m 2 ). Among the herbicidal treatments, T 2 -RM Pendimethalin 30% + Imazethapyr 2% EC @ 860g a.i/ha as PE fb 1 HW at 35 DAS (74.21 g/m 2 ) and T 6 -RM Imazethapyr 35 % + Imazamox 35 % WG @100g a.i /ha as PoE (15-20 DAS) fb 1 HW at 35 DAS (111.18 g/m 2 ) recorded significantly lowest dry weight of weeds. However, significantly the highest dry matter was accumulated in T 8 -Weedy check (410.25 g/m 2

). Similar findings reported by Doba and Maheriya (2021) [9] in dolichos bean, Khairnair et al. (2013) [10] in mungbean, Meena et al.(2020) [4] in cluster bean, Maurya et al. (2016) [5] in pea,

Weed control efficiency varied significantly across the treatments based on biomass suppression. Manual weeding (T 7 ) achieved the highest overall WCE of 92.63%. Among the herbicides, T 2 -RM Pendimethalin 30% + Imazethapyr 2% EC @ 860 g a.i./ha as PE fb 1 HW at 35 DAS delivered the superior chemical weed control efficiency of 81.91%, followed by the post-emergence ready-mix T 6 at 72.90%. Single-molecule applications like quizalofop-ethyl (T 4 ) and imazethapyr (T 5 ) recorded the lowest efficiencies at 46.08% and 57.25% respectively, due to their narrow control spectrum. Similar findings were earlier reported by Doba and Maheriya (2021) [9] in dolichos bean, Manibharati et al. (2024) [11] in cowpea.

Influence of herbicides on weed index

The weed index measurements showed that unchecked competition in (T 8 ) weedy check resulted in the highest crop yield loss of 65.99%. Among the herbicidal options, T 2 -RM Pendimethalin 30% + Imazethapyr 2% EC @ 860 g a.i./ha as PE fb 1 HW at 35 DAS registered the minimum weed index of 6.42%, indicating that this treatment effectively eliminated commercial yield losses. It was followed by T 6 with a moderate yield loss index of 15.46%. These findings confirm that integrating a broad-spectrum pre-emergence ready-mix with a single hand weeding at 35 DAS (T 2 ) matches manual weeding effectiveness while optimizing labor expenses. Similar observations recorded by Doba and Maheriya (2021) [9] in dolichos bean.

The data in respect of plant height is recorded at harvest are presented in table 2 revealed that the, maximum plant height was recorded under farmers practice (71.30 cm). Among herbicidal treatments, T 2 -RM Pendimethalin 30% + Imazethapyr 2% EC @ 860 g a.i./ha as PE fb 1 HW at 35 DAS recorded 70.23 cm plant height. It was followed by T 3 (69.30 cm) and T 6 (67.37 cm). The minimum plant height was recorded in T 1 (55.43 cm), followed by the weedy check (57.27 cm). These results are similar to the findings Maurya et al. (2016) [5] in vegetable pea, Shambhavi et al. (2025) [12] in cluster bean, and Gurung et al. (2026) [13] in vegetable cowpea.

Influence of herbicide on number of leaves

The data in respect of number of leaves is recorded at harvest are presented in table 2 revealed that the, at harvest, farmers' practice recorded the highest number of leaves (49.02 plant -1 ). Among herbicidal treatments, T 2 -RM Pendimethalin 30% + Imazethapyr 2% EC @ 860 g a.i./ha as PE fb 1 HW at 35 DAS recorded 47.19 leaves plant -1 , followed by T 6 (45.23) and T 3 (42.54). The lowest number of leaves was observed under the T 8 -weedy check (33.63). These results are in agreement with earlier findings reported by Rawat et al. (2025) [14] in garden pea, Shambhavi et al. (2025) [12] in cluster bean.

Influence of herbicide on pod yield per plant (gr)

The data in respect of yield plant -1 is recorded at harvest are presented in table 2 revealed that the, farmers practice recorded the highest pod yield per plant (96.83 g) which was found at par with herbicidal treatment T 2 -RM Pendimethalin 30% + Imazethapyr 2% EC @ 860 g a.i./ha as PE fb 1 HW at 35 DAS recorded the highest pod yield (90.61 g plant -1

), followed by T 6 (81.86 g) and T 3 (72.36 g). The minimum pod yield was recorded under the weedy check (32.93 g plant -1 ). The higher yield under T 2 -RM Pendimethalin 30% + Imazethapyr 2% EC @ 860 g a.i./ha as PE fb 1 HW at 35 DAS , Similar findings regarding yield improvement under effective weed management practices were reported by Khairnair et al. (2013) [10] in mungbean, Meena et al. (2020) [4] in cluster bean, Maurya et al. (2016) [5] in pea.

Pod yield per plot was significantly influenced by weed-management treatments. Farmers practice recorded 5.42 kg plot -1 which is at par with treatment T 2 -RM Pendimethalin 30% + Imazethapyr 2% EC @ 860 g a.i./ha as PE fb 1 HW at 35 DAS recorded 5.07 kg plot -1 and T 6 recorded 4.58 kg plot -1 . The lowest pod yield was observed in the weedy check (1.84 kg plot -1 ). Thus, among the herbicidal treatments, T 2 -RM Pendimethalin 30% + Imazethapyr 2% EC @ 860 g a.i./ha as PE fb 1 HW at 35 DAS maintained the highest pod productivity per plot. Similar findings reported by Maurya et al. (2016) [5] in pea, Manjunath and Hosmath (2016) [6] in soyabean.

Effect on pod yield per hectare (q)

The experimental results indicated that effective weed management substantially improved pod yield on a hectare basis. The source document reports the highest yield under farmers' practice, while T 2 -RM Pendimethalin 30% + Imazethapyr 2% EC @ 860 g a.i./ha as PE fb 1 HW at 35 DAS was the leading herbicidal treatment with a reported yield of approximately 89.49 q ha⁻¹ in the results narrative. The weedy check recorded substantially lower yield. The higher productivity under T 2 -RM Pendimethalin 30% + Imazethapyr 2% EC @ 860 g a.i./ha as PE fb 1 HW at 35 DAS was associated with its superior weed suppression and better crop growth. Similar observations on weed control by cultural methods were reported by Doba and Maheriya (2021) [9] in dolichos bean, Parushuraman et al. (2000) [15] in cowpea.

Economics and B:C ratio

The results revealed that, GMR was influenced by different treatments. The highest GMR (Rs. 191260 ha‫-‬ (Choudhary et al., 2007) [

) and NMR (Rs. 107884 ha‫-‬ (Choudhary et al., 2007) [16] ) were recorded in T 7 -Farmers' practice of three hand weedings, which proved superior over all other treatments. Among the herbicidal treatments, pre-emergence application of T 2 -RM Pendimethalin 30% + Imazethapyr 2% EC @ 860g a.i./ha fb 1 HW at 35 DAS as PE registered maximum GMR (Rs. 178980 ha‫-‬ (Choudhary et al., 2007) [16] ) and NMR (Rs. 104304 ha‫-‬ (Choudhary et al., 2007) [16] ), followed by T 6 -RM Imazethapyr 35% + Imazamox 35% WG @ 100 g a.i./ha fb 1 HW at 35 DAS as PoE (Rs. 161700 ha‫-‬ (Choudhary et al., 2007) [16] GMR and Rs. 81,024 ha‫-‬ (Choudhary et al., 2007) [16] NMR). The lowest GMR (Rs. 65040 ha‫-‬ (Choudhary et al., 2007) [16] ) and NMR (Rs. -5836 ha‫-‬ (Choudhary et al., 2007) [16] ) were recorded in T 8 -Weedy check. the treatment T 2 -RM Pendimethalin 30% + Imazethapyr 2% EC @ 860g a.i./ha as PE fb 1 HW at 35 DAS (2.40) was the most profitable herbicidal treatment, followed by T 7 -Farmers' practice (2.29). The lowest B:C ratio (1.08) was observed in T 8 -Weedy check, similar observations recorded by Doba and Maheriya (2021) [9] in dolichos bean, Thind et al. (1997) [17] in cowpea.

Conclusion

On the basis of present investigation uncontrolled weed growth severely cuts dolichos bean productivity due to intense resource competition. While the farmers' practice of three hand (20,40,60 DAS) weedings yields the highest crop growth and pod productivity, it is heavily constrained by high labor costs. Among the herbicidal options, the pre-emergence application of ready-mix Pendimethalin 30% + Imazethapyr 2% EC @ 860 g a.i./ha followed by one hand weeding at 35 DAS is the most effective and profitable treatment. This broadspectrum chemical method optimizes production expenses, yielding 89.49 q ha -1 with a peak benefit-cost ratio of 2.40 and net returns of Rs. 104,304 ha -1 , similar observations recorded by Pandey et al. (2000) [18] in pea.

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