Influence of Integrated Weed Management Practices on Yield and Yield Components of Chickpea in Southeastern of Ethiopia

Type: Research The experiment was conducted on research field of Sinana Agricultural Research center and Goro sub site in the highlands of Bale, south eastern Ethiopia under rain fed conditions during main cropping season of 2018 and 2019 to evaluate the integrated effects of pre-emergence (Dual gold 960 EC), post emergence (Gallant super) herbicides and hand weeding frequencies on yield and yield components of chick pea. The experiment consisted of eight weed management options; sole dual gold 960 EC, dual gold 960 EC + one time hand weeding at two weeks after crop emergence, and dual gold 960 EC at four weeks after crop emergence, sole gallant super, gallant super and one time hand weeding, weedy check, one time hand weeding at two weeks after crop emergence and two times hand weeding at two and four weeks after crop emergence along with two varieties (Dhera and Habru) laid out in randomized complete block (RCBD) with three replications. Analysis of variance showed that a significant difference in number of branches per plant, biological yield (kg ha-1), and grain yield (kg ha-1) were observed on different herbicidal treatments and hand weeding at Sinana while at Goro significant effects of integrated weed management were observed on dry matter, plant height, biological yield, grain yield and harvest index. The remains parameters studied at both locations were no significant for the treatments studied. The highest net return obtained from the application of 1.5 lit ha-1 dual gold 960 EC integrated with hand weeding at four weeks after crop emergence while the highest net return at Goro was obtained from two times hand weeding at two and four weeks after crop emergence and hence can be recommended for the end users. Moreover, similar experiments should be carried out in different cold and warmer regions of chickpea potential areas of the zone to confirm the present findings. Accepted: 23/01/2021 Published: 26/01/2021


INTRODUCTION
Chickpea is widely grown around the world and serves as a multi-use crop. It plays a significant role in improving soil fertility by fixing the atmospheric nitrogen. It can fix up to 140 kg N ha -1 from air and meet most of its nitrogen requirement. It is also an excellent source of protein, fiber, complex carbohydrates, vitamins, and minerals thus can help alleviating malnutrition and improving human health. Chickpea has been characterized into two main categories primarily on seed characteristics: the 'desi' types, with relatively small, angular seeds with rough, usually yellow to dark brown testa; and the 'kabuli' types, which have larger more rounded and creamed colored seeds.
Ethiopia is the top producer of chickpea in Africa. Chickpea has the ability to grow on residual moisture which gives farmers the opportunity to engage in double cropping, where chickpea is sown at the end of the rainy season following the harvest of the main crop. This allows more intensive and productive use of land, particularly in areas where land is scarce. In Ethiopia, chickpea is the third most important grain legume after faba bean (Vicia faba) and common bean (Phaseolus vulgaris L.) by volume for small-scale farm production. The national average yield of chickpea is 1.7 t ha -1 (CSA, 2013), which is far below the potential yield of 4.5 t ha -1 . Chickpea is poor competitor to weeds because of slow growth rate and limited leaf development at early stage of crop growth and establishment, if weed management is neglected under these conditions, resulting in yield loss of 40 to 87%. Weeds are plants which compete with crops for nutrients, space, and light exerting a lot of harmful effects by reducing the quality and quantity of the crop if their populations are left un-controlled (Tepe, 2011). Various methods are used to control weeds in various crops including manual, mechanical, cultural, biological and chemical. Integration of weed control methods is an effective and workable practice that is ecologically and economically viable to the farmers and be the best options for sustainable weed management practices. Generally, for the control of weeds farmers do manual weeding. But with the increase in labour cost and scarcity of labor, manual weed control has become a difficult task in chickpea. Herbicides constitute a new and highly efficient technique for controlling weeds hence increasing yields, improving quality and reducing labor in crop production. When properly used, pre-emergence herbicides accomplish effective and economic weed control, and consequently chickpea seed yields as similar to or only lightly smaller than those of weed free treatments are resulted (Hassan et al., 2003). Efficacy of dual gold herbicide combined with hand weeding has not yet been evaluated in chickpea growing in mid and lowlands of Bale zone. But, dual gold 960 EC is one of the pre-emergence herbicide which is available to kill both grassy and broadleaf weeds at the early and later stage of the crop growth to reduce yield loss. Hence, the objectives of this study is to evaluate the effect of pre emergence herbicide (dual gold 960 EC) with or without hand weeding, to evaluate the effect of post emergence herbicide (gallant super) on yield and yield components of chick pea and to assess the economic feasibility of the herbicides.

Chickpea
variety 'Habru and Dhera' with recommended seed rate of 120 kg per ha was used for the experiment. The experiment consisted of eight weed management options: weedy check, one time hand weeding at two weeks after crop emergence, two times hand weeding at two and four weeks after crop emergence, sole dual gold 960 EC, dual gold 960 EC + one time hand weeding at two weeks after crop emergence, and dual gold 960 EC at four weeks after crop emergence, sole gallant super, gallant super and one time hand weeding laid out in randomized complete block design (RCBD) with three replications.
1.5 lit per hectare of pre-emergence herbicide on second date of planting and 1 lit. per hectare gallant super at 2-6 leaf stage of weed growth stage with 200 lit per hectare of water was used. A field layout was prepared and the treatments were assigned randomly to each plot within a block. Both replications and experimental units were separated by 1.5m. Seeds were sown using row planting. Each plot consisted of 6 rows 30cm spaced apart and 4m in length. The outer most two rows on both sides of each plot and 0.25m length on each side of a row served as a border. The remained net plots were used for data collection.

Partial Budget Analysis
The partial budget analysis was done using CIMMYT (1998) to identify the rewarding treatments. Actual yields from experimental plots were adjusted down ward by 10% to reflect the difference between the experimental yield and the yield that farmers could expect from the same treatment. This is due to optimum plant population density, timely labor availability and better management in weed control and better security under experimental conditions (CIMMYT, 1998). To find out the gross return the price of chick pea (Sale price of 23 Birr kg -1 ) prevailing in the local market at the time of harvest which is the average of one month was taken into account. Similarly, the variable costs that vary included the cost of input; the field price of Dual gold and gallant super herbicides during planting time was 600 and 800 Birr lit -1 respectively. The cost of application of herbicides at Sinana and Goro 500 and 650 Birr ha -1 . Cost of labor for hand weeding and spray of herbicides are different at Goro and Sinana and considered accordingly in the analysis.

Data collection
Data were collected on days to maturity, Number of branches per plant, plant height, number of bolls per branch, Biological yield, grain yield, thousand seed weight, and harvest index recorded from net plot area. The net plot area was attained from six rows by leaving one border row at both sides of every plot.

Data analysis
All the collected data were subjected to analysis of variance (ANOVA) using GENSTAT computer software (GenStat, 2012.Version 15.1.0.8035) to identify main effects and interactions in response to integrated weed managements. Differences among means were determined using the least significance difference at the 0.05 level of significance. Treatment effects from the two locations and across years of the experiment followed a similar trend. Thus, the data from the two independent locations and across years were combined in the analysis.

RESULTS AND DISCUSSION
The experiment was conducted at two different locations of south eastern Ethiopia of Bale zone namely, Sinana on-station and Goro sub-site in the two consecutive main cropping seasons of 2018/19 and 2019/20. All the required field data were collected, analyzed and reported below.

Influence of Integrated Weed Management Practices on Yield and Yield Components of Chickpea at Sinana
The analysis of variance showed that days to maturity, number of branches per plant, plant height, number of seeds per boll, thousand seed weight and harvest index were not significantly influenced by weed management methods (dual gold, gallant super and hand weeding frequencies) and the effect due to variety were not significant for days to maturity, ) was obtained as a result of dual gold plus one time hand weeding and two times hand weeding, but all are statistically at par. The lowest seed yield was recorded under weedy check, sole use of gallant super and dual gold. This might be herbicides alone or hand weeding control methods were less effective in reducing the number of weeds per unit area; instead of both chemical and hand weeding control methods. These results are in conformity with those reported by Diwash et al, (2014), Waktole et al. (2013) and Rahmatizadeh et al. (2013) and others too. Even though statistically at par sole dual gold application showed higher grain yield than using gallant super alone, this might be due to the herbicides mode of action and time of application, dual gold is applied before weeds and crops are emerged. Whereas gallant super was applied during actively growing weeds and crops. As result weeds emerged with crop can easily compete with crop and cause significant yield reduction. The main effect of variety did not show significant effect on grain yield per hectare and this implies that highest seed yield can be obtained using both varieties keeping them weed free using pre or post emergence herbicides supplemented with hand weeding. Thus, emphasis should be given to control weeds.
Results pertaining biological yield indicated that highest value was observed using two times hand weeding followed when dual gold was supplemented with on time hand weeding and are statistically significant. This might be crop plants utilized resources more efficiently that resulted in higher final crop stand. In agreement with this result Mizan et al. (2009) reported the increased biomass yield of the crop was highly governed by the length of weed free period. On the other hand the lowest was recorded under sole use of gallant super and weedy check (Table 1).

Influence of Integrated Weed Management Practices on Yield and Yield Components of Chickpea at Goro
The analyzed data results showed significant effects of integrated weed management on dry matter, plant height, biological yield, and grain yield and harvest index. But, significant (P< 0.05) effects were not observed on number of branches per plant, bolls per plant, number of seeds per boll, thousand seed weight but, numerical differences was reflected among tested treatments. All weed management treatments were boosted yield of chickpea over weedy check treatment (Table 2). Increments in yield might be due to successful weed control and efficiency provided by applied treatments against weeds. This is in line with the findings of Waheedullah et al. (2008) who reported that weed management suppressed the weeds and increased the grain yield and yield components of maize. The highest grain yield was obtained as a result of gallant super plus hand weeding, two times hand weeding, one time hand weeding and dual gold plus one time hand weeding, but all are statistically at par.
The lowest seed yield was, however, recorded under weedy check, sole dual gold and use of sole gallant super. However, the effect of variety showed significance difference on days to maturity, number of branches per plant, plant height, biological yield and thousand seed weight whereas varietal differences did not show significant difference on number of bolls per plant, number of seeds per boll, grain yield and harvest index. This implies that the two varieties did not show significant difference to different weed management in different ways. Hence instead of evaluating weed management independently, similar practices can be recommended for both varieties. The interaction effect of weed management options and variety did not show significance difference (P<0.05) on the studied parameters. The integration of herbicides and hand weeding produced the highest grain yield than herbicides and hand weeding alone. This finding is in agreement with the work of Singh and Sekhon (2013) who reported that integration of herbicides and hand weeding provided the highest grain yield.

Partial Budget Analysis
Marginal analysis is an important step in assessing the results of on farm experiments before making recommendations. For this trial variable cost of dual gold, gallant super and hand weeding frequencies were considered since both locations are different in labor cost availabilities. Partial budget analysis of Sinana location indicated that the use of preemergence herbicide (Dual gold 960 EC) integrated with hand weeding at different time gave a different economic return as compared to post emergence herbicides (gallant super), weedy check and hand weeding alone. Thus, the highest net benefit of were recorded for dual gold integrated with hand weeding at four weeks after crop emergence, one time hand weeding at two weeks after crop emergence and dual gold integrated with one time hand weeding after two weeks after crop emergence respectively while the lowest net benefit was obtained from the control (table  4). Therefore, it can be concluded that the use of dual gold integrated with hand weeding at four weeks after crop emergence could be used as the best weed management options for chick pea production at Sinana areas.
On the other hand, the result of financial analysis (partial budget) at Goro indicated that two times hand weeding at two and four weeks of after crop emergence had highest net benefits (table 4). The pre emergence herbicides tested integrated with hand weeding will be economical only if the price of chick pea raises over 23 birr 100 kg -1 . The differences in marginal rate of return in Sinana and Goro could be due to ecological, labor and herbicides costs differences. More cost prevailed is at Goro than Sinana.