Effect of weed management practices on growth and yield of pigeonpea [Cajanus cajan (L.) Millspaugh]
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Date
2014
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Department of Agronomy, BAU, Sabour
Abstract
Pigeonpea being a kharif season crop is highly infested with narrow and broad leaved weeds. Timely weed control is very essential for realization of yield potential of pigeonpea. Due to wider row spacing and initial slow growth of pigeonpea, weeds pose a major problem to its productivity which may lead to its yield reduction up to 80%. Manual and mechanical methods of weed control are quite effective, but they are costly and time consuming. However, due to frequent rains it becomes difficult to do hand weeding at proper time. Under given circumstances farmers needs alternate production system using chemical and cultural weed management that are more efficient, less labour-intensive and offer a quick response enabling farmers to produce more at less costs. In this context the present research work has been carried out.
A field experiment was conducted during kharif season of 2012-13 at Bihar Agricultural University, Sabour to find out the cost-effective weed management practices in pigeonpea. Soil of experimental field was sandy loam in texture having pH 7.58, organic carbon 0.40%, and 182, 16.4, 186.3 kg ha-1 available N, P and K, respectively. The treatments comprised of twelve weed management options viz; T1 -imazethapyr @ 20g a.i. ha-1 at 15 DAS, T2 -imazethapyr @ 40g a.i.ha-1 at 15 DAS, T3 -imazethapyr @ 60g a.i.ha-1 at 15 DAS, T4 -imazethapyr @ 20g a.i.ha-1 at 30 DAS, T5-imazethapyr @ 40g a.i. ha-1 at 30 DAS, T6-imazethapyr @ 60g a.i.ha-1 at 30 DAS, T7 -pendimethalin @ 750g. a.i. ha-1 as PE, T8-pendimethalin @ 750g. a.i. ha-1 as PE + quizalofop-ethyl @ 50g. a.i. ha-1 as POE, T9-pigeonpea + blackgram intercropping, T10 -metribuzin @ 250 g. a.i. ha-1 as PE, T11-weedy check and T12-weed free. The experiment was laid out in randomized complete block design with three replications.
The results indicated that application of imazethapyr @ 60 g a.i ha-1 at 15 DAS recorded significantly lower weed population at all the growth stages of the crop as compared to other treatments. At 60 and 90 DAS, application of imazethapyr @ 60 g a.i ha-1 at 15 DAS produced the lowest weed dry biomass (5.04 g m-2) and (4.89 g m-2), respectively. Weedy check recorded significantly higher weed index (40.53 %), than all other treatments under study. While, at 60 days after sowing; higher weed control efficiency (80.38 %) was noticed in imazethapyr @ 60 g a.i. ha-1 at 15 DAS which was found statistically at par with application of imazethapyr @ 40 g a.i. ha-1 at 15 DAS (80.16), imazethapyr @ 40 g a.i. ha-1 at 30 DAS (78.80 %), imazethapyr @ 60 g a.i. ha-1 at 30 DAS (78.88 %) and significantly higher than rest of the treatments. The growth and yield attributing characters viz; plant height, dry matter accumulation plant-1, number of primary and secondary branches plant-1, pods plant-1, seeds pod-1 and seed yield plant-1 was higher with application of imazethapyr @ 40 g a.i. ha-1 at 15 DAS which was statistically at par with application of imazethapyr @ 60 g a.i. ha-1 at 15 DAS. The treatment of imazethapyr @ 40 g a.i. ha-1 at 15 DAS recorded higher seed yield of 2526 kg ha- 1which was statistically at par with imazethapyr @ 60 g a.i. ha-1 at 15 DAS (2492.6 kg ha-1) and significantly higher than imazethapyr @ 20g a.i. ha-1 at 15 DAS (2129 kg ha-1). However, maximum and minimum seed yield of 2725.0 kg ha-1 and 1623.3 kg ha-1 was found in weed free and weedy check treatment, respectively. Nutrient depletion due to weeds in different treatments was also affected significantly and lowest values of N P K removal by weeds was noticed in the imazethapyr @ 60 g a.i. ha-1 at 15 DAS applied plot. However, maximum net return (Rs 71059) and B: C ratio (2.74) was recorded with application of imazethapyr @ 40 g a.i. ha-1 at 15 DAS followed by application of imazethapyr @ 60 g a.i. ha-1 at 15 DAS. Hence, it may be concluded that application of imazethapyr @ 40 g a.i. ha-1 at 15 DAS considered as the economic viable option of weed control in pigeonpea.