Studies on integrated weed management in lentil (Lens culinaris Medic)
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Date
2014
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Rajendra Agricultural University, Pusa (Samastipur)
Abstract
A field experiment was planned and conducted during the rabi season of 2012–13 at Tirhut College of Agriculture Farm, Dholi, a campus of Rajendra Agricultural University, Bihar, Pusa (Samastipur) to investigate the effect of manual, herbicidal and integrated treatments on the weed dynamics, growth, yield and economics of lentil. The experiment was laid out in randomized block design with four replications. Treatments constituted viz. quizalofop ethyl @ 50 g ha-1 as POE, imazethapyr @ 37.5 g ha-1 as POE, chlorimuron ethyl @ 4 g ha-1 as PPI, pendimethalin @ 1.0 kg ha-1 as PE, pendimethalin + imazethapyr (ready mix) @ 0.75, pendimethalin + imazethapyr (ready mix) @ 1.0 kg ha-1 as PE, pendimethalin @ 1.0 kg ha-1 as PE + hand weeding at 40 DAS, hand weeding at 20 and 40 DAS and weedy check.
The crop variety KLS-218 was sown on November 14, 2012 and harvested on March 26, 2013. Observations on various growth parameters, yield attributes and yield were recorded. Studies on total and species-wise weed count, weed dry matter accumulation, weed growth rate, weed control efficiency and weed index were made and weeds were collected at 90 DAS for estimation of nutrients (N, P and K) depletion pattern by weeds. The grain and straw samples at harvest were collected for estimation of nitrogen, phosphorus, potash and protein content of grain (%) and total uptake of NPK. Finally, the economics of different treatments were worked out.
Weed control treatments significantly influenced various growth parameters, yield attributes and yield of lentil. Plant height, number of branches plant-1, dry matter accumulation, crop growth rate, yield attributes and yield recorded had significantly higher values under treatment T8 (hand weeding at 20 and 40 DAS) followed by T7 (integrated treatment of pendimethalin @ 1.00 kg ha-1 as PE + hand weeding at 40 DAS) and T6 (ready mix pendimethalin + imazethapyr @ 1.00 kg ha-1 as PE). Hand weeding at 20 and 40 DAS (T8) though recorded maximum grain yield (1826 kg ha-1) but was statistically at par with pendimethalin @ 1.00 kg ha-1 as PE + hand weeding at 40 DAS (1729 kg ha-1) and was significantly superior over remaining treatments.
The prominent weeds found in the experimental plot were Anagallis arvensis, Cannabis sativa, Cyperus rotundus, Cynodon dactylon, Chenopodium album and Parthenium hysterophorus; and these weeds together constituted 63.4 per cent of the total weed population. All the weed control treatments reduced the weed population and dry matter of weeds significantly over weedy check. Hand weeding twice at 20 and 40 DAS (T8) reduced the total weed population and dry matter of weeds significantly over weedy check and was closely followed by pendimethalin @ 1.0 kg ha-1 as PE + hand weeding at 40 DAS (T7) and ready mixture of pendimethalin + imazethapyr @ 1.00 kg ha-1 as PE (T6). All the herbicides were found to reduce the total weed population and dry matter of weeds significantly over weedy check. The pre-emergence herbicides like pendimethalin + imazethapyr (ready mix) at higher dose 1.00 kg ha-1 (T6) as well as its lower dose 0.75 kg ha-1 (T5) and pendimethalin sole @ 1.00 kg ha-1 (T4) were proved more effective than post-emergence and pre-plant incorporated herbicides.
Gross returns ( 88382) and net returns ( 57723) were significantly higher under hand weeding at 20 and 40 DAS, however, the benefit: cost ratio was highest (2.42) under pendimethalin + imazethapyr (ready mix) @ 1.00 kg ha-1 as PE.
In most of the cases, hand weeding twice at 20 and 40 DAS was found superior to other treatments and was followed by integrated treatment of pendimethalin @ 1.00 kg ha-1 as PE + hand weeding at 40 DAS (T7) and pre-emergence treatment of pendimethalin + imazethapyr (ready mix) @ 1.00 kg ha-1 (T6).
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