PLANT WATER EXTRACTS FOR WEED MANAGEMENT IN GROUNDNUT ( Arachis hypogaea L.)
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Date
2018
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Acharya N.G. Ranga Agricultural University
Abstract
A field experiment was conducted on sandy loam soils of S.V. Agricultural
College Farm, Tirupati campus of Acharya N.G. Ranga Agricultural University of Andhra Pradesh, during rabi, 2017-18, to know the effect of different plant water extracts on weed management in rabi groundnut.
The present investigation was laid out in a randomized block design with ten
treatments and replicated thrice. The treatments consisted of ten weed management
practices viz., plant water extracts of sorghum (W1), sunflower (W2), rice straw (W3),
parthenium (W4), lantana (W5) and purple nutsedge (W6) each applied at 15 l ha-1
twice at 15 and 30 DAS, paddy straw mulch 5 t ha-1 (W7), pre-emergence application
of pendimethalin 1 kg ha-1 supplemented with hand weeding at 30 DAS (W8), postemergence application of imazethapyr 75 g ha-1 (W9) and unweeded check (W10). The test variety used in the experiment was Dharani (TCGS-1043).
The weed flora associated with rabi groundnut belongs to nine taxonomic families. The predominant weed species observed in the experimental field were Cyperus rotundus L. (45%), Digitaria sanguinalis (L.) Scop. (15%), Boerhavia erecta
L. (7%), Borreria hispida (L.) K. Schum. (7%) and Digera arvensis L. (6%).
Among the weed management practices, pre-emergence application of pendimethalin 1 kg ha-1 supplemented with one hand weeding at 30 DAS (W8)
recorded significantly lesser density and dry weight of weeds with higher weed control efficiency which inturn enhanced all the growth and yield components and
yield of rabi groundnut, besides realizing higher net returns and benefit-cost ratio.
The lowest density and dry weight of all categories of weeds and total weeds as well as lower nutrient uptake by weeds with higher weed control efficiency were recorded with paddy straw mulch 5 t ha-1 (W7) followed by sunflower water extract spray 15 l ha-1 twice at 15 and 30 DAS (W2), among the organic weed management
practices. All the plant water extracts were not effective as that of synthetic
herbicides. Parthenium (W4) and purple nutsedge (W6) water extracts recorded
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significantly higher density and dry weight of weeds with lower weed control
efficiency, among the plant water extracts tested.
Application of paddy straw mulch 5 t ha-1 (W7) resulted in the highest stature of growth parameters viz., plant height, leaf area index, dry matter production, number
of branches plant-1, number of effective rhizobium nodules plant-1and yield
componets viz., number of filled pods plant-1, 100-pod and kernel weight. Sunflower water extract spray 15 l ha-1 twice at 15 and 30 DAS (W2) was the next best organic weed management practice in recording higher values of above said growth and yield parameters. Parthenium water extract spray 15 l ha-1 twice at 15 and 30 DAS (W4)
resulted in lowest values of above said growth and yield parameters of groundnut. All
the plant water extracts did not showed any phytotoxicity on groundnut.
The highest pod, kernel, oil and haulm yields of groundnut was obtained with paddy straw mulch 5 t ha-1 (W7) followed by sunflower water extract spray 15 l ha-1
twice at 15 and 30 DAS (W2) . The highest harvest index and the lowest weed index was computed with the former weed management practice. Parthenium (W4) and
purple nutsedge (W6) water extracts recorded significantly lesser yields than rest of
organic weed management practices.
The highest nutrient uptake by crop and the lowest nutrient uptake by weeds
were estimated with paddy straw mulch 5 t ha-1 (W7) followed by sorghum water extract spray 15 l ha-1 twice at 15 and 30 DAS (W1), among the organic weed management practices. The major nutrients depleted by weeds due to heavy weed
infestation in unweeded check (W10) was estimated to be 24.4, 13.0 and 27.6 kg ha-1
of nitrogen, phosphorus and potassium, respectively.
Soil microbial load (bacteria, fungi and actinomycetes) was significantly higher with paddy straw mulch 5 t ha-1 (W7) followed by sunflower water extract spray 15 l ha-1 twice at 15 and 30 DAS (W2) and at their lowest with post-emergence application of of imazethapyr 75 g ha-1 (W9).
The highest gross and net returns were realized with paddy straw mulch 5 t ha-1 (W7), whereas, benefit-cost ratio was the highest with sunflower water extract
spray 15 l ha-1 twice at 15 and 30 DAS (W2), among the organic weed management
practices. The lowest values of the above said economic parameters were computed with parthenium water extract spray 15 l ha-1 twice at 15 and 30 DAS (W4) which was at par with unweeded check (W10).
Thus, the present study has revealed that paddy straw mulch 5 t ha-1 (W7) or sunflower water extract spray 15 l ha-1 twice at 15 and 30 DAS (W2) was considered
as best weed management practice for enhancing the productivity, profitability and
sustainability, besides effective control of weeds in rabi groundnut.
Description
D5697
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