CROP ESTABLISHMENT AND WEED MANAGEMENT TECHNIQUES IN RICE FALLOW GREENGRAM (Vigna radiata L.)
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Date
2023-11-15
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Acharya N G Ranga Agricultural University
Abstract
A field experiment was conducted at the Agricultural College Farm, Bapatla, on sandy clay loam soils to study the “Crop establishment and weed management techniques in rice fallow greengram (Vigna radiata L.)” during rabi 2021-22. The experiment was laid out in a split plot design, replicated thrice with three crop establishment techniques as main plots and five weed management practices as sub plots. The main plot treatments consisted of (i) Broadcasting 4 to 5 days before harvesting of paddy, (ii) Drilling with seed drill under zero tillage (iii) Drilling with seed drill under conventional tillage. The subplot treatments consisted of (i) Weedy check, (ii) Hand weeding at 20 and 40 DAS, (iii) Pendimethalin @ 1.0 kg a.i. ha-1 as PE fb Imazethapyr @ 67 g a.i. ha-1 as PoE, (iv) Pendimethalin @ 1.0 kg a.i. ha-1 as PE fb Acifluorfen Na + Clodinafop propargyl @ 160+80 g a.i. ha-1 as PoE, (v) Pendimethalin @1.0 kg a.i. ha-1 as PE fb Fomesafen + Fluzifop p butyl @ 110+110 g a.i. ha-1 as PoE. Cultivar used in the study for greengram was IPM -2- 14 (Shreya).
Greengram crop was sown on the rice-fallow experimental plot. Sowing was done as per the respective treatments and also, application of herbicides was done to the respective treatments as specified. Pre-emergence herbicides were applied at suitable soil moisture after removing paddy sheaves in broadcasting 4 to 5 days before harvesting of paddy (M1) and on very next day of sowing in drilling with seed drill under zero tillage (M2) and drilling with seed drill under conventional tillage (M3) with sand mix application. Post-emergence herbicides were applied on 20th day after sowing on tender and actively growing weeds as blanket spray with hand sprayer fitted with solid cone nozzle. Field operations
such as nutrient spray and plant protection measures were taken as per recommendations of ANGRAU. The data on plant height (cm), dry matter production (kg m-2), crop growth rate, number of pods plant-1, number of seeds pod-1, test weight (g), seed and haulm yield (kg ha-1) and harvest index (%) were recorded as per standard procedures. Data were analyzed using ANOVA and the significance was tested by Fisher's least significance difference.
The predominant weed species observed in experimental plot were grasses like Leptochloa chinensis, Echinochloa colonum and Panicum repens, sedge Cyperus rotundus, Eleocharis geniculata and broad-leaved weeds like Grangea maderaspatana, Alternanthera philoxeroides, Bergia ammanoides and Xanthium strumarium L. etc.
Among crop establishment techniques, drilling with seed drill under conventional tillage recorded significantly higher plant height, drymatter production, yield attributes, grain yield, haulm yield, and gross returns compared to other crop establishment techniques. However, highest benefit cost ratio was observed with broadcasting 4 to 5 days before harvesting of paddy.
Significantly lower weed density and dry weight were observed with all weed management practices over the weedy check. The lowest density and dry weight of weeds were recorded with hand weeding at 20 and 40 DAS. Among the post-emergence herbicides studied, Pendimethalin @ 1.0 kg a.i. ha-1 as PE fb Fomesafen + Fluzifop p butyl @ 110+110 g a.i. ha-1 as PoE at 20 DAS performed better throughout the crop growth period than other treatments studied.
Hand weeding at 20 and 40 DAS recorded significantly higher growth and yield attributes, grain and haulm yield, NPK uptake and gross returns over that of other weed management practices. Whereas the highest net returns and benefit cost ratio was recorded with Pendimethalin @ 1.0 kg a.i. ha-1 as PE fb Fomesafen + Fluzifop p butyl @ 110+110 g a.i. ha-1 as PoE. Though the Hand weeding at 20 and 40 DAS (S2) recorded with high gross returns, expensive hand weeding made it less remunerative than Pendimethalin @ 1.0 kg a.i. ha-1 as PE fb Fomesafen + Fluzifop p butyl @ 110+110 g a.i. ha-1 as PoE (S5).
Uptake of N, P2O5 and K2O by greengram was significantly higher and nutrient depletion by weeds was significantly lower in hand weeding compared to rest of the treatments.
Thus, the present investigation clearly indicated that drilling with seed drill under conventional tillage was found most suitable crop establishment method and among weed management practices, pendimethalin @ 1.0 kg a.i. ha-1 as PE fb Fomesafen + Fluzifop p butyl @ 110+110 g a.i. ha-1 as PoE was proved to be best cost effective method in suppressing weeds in rice-fallow greengram.