Himachal Journal Of Agricultural Research Vol

Himachal Journal of Agricultural Research Vol. 29 (1 & 2) : 1-10, 2003

Influence of seed bed manipulations and herbicides on leaf area index and growth rate of wheat and associated weeds

Deep Kumar, N.N. Angiras and S.S. Rana* Department of Agronomy, CSK H.P. Krishi Vishvavidyalaya, Palampur

Abstract

A field experiment was conducted in a split plot design with three seed bed manipulations viz. stale seed bed, normal seed bed and normal seed bed + triallate 1.00 kg/ha and five weed control methods viz. weedy check, isoproturon 1.00 kg/ha + surfactant 0.5%, dichlofop-methyl 0.75 kg/ha, dichlofop-methyl 0.50 kg/ha + surfactant 0.5% and hand weeding twice as sub plot treatments in wheat under mid hill conditions of Himachal Pradesh. The major weeds found growing in association with wheat crop were, Phalaris minor, Lolium temulentum, Avena fatua amongst grasses and Vicia sativa among broad-leaved weeds. Stale seed bed being at par with normal seed bed followed by triallate 1.00 kg/ha (pre-plant incorporation) decreased LAI and growth rate of P. minor, L. temulentum, and V. sativa and increased tiller number, plant height, crop dry matter, LAI, CGR and consequently wheat grain yield by 21.19% over normal seed bed. Isoproturon + surfactant remaining at par with dichlofop-methyl + surfactant decreased species-wise and total LAI and growth rate of weeds and increased tiller number, dry matter accumulation, plant height, LAI, CGR and grain yield of wheat. Stale seed bed in integration with isoproturon + surfactant resulted in highest marginal benefit cost ratio (MBCR) of Rs. 14.13.

Introduction are available. However, isoproturon or dichlofop-methyl alone or in combination Weeds have posed a serious threat to with a surfactant is more effective (Malik et the productivity of wheat. The adoption of al.., 1985, Angiras and Sharma, 1995 & new fertilizer and irrigation, responsive dwarf 1996, Gauvrit and Dufour, 1990 and varieties, increased use of fertilizers and Mclaughlan. 1982). For sustainable other modern agro-techniques have created production, there is need to integrate cultural the environment favourable for the growth and chemical methods of weed control to and development of weeds particularly favour the crop growth over associated grasses thereby enhancing their competitive weeds. The present investigation was ability with the crop. Stale seed bed (Yadav therefore, conducted to study the effect of et al.., 1995) conditions by pre-sowing integrating herbicides and cultural weed irrigation or rainfall induce sprouting of management practices on growth of wheat in weeds and subsequent harrowing makes land relation to associated weeds. free from weeds in initial stages of growth. Pre-plant incorporation of triallate (Hanson Materials and Methods and Rasmusson, 1983 and Kirkland, 1994) may offer the possibility to substitute stale A field experiment was conducted seed bed. To check the weed growth in during the winter seasons of 1995-96 and wheat, several other post emergent herbicides 1996-97 at Palampur (32º6´ N latitude and *CSKHPKV Mountain Agricultural Research and Extension Centre, Sangla 172106 1 76º3´ E longitude and 1290.8 m above msl) two places. Samples were oven dried at a in split plot design with four replications. The temperature of 70º C till constant weight. soil of the experimental plot was silty clay Grain yield was harvested from a net plot of loam in texture (19.4% sand, 47.3% silt and 12.0 m2. Growth analysis was done using the 33.3% clay) and acidic in reaction (pH, 5.8). formulae given by Watson (1952). The The fertility of the soil was low in growth rate of weeds or crop was worked out available N (272.5 kg/ha), medium in as follows, available P (16.3 kg/ha) and high in available D2 – D1 K (310.4 kg/ha). Fifteen treatment Growth rate (g/day/m2) = ------combinations constituting of three seed bed t2 – t1 manipulations (stale seed bed, normal seed bed and normal seed bed + triallate 1.00 Where D1 and D2 are the dry matter of the kg/ha) as main plot factors and five weed weeds or crop at time t1 (initial observation) control treatments (weedy check, isoproturon and time t2 (observation recorded at one 1.00 kg/ha + surfactant, dichlofop-methyl month later), respectively. 0.75 kg/ha, dichlofop-methyl 0.50 kg/ha + Weed control efficiency (WCE) and Weed surfactant and hand weeding twice) as sub index (WI) were worked out using the plot factors were evaluated for the control of formulae given here as under, grassy weeds in wheat. The sowing of Wc - Wt experiment was done on December 12, 1995 WCE (%) = ------x 100 and December 4, 1996 and was harvested on Wc May 20, 1996 and May 24, 1997. Seeds of Where Wc = weed dry weight in weeded plot wheat variety Sonalika (S-308) were sown @ Wt = weed dry weight in treated plot 120 kg/ha in lines 20 cm apart at a depth of x - y 4-5 cm with the help of hand plough. One WI (%) = ------x 100 x third of recommended N (120 kg/ha) and whole of P O (60 kg/ha) and K O (30 kg/ha) 2 5 2 Where, x is the yield from weed free was applied through urea, single super hand weeded plot (hand weeded stale seed phosphate and muriate of potash, respectively bed in the present study) and y is the yield at the time of sowing in furrows and mixed in from treatment plot. soil. The remaining N through urea was top dressed in two equal splits at crown root and Results and Discussion ear initiation stages. Triallate (Avadex BW 50 EC) as per the treatment was applied Effect on weed flora before sowing and incorporated in upper 2-3 The major weeds associated with cm layer of the soil. Post emergence wheat crop were Phalaris minor Retz., application of isoproturon (Miracle 75 WP) Lolium temulentum L. and Avena fatua L and dichlofop-methyl (Illoxan 28.4 EC) was amongst grass weeds and Vicia sativa L done at 2-3 leaf stage of grassy weeds. among broad-leaved weeds. The other broad- Surfactant (Uphar) at 0.50% was used with leaved weeds were Coronopus didymus, the herbicides as per the treatment. Anagallis arvensis and Lathyrus aphaca Herbicidal treatments were applied with during both the years. maruyama power sprayer using 600 l water/ha. The rest of the crop management Effect of seed bed manipulation practices were followed in accordance with Due to significant influence on the recommended package of practices. killing of the first flush of weeds, stale seed Data on weeds were recorded by bed (SSB) decreased LAI (Table 1) and placing 50 cm x 50 cm quadrate at random at growth rate (Table 2) of P. minor, L. 2 temulentum, V. sativa and other weeds during Integrated effect both the years. However, it was statistically The integration of stale seed bed at par with normal seed bed followed by (fb.) with isoproturon + surfactant decreased triallate 1.00 kg/ha (NSB + T) in reducing the growth rate and LAI of P. minor, L. LAI and growth rate of L. temulentum and temulentum and total weeds significantly growth rate of P. minor. The superiority of (Table 1&2). However, it was at par with the stale seed bed due to stimulation of integration of stale seed bed with dichlofop- germination of first flush of weed seeds by methyl + surfactant, integration of normal irrigation and their destruction by ploughing seed bed with isoproturon + surfactant or action before sowing of the crop has also dichlofop-methyl + surfactant in decreasing been documented by Ray et al... (1982) and the LAI and growth rate of P. minor and L. Yadav et al.. (1995). Normal seed bed fb temulentum, A. fatua and total weeds. triallate was significantly superior in Integration of dichlofop + surfactant with decreasing the LAI and growth rate of A. normal seed bed was equally effective to fatua. The reduction in LAI and growth rate reduce LAI and growth rate of P. minor and of A. fatua may be due to the action of LAI of L. temulentum. In general integration triallate on cell division (Ashton and Crafts, of stale seed bed with herbicides was superior 1973). Similar results have also been reported to other seed bed manipulations which might by Kirkland (1994). be attributed to the combined action of stale seed bed in uprooting and burial action of Effect of weed control methods existing first flush of weeds and control of Post-emergent application of subsequent flushes with post emergent isoproturon 1.00 kg/ha + surfactant 0.50% activity of herbicides. The superiority of stale decreased species wise and total LAI and seed bed and normal seed bed + triallate in growth rate of weeds significantly. However, integration with isoproturon for weed control it was at par with dichlofop-methyl 0.50 over normal seed bed has amply been kg/ha + surfactant 0.50% in decreasing LAI documented (Allcoat, 1985 and Yadav et al.., and growth rate of P minor, L. temulentum 1995). The effectiveness of dichlofop-methyl and A. fatua during both the years. in integration with normal seed bed + triallate Dichlofop-methyl 0.75 kg/ha was as effective to control initial flushes of A. fatua by as hand weeding twice in decreasing LAI and triallate (Hanson and Rasmusson, 1983) and growth rate of P. minor, L. temulentum and later flushes by post emergent application of A. fatua. The superiority of dichlofop-methyl dichlofop-methyl with or without surfactant in controlling P. minor, L. temulentum and A. (Mustafee, 1989 and Maclaughlan, 1982) has fatua has also been reported by Gauvrit and also been reported. Dufour (1990) and Mclaughlan (1982). The The data on weed control efficiency higher efficacy of the herbicide along with (WCE) and weed index (WI) summarized in surfactant is attributed to reduced surface Table 3 also indicated better efficiency of tension of water and increased wettability due isoproturon + surfactant and dichlofop- to the surfactant that makes the entry of methyl + surfactant with stale seed bed or herbicides easily in waxy surfaces of weed normal seed bed + triallate as WCE was leaves (McWhorter, 1985). Malik, et al.. higher and WI was lower due to these (1985) and Angiras and Sharma (1995) treatments over the remaining treatment reported similar findings.

4 Table 1. Effect of seed bed manipulations (SBM) and weed control methods (WCM) on leaf area index (LAI, 120 DAS) of weeds Weed control methods 95-96 96-97 SSB NSB NSB+T Mean SSB NSB NSB+T Mean P. minor Weedy check 0.477 1.008 0.504 0.663 0.453 1.090 0.552 0.698 Isoproturon + 0.148 0.208 0.191 0.182 0.151 0.213 0.208 0.191 surfactant Dichlofop-methyl 0.223 0.348 0.280 0.283 0.235 0.357 0.312 0.301 Dichlofop-methyl + 0.186 0.219 0.198 0.201 0.201 0.234 0.205 0.213 surfactant Hand weeding 0.191 0.377 0.223 0.264 0.210 0.391 0.249 0.283 Mean 0.245 0.432 0.279 0.250 0.457 0.305 Avena Weedy check 0.279 0.577 0.102 0.319 0.252 0.612 0.094 0.320 Isoproturon + 0.091 0.119 0.065 0.092 0.085 0.121 0.066 0.091 surfactant Dichlofop-methyl 0.108 0.196 0.067 0.124 0.132 0.199 0.060 0.131 Dichlofop-methyl + 0.107 0.125 0.054 0.095 0.115 0.132 0.051 0.100 surfactant Hand weeding 0.125 0.207 0.090 0.141 0.114 0.216 0.104 0.145 Mean 0.142 0.245 0.076 0.140 0.256 0.075 Lolium Weedy check 0.158 0.353 0.158 0.223 0.135 0.329 0.183 0.216 Isoproturon + 0.050 0.069 0.050 0.056 0.047 0.065 0.063 0.058 surfactant Dichlofop-methyl 0.080 0.116 0.081 0.093 0.070 0.107 0.092 0.089 Dichlofop-methyl + 0.065 0.070 0.065 0.067 0.058 0.071 0.062 0.064 surfactant Hand weeding 0.061 0.122 0.063 0.082 0.065 0.119 0.075 0.086 Mean 0.083 0.146 0.094 0.075 0.138 0.095 Vicia Weedy check 0.167 0.417 0.407 0.330 0.183 0.443 0.423 0.349 Isoproturon + 0.047 0.069 0.057 0.058 0.063 0.085 0.072 0.073 surfactant Dichlofop-methyl 0.178 0.429 0.385 0.331 0.195 0.445 0.405 0.348 Dichlofop-methyl + 0.170 0.440 0.414 0.341 0.185 0.455 0.430 0.357 surfactant Hand weeding 0.066 0.138 0.393 0.099 0.083 0.155 0.108 0.115 Mean 0.126 0.299 0.271 0.142 0.317 0.288 Total Weedy check 1.156 2.546 1.355 1.264 1.109 2.678 1.450 1.746 Isoproturon + 0.374 0.502 0.397 0.318 0.382 0.530 0.451 0.454 surfactant Dichlofop-methyl 0.656 1.257 0.968 0.720 0.708 1.286 1.052 1.015 Dichlofop-methyl + 0.587 1.034 0.910 0.633 0.643 1.082 0.936 0.887 surfactant Hand weeding 0.483 0.906 0.509 0.474 0.521 0.948 0.582 0.684 Mean 0.651 1.249 0.828 0.673 1.305 0.894 LSD (P=0.05) P minor A fatua Lolium Vicia Total SBM 95-96 0.030 0.032 0.019 0.029 0.157 96-97 0.219 0.026 0.015 0.030 0.204 WCM 95-96 0.031 0.029 0.017 0.131 0.081 96-97 0.037 0.026 0.016 0.015 0.154 Interaction 95-96 0.052 0.051 0.030 0.032 0.16 96-97 0.059 0.045 0.027 0.045 0.20 3

Table 2. Effect of seed bed manipulations and weed control methods on growth rate (WGR, g/day/m 2) of weeds

Weed control methods 95-96 96-97 SSB NSB NSB+T Mean SSB NSB NSB+T Mean

P. minor (60-90 DAS) Weedy check 0.31 0.72 0.35 0.46 0.43 1.30 0.50 0.74 Isoproturon + surfactant 0.06 0.11 0.09 0.09 0.23 0.24 0.25 0.24 Dichlofop-methyl 0.23 0.21 0.07 0.17 0.38 0.48 0.37 0.41 Dichlofop-methyl + 0.13 0.19 0.10 0.14 0.26 0.30 0.30 0.29 surfactant Hand weeding 0.22 0.16 0.14 0.17 0.35 0.28 0.53 0.29 Mean 0.19 0.28 0.15 0.33 0.52 0.39 Avena (90-120 DAS) Weedy check 0.42 0.52 0.37 0.43 0.35 0.50 0.39 0.41 Isoproturon + surfactant 0.15 0.28 0.12 0.17 0.12 0.24 0.10 0.15 Dichlofop-methyl 0.16 0.29 0.28 0.24 0.15 0.24 0.21 0.20 Dichlofop-methyl + 0.17 0.21 0.14 0.18 0.13 0.22 0.15 0.16 surfactant Hand weeding 0.30 0.35 0.23 0.29 0.20 0.46 0.22 0.29 Mean 0.24 0.33 0.23 0.19 0.33 0.21 Lolium (60-90 DAS) Weedy check 0.87 0.95 0.77 0.86 0.83 1.17 0.84 0.94 Isoproturon + surfactant 0.12 0.29 0.20 0.20 0.24 0.41 0.33 0.32 Dichlofop-methyl 0.26 0.57 0.14 0.32 0.39 0.78 0.37 0.51 Dichlofop-methyl + 0.25 0.22 0.25 0.24 0.38 0.50 0.39 0.42 surfactant Hand weeding 0.26 0.52 0.33 0.37 0.44 0.65 0.46 0.51 Mean 0.34 0.52 0.35 0.45 0.69 0.47 Total (90-120 DAS) Weedy check 2.30 3.41 2.28 2.66 2.25 4.05 3.15 3.15 Isoproturon + surfactant 0.73 1.32 0.82 0.96 1.21 2.41 1.53 1.72 Dichlofop-methyl 1.09 2.11 1.43 1.54 1.48 2.66 2.05 2.06 Dichlofop-methyl + 1.17 1.66 1.06 1.30 1.51 2.65 1.77 1.97 surfactant Hand weeding 1.10 1.30 1.20 1.20 1.75 2.60 2.10 2.15 Mean 1.28 1.96 1.36 1.64 2.87 2.12 LSD (P=0.05) P minor Avena Loliu Total m SBM 95-96 0.11 0.07 0.06 0.08 96-97 0.16 0.09 0.09 0.21 WCM 95-96 0.10 0.05 0.07 0.18 96-97 0.14 0.10 0.11 0.25 Interaction 95-96 0.07 0.05 0.11 0.22 96-97 0.04 0.06 0.09 0.45 SSB, stale seed bed; NSB, normal seed bed; T, triallate. combinations. However, combinations of these herbicide treatments with stale seed bed were slightly superior in comparison to their performance of this treatment combination combinations with normal seed bed + was poor as against most herbicide + cultural triallate. Weed indices for treatment treatment combinations. This may be

5 combinations were worked out based upon hand weeded stale seed bed. The Table 3. Effect of treatments on weed control efficiency (WCE) and weed index (WI)

Weed control methods 95-96 96-97 SSB NSB NSB+T SSB NSB NSB+T WCE (%) Weedy check 39.4 - 33.1 39.3 - 29.3 Isoproturon + surfactant 75.0 63.8 72.8 75.2 59.5 68.8 Dichlofop-methyl 66.9 48.0 59.2 65.3 45.7 54.4 Dichlofop-methyl + 71.3 54.8 69.9 68.2 15.8 64.1 surfactant Hand weeding 60.9 55.6 59.4 61.2 52.7 56.6 WI (%) Weedy check 22.35 38.05 28.68 23.24 39.71 27.83 Isoproturon + surfactant -40.33 -4.78 -31.88 -33.82 4.30 -8.82 Dichlofop-methyl -11.10 14.34 0.66 -10.59 26.91 5.88 Dichlofop-methyl + -33.09 3.86 -19.01 -19.60 13.49 -6.18 surfactant Hand weeding - 5.51 -4.41 - 12.87 2.57 of weeds by stale seed bed and control of A. ascribed due to mimicry of grassy weeds with fatua and other grasses by triallate in the the wheat plant which make the hand initial stages which decreased their weeding operation difficult and as a matter of competition with the crop right from early the fact most weeds escape. The WI therefore stages and increased CGR (90-120 DAS) and was negative due to most of the treatment consequently grain yield. Stale seed bed and combinations as a sequel of better normal seed bed + triallate increased grain performance with regard to grain yield over yield of wheat by 21.47 and 16.17%, hand weeded stale seed bed. respectively over normal seed bed during the Effect on crop first year and 20.91 and 17.15%, respectively Effect of seed bed manipulations during the second year. These results are in Due to favorable conditions of close conformity with the findings of Yadav moisture and weed free situation, stale seed et al. (1995). bed being statistically at par with normal seed bed + triallate produced significantly higher Effect of weed control methods tiller number, plant height, dry matter and Isoproturon + surfactant resulted in LAI during both the years (Table 4 & 5). The significantly higher number of tillers, dry increase in all these growth parameters by matter accumulation and plant height. stale seed bed and normal seed bed + triallate However, it was at par with dichlofop-methyl could be ascribed to elimination of first flush + surfactant in increasing the tiller number,

6 dry matter and plant height and with hand Malik and Balyan (1989) and Gauvrit and weeding twice in increasing dry matter and Dufour (1990). The increase in tiller count plant height during both the years (Table 4 & due to effective weed control by these 5). The superior performance of both these treatments resulted in higher LAI and growth herbicidal treatments could be ascribed to rate and consequently higher grain yield. their increased efficacy by addition of Isoproturon + surfactant and dichlofop- surfactant which decreased the LAI and methyl + surfactant increased the grain yield growth rate of weeds significantly. These results are in close conformity with those of Table 4. Effect of seed bed manipulations and weed control methods on growth and yield of wheat

Treatments Plant height at harvest Dry matter LAI (cm) (120 DAS, g/m2) (120 DAS) 95-96 96-97 95-96 96-97 95-96 96-97 Seed bed manipulations

Stale seed bed 89.1 91.2 610.5 575.3 2.657 2.639 Normal Seed bed 79.3 82.4 511.6 480.5 2.218 1.982 Normal seed bed + 85.6 89.3 603.8 545.5 2.613 2.473 triallate LSD (P=0.05) 2.7 2.0 12.0 38.2 0.070 0.220

Weed control methods

Weedy check 82.4 83.7 490.2 468.8 2.115 1.951 Isoproturon + 86.6 90.2 606.9 577.9 2.624 2.673 surfactant Dichlofop-methyl 84.5 86.3 584.5 514.9 2.521 2.175 Dichlofop-methyl + 85.1 88.5 595.5 541.7 2.601 2.533 surfactant Hand weeding 84.8 89.4 599.5 565.3 2.619 2.490 LSD (P=0.05) 1.9 2.5 18.8 37.2 0.080 0.190 combinations were also statistically at par of wheat by 42.10 and 37.10%, respectively with integration of normal seed bed + triallate over unweeded check during the first year with isoproturon + surfactant in increasing and by 39.37 and 34.17%, respectively grain yield. The superiority of isoproturon + during the second year. The increase in yield surfactant and dichlofop-methyl + surfactant over hand weeding was 17.49 and 10.67% in combination with stale seed bed or normal during the first year and 16.50 and 9.10%, seed bed + triallate for increasing grain yield respectively during the second year. could be ascribed to their higher efficacy to

Integrated effects reduce crop weed competition by elimination Seed bed manipulations interacted of first flush of weeds by stale seed bed or significantly with weed control methods in triallate and subsequent flushes with post influencing CGR, number of tillers and grain emergent application of isoproturon + yield (Table 5) of wheat. Integration of stale surfactant or dichlofop-methyl + surfactant. seed bed with isoproturon + surfactant and The superiority of stale seed bed and normal dichlofop-methyl + surfactant being at par seed bed + triallate in integration with resulted in significantly higher number of isoproturon in increasing grain yield over tillers and grain yield. However, these normal seed bed has also been reported by

7 Allcoat (1985), Anonymous (1995) and alone. The superiority of stale seed bed over Yadav et al. (1995). In general stale seed bed normal seed bed with respect to grain yield increased grain yield significantly over other has also been reported by Yadav et al. seed bed manipulations in each of the (1995). Stale seed bed in integration with methods of weed control. However, stale isoproturon + surfactant resulted in highest seed bed was at par with normal seed bed + gross returns, net returns over control and triallate in increasing CGR with all methods marginal benefit cost ratio (MBCR) of Rs of weed control except dichlofop-methyl 27516, Rs 13214 and Rs 13.73, respectively Table 5. Integrated effects of seed bed manipulations (SBM) and weed control methods (WCM) on CGR (g/day/m2, 90-120 DAS), tiller number (120 DAS) and grain yield (q/ha)

Weed control methods 95-96 96-97 SSB NSB NSB+T Mean SSB NSB NSB+T Mean

CGR Weedy check 10.19 8.27 10.32 9.60 10.01 7.18 9.77 8.99 Isoproturon + surfactant 12.67 10.94 12.81 12.14 14.03 9.81 13.88 12.57 Dichlofop-methyl 12.71 10.81 12.36 11.96 11.43 8.76 10.03 10.08 Dichlofop-methyl + 12.66 10.65 12.77 12.03 13.77 9.56 13.72 12.15 surfactant Hand weeding 12.71 10.98 12.90 12.20 12.43 10.24 12.22 11.63 Mean 12.19 10.33 12.24 12.33 9.11 11.81 Tillers/m row Weedy check 82.5 71.3 77.0 73.0 74.5 66.8 70.0 67.8 Isoproturon + surfactant 99.5 84.0 89.3 83.9 95.5 80.0 83.5 80.8 Dichlofop-methyl 90.0 80.8 85.5 78.2 91.8 76.3 81.0 75.0 Dichlofop-methyl + 97.8 83.5 88.5 82.7 95.0 78.0 83.3 79.0 surfactant Hand weeding 94.8 82.5 88.5 81.6 92.0 79.8 80.5 78.5 Mean 86.1 73.4 80.2 82.1 71.9 74.5 Grain yield Weedy check 21.12 16.85 19.40 19.8 19.90 15.42 18.65 18.0 Isoproturon + surfactant 38.17 28.50 35.87 34.2 35.42 25.05 28.62 29.7 Dichlofop-methyl 30.22 23.30 27.02 26.8 29.10 18.90 24.62 24.0 Dichlofop-methyl + 36.20 26.15 32.37 31.6 31.55 22.55 27.90 27.3 surfactant Hand weeding 27.20 25.70 28.40 28.2 26.22 22.72 25.52 24.8 Mean 30.7 24.1 28.8 28.4 20.8 25.1

LSD (P=0.05) CGR Tillers Yield SBM 95-96 0.11 1.0 2.0 96-97 0.32 2.5 0.7 WCM 95-96 0.18 1.4 3.1 96-97 0.44 2.1 2.5 Interaction 95-96 0.23 2.08 3.19 96-97 0.29 2.14 3.24 best combination. Integration of isoproturon during the first year and Rs 29159, Rs 14028 + surfactant and dichlofop-methyl + and Rs 14.57, respectively in the second year surfactant with normal seed bed + triallate (Table 6). though were next best in influencing gross Integration of dichlofop-methyl + returns and net returns over control. surfactant with stale seed bed was the next However, due to higher cost of triallate the

8 combinations of above mentioned herbicides The findings of this investigation with normal seed bed performed suggests an application of isoproturon 1.0 kg/ha + surfactant 0.5% or dichlofop-methyl comparatively better as regard to MBCR. The 0.50 kg/ha + surfactant 0.5% with stale seed superiority of stale seed bed in integration bed or normal seed bed + triallate 1.0 kg/ha with isoproturon than integration of hand for effectively checking the weed growth and weeding twice with stale seed has also been increasing monetary gains in wheat. reported by Yadav et al. (1995) in terms of monetary gains.

Table 6 Economics of treatment combinations

Weed control methods 95-96 96-97 SSB NSB NSB+T SSB NSB NSB+T Gross returns (Rs/ha) 13339 Weedy check 16793 22034 15534 18505 14169 17145 Isoproturon + surfactant 27516 16896 26275 29159 22245 25277 Dichlofop-methyl 22225 19882 20751 24446 16403 21649 Dichlofop-methyl + 26909 20186 24049 27762 20075 24383 surfactant Hand weeding 21588 20762 23174 21444 21464 Net returns over control (Rs/ha) - Weedy check 3121 8066 1669 4003 - 2451 Isoproturon + surfactant 13214 2709 11781 14028 7446 9953 Dichlofop-methyl 7705 5875 6039 9096 1386 6106 Dichlofop-methyl + 12569 4560 9516 12592 5237 9020 surfactant Hand weeding 5629 4610 6384 4987 4482 MBCR (Rs) - Weedy check 9.37 12.81 3.17 12.02 - 4.66 Isoproturon + surfactant 13.73 3.19 10.20 14.57 11.85 8.61 Dichlofop-methyl 6.52 8.79 4.47 7.70 1.63 4.44 Dichlofop-methyl + 12.55 1.99 7.97 12.55 7.83 7.55 surfactant Hand weeding 2.14 1.59

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