Madras Agric. J. 92 (7-9) : 539-542 July-September 2005

539

Research Notes

Evaluation of suitable herbicide for direct seeded rainfed lowland rice T. MYRTLE GRACE, P. BALASUBRAMANIYAN AND T. SUBRAMANI Agricultural Research Station, Paramakudi - 623 707, Tamil Nadu

Under direct seeded rainfed lowland situation, rice seeds are pre-monsoon sown in the unpuddled situation. Rainfall during the early phase of crop growth is unpredictable both in quantity and time, and hence weeds get dominant. Though manual weeding is effective, timely weed control could not be carried out because of the prevailing soil moisture condition and non-availability of labourers. Under such situation, chemical weed control is best option . This will help in reducing the crop- weed competion by timely control of weeds in rainfed rice. Pre-emergence application of butachlor effectively reduce weed competition (Saikia and Pathak, 1993). Herbicide such as butachlor and thiobencarb reduce population and dry weight of weeds (Singh et al., 1996). Application of preemergence herbicides, such as butachlor, anilophos or oxyflourfen in combination with 2,4-DEE was found to control all weeds and increase the productivity of rainfed rice (Satyanarayanan et al., 1997). Singh and Path (2000) recorded control of weeds in direct sown upland rice due to butachlor application or hand weeding. Hence, it is important to evaluate herbicides applied as pre-emergence or combination of herbicides as pre-post emergence in rainfed lowland rice. Field experiment was conducted at Agricultural Research Station, Paramakudi for two years (2001 and 2002) under direct seeded rainfed unpuddled lowland situation. The rainfed rice cultivar PMK 2 was used as the test variety. The soil type was sandy clay loam low in available N, medium P and high in K. The experiment was

conducted in a Randomized Block Design with three replications. Preemergence (PE) and pre-post emergence (PPE) herbicides were compared with hand weedings (HW) and unweeded check. The details of weed control treatments are described below : T1 -

Butachlor (1.0 kg ha-1) as PE on 8 days after soaking rain (DAS) + one hand weeding (HW) on 30-35 days.

T2 -

Thiobencarb (1.0 kg ha-1) as PE 8 DAS + one HW.

T3 -

Pendimethalin (1.0 kg ha-1) as PE 8 DAS + one HW.

T4 -

Pretilachlor (0.45 kg ha-1) as PE on 8 DAS + one HW.

T5 -

Pretilachlor + safener (0.30 kg ha-1) as PE on 4 DAS + one HW.

T6 -

Butaehlor - PE (0.5 kg ha-1) + 2,4-D (0.4 kg ha-1) -as PPE on 20-25 DAS + one HW

T7 -

Thiobencarb - PE (0.5 kg ha-1) + 2,4-D (0.4 kg ha-1) as PPE on 20-25 DAS + one HW

T8 -

Pendimethalin (0.5 kg ha-1) + 2,4-D (0.4 kg ha-1) on 20-25 DAS + one HW

T9

-

Pretilachlor - PE (0.25 kg ha-1) + 2,4-D (0.4 kg ha-1) on 20-25 DAS + one HW

T10 -

Pretilachlor - PE + safener (0.25 kg ha-1) + 2, 4-D (0.4 kg ha-1) on 20-45 DAS + one HW.

T11 -

Two HW on 20-25 DAS and 40-45 DAS

T12 -

Unweeded check

540

T. Myrtle Grace, P. Balasubramaniyan and T. Subramani

Table 1. Effect of weed management practices on weed dry matter production at different crop growth stages 2001 - ’02

Treatment Butachlor + HW Thiobencarb + HW Pendimethalin + HW Pretilichlor + HW Pretilichlor + safenor+ HW Butachlor + 2,4 - D+ HW Thiobencarb + 2,4 - D+ HW Pendimethalin + 2,4 - JD+ HW Pretilichlor + 2,4 - D+ HW Pretilichlor + safenor + 2,4- D + HW Hand Weeding Unweeded check SEd CD (P= 0.05)

2002 - ’03

20 DAS

40 DAS

60 DAS

79.1 96.7 63.6 61.7 55.3 88.6 96.5 88.1 84.1 91.1 89.6 90.4 1.3 2.6

44.6 46.3 38.5 34.3 32.6 30.9 28.6 24.5 21.6 19.8 56.5 279.0 1.2 2.6

73.9 77.2 64.4 63.6 61.8 52.5 53.8 47.2 42.7 42.3 56.5 358.0 8.0 16.6

20 DAS 40 DAS 16.2 21.9 27.1 20.3 20.7 53.4 54.5 55.0 53.2 54.6 53.8 54.5 0.6 1.3

4.3 9.4 11.1 3.9 3.5 57.4 63.8 85.7 60.1 53.4 23.7 183.7 2.5 5.2

60 DAS 14:5 19.6 25.6 12.4 11.4 23.4 26.6 27.3 24.2 23.3 4.3 296.3 2.2 4.5

Table 2. Effect of weed management practices on yield parameters of rainfed rice 2001 - ’02

2002 - ’03

Treatment

Panicles/ m2 (No)

Grains/ Panicle (No)

1000 grain weight (g)

Butachlor + HW Thiobencarb + HW Pendimethalin + HW Pretilichlor + HW Pretilichlor + safenor+ HW Butachlor + 2,4 - D+ HW Thiobencarb + 2,4 - D+ HW Pendimethalin + 2,4 - JD+ HW Pretilichlor + 2,4 - D+ HW Pretilichlor + safenor + 2,4- D + HW Hand Weeding Unweeded check SEd CD (P= 0.05)

140 135 145 146 151 144 138 151 154 157 156 64 1 3

78 74 81 82 86 82 77 83 87 91 88 63 2 4

21.1 21.8 21.1 21.3 21.4 21.3 21.4 21.4 21.2 21.2 21.2 21.0 0.4 NS

Panicles/ Grains/ 1000 grain m2 (No) Panicle weight (g) (No) 150 131 131 162 173 135 128 126 135 137 145 43 7 14

88 81 82 88 90 83 81 79 83 84 88 46 2 5

23.1 22.8 22.4 23.4 23.4 22.7 23.1 22.4 23.5 23.1 23.0 22.4 0.7 NS

Evaluation of suitable herbicide for direct seeded rainfed lowland rice

541

Table 3. Effect of weed management practices on yield and economics of rainfed rice 2001

2002

Treatment

Grain Yield (Kg/ha)

Straw Yield (Kg/ha)

BC ratio

Butachlor + HW Thiobencarb + HW Pendimethalin + HW Pretilichlor + HW Pretilichlor + safenor+ HW Butachlor + 2,4 - D+ HW Thiobencarb + 2,4 - D+ HW Pendimethalin + 2,4 - JD+ HW Pretilichlor + 2,4 - D+ HW Pretilichlor + safenor + 2,4- D + HW Hand Weeding Unweeded check

1732 1605 1725 1844 1863 1799 1691 1810 1940 1951 1918 622

4056 3518 3729 3933 4138 4002 3927 4312 4848 5128 5037 1222

1.29 1.01 1.07 1.28 1.30 1.27 1.16 1.22 1.40 1.42 1.16 0.57

1866 1701 1720 1867 1898 1750 1613 1612 1743 1754 1832 237

4211 3632 3770 435 4535 4024 3526 3456 3918 3838 4194 520

1.38 1.11 1.07 1.31 1.34 1.25 1.10 1.06 1.23 1.23 1.06 0.22

35 73

125 260

-

53 109

124 256

-

SEd CD (P= 0.05)

Herbicides were sand-mixed and broadcast applied on 4 or 8 days after soaking rainfall (DAS) for pre-emergence and 20-25 DAS for pre-post emergence herbicides. For herbicide treated plots, one hand weeding was done on 30-35 DAS or 4045 DAS for PE or PPE respectively. Two hand weedings on 20-25 and 40-45 DAS were carried out for manual weeding treatment. Unweeded check was also maintained without any weeding or herbicide application. Weed dry matter on 20 DAS was greatly reduced with the pre - emergence application of pretilachlor + safener (T5) (55.3 and 20.7 g /m2 during 2001 and 2002 respectively). During 2002, weed dry matter on 20 DAS was found to be reduced (16.2 g /m2) with the pre- emergence application of butachlor. At later stage, weed dry matter was found to be high with the control plot (0.4 and 54.5 g/m2 during 2001 and 2002 respectively). At later stages, however, weed dry matter was reduced greatly due

Grain Straw Yield Yield (Kg/ha) (Kg/ha)

BC ratio

to prepost emergence application of pretilachlor + safener and 2,4-D (T10). Number of panicles/m2 was high with the application of pretilachlor + safener + 2,4-DEE + HW. The same trend was observed with the number of grains per panicle during 2001-2002. However, number of panicles/m2 was high with the application of pretilachlor + safener and was on par with pretilachlor alone during 2002-2003. The number of grains per panicle increased with the application of pretilachlor + safener and was on par with that of pretilachlor or butachlor alone. Thousand-grain weight did not show any significant variation due to different weed management practice. Higher grain and straw yield was realized with the application of the preemergence application of pretilachlor + safener or pre- post emergence application of pretilachlor with 2,4-DEE with HW. The next best treatment was pretilachlor safener or

542

pretilachlor + HW. These treatments also gave higher benefit cost ratio during 2001-2002. However, during 2002-2003, higher grain and straw yield was recorded with the application of pretilachlor + safener and was on par with pretilachlor and butachlor alone. On an average, grain yield was higher with the application of pretilachlor + safener (1880 kg/ha) with one HW. The BC ratio was more with butachlor followed by pretilachlor + safener and pretilachlor alone. The average BC ratio with these treatment was 1.32. Behera and Jena (1998) reported that application of either butachlor or anilophos supplemented with 2,4-D Na salt gave higher BC ratio The next best treatment was pretilachlor or butachlor with one hand weeding. Hence, pre-emergence application of pretilachlor + safener (0.3 kg ha-1) or butachlor (1.0 kg ha-1) with one hand weeding on 30-35 DAS was found to be beneficial for direct seeded rainfed low land rice.

T. Myrtle Grace, P. Balasubramaniyan and T. Subramani

References Behera, A.K. and Jena, S.N. (1998). Weed control in direct-seeded rainfed upland rice. Indian J. Agron., 43(2) : 284-290. Saikia, T.P. and Pathak, A.K. (1993). Integrated Weed Management in rainfed direct seeded upland rice. Indian J. Agron., 38(2) : 300301. Singh, A.N., Sahadeva Singh and Bhan, V.M. (1996). Effect of herbicide on direct sown, drilled rice and associated weeds. Indian J. Agron., 41(2) : 233-236. Singh, S.K. and Path, P.C. (2000). Relative efficiency of different weed control methods in direct sown and transplanted rainfed upland rice. Oryza, 37(2) : 62-63. Satyanarayana, V., Latchanna, A. and Varaprasad, P.V. (1997). Weed management in direct seeded upland paddy. Ann Agric. Res., 18(3): 375 - 387. (Received : March 2004 Revised : June 2005)

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Madras Agric. J. 92 (7-9) : 542-544 July-September 2005

Research Notes

Agronomic management for perennial redgram through irrigation and mulching V.K. DURAISAMY AND P. MANICKASUNDARAM Agricultural Research Station, Tamil Nadu Agricultural University, Bhavanisagar - 638 451.

Perennial redgram BSR 1 has a long duration of 180 days. It can be kept in fields for more than two years after ratooning. Being a new introduction, no work has so for been carried out to evaluate the irrigation requirement and mulching. Ram babu et al. (1999) reported that pan evaporation showed the least deviation. Venugopal and Rao (1999) also found that the seed and dry-matter yields of redgram were linearly associated with seasonal evapotranspiration. The practice of mulching has been proved to be effective in conserving the soil

moisture and improving the yield in many crops. Deho et al. (2002) also claimed that sugarcane trash as a mulch showed the highest cane yield. Therefore, the present study was carried out to assess the optimum irrigation regime and a suitable mulch for increasing the productivity of perennial redgram. Field experiment was conducted at Agricultural Research Station, Bhavanisagar with perennial redgram variety BSR 1 during the year