Scope of growing lathyrus and lentil in relay cropping systems after rice in West Bengal, India S. Gupta* and M.K. Bhowmick Pulses and Oilseeds Research Station (PORS) Berhampore-742-101, West Bengal, India. * Email: pors2098@sancharnet.in OR gupta_supravo@yahoo.co.in Introduction The State of West Bengal in the eastern part of India, bordering Bangladesh, is a unique example where rice is cultivated in all the three seasons viz., summer, autumn and winter. The State has to feed almost 70 million people with the support of only 5.8 million hectares of cultivable land. Since independence the state has, therefore, had to resort to more areas under rice than for other crops, especially pulses, the productivity of which are comparatively low. At present the area under rice occupies about 66 percent of the total gross cropped area, which is about 9.24 million hectares with an average cropping intensity of 171 percent (9). The total area under pulses has diminished gradually every year from 582,000 ha during 1957-58 to 242,000 ha during 2002-03 (11). It is a general practice of the farmers of this region to sow various winter pulse crops like lentil (Lens culinaris L.), lathyrus (Lathyrus sativus L.), chickpea (Cicer arietinum L.) and pea (Pisum sativum) in the standing rice crop field, just before the harvest to ensure germination using the residual moisture and to avoid tillage operations during pulse growing. Such a relay cropping operation (known by the terms utera or paira) is very popular for growing lathyrus. Subsequently due to high ODAP content of local land races and also with the advent of irrigation facilities, the farmers tended to shift from relay cropping of lathyrus to more remunerative crops like rapeseed, mustard, potato, other vegetables and winter rice which require more water. Thus the area under lathyrus, in particular, diminished drastically from 54,000 ha during 1981-82 to 40,000 ha during 2000-01 (10). With the backdrop of the aforesaid facts, efforts were concentrated to develop high yielding lathyrus varieties with ODAP content less than a critical limit (0.20 %). A variety Nirmal (B-1) was developed at the Pulses and Oilseeds Research Station (PORS). Other varieties (BioL 212, BioR 202, LSD-3 and P-24) are also of late recommended by the Indian Council of Agricultural Research for cultivation in India. Therefore, the PORS conducted a series of experiments to establish the suitability for growing pulses in the utera cropping system; especially in the mono-cropped areas of the state situated in the Coastal, Old Alluvial and Terai (Foot Hills) Zones of West Bengal with total area under cultivation comprising nearly 1.36 million hectares. Recently efforts are also going on to grow black gram (Vigna mungo) and green gram (Vigna radiata) under utera condition in wheat fallows with the objective to grow an early duration pulse as a catch crop and to sustain soil health in wheat-rice rotations. Experimental Findings and Discussion The PORS, Berhampore, West Bengal, India has engaged in various field experiments since 1970-71 to identify the cultivars suitable for the utera system, to standardize the improved package of practices. As such, a trial was undertaken at the Block Seed Farm, Kandi, Murshidabad, West Bengal in 1970-71 with different varieties of lentil and lathyrus. Seeds of lentil and lathyrus were broadcast on standing aman (wet season) paddy field (variety Bhasamanik) @ 50 kg per hectare on 13 th and 14 th November 1970, respectively, 15 days before rice harvest. The variety yields are presented in Table 1. Table 1. Yield of different varieties of lentil and lathyrus grown as utera at Block Seed Farm, Kandi, Murshidabad, India in 1970-71. Lentil Yield Lathyrus Yield L6-42 578 Kh-3 3878 L6-8 1022 Kh-4 3306 L6-85 1056 Kh-18 2817 LL6-4 1089 Kh-17 2672 L6-77 1111 B-77 1133 L6-21 1478 L6-36 1500 L6-20 1556 L6-23 2256 Source: Chakraborty et al. (13) 28
It is evident from Table 1 that both lentil and lathyrus could be successfully grown under muddy land conditions in the standing rice crop 15 days before its maturity, provided that there is no standing water in the field. The yield ranged from 578 to 2256 kg/ha in case of lentil and 2672 to 3878 kg/ha in case of lathyrus, compared to the respective average yield of 485 kg/ha and 511 kg/ha for these two crops in the state (13). During 1999-2000 and 2000-01 different genotypes of lathyrus were tested for their suitability and competitiveness for growing under utera conditions in muddy land of standing rice fields in mono-cropped coastal saline tracts of West Bengal. The trials were laid out in two Government Farms viz., Sub-Divisional Adaptive Research Farm, Baruipur and Block Seed Farm, Mathurapur. The yield data obtained are in Table 2. The variety Nirmal developed at PORS is the most adapted (Table 2) in the rice-utera system in the Coastal Zone of the state. The field experiments were conducted under rainfed conditions on a clayey soil where salinity develops gradually after cessation of rainfall in the dry winter months, when the crop was grown. Table 2. Seed yield of lathyrus after rice in utera conditions at 2 sites (Mathurapur and Baruipur) in the coastal zone of West Bengal. Varieties 1999-2000 2000-2001 Mean yield Mathurapur Baruipur Baruipur BioL 212 2083 1104 775 1321 BioR 202 1875 1251 650 1259 LSD 3 1782 923 670 1125 P-24 1771 855 570 1065 P-505 1375 1004 670 1016 Nirmal 1729 1529 1295 1494 LSD (P<0.05) 268 162 104 - CV (%) 10.1 9.7 10.2 - Source: Annual Reports (4,5) Table 3. Performance of lentil genotypes in rice-utera conditions. Variety Seed yield 2001-02 2003-04 L 4661-1233 WBL-75-1642 ILL 8006-666 B-77 903 1366 WBL-58 1158 1708 PL-639-908 IPL-304-592 K-75 841 - LSD(P <0.05) 26.8 - Source: Annual Reports (6,8) Table 4. Time to flowering and maturity and 1000 grain weight of 7 varieties of lentil grown in riceutera conditions. Variety Days to 50% flowering Days to maturity 1000 grain wt. (g) L-4661 77 122 22.33 WBL-75 84 127 18.29 ILL 8006 66 114 20.32 B-77 69 120 19.98 WBL-58 68 126 21.48 PL-639 70 133 15.62 IPL-304 73 139 28.76 Source: Annual Report (8) Likewise, variety suitability and competitiveness of lentil genotypes under rice-utera system were tested for two years at PORS. Altogether 8 cultivars were included in the experimentation during 2003-04, whereas only 3 varieties were tested during 2001-02. The yield data of individual lentil genotype tested for the two years are presented in Table 3. The duration and other characters of individual variety recorded during 2003-04 are in Table 4. The rice variety cultivated in the experiment was MTU 7029, which matured in 140-145 DAS. The maturity period of all lentil varieties (Table 4) were delayed for at least 10 days when grown under utera cropping system. Genotypes with characteristics of early vigour and comparatively tall stature could perform well under utera conditions. Similar observations were made of lathyrus cultivars when grown under utera conditions. Some experiments were conducted to optimise sowing times and other agronomic management in the utera system of sowing of pulses in muddy fields of standing rice, utilizing residual moisture and fertilizer. One such trial was conducted in 1994-95 with lathyrus under riceutera conditions and the results are given in Table 5. 29
Table 5. Effect of sowing time and weed management on lathyrus yield under rice-utera conditions during 1994-95 (rice variety IR-36 and lathyrus variety Nirmal). Seed yield Sowing time (days before rice harvest) 10 743 20 973 30 824 LSD (P<0.05) 100 Weed Management No hand weeding 500 One hand weeding at 45 DAS 932 Two hand weedings at 45 and 60 DAS 1100 LSD (P<0.05) 100 CV (%) 14.04 LSD(P<0.05) for sowing time x NS weeding interaction Source: Annual Report (3) The yield of lathyrus variety Nirmal was maximum when sown 20 days before harvest of rice (Table 5). Keeping the plot weed free after rice harvest was found to be significantly superior to the existing farmers practice of not weeding the plot. Another experiment was conducted during 1999-2000 and 2001-2002 to verify the sowing time results of 1994-95 and to examine whether basal fertilizer by means of placement of fertilizer in between the rows of standing rice crop had any effect on yield of utera crop of lathyrus. The results are given in Table 6. The results in the Table 6 clearly corroborated the results of the previous experiment of 1994-95. Sowing at 15-20 days before rice harvest gave a better result in respect of yield, probably due to the fact that earlier sowing might have more effective utilization of residual moisture in the rice field. Duary et al. (14) were of the same opinion. The utera crop might need some initial nutrition as a starter dose of NPK, possibly to enhance symbiotic activities with the Rhizobium bacteria. Table 6. Effect of sowing time and fertilizer management on seed yield of lathyrus under rice-utera conditions (rice variety MTU 7029 and lathyrus variety Nirmal) Seed yield 1999-2000 2001-2002 Mean Sowing time (days before rice harvest) 0-889 889 10 1150 912 1031 15 1225 993 1109 20 1525-1525 LSD (P<0.05) 69 - - CV (%) 6 - - Fertilizer(N:P 2 0 5 :K 2 0 in kg/ha) No fertilizer (Control) 1033 799 916 10 : 25 : 20 (Basal) 1300 890 1095 20 : 50 : 20 (Basal) 1317 1022 1169 10 : 25 : 20 (Basal) + DAP spray (2% 1550 1013 1282 solution) at flowering LSD (P<0.05) 88 - - CV (%) 8 5 - LSD (P<0.05) for sowing time x fertilizer interaction 153 71 - Source: Annual Report (4,6) 30
Table 7. Effect of seed soaking and foliar nutrition on lathyrus under rice-utera conditions during 2003-04 (rice variety IR-36 and lathyrus variety BioL 212). Mature plant height (cm) Branches/ plant Pods/ plant Seeds/pod 1000 seed weight (g) Seed yield Seed priming No soaking 45 3.69 8.94 2.22 63.6 731 Soaking in water for 6 h 50 3.87 9.48 2.54 66.6 802 Soaking in 2% KH 2 PO 4 solution for 6 h 52 3.92 10.70 2.76 70.4 910 Sowing of sprouted seeds 54 4.26 11.55 3.00 71.8 938 LSD (P<0.05) 3.0 0.23 0.90 0.18 1.7 53 Foliar nutrition Control 46 3.68 9.18 2.44 66.4 675 Water spray 48 3.79 9.62 2.54 67.7 798 Urea spray (2% solution) 54 4.29 11.25 2.87 69.5 963 DAP spray (2% solution) 51 4.11 10.84 2.69 68.7 912 KCl spray (2% solution) 51 3.81 9.95 2.63 68.1 878 LSD (P<0.05) C.V.(%) Source: Annual Report (8) 3.4 8.2 0.26 8.1 1.01 12.1 0.20 9.33 1.9 3.5 58.7 8.4 Table 8. Effect of sowing time and seed priming on yield and other characters of lentil sown under rice-utera conditions during 2003-04 (lentil variety WBL-58 and rice variety MTU-7029). Plant population ( 000/ha) Mature plant height (cm) Pods/plant 1000 seed weight (g) Seed yield Sowing time 14 Nov 2003 842 36 64 18.3 1162 21 Nov 2003 940 38 77 19.7 1232 LSD (P<0.05) 85 NS 4.5 NS 41 Seed priming No soaking 773 34 62 17.7 1018 Soaking in water for 6 h 855 35 70 18.5 1174 Soaking in 2% KH 2 PO 4 solution for 6 h 928 36 74 19.0 1266 Sowing of sprouted seeds 1007 42 77 20.7 1330 LSD (P<0.05) 120 3.2 6.4 NS 58 LSD (P<0.05) for sowing time x priming interaction NS NS NS NS NS C.V. (%) 10.9 7.0 7.3 10.4 3.89 Source: Annual Report (8) 31
Table 9. Effect of weed management and seed rate on seed yield of lentil under rice-utera conditions. Seed yield 1991-92 1992-93 Mean Weed management Control 599 741 670 Weed free (Hand weeding at 30, 45 and 815 831 823 60 DAS) One hand weeding (30 DAS) 730 824 777 One hand weeding (45 DAS) - 931 931 Two hand weedings (30 and 50 DAS) 746 918 832 Oxyfluorfen @ 50 g/ha as post- 704 927 816 emergence (30 DAS) LSD (P<0.05) 79 54 - CV (%) 10.2 6.0 - Seed rate 60 676 755 716 80 762 969 866 LSD (P<0.05) 57 27 - CV (%) 11.7 5.0 - LSD (P<0.05) for weeding x seed rate interaction NS 65 - Source: Annual Report (1,2) As no tillage operation is done for sowing pulses as a relay (paira) crop, it is difficult to apply fertilizer either through placement or through top dressing and consequently, no fertilization is made by the farmers to the succeeding pulse crops (12). Therefore, the scope of fertilization becomes confined to foliar spray or top dressing. With this view, an experiment was conducted to study the effect of pre-sowing seed soaking and foliar nutrition on yield improvement in lathyrus. This was done in 2003-04 at PORS Sub-Station at Beldanga and the results are given in Table 7. Sowing of sprouted seeds significantly increased yield. Spraying of 2% urea solution at 10 days after rice harvest had the greatest beneficial effect and it was followed by 2% solution of di-ammonium phosphate. The effect of seed soaking of lentil genotypes under rice-utera conditions was also tested in the same year at PORS Sub-Station, Beldanga. The results are given in Table 8. The sowing of sprouted lentil seeds increased the plant stand and yield quite significantly. This was also true in the case of lathyrus (Table 7). The significantly increased yields are possibly due to increased germination and crop emergence. An experiment was conducted to ascertain the effect of weeding and also to determine the actual seed rate of lentil. It was felt that seed rate should be higher when either lentil or lathyrus were sown under utera conditions in comparison to being sown as a sole crop. The results of two consecutive year- trials (1991-92 and 1992-93) are shown in Table 9. The higher seed rate (80 kg/ha) was effective in significantly increasing both the plant stand and yield. Thus, it is recommended that seed rate should be more than double of the normal rate (30-35 kg/ha ) when lentil is sown under rice-utera conditions, presumably indicating that lathyrus will respond similarly. 32
Future strategies To achieve higher productivity of the pulses under utera conditions, the following points should be considered: 1. Generation and/or selection of efficient genotypes: Location specific high yielding genotypes with early vigour, earliness, close canopy, synchronous maturity, resistance to key diseases and insect-pests and tolerance to moisture stress need to be developed for various agroclimatic zones of West Bengal. 2. Development of an efficient fertilizer use schedule: A. Identification and use of efficient strains of Rhizobium and phosphate solubilizing bacteria (PSB) for seed inoculation B. Developing an integrated nutrient management schedule for the system as a whole. C. Exploring the possibilities of foliar nutrition. D. Maintaining proper plant population: E. Using quality seeds of small-seeded varieties. F. Timely sowing to exploit the residual soil moisture. G. Finding the optimum seed rate. H. Seed treatment with effective fungicide to combat seedling mortality and seed borne diseases. I. Following specific technique for pre-sowing seed soaking (seed priming) to enhance drought tolerance and seedling vigour. 4. Weed management: A. Choosing genotypes with higher weed suppression ability. B. Higher seed rate to increase smothering effect. C. Identification of post-emergence herbicides and efficient application techniques. D. Utilizing residual efficacy of herbicides by applying the same in preceding crops. E. Timely intercultural operation. Epilogue The above observations indicate some trend in maximizing the productivity of lathyrus and lentil under utera conditions in rice. Similar progress can be made for other utera crops grown in rotation with wheat, such as green gram (Vigna radiata) and black gram (Vigna mungo). Further experiments on utera cropping need to be conducted in order to make recommendations to the farmers. However, such research is being continued on this unique system of growing pulses under residual moisture and fertility, paving the way towards increasing cropping intensity in mono-cropped areas. This will practically maintain soil health, productivity and production of high protein legume crops in developing countries, where many people currently suffer from malnutrition. In conclusion, paira (utera) cropping with winter pulses in low land rice-fallows holds great promise, which would not only step up the pulse production but also help in protecting the environment from the risks of high input agriculture. References 1. Annual Report (1991-92). Pulses and Oilseeds Research Station (PORS), Berhampore-742101, Govt. of West Bengal, India. 2. Annual Report (1992-93). PORS, Berhampore- 3. Annual Report (1994-95). PORS, Berhampore- 4. Annual Report (1999-2000). PORS, Berhampore- 5. Annual Report (2000-01). PORS, Berhampore- 6. Annual Report (2001-02). PORS, Berhampore- 7. Annual Report (2002-03). PORS, Berhampore- 8. Annual Report (2003-04). PORS, Berhampore- 9. Anonymous (2000). Status of Agriculture 2000. Dept. of Agriculture, Govt. of West Bengal, India. 10. Anonymous (2002-03). Area, Production and Productivity of Some Principal Crops in West Bengal (2002-03). Socio-Economic and Development Branch, Dept. of Agriculture, Govt. of West Bengal, India. 11. Anonymous (2003-04). Area, Production and Productivity of Some Principal Crops in West Bengal (2003-04). Socio-Economic and Development Branch, Dept. of Agriculture, Govt. of West Bengal, India. 12. Bhowmick MK, Aich A, Aich SS, Shrivastava MP, Gupta S, Man GC. 2005. Crop diversification through paira (utera) cropping with rabi pulses. SATSA Mukhapatra-Annual Technical Issue 9, 43-60. 13. Chakraborty LN, Sen SN, Mandal SK, Sengupta K and Mukherjee D. 1973. Possibility of utilizing rice fallow in West Bengal. Proc. Sem. on possibility of growing a second crop after rice in West Bengal (Das Gupta DK, ed.), Sept. 15, 1973, Calcutta: 71-76. 14. Duary B, Hazra D, Ghosh AK. 2004. Response of lathyrus (Lathyrus sativus L.) to different dates of sowing and fertilizer application under paira cropping in rice. Indian Agriculturist 48, 157-159. 33