Influence of nutrient source on yield, quality and economics of seed production in vegetable cowpea (Vigna unguiculata ssp. sesquipedalis) Sheeba Rebecca Isaac* and Babu Mathew Kerala Agricultural University Farming Systems Research Station, Sadanandapuram Kottarakkara, Kollam 691 531, Kerala, India *E-mail: sheebarebecca@yahoo.co.in ABSTRACT Field investigation was carried out to study the influence of different sources of nutrients on seed production in vegetable cowpea (Vigna unguiculata ssp. sesquipedalis) during 2010-11 in Randomized Block Design, with twelve combinations of nutrient sources. Results showed significant variation in seed yield potential in the crop. Highest seed yield (435.97kg ha-1) was recorded in the treatment where recommended NPK dose for the seed crop was applied along with vermicompost at 50 per cent nitrogen substitution. Yield attributes were found non-significant, but had a positive influence on seed yield. Germination percentage and 100-seed weight was significantly higher in treatments receiving a combination of vermicompost and poultry manure. Benefit:Cost analysis revealed that 50 per cent N substitution with vermicompost and 25% N with poultry manure were the most profitable in cowpea seed production. Key words: Economics, integrated, nitrogen, quality seed, vermicompost J. Hortl. Sci. Vol. 11(1):72-75, 2016 Short communication Cowpea (Vigna unguiculata ssp. sesquipedalis) is one of the most popularly grown vegetable crops in Southern Kerala on account of its high yield and market preference. Local varieties predominate in the market, but recent trends show a shift towards preference for improved and newer varieties released from various research institutions. Non-availability of quality seeds in adequate quantity and in time has hampered adoption of improved varieties. Quality seed is a pre-requisite in crop production, as, nearly 25 per cent of the yield realized in the crop is decided by quality of the seed material used (KAU, 1991). Conjunctive use of good quality seeds with inputs like water, fertilizer and plant protection chemicals can help tap the superior genetic potential of high-yielding varieties and accrue benefit to the farmer (Kannaiyan, 2005). It is in this background that an experiment was envisaged with an objective of exploring the influence of various nutrient sources on seed production in vegetable cowpea and assessing the economics of integrating different nutrient sources. The experiment was laid out in Kollam district, Kerala (9016’N latitude, 76037’E longitude, 91.44m above MSL) during October 2010 - January 2011 in Randomized Block Design, with 12 treatments replicated thrice, involving different nutrient sources. ‘Vellyani Jyothika’ variety released from Kerala Agricultural University was used in the study. This variety is characterized by long, light-green pods with seeds tinged cream and red. The soil was ultisol lateritic with 0.65% organic carbon, and, 257.15, 7.89 and 45.75kg ha -1 available N, P and K, respectively. Recommended dose (RD) of NPK for cowpea seed crop (25:30:12.5kg ha-1) was adopted as per KAU, 2007. The experiment constituted twelve treatments, viz., T1 - 100% RD as chemicals; T2 - 25% RD N and K as foliar spray; T3 - 50% of RD N and K as foliar spray; T4 - 25% N as vermicompost; T5 - 25% RD N as poultry manure; T6 - 25% RD N as vermicompost + poultry manure; T7 - 50% RD N as vermicompost; T8 - 50% RD N as poultry manure; T9 - 50% RD N as vermicompost + poultry manure; T10 - 100% RD with organic sources; T11 - 150% RD as chemical fertilizers; T12 - 150% RD with organic sources. Chemical and organic manures were applied (alone, or in combinations as per treatments) in three splits: basal, one month after planting, and after the first harvest. Full dose of phosphorus was applied at the time of sowing. The first two harvests were made for use of cowpea as vegetable, and thereafter, the fruits were left on the plant for maturation. Four pickings 73 Influence of nutrient source in vegetable and seed cowpea production of mature pods were undertaken for seed extraction, and, the last-formed fruits were harvested as vegetable. Mature pods were dried in the open, avoiding peak sunshine hours during noon. Seeds were extracted and dried to safe a moisture level (5-7%) in a seed drier and observations were made on germination percentage, 100-seed weight and vigour index. The observations recorded were analyzed statistically for variation among treatments as per Gomez and Gomez (1983). Cost of cultivation and returns were worked out to compute Benefit:Cost ratio for comparison between treatments. Data on fruit yield, yield attributes and seed yield in cow pea fertilized with various combinations of nutrient sources are presented in Table 1. Data revealed that influence of the nutrient source on vegetable and mature pod yield, and pod characters, were not significant; but, the effect on seed yield was significant. Seed yield was significantly higher when vermicompost was used for 50 per cent N substitution (435.97kg ha-1), which was on par with full organics (421.75 and 409.33kg ha-1) and 25 per cent substitution with poultry manure (413.38kg ha-1). Vegetable yield and mature pod yield also followed a similar trend as seed yield, confirming the response to integration of sources. It was also observed that inclusion of organic manures significantly improved seed yield in cow pea. However, substitution level varied with type of manure used. In the treatment concerning integrated application, chemical fertilizers may have supplied initial nutrient requirement, and, the organic sources would have supplied the nutrients at seed maturation stages. Increased availability of nutrients to plants with application of organics may have even enhanced the efficiency of the N and P applied. Keiko et al (1997) reported efficiency of inorganic manures applied as more pronounced when combined with organic fertilizers. Similar results were reported by Pandey et al (1980) in okra, Chavan et al (1997) and Suagundi (2000) in chilli and Rekha and Gopalakrishnan (2001) in bitter gourd. A positive effect of organic manures, vermicompost and poultry manure on seed yield has been documented earlier (Singh et al, 1997; Channabasanagowda et al, 2008; Menon et al, 2010). The differential action observed may be attributed to differences in mineralization rate and availability of the nutrients to the plants throughout their growth period. Yield attributes, pod size, pod weight, number of seeds per fruit and seed weight, also substantiate higher yields recorded in these treatments. Poultry manure at 25% substitution was found to be ideal for good seed yield but, at 50% substitution, the concentrated form and the uric acid present may have affected mother plant growth in the early stages, and have had a bearing on yielding ability of the mother crop. Among seed quality parameters, germination percentage did not vary significantly with nutrient source (Table 2), while, 100-seed weight, vigour index and moisture content showed significant variation. Lowest vigour in seeds was recorded in the treatment T8 at 50% N substitution with poultry manure, and with 150% recommended dose applied as chemical fertilizer (T11). The economics of seed production with the different sources of nutrients was worked out as the benefit:cost ratio (Table 3) and it was proven that irrespective of the treatment, BC ratio were more than one, the maximum being with 50 per cent POP nitrogen as vermicompost (2.09) on par with 25 % N substitution with poultry manure (2.00) and 100 % nutrients as chemicals (2.05) for the seed crop. Organic nutrition recorded significantly lower values for the BC ratios. Detailed analysis revealed that chemical fertilizer, despite resulting in lower yields, gave a high B:C ratio due to lower cost of cultivation. In the treatments with organic manure, cost of cultivation was 16 to 39.80% higher, as, these were considered as purchased inputs. Nutrient content Table 1. Influence of nutrient source on yields and pod characters in cowpea Treatment Vegetable Mature Pod Pod Pod yield pod yield length girth weight (kg ha-1) (kg ha-1) (cm) (cm) (g) T1 100% RD as 187.92 594.00 30.53 2.60 6.71 chemical fertilizer T2 25% RDN & 199.00 580.25 31.33 2.30 7.87 K - foliar T3 50% RDN & 239.98 627.00 32.40 2.10 6.83 K - foliar T4 25% RDN as VC 206.58 466.58 30.60 2.23 7.28 T5 25% RDN as PM 242.92 781.00 28.67 1.80 9.72 T6 25% RDN as 172.33 668.25 29.87 1.53 7.49 VC+PM T7 50% RDN as VC 203.50 800.25 32.83 1.68 7.51 T8 50% RDN as PM 160.42 550.00 30.50 1.63 5.85 T9 50% RDN as 214.67 577.13 32.73 1.67 5.62 VC+PM T10 100% RD as OM 196.00 671.00 32.07 1.63 7.31 T11 150% RD as 187.92 603.17 29.97 1.90 7.98 chemical fertilizer T12 150% RD as OM 184.10 670.08 30.33 1.47 7.02 CD (P=0.05) NS NS NS NS NS VC- Vermicompost; PM- Poultry manure; OM- Organic manure; NS- Non-significant J. Hortl. Sci. Vol. 11(1):72-75, 2016 74 in organic materials varies greatly; vermicompost used in the study was prepared from crop residues including the banana pseudostem, leguminous materials and grasses, and contained 0.8 per cent nitrogen; while, poultry manure contained 1.2% N. This added to the quantum of material required and, hence, to the cost of cultivation. As a result, Benefit:Cost ratio, despite higher yield and gross returns, was narrowed down, especially when compared to use of chemicals. Organic nutrition, despite comparable yields, recorded lower profits on this account. This clearly proves that unless organic manures are produced in situ by the farmer, cost of cultivation would remain high, and B:C may could be even negative (incurring loss) despite reaping very good harvests. Reports of Sheela et al (2010) are in conformity with this observation. Our study brings to light the importance of integration of nutrient sources for seed production in cow pea. Best yields can be realized by integrating chemical fertilizers with vermicompost, with requirement for nitrogen of the seed crop being met @ 50 per cent each from the two sources. The recommendation would be more economical if the vermicompost were produced in situ at the farm itself. Organic cultivation of cowpea seed crop can also be recommended with availability of various nutrients sources that can be integrated for commercial production. REFERENCES Channabasangowda, N.K., Patil, B.N., Patil, J.S., Awaknavar, B.T. and Hunje, R. 2008. Effect of organic manures on growth, seed yield and quality of wheat. Karnataka J. Agril. Sci., 21:366-368 Chavan, P.J., Syedismail, G.B., Malewar, G. and Baig, M.I. 1997. Effect of various nitrogen levels through FYM and urea on yield, uptake of nutrients and ascorbic acid content in chilli (Capsicum annuum L.). J. Indian Soc. Soil Sci., 45:833-835 Gomez, K.A. and Gomez, A.A. 1983. Statistical procedures for agricultural research. John Wiley & Sons, Inc., Canada Kannaiyan, S. 2005. Participatory approached in quality seed production. In: Recent techniques and participatory approaches on quality seed production. Vanangamudi, K., Natarajan, N., Natesan, P., Natarajan, K., Bharathi, A., Jerlin, R. and Saravanan, T. (eds), T.3-5, Kalyani Publishers, New Delhi, India KAU (Kerala Agricultural University). 2007. Package of practices - Recommendatins: Crops. 13th Edition, Kerala Agricultural University, Thrissur, Kerala, India KAU Technical Bulletin No. 20. 1991. Tips on vegetable seed production. Rajan, S. (ed), KAU Press, Thrissur, Kerala, India Keiko, I., Nunomura,O., Nakamura, N., Matsufuji, H. and Table 2. Seed yield and quality characters as influenced by various nutrient sources in cowpea Treatment Seed 100 Germination Vigour Moisture yield seed (%) index (%) (kgha-1) weight (g) T1 100% RD as 351.77 16.48 89.81 2275.67 7.07 chemical fertilizer T2 25% RDN & 359.74 16.22 93.27 1851.33 6.30 K - foliar T3 50% RDN & 355.67 14.19 86.60 2058.00 6.77 K - foliar T4 25% RDN 284.53 15.61 93.27 2329.00 6.67 as VC T5 25% RDN 413.38 17.05 96.61 2797.33 5.87 as PM T6 25% RDN 358.04 17.73 89.81 1994.00 6.63 as VC+PM T7 50% RDN 435.97 16.47 89.81 1910.67 7.57 as VC T8 50% RDN 284.44 14.28 83.27 1669.00 6.03 as PM T9 50% RDN 333.13 15.33 96.61 2194.00 5.70 as VC+PM T10 100 % RD 421.75 17.14 93.27 2198.00 6.00 as OM T11 150% RD as 318.54 15.05 79.79 1733.33 6.10 chemical fertilizer T12 150% RD 409.33 16.16 96.61 2266.67 5.93 as OM CD (P=0.05) 82.28 0.56 NS 904.55 0.73 VC- Vermicompost; PM- Poultry manure; OM- Organic manure; NS- Non-significant Table 3. Cost of cultivation of seed crop in cowpea and Benefit:Cost ratio under various nutrient sources Treatment Cost of B:C ratio cultivation (Rs. ha-1) T1 100% RD as chemical fertilizer 206300 2.07 T2 25% RDN & K - foliar 218800 2.00 T3 50% RDN & K - foliar 231300 1.87 T4 25% RDN as VC 239310 1.45 T5 25% RDN as PM 244960 2.05 T6 25% RDN as VC+PM 246685 1.76 T7 50% RDN as VC 253020 2.09 T8 50% RDN as PM 246120 1.40 T9 50% RDN as VC+PM 249570 1.62 T10 100 % RD as OM 282140 1.81 T11 150% RD as chemical fertilizer 219520 1.76 T12 150% RD as OM 288360 1.72 CD (P=0.05) 0.054 VC- Vermicompost; PM- Poultry manure; OM- Organic manure; NS- Non-significant Sheeba Rebecca Isaac and Babu Mathew J. Hortl. Sci. Vol. 11(1):72-75, 2016 75 Takeda, H. 1997. High ascorbic acid content in the fruits of a deep-green cultivar of Capsicum annuum throughout the fruit development. Capsicum and Eggplant Newslett., 16:52-55 Menon, M.V., Reddy, D., Bhaskar, Prameela, P. and Krishnankutty, J. 2010. Seed production in vegetable cow pea [Vigna unguiculata (L.) Walp.] under integrated nutrient management Legume Res., 33(4):299-301 Pandey, V.C., Lal, S., Pandita, M.L. and Singh, G. 1980. Effect of nitrogen and phosphorus levels on seed production of okra (Abelmoschus esculentus L. Moench.). Haryana J. Hortl. Sci., 9(3-4):165-169 Rekha, C.R. and Gopalakrishnan, J.R. 2001. Effect of levels and frequencies of organic manures and inorganic fertilizers on growth and productivity of bitter gourd (Momordica charantia L.). South Indian Hort., 49:137-139 Sheela, K.R., Lakshmi, S., Shehana, R.S., Pushpakumari, R. and Nandakumar, C. 2010. Performance of intercrops as influenced by sources and levels of nutrients in coconut based cropping systems. Geobios, 37(1):13-16 Singh, J.B., Sreekrishna, B. and Sundharaman, M.R. 1997. Performance of Scotch bonnet chilli in Karnataka and its response to vermicompost. Indian Cocoa, Areca nut and Spices J., 21:9-10 Sutagundi, R.B. 2000. Effect of mulches and nutrient management on growth and yield of chilli (Capsicum annuum L.). M.Sc. (Agri.) Thesis, University of Agricultural Sciences, Dharwad, Karnataka, India J. Hortl. Sci. Vol. 11(1):72-75, 2016 (MS Received 16 August 2014, Revised 06 December 2015, Accepted 18 January 2016) Influence of nutrient source in vegetable and seed cowpea production