Optimizing planting geometry and fertilizer levels for enhanced yield and economics of greengram (Vigna radiata L.) genotypes in summer

Introduction

Pulse crops are usually referred to as soil fertility restorer. They have been neglected in diversified cropping systems in previous decades which lead to the loss of biodiversity and soil fertility. Inclusion of pulses in the cropping system provides a better optioning restoration of soil fertility, achieving production sustainability and obtaining economic gain in the intensified agricultural production. Pulses need less nitrogen as external input as nitrogen requirement is met through biological N-fixation to an extent of 25 to 30 kg ha -1 (Kalsaria et al., 2017) [10] and improve organic matter status of the soils, thus playing an important role in sustainable agriculture. Pulses are considered the most economical source of dietary protein, supplementing approximately 20-30 per cent of the protein requirements of the Indian population (Grover and Singh, 2015) [19] . Greengram (Vigna radiate L.) is one of the important pulse cropsin India containing high quality vegetable protein and satisfactory amounts of minerals and vitamins. In India, greengram is cultivated over an area of 4.3 million hectares, with a total production of 2.0 million tonnes and an average productivity of 472 kg ha⁻¹. During the rabi and summer seasons, it occupies 0.96 million hectares, producing 0.56 million tonnes with an improved productivity of 582 kg ha⁻¹.In Karnataka it is grown in an area of 0.42 m ha with production of 0.142 m tonnes and productivity of 339 kg ha -1 . During summer, it is being grown in an area of 1,025 ha, (Anon., 2018) [1] . The productivity gap analysis revealed that the national average yield of greengram is 472 kg ha -1 as against 339 kg ha -1 in Karnataka. This indicates the scope for increasing the productivity of summer greengram by best agronomic management practices. The low yield in greengram is attributed to several reasons. The main reason includes low plant population, poor nutrient management and selection of varieties suitable for the given region. In recent decades with development of short duration, photo and thermo insensitive as well as yellow vein mosaic resistant varieties provided excellent opportunity for greengram cultivation during summer. Plant geometry plays an important role in the dominance and suppression during the process of competition. Ideal plant geometry is precious and important for better and efficient utilization of available plant growth resources in order to get maximum productivity in crops. Nutrient management is one more agronomic manipulation, playsan important role in yield maximization in greengram. Even though greengram can fix atmospheric nitrogen, application of nitrogen fertilizer as starter dose at the time of sowing helps to improve the growth and development of greengram. It is also essential constituent of protoplasm, chlorophyll, coenzyme and protein. Phosphorus as major nutrient essential for cell formation, root development, photosynthesis, nucleic acid, sugar and starch transformation, grain formation, uniform and early maturity of the grains. Application of another major nutrient i.e. potassium is again neglected, but its application plays an important role in growth and development of crop as it helps in maintaining turgor pressure of cell which is necessary for the cell expansion and also helps in plant cell osmo-regulation. Sulphur is an essential element in forming proteins, enzymes, vitamins, chlorophyll and photosynthesis in plants. It is crucial in nodule development and caused for efficient nitrogen fixation in legumes. Sulphur increases crop yield and improves quality of the produce thus determining the market price a farmer would get for his produce. Keeping all these points in view, the experiments were conducted to find out the effect of different fertilizer levels, genotypes and spacing on yield attributes, yield and economics of greengram during summer seasons.

Materials and Methods

A field experiment was conducted during summer season of 2019 at Regional Research Centre (RRC), UAS Dharwad.The experiment was laid out in split-split plot design with two planting geometry (S 1: 30 cm × 10 cm and S 2: 45 cm × 7.5 cm) in main plot, two genotypes V 1: Shreya (IPM 02-14) and V 2: Meha (IPM 99-125)) in sub plot and three fertilizer levels in sub-sub plot {F 1: RDF (25:50:0 kg N: P 2 O 5 :K 2 O ha -1 + 20 kg S) ha -1 , F 2: 25:50:20 kg N: P 2 O 5 :K 2 O ha -1 + 20 kg S ha -1 and F 3: 31.25:62.5:25 kg N:P 2 O 5 :K 2 O ha -1 + 20 kg S ha -1 }. The crop was sown on February 7 th , 2019 and entire dose of nitrogen, phosphorus (P 2 O 5 ), potassium (K 2 O) and sulphurwas applied as basal at the time of sowing in the form of urea, DAP, MOP and gypsum, respectively as per the treatments. Seed rate used was 12 kg ha -1 for both planting geometry.Seeds were treated with Rhizobium and Phosphorus Solubilizing Bacteria (PSB)each at the rate of 500 gha -1 . The crop was grown under protective irrigation. Overall, five irrigations were provided with sprinklersfor the successful growth and development of the crop. The crop was harvested by picking the pods on 13-04-2019 and 20-04-2019.

Result and Discussion

Performance of genotypes Genotype Shreya recorded 14.6 and 10.1 percent higher seed yield and haulm yield, respectively, as compared to genotype Meha. This might be due to itsbetter growth and yield attributing parameters, primarily dry matter production, number of pods per plant and number of seeds per pod. These results are in accordance with the findings of Begum et al. (2009) [4] , Dash and Rautaray (2017) [6] and Singh et al. (2017a) [19] . The genotype Shreya recorded significantly higher number of pods per plant, pod weight per plant, number of seed per pod andthousand seed weight per plant (23.74, 9.87, 10.46 and 44.74 g,respectively) (21.70, 8.56,9.49 and 42.37g, respectively).This might be due to genetic make-up of the cultivar. These results are in-line with those of Khan and Malik (2001) [13] , who observed that genotypes differ significantly in number of pods per plant and number of seed per pod in greengram. Similar results were observed by Miah et al. (2009) [14] and Bhagwanrao (2011) [5] . Another important parameter to evaluate the translocation efficiency is harvest index (HI). Further it has been stated that the yielding capacity of genotype is correlated with increased seed to stalk ratio (HI). Total dry matter was the sole determinant of yield, whereas the harvest index of genotypes determines the efficiency of dry matter utilization. In the present study, genotype Shreya recorded a maximum harvest index (25.67%) than Meha (24.88%), attributing to greater dry matter accumulation towards seed development and these results are in line with findings of Miah et al. (2009) [14] , Bhagwanrao (2011) [5] and Singh et al. (2017a) [19] .

Effect of planting geometry on yield and yield components

The yield potential of a particular genotype can be exploited under optimal planting geometry in a given environment where competition between plants is minimum. Optimum planting geometry leads to efficient utilization of soil moisture and nutrients and also avoids competition among the plants. In the present study effect of planting geometry on yield components were found to be non significant. This might be due to plant population remains same in both 30 cm × 10 cm and 45 cm × 7.5 cm. However, numerically 30 cm × 10 cm recorded higher seed (684 kg ha -1 ) and haulm yield (2,594 kg ha -1 ) than 45 cm × 7.5 cm (610 and 2,519 kg ha -1 , respectively). Higher yield in 30 cm × 10 cm was due to efficient utilization of natural resources than 45 cm × 7.5 cm as a result of optimum spacing. These results are in accordance with findings of Srivastava and Dawson (2017) [20] , who found on par yield and harvest index at 30 cm × 10 cm and 45 cm ×6.5 geometry, similar results were foundby Ihsanullah et al. (2002) [9] .

Effect of nutrient management on growth and yield

Application of 31.25:62.5:25 kg N:P 2 O 5 :K 2 O ha -1 + 20 kg S recorded significantly higher seed (743 kg ha -1 ) and haulm yield (2,784 kg ha -1 ) as compared to application of 25:50:20 kg N:P 2 O 5 :K 2 O ha -1 + 20 kg S (608 and 2,477 kg ha -1 , respectively) and RDF (591 and 2409 kg ha -1 , respectively). The increase in yield may be attributed to adequate and balanced supply of plant nutrients to the crop during the growth period, which increased the availability of nutrients to plants and favourable increase in plant height, accumulation of dry matter, increased photosynthetic activity due to increased leaf area, higher number of pods, 1000 seed weight and finally seed and haulm yield. These results are in conformity with the findings of Awomiet al., 2012 [2] , Bairwa et al., 2012 [3] and Suryavanshi et al., 2017 [21] . The increased yield was also due to higher harvest index with application of 31.25:62.5:25 kg N:P 2 O 5 :K 2 O ha -1 + 20 kg S (26.73%) as compared to application of 25:50:20 kg N:P 2 O 5 :K 2 O ha -1 + 20 kg S (24.64%) and RDF (24.46%). This was due to efficient translocation of photosynthates from source to sink (leaf and stem to pods). These results confirm the findings of Rajput and Rajput (2017) [18] . Application of 31.25:62.5:25 kg N:P 2 O 5 :K 2 O ha -1 + 20 kg S recorded significantly higher number of pods per plant (24.72), number of seeds per pod (10.98), pod weight per plant (10.50 g), thousand seed weight (45.54 g) and harvest index (26.73%) as compared to 25:50:20 kg N: P 2 O 5 :K 2 O ha -1 + 20 kg S and RDF (Table 1,2 and 3). The increase in number of seeds per pod may be due to adequate availability of nutrients during crop growth period and the important role played by potassium in energy transformation, enzyme activation, which are involved in carbohydrate metabolism and simultaneously higher transformation of photosynthates into reproductive parts which resulted in increased number of seeds per pod. Higher pod weight per plant is mainly due to increased number of pods per plant. Increased thousand seed weight can be attributed to the enhanced photosynthetic capacity resulting from greater number of leaves, increased leaf area and chlorophyll content. This led to higher rate of photosynthesis providing a greater supply of photosynthates to sink, which could have enabled the seeds to grow to full size, contributing to a significant increase in thousand seed weight. Similar findings were reported by Mondal et al. (2003) [15] , Oad et al. (2003) [16] and Rajput and Rajput (2017) [18] .

Interaction effect of genotypes, planting geometry and nutrient management on growth and yield of greengram

In the present investigation interaction effects between genotypes, planting geometry and nutrient management were non significant. However, genotype Shreya sown at 30 cm × 10 cm planting geometry along with application of 31.25:62.5:25 kg N:P 2 O 5 :K 2 O ha -1 + 20 kg S ha -1 recorded higher seed (845 kg ha -1 ) and haulm yield (2979 kg ha -1 ) as compared to other treatment combinations (Table 3). Increase in seed yield was attributed to increased growth and yield attributes. Increased yield parameters attributed to higher harvest index (28.72%) over other treatment combinations. The results are in accordance with results reported by Hussain et al., 2011 [8] , Gorakhnath, 2012 [7] and Srivastava and Dawson, 2017 [20] . Lower seed yield and haulm yield were recorded with genotype Meha sown at 45 cm × 7.5 cm spacing with application of RDF (551 and 2300 kg ha -1 , respectively). This might be due to less availability of nutrients and less intra row spacing which increases competition for solar radiation that ultimately reduces growth of some intra row plants at vegetative phase and they were unable to reach reproductive phase which results in low yield. These results are in accordance with findings of Kalsariaet al., 2017 [10] .

Economics

Economics is the primary criterion for assessing the best treatment in terms of efficient utilization of growth resources, namely solar radiation, water and nutrients. Genotypes and nutrient levels have a significant effect on economics. Genotype Shreya recorded significantly higher gross return, net return and B: C ratio than Meha (Table 4). Variation in all economic constituents among genotypes was a result of higher yield. Similar findings were reported by Gorakhnath (2012) [7] ,Rajput and Rajput (2017) [18] and Kartik et al. (2020) [11] . Greengram sown with 30 cm × 10 cm recorded significantly higher gross return ( 51,967 ha -1 ), net return ( 10,867 ha -1 ) and B: C ratio (1.26) as compared to greengram sown at 45 cm × 7.5 cm ( 46,297 ha -1 , 10,625 ha -1 and 1.13, respectively). This isattributed to higher yield and high market price during the cropping period. These results are in line with findings of Chetan (2015) and Rohidas, (2015). Among nutrient levels, application of 31.25:62.5:25 Kg N: P 2 O 5: K 2 O ha -1 + 20 kg S ha -1 recorded significantly higher gross return ( 56,350 ha -1 ), net return ( 13,850 ha -1 ) and B: C ratio (1.33) as compared to application of 25:50:20 Kg N: P 2 O 5 :K 2 O ha -1 + 20 kg S ( 46,146 ha -1 , 5,784 ha -1 and 1.14, respectively) and RDF ( 44,900 ha -1 , 4,961 ha -1 and 1.12, respectively). This might be due to higher yield. These results are in confirmation with findings of Khairnar and Solanke (2009) [12] and Patil and Dhonde (2009) [17] . Among the treatment combinations genotype Sherya sown at 30 cm × 10 cm spacing along with application of 31.25:62.5:25 kg N: P 2 O 5: K 2 O ha -1 + 20 kg S ha -1 recorded higher gross return ( 64,000 ha -1 ), net return ( 21,500 ha -1 ) and B: C ratio (1.51) as compared to other combinations. The lower gross return ( 39,700 ha -1 ), net return ( 492 ha -1 ) and B:C ratio (1.01) were recorded in genotype Meha sown at 45 cm × 7.5 cm with application of RDF. This is attributed to lower yield and higher cost of inputs.

Conclusion

Based on the results of the experiment, it is concluded that genotype Shreya exhibited superior performance in terms of seed yield, haulm yield, gross return, net return and B:Cratio. The application of 31.25:62.5:25 kg N:P₂O₅:K₂O per hectare, along with 20 kg sulphur per hectare, further enhanced these parameters. However, planting geometry did not significantly affect yield and economic outcomes.

References

1. Anonymous. Area and Production. Directorate of Economics and Statistics, Department of Agriculture and Cooperation, New Delhi; 2018. Available from: www.indiastat.com
2. Awomi TA, Singh AK, Manoj K, Bordoloi LJ. Effect of phosphorus, molybdenum and cobalt nutrition on yield and quality of mungbean (Vigna radiata L.) in acidic soil of Northeast India. -Indian J Hill Farming. 2012;25(2):22-6.
3. Bairwa RK, Nepalia V, Balai CM, Upadhyay B. Effect of phosphorus and sulphur on yield and economics of summer greengram (Vigna radiata L.). Madras Agric J. 2012;99(79):523-5.
4. Begum MST, Begum M, Anwar PMD, Juraimi AS. Optimizing seed rate for summer mungbean varieties. J Agric Soc Sci. 2009;5:114-8.
5. Bhagwanrao BA. Effect of varieties and plant geometry on growth and yield of summer greengram [MSc (Agri.) thesis]. Parbhani: Marathwada Krishi Vidyapeeth; 2011.
6. Dash SR, Rautaray BK. Growth parameters and yield of greengram varieties (Vigna radiata L.) in east and south east coastal plains of Odisha, India. Int J Curr Microbiol Appl Sci. 2017;6(10):1517-23.
7. Gorakhnath JR. Response of greengram varieties to plant geometries during summer [MSc (Agri.) thesis]. Parbhani: Marathwada Krishi Vidyapeeth; 2012.
8. Hussain MS, Karim MF, Biswas PK, Kawochar MA, Islam MS. Effect of rhizobium inoculation and chemical fertilization on the yield and yield components of mungbean. J Expt Biosci. 2011;2(1):69-74.
9. Ihsanullah, Taj FH, Akbar H, Basir A, Ullah N. Effect of row spacing on agronomic traits and yield of mungbean (Vigna radiata L. Wilczek). Asian J Plant Sci. 2002;1(4):328-9.
10. Kalsaria RN, Vekariya PD, Hadiyal JG, Ichchhuda PK. Effect of spacing, fertility levels and bio-fertilizers on growth and yield of summer greengram (Vigna radiata L.). J Pharmacogn Phytochem. 2017;6(5):934-7.
11. Kartik HP, Shah KA, Patel HB. Response of summer greengram [Vigna radiata (L.) Wilczek] varieties to different nutrient management under South Gujarat condition. Int J Curr Microbiol Appl Sci. 2020;9(5):104350.
12. Khairnar AV, Solanke AV. Response of potash levels and foliar spray of vermiwash on growth and yield of greengram. J Maharashtra Agric Univ. 2009;34(2):215-6.
13. Khan A, Malik MA. Determining biological yield potential of different mungbean cultivars. Online J Biol Sci. 2001;1(7):575-6.
14. Miah MAK, Anwar MP, Begum M, Juraimi AS, Islam MA. Influence of sowing date on growth and yield of summer mungbean varieties. J Agric Soc Sci. 2009;5:73-6.
15. Mondal SS, Chettri M, Sarkar M, Nita C. Growth and productivity of greengram as influenced by levels of potassium and sulphur under irrigated and unirrigated condition. J Potassium Res. 2003;19:107-10.
16. Oad FC, Nadi A, Shah GH, Galoo SH. Phosphorus and potassium requirement of mungbean (Vigna radiata L.). Pak J Appl Sci. 2003;3(6):428-31.
17. Patil SM, Dhonde MB. Effect of potash levels and foliar spray of cow urine on growth and yield of summer greengram. J Maharashtra Agric Univ. 2009;34(1):106-7.
18. Rajput BS, Rajput RL. Response of promising rainy summer season greengram (Vigna radiata L.) genotypes to phosphorus fertilization. Legume Res. 2017;40(1):170-2.
19. Srivastava N, Dawson J. Effect of spacing, source of nutrient and methods of zinc application on yield and yield attributes of summer greengram (Vigna radiata L.). Int J Chem Stud. 2017;5(5):1789-91.
20. Suryavanshi BR, Bhosale AS, Jadhav YR, Kurne RA. Effect of fertilizer levels and plant densities on growth and yield of summer greengram (Vigna radiata L.). Trends Biosci. 2017;10(26):5577-80.