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B. SIVAKUMAR, M. SRINIVASA REDDY*, P. KAVITHA AND S. TIRUMALA REDDY
Department of Agronomy, Agricultural College, Mahanandi, ANGRAU, Kurnool (Dist) (A.P.), India.
A field experiment was conducted during kharif, 2014 to study the influence of different sowing dates and plant densities on productivity of soybean. It was comprised of nine treatments with three sowing dates (June 28, July 14 and July 29) and three row spacing’s (30 cm × 10 cm, 45 cm × 10 cm and 60 cm × 10 cm) and replicated thrice. Plant height, drymatter production, leaf area index (LAI), days to 50 per cent flowering, numbers of pods plant-1 (44.7), number of seeds per pod-1 (2.2), seed yield (1487 kg ha-1), haulm yield (2496 kg ha-1), harvest index (39.1%) and test weight (9.9 g) increased with early sowing on June 28 than later. Productivity of soybean was inconsistent with different row spacing’s. The highest plant height, drymatter production, leaf area index (LAI), seed yield (1396 kg ha-1), haulm yield (2386kg ha-1) and harvest index (39.2%), were recorded at a spacing of 30 cm × 10 cm. More number of days to 50 per cent flowering, highest number of pods plant-1 (48.1), number of seeds pod-1 (2.1) and test weight (9.9 g) were recorded at a spacing of 60 × 10 cm. The interaction between sowing dates and row spacing’s was significant with all the growth parameters and yield attributes except number of seeds pod-1 and test weight.
Growth, Plant densities, Sowing dates, Soybean, Yield attributes and Yield.
Soybean [Glycine max (L.) Merrill] is an important oilseed crop, which plays an important role in Indian economy. Soybean has now established as number one crop, among oilseeds and contributes more than 50 per cent of oilseed production and 30 per cent of vegetable oil production. In India, it is mainly grown in Madhya Pradesh, Maharashtra and Rajasthan (AICRPS, 2008). It occupied an area of 12 mha and production of 12.8 mt and with productivity of 1079 kg ha-1. It is a good source of protein (40%), oil (20%), unsaturated fatty acids and minerals like Ca and P including vitamin A, B, C, D which can meet different nutritional needs of human and animals (Mondal et al., 2002). Besides, its main use for oil extraction, it can be used for dal, soya milk, tofu etc. The productivity of soybean is low due to various constraints. Time of sowing has a considerable influence on growth and yield of soybean. Early sowing in the season may encourage higher vegetative growth which may invite various diseases and insects pests. However, delayed sowing may shrink the vegetative phase, which in turn reduces dry matter accumulation leading to poor realization of the potential yield. In addition to sowing time, planting density is one of the main factors that has
an important role on the growth and yield of soybean. The optimum plant density and time of sowing for higher yield may differ from location to location. Therefore, an experiment was initiated to study the optimum sowing time and optimum plant density.
A field experiment was conducted during kharif, 2014 at college farm, Agricultural College, Mahanandi, ANGRAU. The soil of the experimental site was sandy loam and it was slightly alkaline in reaction with a pH of 7.98, EC of 0.06 dSm 1 and low in organic carbon (0.46%) and available nitrogen (266 kg ha-1), high in available phosphorous (145 kg P 2O5 ha-1) and high in available potassium (774 kg K2O ha-1). The experiment was laid out in factorial randomized block design and replicated thrice. The treatments consisted of three sowing dates viz., D1 (June 28), D2 (July 14) and D3 (July 29) and three plant densities, viz., S1: 30 × 10 cm (3.33 lakh plants ha-1), S2: 45 × 10 cm (2.22 lakh plants ha-1) and S3: 60 × 10 cm (1.66 lakh plants ha-1) . Variety JS-335 which matures in 80-85 days was tested in the experiment. Recommended fertilizer dose of 60kg P2O5 and 40kg of K2O through Single Super Phosphate and muriate of potash respectively was applied as basal at the time of sowing. Whereas nitrogen @ 30kg was applied through urea in two equal splits, one at the time of sowing and another at 30 days after sowing (DAS). No serious attack of pests and diseases was observed. However, minor incidence of tobacco caterpillar (Spodoptera litura (Fab.) was observed at flowering. Monocrotophos @ 2 ml L-1 and Acephate (0.08%) @ 2g L-1 were used for effective control of pest. Weeding was done at 15 and 30 DAS for each sowing date to keep the plots weed free. When crop was subjected to prolonged dry spell irrigation was given to protect the crop. The total rainfall received during crop growth was 515.2 mm in 28 rainy days. Five plants were randomly selected in the net plot area and tagged. The biological data was collected from the tagged plants at 30 days interval up to harvest, where as the yield attributes and yield were recorded at harvest.
The differences in plant height, total drymatter production, leaf area index and days to 50 per cent flowering were significant due to different sowing dates. Sowing of soybean on June 28 recorded significantly higher plant height, total drymatter production and leaf area index over rest of the sowing dates i.e. July 14 and July 29 (Table 1). The increase in growth parameters in early sowing date might be due to favorable environment enjoyed by early sown crop than that sown at later dates even after receiving similar inputs resulting in more plant height and vigorous vegetative growth. The less number of nodes and reduced inter nodal distances caused by non-optimal sowing time could be also the reason for reduction in plant height under delayed sowing. Sowing of soybean on July 29 resulted in early flowering followed by July 14 sowing. The reduction in total duration from sowing to 50 percent flowering might be due to photosensitivity of soybean.
Yield attributes such as number of pods plant-1, number of seeds pod-1, test weight and yield significantly influenced by different sowing dates. The higher number of pods plant-1 (44.7), number of seeds pod-1 (2.2) and test weight (9.9 g) were recorded with sowing at June 28 over other two sowings (Table 2). This might be due to adequate and increased availability of nutrients for development of more number of pods plant-1 and better seed filling with maintenance of better source-sink relationship. Similar results have been reported by Halvankar et al. (2001) .
Significantly highest seed yield (1487 kg ha-1), haulm yield (2496 kg ha-1) and harvest index (39.1) were recorded with early sowing of June 28 over other sowings and this might be due to partition of higher proportions of its total drymatter into component parts of the plant. Added to the above, better growth and development of crop sown at June 28 date when compared to other dates of sowing in all aspects might have reflected in better yield expression. Billore et al. (2000) also reported higher yield in early sowing which was ascribed to higher values of harvest index. The seed yield and haulm yield were decreased from June 28 to July 29 sowing. Delayed sowings on July 29 produced the lowest seed yield and haulm yield. This might be due to best performance of early sown crop due to prevailing high temperature and moisture during crop growth period that resulted in increased drymatter and which in turn reflected in higher seed yield. Similar results were also reported by Amarajyothi and Pullarao (2002).
With regard to spacing’s, narrow row spacing 30 cm× 10 cm recorded significantly highest plant height, total drymatter production, leaf area index and reduced number of days to 50 per cent flowering followed by medium row spacing (45 cm × 10 cm). The positive relationship of closer spacing on growth attributes might be attributed to the cumulative effect of more number of plants unit area-1, high inter-plant competition which caused internodal elongation, higher leaf area index and more light interception as reported by Halvankar et al. (1993). With regard to row spacing narrow row spacing 30 cm × 10 cm resulted in early 50 per cent flowering than 45 cm × 10 cm and 60 cm × 10 cm spacing’s. The reduction in days to 50 per cent flowering might be due to intra plant competition in dense planting. This was also observed by Hariram et al. (2010).
With regard to row spacings, the number of pods plant-1, number of seeds pod-1 and test weight were increased significantly with increasing row spacing from 30 cm × 10 cm, 45 cm × 10 cm to 60 cm × 10 cm spacings. Significantly highest number of pods plant-1 (48.1), seeds pod-1 (2.1) and test weight (9.9 g) were recorded with the spacing of 60 cm × 10 cm than other row spacing’s. Less
competition in wider spacing and ample availability of light, moisture, better source sink relationship and nutrients might had resulted in more number of branches plant-1 which in turn might have increased more number of pods plant-1, more number of seeds pod-1 and also increased test weight. Increase in number of pods plant-1, number of seeds pod-1 and test weight with wider row spacing was also reported by Masum Akond et al. (2012).
Among different row spacing significantly highest seed yield, haulm yield and harvest index were recorded with narrow row spacing of 30 cm × 10 cm over other two spacings. Though all the yield attributing characters were higher at wider spacings, these improvements were not sufficient to compensate the yields that were obtained due to higher plant population per unit area from closer spacing. Similar increase in seed yield, haulm yield and harvest index at closer spacing was also reported by Manjappa et al. (2002).
The interaction between sowing dates and row spacings had significant influence on growth parameters, yield parameters and yield of soybean.
Sowing of soybean on June 28 with the spacing of 30 cm × 10 cm attained maximum plant height, total drymatter production and leaf area index over other combinations of sowing dates and row spacing. Sowing of soybean on July 29 with a spacing 30 cm × 10 cm resulted in early flowering. Sowing of soybean on June 28 with the spacing of 60 cm × 10 cm attained the maximum number of pods plant-1 over other combinations of sowing dates and row spacing’s. The interaction between date of sowing and row spacing was not significant with regard to number of seeds pod-1 and test weight. Sowing of soybean on June 28 with the spacing level of 30 cm × 10 cm attained the maximum seed yield, haulm yield and harvest index over other combinations of sowing dates and row spacings.
From above investigation, it can be concluded that sowing of soybean on June 28 with the spacing of 30 cm× 10 cm row spacing was more beneficial for getting higher seed yield in soybean on sandy loam soils of scarces rainfall zone of Andhra Pradesh.