The effect of various organic nutrient management techniques on growth attributes of pearl millet

Introduction

Pearl millet (Pennisetum glaucum L.) belongs to the grass family Graminaceae. The world's tropics and subtropics are home to the plant genus Pennisetum. Pearl millet has an extremely high photosynthetic efficiency since it is a C4 plant. The primary reason for pearl millet's widespread cultivation in arid and semi-arid locations is its greater adaptability to water stress and nutrient-depleted soils than other cereal crops. India is the largest pearl millet producer in the world, producing 10.86 million tonnes annually on an area of 7.65 million hectares with a 1420 kg ha -1 average productivity. It is primarily grown in the states of Rajasthan, Gujarat, Maharashtra, Haryana, Uttar Pradesh, and Karnataka. The use of organics, among the various agronomic management approaches, is of immense important in rainfed areas in order to produce healthy plants. Building and maintaining an active and rich soil type is essential, despite the fact that they have a lower concentration of nutrients and need more labour to handle, they have seen a significant growth in their use as a nutrition source over inorganic fertilizer (Kannan et al., 2005) [5] . By increasing the activity of soil microflora and fauna, organic liquid manures like jeevamrutha help in the quick growth of soil fertility (Devakumar et al., 2014) [1] . These functions both as fertilizer and a biopesticide and they serve an important function in stimulating plant development and giving the plant system immunity. Since there is currently a significant difference between the amount of nutrients applied and the amount of nutrients utilised by the crop, nutrient mining is a significant issue for agricultural productivity. Farmers using fertilizers indiscriminately without knowing the soil fertility status and poor nutrient management are two of the main causes of reduced productivity. Numerous studies have demonstrated the effectiveness of nitrogen fertilization in increasing millet production, as well as the relationship between a sufficient nitrogen supply and vigorous vegetative growth. It also responds effectively to phosphorus that has been applied (Malik et al., 1990) [7] . Farmyard manure improves the crop's nitrogen usage efficiency, as well as the status of organic carbon, accessible nitrogen, P2O5 and trace elements in the soil, while reducing the negative impacts of salinity ,soil acidity, and alkalinity. Vermicompost improves humus content, lowers the C: N ratio, and provides a variety of readily available nutrients for plants, including nitrate, phosphate, potassium, calcium, and magnesium. (Talashikar et al., 1999) [12] .

Materials and Methods

A field experiment was carried out during Kharif, 2021 at College of Agriculture farm, Vijayapur, Karnataka on vertisol with pH 8.32 and EC 0.22 dS m-1. The soil had a medium level of P2O5 that was readily available. (31 kg ha-1 ) and organic carbon (0.47%), while having low levels of available N (168 kg ha -1 ) and high levels of available K2O (410 kg ha -1 ). The experimental site had coordinates of 16° 77' North, 75° 74' East, and an elevation of 516.29 metres above mean sea level. It was located in the Northern Dry Zone of Karnataka (Zone 3). A fully randomised block design with three replications was used to set up the experiment. Twelve different combinations of organic manures, including jeevamrutha foliar sprays, vermicompost, and FYM, were used in the experiment's 12 treatments. After the previous crop was harvested, the area had one ploughing and two harrowings. The plots were laid out and the land was treated to a good seedbed before sowing. The variety VPMV-9 was used and fertilizers were applied according to the treatments. The crop was sown on 26 th July 2021 with a spacing of 45 × 10 cm. Harvesting was done on 25 th October 2021, As the crop reached the milky dough stage, five randomly chosen and tagged plants from each treatment were picked and used individually for documenting various observations. The Bajra heads from the net plot were cut, sundried and threshing was done with threshing machine, grains per plot thus collected were winnowed, cleaned and weighed. Intercultivation was done to remove all weeds from the field in order to check crop weed competition. The experiment's data was collected at various growth phases as well as upon harvest, and they were statistically analysed as per Gomez and Gomez's (1984) [3] instructions. The 'F' and 't' tests' level of significance was set at P=0.05. Critical difference (CD) values were computed at a 5% level of confidence if the F test is significant.

Results and Discussion

Growth parameters such as plant height (177.7 cm), the number of tillers per plant (4.01) the number of green leaves per plant (14.33) and SPAD values (38.52) were significantly higher in the treatment (T1) with the recommended package of practices, compared to all other treatments. However, among various combinations of organic sources applied, the soil application of FYM @ 5 t ha -1 + foliar application of 20% jeevamrutha at 45 DAS (T5) recorded higher plant height (177.7 cm), the number of tillers per plant (4.01) the number of green leaves per plant (14.33) and SPAD values (38.52) than other organic sources (Table 1). Due to the polysaccharides and other organic chemicals that are released as organic matter breaks down and has a cementing effect, taller plants, more leaves, more tillers, and ultimately a higher yield are produced when FYM and jeevamrutha are applied together. The objective is to supply nutrients to crops in accordance with demand at various stages, which can increase agricultural productivity. Studies revealed that combining different organic sources produced improved results and increased productivity than using them individually. ( [9,2,8,11,6] . The total amount of dry matter produced is a sign of overall resource use efficiency and better light interception. The results on the total dry matter and its partitioning (leaf, stem, and reproductive sections) showed that the combination of different organic manures applied had a significant impact on the dry matter. There has been an improvement in the dry weight of the leaves (26.55 g plant-1), stems (120.4 g plant-1), and panicles. (97.04 g plant -1 ) and total dry matter production of 243.9 g plant - 1 with the recommended package of practices (T1) than all other treatments. However, among different combinations of organic sources applied, treatment (T5) with soil application of FYM @ 5 t ha -1 + foliar application of 20% jeevamrutha at 45 DAS recorded significantly higher stem dry weight, leaf dry weight, panicle dry weight and total dry matter production than other organic sources. Increased nutrition availability from organic and foliar sources as well as the efficient conversion of nutrients from organics may be the cause of this increased dry matter production. Additionally, the use of liquid organic manures has increased leaf area production, solar radiation absorption, photosynthesis, and consequently improved all growth parameters, leading to an increase in dry matter production. These results are similar to the findings of Shete et al. (2010) [9] , Ghanshyam et al. (2010) [2] , Meena and Ram (2013) [8] , Sohu et al. (2015) [11] and Kiran et al. (2016) [6] . Crop growth rate and relative growth rate indicates the change in dry weight or logarithmic growth of plant over a period of time. The recommended package of practices recorded significantly higher CGR at 40-70 DAS (0.82 mg dm -2 day -1 ) and numerically the higher value of 1.18 mg dm -2 day -1 at 70-90 DAS. However, among the different organic nutrient management practices the soil application of FYM @ 5 t ha -1 + foliar application of 20% jeevamrutha at 45 DAS recorded significantly higher CGR at 40-70 DAS (0.76 mg dm -2 day -1 ) and numerically higher value of 1.18 mg dm -2 day -1 at 70-90 DAS than other organic sources. This might be due to the foliar application of organics manures which contains macro and micro nutrients along with that vitamins and plant growth promoting substances and beneficial organisms.The soil application of vermicompost @ 1.25 t + FYM @ 2.25 t ha -1 + Foliar spray of 10% jeevamrutha at 45 DAS recorded numerically higher value (24.22 mg g -1 day -1 ) of relative growth rate at 40-70 DAS and at 70-90 DAS numerically higher RGR of 13.68 mg g -1 day -1 was recorded with the soil application of vermicompost @ 2.5 t ha -1 + Foliar spray of 20% jeevamrutha at 45 DAS as compared to other treatments. Economic gain is one of the main factors in any technology's success and will not be embraced by the farming community unless it is economically viable. Economic analysis indicated that treatments receiving RDF recorded significantly higher net returns (₹ 22068 ha -1 ) and BC ratio (2.05). However, among different organic nutrient management practices soil application of FYM @ 5 t ha -1 + foliar spray of 20% jeevamrutha at 45 DAS recorded significantly higher net returns and BC ratio than other organic sources. This was attributed to higher grain yield and haulm yield of pearl millet due to the combined application of organics. These results are similiar with the findings of Shwetha (2008) [10] and Kiran et al. (2016) [6] .

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