Influence of nutrient inputs on growth and yield of zero-tillage cowpea in coastal Konkan conditions

Introduction

A unique gem of Indian crop husbandry, pulses. Farmers have farmed pulses for millennia, supplying India's people with nutritious sustenance. Pulses are a valuable gift from nature to humanity. They feed, increase soil health and boost crop yield. Pulses are an essential part of cropping systems nationwide because to their nitrogen fixation capabilities, deep root system, low water need and drought resistance. Pulses help save soil, water and nutrients. Pulses need less water than grains. Cereals use 60% of global water, whereas pulses consume 4%. Pulses utilize water more effectively than other crops owing to their morphology and physiology. Pulses boost crop nutrient efficiency and nitrogen utilization efficiency (Sharma, 2013) [19] . Cowpea is a widely adapted and variable crop grown worldwide as a pulse, vegetable, cover crop and fodder. It is also known as crowder pea, black eyepea, kaffirpea, chinapea, sourthen pea, lubia, niebe and coupe. Cowpea (Lobia) is a pulse, fooder and green manure crop. Cowpea, Vigna unguiculata L., is a Leguminoceae plant with chromosome 2n = 22. It is called vegetarian meat since it is high in proteins and other nutrients. Cowpea grains include 23.4% proteins, 1.8% lipids, 60.3% carbs, 3.4% fiber, 3.3% ash and 9-11% moisture by dry weight. For human consumption and concentrated animal feed (Singh, 2007) [21] . Most wild cowpeas originate from Central Africa. Many nations currently have it. The most pulses are grown in Maharashtra, followed by Madhya Pradesh, Uttar Pradesh, Rajasthan and Andhra Pradesh. Pulses yield, area and output were low and constant. Very few districts harvested more than 0.8 or 1 t/ha of kharif pulses (Anonymous, 2013) [1] [2] . Tillage is mechanically loosening the soil to promote seed germination, seedling planting and crop development. Tilth is the physical conditions created by tillage. Recently, research has shifted the perception of tillage from a "art" to a "science". Zero tillage involves planting seeds directly into untilled soil that retains crop leftovers. Also called no-till. Zero-tillage agriculture practices save water, protect soil fertility, improve output and enhance farmer profitability by lowering production costs. Zerotillage involves planting crops into untilled soil by opening a thin hole or trench only wide enough to cover the seeds. Other soil tillage is avoided. Zero-tillage cuts expenditures by 15-16%. Positive environmental consequences of zero tillage in Indo-Gangatic plains. It conserves fossil fuels, greenhouse gases and water (Onuh, 2009) [13] . Weed management has traditionally been a resource-intensive crop production process. Weeds deprive agricultural plants of nutrients and water, host insects and pests and complicate harvesting and processing. Good weed control frequently combines available technology with traditional and cultural traditions. Today's intense agriculture causes micronutrient deficiencies. Therefore, micronutrient status and pulse response must be studied. Micronutrients' extensive influence on nodulation and physiological activities has drawn attention to their active function (Pramanik et al.2008) [15] . A micronutrient is a small-quantity element needed for plant development. Micronutrients, like all important nutrients, have specialized functions in plants and must be present in soil above threshold levels in accessible form for the plant to complete its lifespan. These critical nutrients cannot be replaced by other nutrients. The micronutrients (B, Zn, Cu, Mo) are crucial for plant enzymatic processes, chlorophyll synthesis, glucose generation and respiration (Rajesh, 2015) [16] . Foliar sprays need fewer nutrients and absorb them quickly. Foliar nutrients enter cells via the leaf cuticle. Foliar feeding is an essential fertilizing strategy in contemporary agriculture. Increasing cowpea yield requires water management. Based on new scientific information, pulse water needs must be determined urgently. Pulses may produce little because to excessive vegetative growth, flower shedding and immature pods (Vikas et al., 2014). Cowpea yields better in optimal conditions, but environmental changes can cause hormonal imbalance and abscission of assimilatory structures. Plant growth regulators regulate excessive vegetative growth and promote source-sink balance, boosting crop yield (Nagaraju, 1996) [12] .

Materials and Methods

The Present investigation was carried under Konkan condition at Agronomy farm, College of Agriculture, Dapoli, Dist Ratnagiri (M.S.) during rabi hot weather season of the year 2016-17. The analytical work was done in research laboratory of the Department of Agronomy. The field experiment was performed at the Agronomy Farm, College of Agriculture, Dr. Balasaheb Sawant Konkan Krishi Vidyapeeth, Dapoli, Dist. Ratnagiri (M.S.) on plot 22 of 'A' block during rabi season 2016. Rabi cowpea was grown soon after kharif rice harvest using zero-tillage techniques. Precipitation in this subtropical region averages 3500 mm per year, falling from June to October in 95 to 100 days. The meteorological observatory at Agronomy farm, College of Agriculture, Dapoli collected weather data from 46th MW of 2016 to 7thMW of 2017 (the trial phase). In 2016-17, morning and afternoon RH ranged from 88 to 91.3 percent and 38 to 67.9 percent, respectively. The bright sunshine hours in 2016-17 varied from 6.9 (46th MW) to 9.3 (04th MW). The experimental plot has lateritic soil from mixed parent material. These soils include mostly kaolinite and some illite. Flat terrain makes the experimental field excellent for rabi cowpea growing. By screw auger, composite soil samples were obtained from 30 m deep before the experiment to examine physical and chemical parameters. The recovered soil was dried and stored in aluminum bins. Its physico-chemical characteristics were then examined. The experiment was conducted on cowpea (variety Konkan Sadabahar) using a spacing of 30 × 15 cm. A Randomized Block Design was adopted with three replications to ensure accuracy. Each treatment was applied within a gross plot size of 6.0 m × 4.5 m under uniform agronomic conditions. Plant height (cm): Plant height was recorded from randomly selected five plants and then average was worked out. Height of plant was measured in centimeter from the ground level to the tip of joining of the trifoliate on peduncle.

Number of functional leaves per plant:

The number of functional leaves per plant was recorded by counting functional leaves of five sample plants from the net plot and then the average was computed.

Number of branches per plant:

Number of branches per plant was studied by counting the main and lateral branches collectively of five randomly selected plants from each net plot and the average number of branches per plant was worked out.

Number of pods per plant:

The number of green pods per plant were counted from the five sample plants and the average mean was calculated.

Grain yield (q ha -1 ): The plot wise grain yield data was recorded after proper drying, threshing and cleaning of cowpea grains. The plot wise data was then converted on hectare basis (q ha -1 ).

Stover yield (q ha -1 ): The straw obtained from each treatment plot was sundried for about 10 days, weighed and then per plot straw yield data was recorded and converted on hectare basis (q ha -1 ).

Statistical tool: Analysis of variance was used to analyze experimental data in randomized block design. Panse and Sukhatme (1967) [23] tested the significance of the treatment difference using a variance ratio test (f value), critical difference (C.D.) at 5% probability and treatment means for statistical interpretation.

Results and Discussion

Plant height (cm) Plant height (Table 2) in cowpea exhibited a consistent and significant increase with the progressive addition of inputs across treatments. The tallest plants were recorded in T 8 (20.15 cm), which was significantly superior to all other treatments and at par with higher input treatments like T 6 and T 7 . Treatments T 3 to T 5 also showed marked improvement over T 1 (absolute control) and T 2 , indicating the positive influence of RDF, biofertilizers and multinutrient application. The lowest plant height was recorded in T 2 (7.25 cm), even lower than control (13.06 cm), possibly due to initial stress or treatment imbalance. The overall trend clearly indicates that integrated nutrient management, plant protection and irrigation significantly enhanced vegetative growth. Similarly increase in plant height under application of different fertilizers and bio-fertilizers was observed by Swain and Rathore (2006) [22] , Meena et al. (2006) [10] , Mohite et al. (2012) [11] . Increased plant height due to fertilizers, micronutrients and plant growth regulators was observed by Marimuthu et al. (2015) [8] , increased plant height due to irrigation and fertilizer was recorded by Borse et al.

Number of functional leaves per plant

The number of functional leaves per plant (Table 2) increased significantly with the advancement of treatments. T 8 recorded the highest number of leaves (13.05), followed closely by T 7 (12.22) and T 6 (12.19), showing statistical superiority over lower treatments. The treatments involving RDF, biofertilizers and multinutrient sprays (T 3 -T 5 ) also showed improved leaf production compared to control. The lowest number of leaves was observed in T 1 (7.43). This increase in leaf number can be attributed to improved nutrient availability, better physiological activity and enhanced photosynthetic capacity under integrated crop management practices. These results are in agreement with the results reported by Meena et al. (2006) [10] , Shah et al.

(2006), Khan et al. (2009) [7] Choudhary et al. (2012), Marimuthu et al. (2015) [8] in case of fertilizer and irrigation application Borse et al. (2002) [4] .

Number of branches per plant

Branch development followed a similar increasing trend with the addition of inputs. The highest number of branches per plant (Table 2) was recorded in T 8 (8.38), which was significantly higher than all other treatments. T 7 (7.93) and T 6 (7.84) were statistically comparable and also superior to the rest. Lower treatments like T 1 (4.90) and T 2 (6.19) recorded significantly fewer branches. The increase in branching can be linked to improved plant vigor due to balanced nutrition, growth regulation through paclobutrazol and favorable growth conditions created by irrigation and plant protection measures. Similar findings were recorded by Pramanik et al. (2014) [15] , for weeding and bio-fertilizers, Mathur (2000) [9] , Meena et al.

(2006) [10] , Gami and Thanki (2011) [6] .

Number of pods per plant

The number of pods per plant (Table 2) showed a marked and significant improvement with treatment intensification. T 8 recorded the highest pod number (8.19), which was significantly superior to all other treatments. Treatments T 6 (6.23) and T 7 (6.37) also performed well but were inferior to T 8 . The lowest number of pods (2.5) was observed in control (T 1 ). Intermediate treatments (T 3 to T 5 ) showed gradual improvement, indicating the role of RDF, biofertilizers and micronutrients in enhancing reproductive growth. Increased pod formation is likely due to better flowering, reduced flower drop and improved nutrient translocation. These findings are close conformity with those of, Shinde et al. (1991) [20] Balachandran et al. (2005) [3] , Dhane et al. (2010) [5] , Gami and Thanki (2011) [6] , Mohite et al. (2011) [11] , Zaghloul et al. (2015) [25] .

Grain yield (q ha⁻¹) Grain yield (Table 2) increased significantly with the integration of improved agronomic practices. The highest grain yield was recorded in T 8 (11.16 q ha⁻¹), which was significantly superior to all other treatments. T 7 (8.55 q ha⁻¹) and T 6 (8.40 q ha⁻¹) were next best and statistically comparable. Treatments involving RDF, biofertilizers and multinutrient application (T 3 -T 5 ) showed moderate yields, while the lowest yield was observed in control (1.98 q ha⁻¹). The substantial increase in yield under T 8 can be attributed to combined effects of balanced nutrition, effective plant protection, growth regulation and irrigation, leading to improved source-sink relationship and higher productivity. These results confirm with the findings of Sarkar et al. (1998) [17] , Sawargonkar et al. (2006), Khan et al. (2009) [7] , Dhane et al. (2010) [5] Patil et al. (2011) [14] , Marimuthu et al. (2015) [8] .

Stover yield (q ha⁻¹) Stover yield (Table 2) followed a trend similar to grain yield, showing significant increases with higher treatment levels. The maximum stover yield was recorded in T 8 (22.24 q ha⁻¹), which was significantly higher than all other treatments. T 7 (15.51 q ha⁻¹) and T 6 (15.50 q ha⁻¹) were statistically at par and superior to lower treatments. The control (T 1 ) recorded the lowest stover yield (3.92 q ha⁻¹). The gradual increase in stover yield from T 3 onwards reflects the positive impact of integrated nutrient management and improved agronomic practices on vegetative biomass production. Enhanced plant growth, better nutrient uptake and improved physiological efficiency contributed to higher biomass accumulation. These results confirm with the findings of Sarkar et al. (1998) [17] , Sawargonkar et al. (2006), Khan et al. (2009) [7] , Dhane et al. (2010) [5] Patil et al. (2011) [14] , Marimuthu et al. (2015) [8] .

Conclusion

The present investigation clearly demonstrates that cowpea productivity and growth performance can be substantially enhanced through the adoption of integrated crop management practices under zero-tillage conditions. The study highlights the cumulative and synergistic effects of nutrient management, biofertilizer application, micronutrient supplementation, plant protection measures, growth regulation and irrigation on improving both vegetative and reproductive parameters of cowpea. The progressive increase in plant height, number of functional leaves and number of branches per plant from lower to higher treatment levels reflects the positive influence of balanced and integrated nutrient supply. The combined application of recommended dose of fertilizers (RDF), biofertilizers such as Rhizobium and PSB and multinutrient solutions significantly improved plant vigor by enhancing nutrient availability, uptake efficiency and physiological activities. The addition of paclobutrazol further optimized plant growth by regulating excessive vegetative development and promoting better canopy structure, which ultimately contributed to improved photosynthetic efficiency. The yield attributes, particularly number of pods per plant, showed a marked improvement with the intensification of treatments. This indicates that reproductive efficiency in cowpea is highly responsive to improved agronomic practices. Enhanced flowering, reduced flower drop and efficient translocation of assimilates from source to sink contributed to increased pod formation. Moreover, the study validates the effectiveness of zero-tillage practices in cowpea cultivation under Konkan conditions. Zero tillage not only reduces production costs but also conserves soil moisture, improves soil structure and supports sustainable crop production. When combined with integrated nutrient and crop management practices, it can significantly enhance crop productivity and resource-use efficiency.

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