Influence of organic and inorganic fertilizers on yield potential of linseed (Linum Usitatissimum L.)

Introduction

Oilseeds, the principal source of vegetable oils, rank second only to food grains in their significance to the Indian economy, accounting for approximately 10% of the country's cultivated land and contributing substantially to the total agricultural output. Given the current per capita consumption of fats and oils at 8.5 kg per annum and its projected escalation, the demand for vegetable oilseeds is estimated to reach nearly 34 million tonnes by 2030. Notably, rapeseedmustard is anticipated to contribute approximately 14 million tonnes to meet the annual domestic demand. Over the past three decades, the oilseeds sector has expanded at an annual growth rate of 4.1%, surpassing the growth of livestock products and other agricultural commodities. This dynamism has positioned the sector as one of the most robust components of global agriculture. Despite facing challenges such as erratic weather patterns and global price fluctuations, domestic oilseed production has demonstrated resilience, catering to the escalating national demand. However, from 2010 to 2019, the growth rates in the area under cultivation, production, and yield of oilseeds have exhibited a decline in contrast to the period spanning 1986 to 1998. As per the Directorate of Oilseed Development, Ministry of Agriculture and Farmers Welfare, Government of India (2020-21), oilseeds account for 13% of the gross cropped area, contribute 3% to the Gross National Product (GNP), and represent 10% of the total value of agricultural commodities. A significant portion approximately 72% of oilseed cultivation is undertaken under rainfed conditions by marginal and small-scale farmers. Linseed (Linum usitatissimum L.), commonly known as flax, is among the most ancient, cultivated crops, valued for its oil, fibre, and seeds. Distinct from other oilseeds, linseed produces technical-grade vegetable oil and superior-quality fibre known for its exceptional strength and durability. With an oil content ranging from 35% to 45%, linseed is notably rich in omega-3 fatty acids, particularly alpha-linolenic acid (ALA). These bioactive compounds play a crucial role in reducing triglyceride levels, thereby mitigating cardiovascular risks, and exhibit potential efficacy against rheumatoid arthritis. Linseed oil contains omega-3 fatty acids in a ratio threefold higher than omega-6 fatty acids. Furthermore, linseed seeds contain approximately 36% protein, of which 85% is digestible. The residual oil cake, a by-product of oil extraction, serves as an essential feed supplement for dairy and meatproducing animals, thereby enhancing milk and meat yields. The linseed crop in India covers an estimated area of 1.82 lakh hectares, yielding approximately 1.22 lakh tonnes, with an average productivity of 671 kg/ha for the year 2019-20 (Anonymous, 2020). Owing to its high iodine value exceeding 180 linseed oil is regarded as the most suitable vegetable oil for applications such as painting and varnishing, owing to its excellent drying properties. Consequently, a significant proportion of the global linseed production is allocated for industrial use. Despite its classification as an inedible oil, approximately 20% of the linseed produced in India is utilized for dietary purposes, particularly in states like Madhya Pradesh, Uttar Pradesh, Bihar, and Chhattisgarh. Uttar Pradesh is a prominent linseed-producing state, with linseed cultivation extending over 26.90 thousand hectares, yielding 17.89 thousand tonnes, and recording an average productivity of 150 kg/ha (Anonymous, 2021). The state accounts for 9% of the total oilseed cultivation area and contributes 6.29% to the overall oilseed production in India. Predominantly cultivated on marginal and sub-marginal soils under rainfed conditions, linseed is frequently grown as a relay (utera) crop during the rabi season (Agrawal et al., 2014) [1] . Additionally, linseed is often cultivated as an intercrop to optimize land use efficiency. The application of farmyard manure (FYM) in conjunction with inorganic fertilizers significantly enhances soil structure, water retention capacity, and overall system productivity. Organic nutrient sources applied to preceding crops confer substantial residual benefits to succeeding crops, promoting long-term agricultural sustainability (Hegde & Dwivedi, 1992). Conservation tillage systems have been shown to exert notable positive effects on various physical and chemical soil properties (Ismail et al., 1994) [7] . Organic amendments in agriculture primarily encompass plant and animal waste materials, which undergo decomposition to release essential nutrients. The practice of incorporating organic residues into agricultural systems is as old as agriculture itself, historically serving as a means to enhance soil fertility and crop productivity. Manures are organic amendments derived from the decomposition of animal, human, and plant residues, supplying a spectrum of phytonutrients in complex organic forms. In contrast, fertilizers whether natural or synthetic are formulated to provide essential plant nutrients in a readily available form. Although fertilizers exhibit a higher nutrient concentration per unit, manures offer distinct agronomic advantages, including improvements in soil structure, microbial activity, and long-term soil fertility. Unlike high-analysis fertilizers, organic manures contribute to a gradual and sustained nutrient release, ensuring prolonged soil fertility and enhanced crop health. Farmyard manure, a composite of cow dung, urine, straw, and other organic materials, plays a pivotal role in augmenting soil fertility. While its initial nitrogen availability is limited, the decomposition process gradually enriches the nitrogen content, ensuring sustained nutrient release. The combination of cow dung and urine furnishes a balanced nutrient profile for plant growth. The phosphorus and potassium content of farmyard manure is comparable to that of synthetic fertilizers, making it a viable alternative for nutrient management. Typically, well-decomposed farmyard manure contains approximately 0.5% nitrogen (N), 0.2% phosphate (P2O5), and 0.5% potassium (K2O). Moreover, FYM enhances soil phosphorus availability and influences the solubility of applied phosphorus when used in conjunction with inorganic phosphorus fertilizers. It is imperative to recognize that neither organic amendments nor synthetic fertilizers alone can sustain high-yielding, intensive agricultural systems. An integrated approach, combining both organic and inorganic nutrient sources, is essential for ensuring long-term agricultural productivity and sustainability (Singh, 2019) [17] . Vermicompost, an organic amendment derived through the decomposition of organic materials facilitated by earthworms such as Eisenia foetida and Lumbricus rubellus, represents a highly effective soil amendment. The vermicomposting process entails the bioconversion of organic waste into a nutrient-rich substrate through microbial and enzymatic activity within the earthworm gut. The resultant vermicompost is characterized by elevated concentrations of essential macro-and micronutrients, beneficial soil microorganisms, and plant growth regulators. Chemically, vermicompost comprises nitrogen (2-3%), potassium (1.852.25%), and phosphorus (1.55-2.25%), alongside vital micronutrients and bioactive compounds. The presence of plant growth hormones and enzymes further enhances its agronomic efficacy. Scientifically, vermicompost has been validated as an effective growth promoter, conferring resistance against pests and diseases (Tiwari & Singh, 2021) [18,20] . This makes vermicompost an indispensable component in sustainable agricultural systems, particularly within organic farming frameworks.

Material and Methods

This study aimed to explore how varying levels of organic and inorganic fertilizers on growth and yield of linseed variety BLS-4. The research was conducted at the Student Research Farm within the Department of Agronomy at the School of Agriculture Science Technology and Research, Sardar Patel University, Balaghat, Madhya Pradesh, during the Rabi season of 2023, detailing the materials utilized and the methodologies employed throughout the investigation. Balaghat District is situated in the south-eastern region of the Satpura Range and the upper Wainganga River valley, spanning from 21°19' to 22°24' north latitude and 79°31' to 81°30' east longitude. The treatments were The treatments consisted of T1 (Control); T2 (20:10:30 kg NPK ha -1 ); T3 (30:15:40 kg NPK ha -1 ); T4 (40:20:50 kg NPK ha -1 ); T5 (50:25:60 kg NPK ha -1 ); T6 (60:30:70 kg NPK ha -1 ); T7 (FYM 5.0 MT ha -1 ); T8 (FYM 3.75 MT ha -1 ); T9 (FYM 2.5 MT ha -1 ); T10 (Vermicompost 3.00 MT ha -1 ); T11 (Vermicompost 2.25 MT ha - 1 ); and T12 (Vermicompost 1.50 MT ha -1 ). A measuring tape was employed to determine the height of five randomly selected plants per plot at 30, 60, and 90 days after sowing (DAS), measuring from the soil surface to the leaf apex. The recorded plant heights for each replication were meticulously documented and subjected to statistical analysis. Similarly, the number of branches was enumerated in randomly chosen plants from each plot at the aforementioned intervals, with the average branch count per plant computed for each replication and analyzed statistically. The fresh shoot weight of five randomly selected plants (excluding roots) per plot was measured in grams using an electronic balance at 30, 60, and 90 DAS. The mean fresh shoot weight for each replication was calculated and statistically examined. To determine the dry matter accumulation, the same harvested plants used for fresh weight assessment were initially sun-dried and subsequently oven-dried at 70°C for 24 hours. The resultant dry weight of these five plants per plot was recorded using an electronic balance, and the average dry shoot weight for each replication was derived and analyzed statistically. The number of capsules per plant, a crucial yield-attributing parameter, was enumerated from the selected plants post-harvest for each treatment and replication. The recorded data were systematically analyzed. Additionally, the 1000-seed weight was determined using a precision balance from seeds obtained from five randomly selected plants. The mean seed weight was computed and subjected to statistical evaluation. The yield was calculated by weighing the total seed yield per plot. The readings for all the harvest per plot were recorded. The total seed yield/hectare was calculated by unitary method formula given below:

Seed yield per hectare = X 10,000 m 2

Harvest index was computed by using following formula as suggested by Singh and Stoskoff (1971) [19] . The harvest index was worked out by using following formula: Harvest index (%) = X 100

The statistical analysis was conducted using Fisher and Yates (1967) [5] .

Results and Discussion

BLS-4 is an exceptionally early maturing linseed selection developed at JNKVV. This genotype exhibits a medium stature with an open, semi-spreading growth habit. Its flowers typically range in hue from violet to sky blue, while the seeds are diminutive in size and light brown in colour. Farmyard manure (FYM) serves as a principal organic fertilizer for field crops; however, its widespread application is hindered by limited availability, posing a considerable challenge to its efficacy as a nutrient source. Nitrogen plays a pivotal role in various metabolic processes fundamental to plant development, serving as an essential constituent of proteins and chlorophyll (Meena et al., 2014) [13] . Both nitrogen and phosphorus exert a profound influence on root activity and the establishment of cowpea root architecture. The initial availability of nitrogenous compounds facilitates robust seedling establishment before the onset of biological nitrogen fixation. Plants supplemented with organic nitrogen during their vegetative phase exhibit significantly greater biomass accumulation by the time of flowering than those dependent solely on symbiotic nitrogen fixation. Phosphorus, a vital element in plant metabolism, constitutes a key component of numerous organic molecules and is indispensable for photosynthesis, respiration, and other physiological functions. Potassium, on the other hand, modulates plant growth both directly and indirectly. Its application mitigates excessive transpiration, enhances water uptake, and optimizes internal physiological conditions, thereby augmenting drought tolerance (Nazneen et al., 2022) [14] . Vermicompost emerges as a highly efficacious organic fertilizer and a viable alternative to conventional agrochemicals in organic farming systems. Its incorporation markedly improves soil biological properties, enhances water retention capacity, and fosters a loose, porous soil structure conducive to root proliferation. Moreover, vermicompost plays a crucial role in regulating soil pH in acidic environments, thereby stimulating microbial activity and enriching soil fertility (Kirubashre et al., 2023) [11] .

Growth parameters Plant height and number of branches per plant

The in the linseed crop can be attributed to the balanced nutrient supply that meets the crop's developmental requirements more effectively than other treatments. Nitrogen (N) at an optimal level enhances vegetative growth, promoting cell division and elongation, while phosphorus (P) plays a critical role in root development, which facilitates better nutrient uptake. Potassium (K) contributes to overall plant vigour and stress tolerance, aiding in consistent growth. The specific NPK ratio in T3 likely ensures a synchronized nutrient release, fostering uniform and sustained growth. In contrast, treatments relying on organic fertilizers may have slower nutrient mineralization rates, which can limit immediate availability, while other inorganic treatments may not have the optimal NPK balance for maximal growth. This tailored nutrient approach in T3 supports a robust growth habit, culminating in superior plant height compared to all other treatments. Findings were in accordance with conclusions by Kaushal and Umrao (2020) [10] ; Singh et al., (2021) [18] . [9,12] .

Fresh shoot weight and dry shoot weight

Yield parameters Number of capsules per plant and test weight

The highest capsules count ( [8] and Rensang et al., (2021) [16] .

Seed and straw yield per hectare

The maximum seed yield per hectare (642.62 kg/ha) was observed with treatment T3 (30:15:40 Kg NPK ha -1 ) followed by T4 (40:20:50 Kg NPK ha -1 ) with 623.15 kg/ha. Minimum seed yield per hectare (213.26 kg/ha) was observed in T1 (control). The maximum straw yield per hectare (902.30 kg/ha) was observed with treatment T3 (30:15:40 Kg NPK ha -1 ) followed by T4 (40:20:50 Kg NPK ha -1 ) with 863.50 kg/ha. Minimum straw yield per hectare (471.00 kg/ha) was observed in T1 (control. The superior seed and straw yield per hectare (table 3) in T3 (30:15:40 kg NPK per hectare) for linseed is primarily due to the balanced nutrient availability that meets the crop's specific demands for growth and yield components. Nitrogen (N) supports vigorous vegetative growth and optimizes photosynthetic activity, which contributes directly to biomass accumulation, including straw production. Phosphorus (P) enhances root growth and energy transfer, crucial during reproductive stages, supporting both seed setting and development. Potassium (K) plays an important role in nutrient translocation and water regulation, improving overall plant health, seed filling, and straw strength. This specific NPK combination in T3 ensures consistent nutrient release, promoting both vegetative and reproductive growth, resulting in better seed and straw yield. Organic treatments may have slower nutrient mineralization, limiting immediate yield impact, while other inorganic treatments without the optimal NPK ratio fail to match the high yield efficiency seen in T3. Similar findings were reported by Neware and Bobade (2018) [15] and Choudhary and Rai (2021) [4] .

Biological yield and harvest index

The maximum biological yield (1544.92 kg/ha) was observed with treatment T4 (30:15:40 Kg NPK ha -1 ) followed by T4 (40:20:50 Kg NPK ha -1 ) with 1486.65 kg/ha. Minimum biological yield (684.27 kg/ha) was observed in T1 (control). The maximum harvest index (33.48%) was observed with treatment T12 (Vermicompost 1.50 MT ha -1 ) and at par with T11 (Vermicompost 2.25 MT ha -1 ) with 29.96%. Minimum Harvest index (18.46%) was observed in T1 (control). The higher biological yield and harvest index (table 3) in T3 (30:15:40 kg NPK per hectare) for linseed is attributed to a balanced NPK application that effectively meets the crop's overall growth requirements. Nitrogen (N) promotes vegetative growth and photosynthetic efficiency, increasing biomass production, while phosphorus (P) enhances root development, aiding nutrient uptake. Potassium (K) supports plant vigour and water regulation, contributing to a stronger and more extensive shoot system. This optimal nutrient balance leads to robust biomass accumulation, maximizing biological yield in T3. Conversely, the superior harvest index observed in T12 (vermicompost at 1.50 MT per hectare) can be attributed to the gradual release of nutrients, which supports a balanced growth pattern, favouring reproductive development over excessive vegetative growth. Vermicompost improves soil structure and microbial activity, promoting efficient nutrient use. This gradual nutrient release allows the plant to allocate resources efficiently toward seed production, enhancing the harvest index in T12 over other treatments. Similar findings were reported by Neware and Bobade (2018) [15] and Jangid et al., (2022) [8] .

Economics parameters

Maximum cost of cultivation incurred (table 4) in treatment T6 (60:30:70 Kg NPK ha -1 ) with (Rs 38250 ha -1 ) and the minimum (Rs 34350 ha -1 ) was recorded in treatment T1 (Control). Maximum gross returns were recorded in treatment T3 (30:15:40 Kg NPK ha -1 ) with (Rs 61,841 ha -1 ) followed by T4 (40:20:50 Kg NPK ha -1 ) having Rs 59,876 ha -1 and the minimum (Rs 21,895 ha - 1 ) was recorded in treatment T1 (Control). Maximum net returns were recorded in treatment T3 (30:15:40 Kg NPK ha -1 ) with (Rs 25,390 ha -1 ) followed by T4 (40:20:50 Kg NPK ha -1 ) having Rs 22,842 ha -1 and loss of Rs 12,462 ha -1 ) was recorded in treatment T1 (Control). Highest benefit cost ratio was recorded in treatment T3 (30:15:40 Kg NPK ha -1 ) with 1.70 followed by T4 (40:20:50 Kg NPK ha -1 ) having 1.62 and the minimum (0.64) was recorded in treatment T1 (Control). Similar findings were reported by Kumar and Yadav (2022) [12] . Thus, use of NPK at higher dose may be suggested for higher crop productivity along with over all betterment of linseed under Balaghat (M.P.) conditions.

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