Influence of gradient levels of Konkan Annapurna Briquette (KAB) fertilizers on growth parameters and yield attributes of rice (Oryza sativa L.)

Introduction

Rice (Oryza sativa L.) is one of the most important cereal crops, serving as a staple food for more than half of the world's population and contributing significantly to global food security. In India, rice occupies a major share of cultivated area and production; however, its productivity is often constrained by inefficient nutrient management and low fertilizer use efficiency, particularly under intensive cropping systems. Nitrogen (N), phosphorus (P), and potassium (K) are key nutrients governing growth characters such as plant height, tillering, leaf production, and dry matter accumulation, which ultimately determine yield formation. However, under conventional fertilizer application methods, a large proportion of applied nutrients is lost through volatilization, leaching, and runoff, resulting in low nutrient use efficiency (Ladha et al., 2016; Rahman and Samanta, 2024) [5,8] . Therefore, improving nutrient use efficiency while maintaining or enhancing crop productivity remains a major challenge in rice cultivation. Fertilizer briquette technology, particularly deep placement of urea and NPK briquettes, has emerged as an effective strategy to improve nutrient use efficiency and crop performance. Deep placement ensures that nutrients remain available in the root zone for a longer duration, thereby minimizing losses and enhancing uptake (Savant et al., 2017; IFDC, 2024) [3,10] . Several studies have reported that briquette application significantly improves growth parameters, yield attributes, and grain yield of rice compared to conventional fertilizer application (Sarker et al., 2021; Naveen et al., 2024) [7,9] . Konkan Annapurna Briquette (KAB), a composite fertilizer containing essential nutrients, offers a balanced and efficient nutrient supply for rice cultivation. Application of KAB has been shown to enhance vegetative growth, improve dry matter accumulation, and increase yield attributes such as number of panicles and grains per panicle (Jadhav et al., 2024) [4] . Improved nutrient availability through briquette application also promotes better canopy development and photosynthetic efficiency, leading to higher productivity (Lan et al., 2024) [6] . Growth characters such as plant height, number of tillers, number of leaves, and dry matter accumulation are important indicators of crop vigor and are closely associated with yield attributes. Enhanced vegetative growth under improved nutrient management leads to better source-sink relationships and efficient partitioning of assimilates towards grain yield (Fageria et al., 2016; Naveen et al., 2024) [2,7] . Although the benefits of briquette fertilizers have been widely reported, information on the response of rice growth characters and yield attributes to gradient levels of Konkan Annapurna Briquette (KAB) is limited under field conditions. In particular, identification of the optimum level of KAB for maximizing growth and yield without excessive fertilizer use remains an important research need. Therefore, the present study was undertaken to evaluate the effect of gradient levels of Konkan Annapurna Briquette (KAB) fertilizers on growth characters, yield attributes, and yield of rice.

Materials and Methods

The field experiment was conducted during the kharif seasons of 2020 and 2021 at the Experimental Farm, Department of Agronomy, College of Agriculture, Dr. Balasaheb Sawant Konkan Krishi Vidyapeeth, Dapoli, Maharashtra, India. The soil of the experimental field was lateritic, well-drained and sandy clay loam in texture. Composite soil samples (0-30 cm depth) were collected before the initiation of the experiment and analyzed using standard procedures. The soil was slightly acidic in reaction (pH 5.74), medium in available nitrogen (286 kg ha -1 ) and phosphorus (12.9 kg ha -1 ), high in available potassium (257 kg ha -1 ), and rich in organic carbon (1.26%). The experiment was laid out in a Randomized Block Design (RBD) with nine replications. The treatments consisted of three gradient levels of Konkan Annapurna Briquettes (KAB). B1; 80% Recommended Dose of Fertilizers (RDF) through KAB, B2; 100% RDF through KAB and B3; 120% RDF through KAB. Rice variety 'Ratnagiri-8' was used for the study. Twenty-four day old seedlings were transplanted at a spacing of 25 cm × 15 cm, maintaining 2-3 seedlings hill -1 . Well-decomposed farmyard manure (5 t ha -1 ) and Glyricidia green biomass (7.5 t ha -1 ) were incorporated during land preparation. Konkan Annapurna Briquettes (KAB) were applied as per treatment levels (80%, 100% and 120% RDF equivalent to 175 kg ha -1 ) through deep placement at 5 Days after Transplanting (DAT). Necessary plant protection measures were undertaken to control insect pests and diseases. All other agronomic practices were followed as per recommended package of practices. Observations on various growth parameters were recorded at different stages (30, 60, 90 DAT and at harvest). At harvest, the observations were recorded on Number of panicles hill -1 , Panicle length (cm), Weight of grains panicle - 1 (g), Number of filled grains panicle -1 , Number of unfilled grains panicle -1 , Grain yield (q ha -1 ) and Straw yield (q ha -1 ). Grain and straw yields were recorded from net plot area and converted to hectare basis. The experimental data were analyzed using analysis of variance (ANOVA) appropriate for Randomized Block Design as described by Gomez and Gomez (1984). The significance of treatment differences was tested using the Critical Difference (CD) at 5% level of probability (P = 0.05).

Results and Discussion

Growth characters

Plant height of rice increased progressively with crop growth and was significantly influenced by gradient levels of Konkan Annapurna Briquette (KAB) fertilizers at all stages during both years. [2] , Savant et al. (2017) [10] , Sarker et al. (2021) [9] , and Naveen et al. (2024) [7] , who reported significant improvement in plant height under improved nutrient management and briquette fertilization.

The number of tillers increased up to 60-90 DAT and declined slightly at harvest due to tiller mortality. Treatment B3 recorded the highest number of tillers at all stages, followed by B2 and B1. Higher tiller production under increased KAB levels may be due to enhanced nitrogen availability and improved root growth, which stimulate tiller initiation and survival. The improved tillering capacity also reflects better early crop vigor under higher nutrient supply. Similar results were reported by Sarker et al. (2021) [9] , Eldridge et al. (2022) [1] , Naveen et al. (2024) [7] , and Jadhav et al. (2024) [4] , who observed increased tiller production under briquette fertilizer application.

The number of leaves increased up to 90 DAT and declined thereafter due to leaf senescence. Treatment B3 recorded significantly higher number of leaves, which remained statistically at par with B2 but superior over B1. The increase in leaf number under higher KAB levels may be attributed to adequate nitrogen supply, which enhances leaf initiation, expansion, and chlorophyll content, resulting in better canopy development. These findings are supported by Rahman and Samanta (2024) [8] , Lan et al. (2024) [6] , and Jadhav et al. (2024) [4] , who reported improved leaf production and canopy growth under briquette fertilization. Dry matter accumulation increased continuously from 30 DAT to harvest and was significantly influenced by KAB levels. Treatment B3 recorded the highest dry matter accumulation at all stages, followed by B2 and B1. Higher biomass production under increased KAB levels may be attributed to enhance photosynthetic efficiency, improved leaf area, and sustained nutrient availability, leading to greater assimilate production. These results are in conformity with Eldridge et al. (2022) [1] , Lan et al. (2024) [6] , Naveen et al. (2024) [7] , and Fageria et al. (2016) [2] , who reported increased dry matter production under improved nutrient management practices.

Yield and yield attributes

The number of panicles increased significantly with increasing KAB levels. Treatment B3 recorded the highest values, which were at par with B2 but significantly superior over B1. This may be attributed to improved tiller survival under better nutrient availability. Panicle length was not significantly influenced by treatments, indicating its strong genetic control. [10] , Sarker et al.

(2021) [9] , Lan et al. (2024) [6] , and Jadhav et al. (2024) [4] . Grain and straw yields were significantly influenced by gradient levels of KAB fertilizers. Treatment B3 recorded the highest grain yield (52.31 q ha -1 pooled), which was statistically at par with B2 but significantly superior over B1. The increase in grain yield under higher KAB levels may be attributed to improved growth parameters, higher dry matter accumulation, better yield attributes and enhanced sourcesink relationship. Straw yield also followed a similar trend, reflecting improved vegetative growth. These findings are in agreement with Eldridge et al. (2022) [1] , Lan et al. (2024) [6] , Naveen et al. (2024) [7] , Sarker et al. (2021) [9] , and IFDC (2024) [3] , who reported significant yield improvement under briquette deep placement.

Conclusion

The present study clearly demonstrated that gradient levels of Konkan Annapurna Briquette (KAB) fertilizers significantly influenced growth characters, yield attributes, and productivity of rice (Oryza sativa L.) under the agroclimatic conditions of Konkan region. Application of KAB fertilizers markedly improved growth parameters such as plant height, number of tillers, number of leaves, and dry matter accumulation, which in turn enhanced yield attributes including number of panicles, grain weight panicle -1 , and number of filled grains. The number of unfilled grains was reduced with increasing KAB levels, indicating improved grain filling and assimilate translocation. Among the treatments, 120% RDF through KAB (B3) consistently recorded higher values for growth, yield attributes, and yield; however, it remained statistically at par with 100% RDF (B2) in most cases. This suggests that 100% RDF through KAB is sufficient to achieve optimum crop growth, yield attributes, and productivity, while further increase to 120% RDF results in only marginal gains. The improvement in productivity under KAB application can be attributed to efficient nutrient availability through deep placement, enhanced nutrient uptake, improved canopy development, and better source-sink relationship. Therefore, it can be concluded that application of 100% recommended dose of nutrients through Konkan Annapurna Briquettes is an effective and sustainable nutrient management strategy for enhancing growth and yield of rice.

References

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