Interactive effect of establishment methods, solid and liquid organic manures on growth of Black rice (Oryza sativa L.)

Introduction

Black rice (Oryza sativa L.) is a distinctive rice genotype characterized by the presence of a dark black pigmented bran layer surrounding the endosperm. During cooking, the grain develops a characteristic deep purple colour due to its high anthocyanin content. In comparison with conventional white rice, black rice generally requires a longer cooking time and exhibits a relatively sticky texture. Its attractive appearance, unique aroma, and mildly sweet, nutty taste have contributed to its increasing popularity across several Asian countries, including China, Japan, Thailand, and South Korea. Historically, black rice was known as "Forbidden Rice" in ancient China because its cultivation and consumption were restricted to emperors and members of the royal household. According to Budhar and Mani (2008) [3] , China accounts for approximately 62% of the world's black rice resources, followed by Sri Lanka (8.6%), Indonesia (7.2%), India (5.1%), the Philippines (4.3%), and Bangladesh (4.1%), while smaller proportions are found in Malaysia, Thailand, and Myanmar. Owing to its high antioxidant activity and remarkable free radical scavenging capacity, black rice is increasingly recognized as a valuable raw material for the development of functional and health-promoting food products (Sui et al., 2016) [21] . The System of Rice Intensification (SRI) has emerged as an innovative rice cultivation approach that improves both grain yield and water-use efficiency. Studies have demonstrated that SRI enhances crop productivity while optimizing the utilization of available water resources (Mazumdar et al., 2016) [14] . Improved crop establishment and management practices under SRI have also been found to suppress weed growth and minimize nutrient losses, particularly nitrogen depletion caused by weed competition, thereby contributing to superior yield attributes and higher productivity (Singh et al., 2021) [19] . Furthermore, Kumar et al. (2021) [10] reported significant improvements in growth and yield parameters under SRI compared with conventional rice cultivation methods. The incorporation of alternate wetting and drying (AWD) irrigation within the SRI framework further enhances water-use efficiency and can reduce water consumption by nearly 30-40% relative to traditional flooded rice cultivation systems. The declining use of organic manures has been associated with adverse effects on soil carbon-toNitrogen ratios, microbial activity, aggregate stability, and nutrient cycling processes (Gandla et al., 2023) [6] . Organic farming systems have been reported to support greater belowground biodiversity and microbial biomass, thereby improving soil food-web dynamics and overall soil quality when compared with conventional agricultural practices, which often result in soil degradation (Ghadimi et al., 2021) [7] . Consequently, organic manures and biofertilizers have become integral components of sustainable agriculture due to their positive influence on the physical, chemical, and biological characteristics of soil. Their application contributes significantly to maintaining soil fertility, improving nutrient availability, and sustaining agricultural productivity over the long term (Ramesh et al., 2008) [17] . Liquid organic manures are increasingly recognized as effective bio-inputs that enhance crop performance by providing readily available nutrients, beneficial microorganisms, enzymes, and naturally occurring plant growth-promoting compounds. In the present study, Vermiwash, Jeevamrutha, and Panchagavya were applied at 20-day intervals after sowing. These liquid formulations improve nutrient absorption, stimulate beneficial microbial activity in the rhizosphere, and promote vigorous plant growth and development. In addition, regular application of liquid organic manures enhances soil fertility, improves plant resilience against biotic and abiotic stresses, and contributes to higher crop productivity under organic production systems (Golakiya et al., 2019) [8] .

Material and Methods

A field experiment was carried out during the kharif seasons of 2022 and 2023 at the Crop Research Farm, Department of Agronomy, Sam Higginbottom University of Agriculture, Technology and Sciences, Prayagraj, Uttar Pradesh, India. The experimental site is located at 25.57° N latitude and 87.19° E longitude, with an elevation of 98 m above mean sea level. Black rice was cultivated under two transplanting methods: conventional transplanting with a spacing of 20 cm × 10 cm and the System of Rice Intensification (SRI) method with a spacing of 25 cm × 25 cm. Under the conventional method, two seedlings per hill were transplanted at a spacing of 20 cm × 10 cm. In contrast, the SRI method involved transplanting single seedlings of 12 days age at a wider spacing of 25 cm × 25 cm. For nursery raising, wellprepared and levelled fields were used to construct raised nursery beds measuring 10 m × 1 m × 0.15 m (length × width × height), with a 30 cm gap maintained between adjacent beds. Pregerminated seeds were uniformly sown on puddled and finely levelled nursery beds. A thick layer of organic manure was incorporated during nursery bed preparation, and the seeds were subsequently covered with a thin layer of soil. Irrigation was applied as and when required to maintain optimum soil moisture. Excess water resulting from irrigation or heavy rainfall was drained promptly. Irrigation was discontinued ten days before harvest when the crop attained physiological maturity. Weed management was carried out manually through two hand weedings at 25 and 45 days after transplanting (DAT). Growth observations, including plant height, total number of tillers per hill and dry weight were recorded at 20-day intervals throughout the crop growth period. Organic nutrient requirements were met through the application of farmyard manure (FYM), poultry manure, and vermicompost. Liquid organic formulations such as vermiwash, Jeevamrutha, and Panchagavya were applied at 20-day intervals after sowing. All recommended agronomic and crop management practices were followed throughout the experiment. No significant incidence of pests or diseases was observed during the crop growth period. The experimental data collected were subjected to statistical analysis using Fisher's Analysis of Variance (ANOVA) technique, following the procedure described by Gomez and Gomez (1984). Whenever the F-test indicated significance at the 5% probability level, the Critical Difference (CD) was calculated to compare treatment means.

Result and Discussion

Plant height

There was no significant effect of establishment methods combined with application of solid and liquid organic manures at 20 DAT. However maximum plant height was recorded in 30. 94 [2,4] , while PM supplied readily mineralizable nitrogen and micronutrients to fuel meristematic expansion, and liquid biostimulants accelerated phytohormone signaling (auxins, gibberellins) for internodal elongation (Khatun et al., 2025) [9] . This combined effect optimizes nutrient uptake efficiency via improved soil microbial consortia and reduced transplant shock Mohanty et al. (2014) [15] , leading to protracted vegetative growth phases with minimal antagonism between treatments.

Number of tillers

At 20 DAT there was no significant effect of interaction. However, at 40 DAT in 2022 SRI + Poultry manure + Panchgavya was found to be significantly higher having 18.93 tillers/hill. Although, SRI + FYM + Panchgavya, SRI + VC + Panchgavya, SRI + PM + Vermiwash and SRI + VC +Vermiwash recoded statistical party with SRI + Poultry manure + Panchgavya. Similarly in second year of 60 DAT significantly higher tillers /plant was recorded in SRI + Poultry manure + Panchgavya (22.87 tillers/hill). Further, SRI + VC + Panchgavya, SRI + PM + Vermiwash and SRI + VC +Vermiwash recoded statistical party with SRI + Poultry manure + Panchgavya. This integration yielded superior outcomes, with studies confirming higher tiller count from FYM/PM + Panchgavya under SRI versus controls, due to improved soil aeration, humic acid chelation, and microbial N-fixation. Poultry manure's soluble phosphorus and Panchgavya's enzyme activity further optimized source-sink dynamics, as evidenced in SRI-rice trials showing elevated biomass and quality metrics as observed by Aktar et al., 2020 and Rameshwar et al., 2017 [1,18] .

Dry weight

There was no significant effect of combined application of establishment methods, solid and liquid organic manures at 40 DAT. Maximum dry weight was recorded in SRI + Vermicompost + Panchgavya (1.57 g) in first year, in second year SRI + FYM + Jeevamrut recorded 1.52 g/plant and in pooled SRI + PM + Vermiwash (1.52 g/plant). Further, at 40 DAT in both the years and pooled SRI + PM + Panchgavya recorded maximum dry weight having 6.27, 6.61 and 6.44 g/plant. The integration of SRI, poultry manure (PM), and Panchgavya profoundly augmented black rice dry matter production via SRI's facilitation of expansive root systems and tillering under aerobic regimes (Rameshwar et al., 2017) [18] , PM's supply of labile organic N (3-5%) and phosphorus for accelerated photosynthetic tissue formation, and Panchgavya's infusion of growth regulators and microbial biofertilizers that elevate chlorophyll fluorescence and starch synthase activity as corroborated by Parmeshwari et al., 2025 and Dekhane et al., 2019 [5,16] . pH There was no significant effect of interaction of establishment method, solid and liquid organic manure on pH of soil. However, the plots transplanted with SRI method and treated with poultry manure and Panchgavya in a combination recorded lower pH having 7.82, 7.92 and 7.89. The slight reduction in soil pH may be attributed to enhance rhizosphere activity, greater root growth, and increased microbial processes under alternate wetting and drying conditions (Sugathas et al., 2025) [20] . Since the pH remained within the optimum range for rice cultivation, the observed reduction is considered beneficial for nutrient availability and soil biological activity (Lal et al., 2016) [13] . These findings support the superior soil health and nutrient-use efficiency commonly associated with SRI over conventional transplanted rice. Poultry manure significantly increased soil pH in black rice cultivation due to its alkaline nature, ammonification processes releasing OH⁻ ions during organic matter decomposition, thereby neutralizing H⁺ acidity in slightly acidic soils as corroborated by Ghadimi et al., 2021, Kumar et al., 2022 [7,11] . Panchgavya significantly buffered soil pH in black rice cultivation toward optimal neutrality (pH 6.5-7.5) through its organic acid fermentation products (lactic, acetic).

EC

There was no significant effect of interaction on EC. However, in first year SRI + PM + Panchgavya was found to be having the lowest EC. Further, in second year and pooled SRI + VC + Vermiwash was found to be lowest EC having 0.43 and 0.46 dS/m. The lower EC observed under SRI suggests reduced accumulation of soluble salts in the rhizosphere. Alternate wetting and drying cycles, coupled with greater nutrient uptake by the crop, may have reduced the concentration of dissolved ions remaining in the soil solution. Lower EC is generally associated with improved rootzone conditions and reduced osmotic stress on plants (Kumar et al., 2023) [12] . Poultry manure is a rich source of micronutrients such as zinc, copper, manganese, iron, and boron, as well as secondary nutrients including calcium, magnesium, and sulfur, making it a valuable organic amendment for soil fertility. This composition, corroborated by Aktar et al. (2020) [1] and supported by Kumar et al., 2023 [10] . This temporal variation aligns with observations where Panchgavya's inherent nutrient salts and microbial activity increase EC through ion mobilization, as reported in studies on its soil application effects (Tamilrasai et al., 2019).

Conclusion

Transplanting black rice seedlings along with application of solid organic manure of Poultry manure and Panchgavya recorded significantly higher growth attributes in black rice.

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