Productivity and profitability of black rice as affected by transplanting methods and crop geometry

Black rice is a highly nutritious cereal that has been introduced to Nepal recently. Due to its late introduction, only a few agronomic research have been conducted so far. Hence, farmers are not aware about the appropriate transplanting methods and cropping geometry for profitable black rice cultivation. To fulfill the research gap and to establish a basic benchmark for further studies, the research focuses on responses of two black rice genotypes at different transplanting methods and cropping geometry. The profitability analysis with respect to transplanting methods and cropping geometry revealed, transplanting 21 days old seedlings with any geometrical pattern would yield and profit more as compared to SRI. Similarly, farmers can get a highest net revenue of 9379.3 $ at the B/C ratio of 12.07 from fine black rice as compared to coarse black rice that has a net revenue of 4485.7 $ at the B/C of 7.38. The highest productivity (2.70 t ha^-1), net revenue (6018.5 $), and B/C ratio (13.7) were observed at the crop geometry of 20 cm × 15 cm for coarse black rice. Whereas, the highest yield (4.60 t ha^-1), net revenue (10889.8 $), and B/C ratio (19.5) was observed in 20 cm × 10 cm for fine black rice. The higher net revenue and B/C ratio of premium black rice genotypes was due to their higher market price. The correlation analysis suggested tillering index (T_i) and net biomass accumulated up to 60 days after transplanting (DAT) had the highest positive correlation with yield of both black rice genotypes. Hence, the authors recommend researchers to work on additional agronomic practices that enhance the tillering index and net biomass production up to 60 DAT considering transplanting methods yield more as compared to SRI and crop geometry of 20 cm × 15 cm and 20 cm × 10 cm are the most productive and profitable cropping geometry for coarse and fine black rice genotypes, respectively.