Effect of chemical sprays and management practices on Brachiaria ruziziensis seed production

Abstract

The demand for Brachiaria ruziziensis seeds and planting material is increasing in India as it is spreading into new niche areas of silvi-pastoral systems, horti-pastoral systems, mango orchards, and coconut plantations due to its resilience to drought and low light intensities. Brachiaria ruziziensis produces low numbers of pure seeds. In this study, seeds were collected periodically after a single destructive harvest (SDH) and shade drying. Application of irrigation and fertiliser produced a 2.3 fold increase in seed yield compared to the control. However, when seeds were collected through a single destructive harvest (SDH) and shade drying, rather than sweating, the seed qualitative parameters such as seed germination and seed viability improved three and five folds, respectively. Field management techniques such as irrigation and fertiliser application influenced the quantity of seeds produced whereas harvesting methods promoted the quality of seeds produced in B. ruziziensis. Seed germination could also be improved (50%) by treating the seeds with raw cow dung which contains many beneficial microorganisms that produce cellulolytic enzymes, alleviating seed dormancy. Seed yield improved in B.ruziziensis with chemical sprays such as Brassinosteroid 10ppm (145kg/ha) and Tryptophan 100ppm (147kg/ha) compared to the control, water spray (131kg/ha). Brassinosteroid sprays could enhance pollen fertility and yield probably through interactions with anther development and sugar metabolism, respectively. Brachiaria ruziziensis produces more vegetative growth in the second year due to its perennial growth habit. The filled seed yield from the second-year crop was 0.8 times less in the control compared to the first year, even with chemical sprays. Perennial plants, in general, maintain their longevity through a physiological trade-off between seed yield and underground growth. Hence, it is beneficial to replant B. ruziziensis every year if grown for seed purposes.