Chitosan-induced growth enhancement, piperine production and relative expression of piperine synthase gene in long pepper (Piper longum L.)

A study was undertaken to investigate the effects of chitosan (CS) at varying concentrations (0 g/L, 1 g/L, 2 g/L, 3 g/L and 4 g/L) on Piper longum. CS, a naturally occurring polysaccharide, has garnered attention for its potential to enhance plant growth and yield. The experiment involved foliar applications of CS at 2, 4 and 6 months after planting (MAP), followed by observations 1 month postapplication (3, 5 and 7 MAP). This allowed for a comprehensive assessment of the impact of CS on the growth, physiological, biochemical and yield parameters of P. longum. Notably, the findings highlighted that foliar spraying of CS at lower concentrations (1 g/L and 2 g/L) significantly stimulated the growth and yield attributes and expression of the piperine synthase gene in P. longum. These concentrations positively affected various parameters, including shoot length, physiological functions, biochemical processes and yield metrics. Conversely, higher concentrations of CS (3 g/L and 4 g/L) exhibited inhibitory effects, leading to compromised performance across the assessed parameters. Moreover, these concentrations produced poorer results than the control treatment, highlighting the detrimental effects of excessive CS application on P. longum. Overall, these findings emphasize the importance of optimizing CS concentrations for effective enhancement of growth and yield in P. longum cultivation, while also highlighting the potential risks associated with excessive CS application.