Effect of thermophysical methods like hot water, hot air and microwave seed treatment on seed quality parameters, seedling growth parameters and diseases incidence in bell pepper (Capsicum annuum)

The study was conducted to standardise effect of temperature and duration of thermophysical seed treatment on seed quality and plant growth parameters in bell pepper. In vitro screening of thermophysical methods viz hot water treatment at four different temperature-duration combinations of 49, 50, 51 and 52°C for 30, 45 and 60 min; hot air treatment at four different temperature-duration combinations of 70, 72, 74 and 76°C for 24, 36, 48 and 60 min and microwave seed treatment for 5, 10, 15, 20 and 30 sec along with control was done. The three best treatments among each category viz hot water, hot air and microwave seed treatment were used for further evaluation under nursery condition. In hot water, seed treatment at 50°C for 60 min resulted in highest seed germination (89.50%). In hot air, seed treatment at 72°C for 24 h resulted in highest seedling length (10.43 cm) at par with control (10.48 cm) and SVI- I (length) (769.25) and SVI-II (mass) (159.46), though lower than control. In microwave seed treatment, highest germination (91.25 and 90.00%), SVI-I (length) (1,092.83 and 1,057.73) and SVI-II (mass) (218.33 and 214.20) were recorded in 5 and 10 sec exposure, respectively. In the nursery, seed treatment in hot water at 50°C for 60 min and in microwave for 5 sec resulted in highest total seedling emergence (85.16 and 84.00% respectively) and height at 42 days after sowing (11.20 and 11.40 cm respectively); in hot water at 50°C for 60 min and microwave for 5 sec to minimum ungerminated seeds (14.84 and 16.00% respectively); in hot water at 50°C for 60 min in lowest damping- off incidence (6.94%) and in hot air at 74°C for 48 h (4.44%) and in hot water at 50°C for 60 min (5.00%) in minimum virus infection.