Effect of Accelerated Ageing on Germination and Seedling Vigour of Manually and Mechanically Harvested and Threshed Rice Seeds

The study was conducted at Department of Seed Scie nce and Technology, Tamil Nadu Agricultural Univers ity, Coimbatore during kharif 2016 to find out the effec t of accelerated ageing on germination, seedling vi gour and biochemical constituents of manually and mechanical ly harvested and threshed rice varieties viz., CR10 09 Sub 1, improved white ponni and CO51. The germination, see dling vigour, dehydrogenase and alpha amylase activ ity was high in fresh seeds compared to aged seeds in all the va rieties in different methods of harvesting and thre shing at different intervals after accelerated ageing. Among the varie ties CR1009 Sub 1 recorded the maximum germination, seedling vigour and biochemical constituents followed by CO5 1, while improved white ponni recorded minimum. Amo ng the treatments manual harvesting and threshing register ed the maximum germination and seedling vigour foll owed by combine harvesting, the minimum was recorded in man u l harvesting and mechanical threshing. The electr i al conductivity of seed leachates gradually increased by the period of accelerated aging and was high in 20 days of ageing in all the varieties. The increase in EC was more in C R1009 Sub 1 (109.6 μSm ), followed by CO51 (95.3 μSm ) and improved white ponni (93.3 μSm ).