Standardization of Radicle Emergence Test to Predict Seed Vigour and Field Emergence in Blackgram [Vigna mungo (L.) Hepper]

Background: Blackgram is an important pulse crop grown in India. In which, prediction of planting value of seeds before sowing is important for assured yield. Standard germination test is time consuming and doesn't always show the seed lots potential performance, especially if field conditions are not optimal. Radicle emergence test is considered as one of the important physiological vigour test. This is a quick vigour test and also determines the planting value of various seed lots under wide range of climatic conditions. Methods: The laboratory experiment was carried out at the Department of Seed Science and Technology, Tamil Nadu Agricultural University, Coimbatore during 2019-2020 to standardize the radicle emergence test to predict seed vigour and field emergence in ten different seed lots [L-1 to L-4: high vigour lots (> 90% germination), L-5 to L-7: medium vigour lots (80-90% germination) and L-8 to L-10: low vigour lots (<80% germination)] of blackgram var. VBN 6. The radicle emergence test was conducted through top of paper method adopting ISTA rules. Result: The results showed that the significant differences were observed between seed lots in terms of physiological parameters viz., speed of germination, germination percentage, root length, shoot length, dry matter production, vigour index, mean just germination time (MJGT), mean germination time (MGT), radicle emergence and field emergence and biochemical parameters viz., electrical conductivity of seed leachate and dehydrogenase enzyme activity. The results also revealed that the seed vigour can be grouped in three categories viz., high, medium and low vigour based on the relationship between MGT and field emergence. When the MGT was <25 hours, the seed lots which exceeds 85 per cent field emergence could be considered as high vigour; when the MGT was 25-26 hours, the seed lots with 70-85 per cent field emergence could be considered as medium vigour and when the MGT was>26 hours, the seed lots with below 70 per cent field emergence which could be considered as low vigour.