Abstract

                                Studies on seed vigour tests in Bt and non Bt cotton hybrids were taken up during 2007 at Seed Research and Technology Centre, Rajendranagar, Hyderabad. Irrespective of Bt and Non Bt cotton hybrids, TP (87%), S methods (85%) recorded higher germination than BP (83%) and soil method (82%). Among the vigour tests, first count (78%), final count (86%), brick gravel test (81%) and cold test (79%) recorded higher germination in all the Bt cotton hybrids than Non Bt hybrids which recorded superior values for speed of germination (74%), field emergence (76%), paper exhaustion test (68%) and tetrazolium test for viability. Bt cotton hybrids especially TCH 9 and PRCH 31 recorded higher germination in all germination testing methods as well as vigour tests. Germination and seedling vigour gradually declined with an increase in period of accelerated ageing from 0 to 30 days. Such decline was more in Non Bt cotton hybrids when compared to Bt cotton hybrids. Among different Bt cotton hybrids, PRCH 31 and TCH 9 have shown higher values in all vigour tests as against the other hybrids. There was a rapid decline in germination and vigour in NCS 145, NCS 207, Rudra and Sandeep.

Key words : Bt and Non Bt cotton hybrids, germination and vigour tests.