Breeding for photo-period insensitive Tossa jute (Corchorus olitorius L.) with high fibre yield

The reported photo-period insensitive olitorius mutant (German, maturing in 35–40 days after sowing) was crossed with photo-period sensitive standard variety, JRO 7835 and two selections (named as BCO 100 and BCO 120) were isolated from segregating F₂ generation based on flowering in 90 and 110 days respectively after sowing. Pedigree selection continued up to 8th generation when the flowering character became stable. These two selections and the standard JRO 7835 were sown every month throughout the year to test their sensitivity to photoperiod under varied day length in different months. The two selections flowered in almost 90 and 110 days throughout the year whereas the standard had variable days to flowering. The two selections (BCO 100 and BCO 120) along with three standard varieties (JRO 524, JRO 7835, JRO 878) were put to yield trial twice -on 1st April and 1st June. In case of the 1st sowing all entries were harvested at 100 days when only BCO 100 had flowering on 90 days. Here the yield of BCO 100 and BCO 120 significantly exceeded that in the standards. In case of the second sowing BCO 100 was also harvested on 100 days (flowering in 90 days) while others including BCO 120 were harvested at 120 days when all were in flowering stage as the critical photo-period prevailed on and around 15th September. Here the fibre yield of BCO 120 significantly exceeded all entries including BCO 100. However, the fibre yield of BCO 100 was at par with the standards though numerically slightly less. The yield trials and the sowing throughout the year conclusively proved the photoperiod insensitiveness of BCO 100 and BCO 120 and yield of BCO 120 had better yield as compared to that in the standard while BCO 100 had advantage of 20 days over the entries with equal fibre yield.