Background

Efforts to develop and use hybrid rice technology in India were initiated at the Indian Agricultural Research Institute in early 1970's. However, systematic research work was started in 1989 under a mission mode project of ICAR. With the concerted research work, the country developed many rice hybrids, of which 23 have been officially released.
High cost of hybrid seed is one of the major constraints in the adoption of the hybrid rice technology. This is primarily attributed to the low hybrid seed yield which is around 1-1.5 t/ha. It is necessary to enhance the seed yield level to more than 2.5 t/ha in order to economise the seed cost. Currently hybrid rice seed production is taken up in the rabi season primarily in Karimnagar district of Andhra Pradesh. In this region, the seed is harvested by April-May, which after drying, processing, testing, packaging and transportation reaches north India only by the beginning of June. As the nursery sowing is taken up in this region by the end of May, the delay in the availability of hybrid seed affects the development of hybrid rice cultivation in north India.
The Division of Seed Science &: Technology of the Institute, therefore, undertook a programme on standardization of hybrid rice seed production technology in the main khari season. Concerted research carried out for more than a decade resulted in the development of an economically feasible technology for north India. The primary benefit of this technology is that the hybrid seed is harvested, processed and tested in November­December and stored for a short period up to March under cool and dry conditions. This seed is available to the farmers by April-May. Growing the hybrid seed in kharifseason also allows sufficient time to undertake hybrid purity testing through growout test during December-March.

Optimization of the dose of gibberellic acid (GAa) for hybrid rice seed production

Cost of the female parental lines of rice are based on wild abortive (WA) cytoplasm due to which about 25 -33 per cent of the spikelets are enclosed in the flag leaf sheath making them unavailable for pollination. Foliar application of GA} at the start of panicle emergence has been widely adopted as an essential technique for enhancing panicle excertion