Development of a technique for in vitro unpollinated ovary culture in rice, Oryza sativa L.

A simple and efficient technique for in vitro unpollinated ovary culture in rice which is also applicable for indica genotypes was developed for breed ing and genetic studies. Sampling explants at the auricle distance of 7-12 cm between the two uppermost leaves of a tiller, providing a chilling pretr eatment and ovaries with 1/3 of the hulls intact gave optimum response to c ulture. For callus induction with the spontaneous breaking of ovaries, Ng m edia supplemented with NAA (2 mg/l) and DMSO (0.6-0.8%) gave a mean PCI val ue of 3.8% and range of 0.8-12.5% among genotypes. Media combining 2,4,5-T or 2,4-D with NAA in Ng medium also has reasonably good callus induction. F or calli induced inside, 2,4-D (0.2-0.5 mg/l), NAA (2 mg/l) and KT (1 mg/l) contained media were superior. The maximum green plant regeneration (PPR) of 77.3% was found with the medium containing NAA 0.25 mg/l, IAA 0.5 mg/l a nd KT 2.0 mg/l. Significant genotype, medium and their interaction effects for per cent ovary survival and callus induction were observed.