The low percentage of callus induction and green-plant regeneration has limited the application of anther culture techniques in indica rice breeding programmes. The aim of this work was to investigate the inheritance of the two characters and to determine whether good combinations with high-frequency callus induction and green-plant regeneration could be selected by sexual hybridization of suitable parents. So, a 3 · 4 incomplete diallel crosses were conducted between 7 parental lines. Three of them were believed to possess relatively high callus induction capacity and the other four relatively high green-plant regeneration capacity, based on our previous studies. Analysis of combining abilities and heritabilities revealed that both additive and non-additive effects were found to be important in the genetic control of callus induction. In case of green-plant regeneration, non-additive effects were predominant. Broad sense heritability values of 0.92 for callus induction and 0.98 for greenplant regeneration suggested that more than 90% of the observed variation was due to genetic effects, with just less than 10% attributed to nongenetic or environmental effects. In addition, the moderate narrow sense heritability values of 0.49 for callus induction, 0.29 for green-plant regeneration showed that the potential to introduce high responding ability into low lines was moderate. It was therefore conceivable that the frequency of anther culture response might be improved by suitable hybridization and selection strategies. A hybrid combination of code no. 67/ 107 incorporating high callus induction and high green-plant regeneration ability was selected in which genotype with high values of general combining ability (GCA) and positive effects of specific combining ability (SCA).

BackgroundThe cryopreservation of orchid seeds is an important conservation method, studies of the effects of cryopreservation on the seeds of wild orchids are scant. This investigation was to establish a method for the vitrification and cryopreservation of seeds of B. formosana that may be suitable for the long term storage of Taiwan native orchid germplasm for conservation purposes.ResultsThe germination rate and morphological stability of seeds from spontaneous-dehiscent capsules of Bletilla formosana (Hayata) Schltr. were evaluated after cryopreservation by vitrification. The germination rates of cryopreserved seeds varied according to immersion time and the vitrification method used. Seeds that were dehydrated by immersion in loading solution (LS; 2.0 M glycerol, 0.4 M sucrose) for 10 min to 30 min then transferred to plant vitrification solution 2 (PVS2) for 30 min prior to freezing in liquid nitrogen (LN) showed significantly higher germination rates than seeds immersed in PVS2 only. The optimal immersion times were 10 min for LS and 30 min for PVS2, resulting in an in vitro germination rate of 91%. Germination was not observed for cryopreserved seeds that were dehydrated by immersion in LS only. Seed viabilities and germination rates did not vary significantly for cryostorage times from 10 minutes to 1 year.ConclusionsThis study improve, an efficient protocol was established that maintained seed viability and enhanced the germination rates of seeds, compared with previously described cryopreservation methods, and the germinated seeds showed normal morphology of both vegetative and reproductive organs.Electronic supplementary materialThe online version of this article (doi:10.1186/1999-3110-54-33) contains supplementary material, which is available to authorized users.