Emasculation techniques and detached tiller culture in wheat x maize crosses

Intergeneric hybridization of wheat with maize has been exploited to achieve instant homozygosity in wheat with the production of doubled haploids. A study was conducted at Agricultural Biotechnology Research Institute, AARI, Faisalabad during 2007-08 and 2008-09 to enhance the efficacy of haploid production, in terms of frequency of seed and embryo development. In wheat crop manual emasculation of spikes is laborious and time consuming. Different emasculation techniques like hand emasculation with cut and intact glumes, hot water emasculation and no emasculation were compared. The results reflected that laborious exercise of hand emasculation can be substituted with no or hot water emasculation methods with above 10 percent embryo frequency. Alternative technology to reduce the space required for pollinated wheat heads was also studied by tiller culture method. Detached tillers were kept in liquid nutrient medium after emasculation to increase turnover for greenhouse materials. The results indicated that wheat spikes can be successfully cultured in a liquid medium before anthesis till embryo rescue. There is a close similarity for grain formation and embryo development in the detached wheat spikes in liquid medium and intact plant method. Detached tiller culture was found highly successful in wheat x maize crossing (17.15% embryo formation in emasculated florets). This technique had great edge over intact plant method with respect to saving of time and space, delaying of pollination due to storage of tillers under controlled conditions, simple hot water emasculation of detached tillers and application of plant growth regulators. Solution containing 40 g/L sucrose, 100 mg/L 2, 4-D and 8 ml/L sulphurous acid was identified as the best medium for culture of wheat x maize crossed tillers for getting maximum frequency of haploid embryos per pollinated floret.