Advances in Hybridization Techniques in Small Millets
摘要
Small millets are important crops for future food supplies. They withstand drought, are nutrient-rich, and are also used for fodder purposes. Millet crops include finger millet, barnyard millet, kodo millet, foxtail millet, little millet, browntop millet, and proso millet. These crops belong to the family Poaceae, and they are predominantly self-pollinated in nature. Crossing is necessary to create genetic variation and to make use of the genetic resources that are accessible. Because the flowers of these crops are tiny, physical emasculation and pollination are almost impossible. Although the contact method of hybridization is mostly used in all millets, only 2% to 3% of them successfully produce true F1. Hot water treatment is followed for emasculation other than contact method in the case of foxtail millet, finger millet, and barnyard millet. The success rate is more in hot water treatment compared to contact method in all the crops. Utilization of male sterile lines is also in practice in foxtail millet. In finger millet partial male sterile (PS) line is used for crossing, which sets 27.4–49.4% of seeds upon crossing and ~10 percent of seeds upon selfing. This PS line can be effectively utilized in finger millet crossing program. Treatment with hot water, manual emasculation-pollination, and USSR methods of hybridization are frequently used in proso, little, and browntop millets in addition to the contact method for effective crossing. To generate genetic variability among proso and little millet genotypes, a novel modified crossing method called Small millets, University of Agricultural Sciences, Bengaluru (SMUASB) is used, which has a 56%–60% success rate in producing true hybrids. A 75% success rate was observed in seed establishment during manual emasculation and hand pollination of foxtail millet under growth chamber and greenhouse conditions. Kodo millet has cleistogamous flowering behavior; therefore mutation breeding and pure line selection is practiced more. In each different millet crop, different hybridization techniques are followed to create variability depending upon the breeding behavior of the crops.