Today rice, on average of three eco-types covers 281,444,000 acres (2013-2016) or 73.77% of the gross cropped areas of 38148,000 acres (2015-16) of Bangladesh. It uses 73.48% of irrigation water of total 18405,000 acres and also uses 71.99% or close to that of N fertilizer of 36,82,670 tm. in 2005-6. Such high percentages of input use by rice with an average yield of only 1178kg/acre or 2910kg/ha are certainly not the good return on investment (RoI) in rice. Again the farmers and the policymakers cannot afford reducing rice acreage giving space for wheat or maize for a mixed food system. So, there is a need for improvement of rice varieties with a target expectation of rice yield close to 10 tons/hac. In reaching that target a combination of Conventional-Molecular-Participatory breeding system is necessary in a team of breeders to coordinate and not in isolation. The trait specific breeding will help us to get desirable types faster than the yield alone.
It is necessary to breakdown both photo and thermo sensitivity of the rice varieties/lines. This can be done easily by identifying gene/genes using our rice genetic resources and creating new diversity. Also, we need to determine the presence of gene/genes using RGA followed by molecular and conventional selection. Once identified, testing of the materials for G-E interactions under varied agro-ecological conditions is important. These materials may then be available for sharing on MTA, or direct or royalty payment system whichever is acceptable to the breeders/ organizations like in the CGIAR System.
In addition to the photo and thermo sensitivity major emphasis should be on plant ideotype, strong erect leaves with delayed senescence, closely netted veins on the leaves, high root biomass with longer root system, plants having fast and uniform tillering ability with longer panicles having neatly arranged grains close to 250. The grain maturity time should be 60+ days. Recently, there have been attempts to increase nutrients of different types including Zinc, Iron, Vitamins, etc. inclusion of those traits should be planned for the variety with higher yields at farmer’s level for faster adoption. Thus, the breeder has to tailor his/her plants as per need of the present and future of rice. We usually do not plan considering both genetics of traits and their combination effects on ultimate yield against environment and diseases. Development of varieties for T.Aman should be encouraged than Boro which can help reduce water use. ASRBC rice programs (2012-2015) before start of the ACI-IRRI-PPP project have successfully developed eight lines through TILLING that produced more than 10tons yield/ha with one produced 11.20tons in Boro season of 2015-16 and was close to that of BR-29, but a week earlier than the other while 4 lines were much better than BR-28 producing more than 7tons/ha compared to BR28 (6.85/ha tons). (Source: R&D Achievements of ASRBC June 30,2016 A.Islam et al.Page 17.)