Breeding for Nutrient Efficiency: A Model for the Future

K.K.Vinod

Having identified a plethora of putative QTLs that contribute to nutrient use efficiency, the logical next step is to design appropriate selection strategies for improving genotype efficiency against low nutrient stress. However, not-so-significant effects of the identified QTLs are a serious concern in designing robust MAS strategies, since QTL-by-environment interaction may jeopardize the selection process. Further, the arcane effects of the identified QTLs confound the scientific soundness of the selection programmes. It is unlikely that many major-effect QTLs may emerge for nutrient use efficiency in future. This reduces us to the option of using small effect QTLs for future rice improvement.

One of most encouraging observations in the abiotic stress breeding so far is the interoperability of abiotic stress resistance across the causative factors. Armed with strict phenotyping tools, it is likely that an integrated approach of marker assisted selection may help us in improving abiotic stresses together, rather than the individualistic approach for each causative factor. I prefer to propose a model of recurrent selection for improving nutrient use efficiency, by channelizing the genotypes that has been selected for drought, salinity, submergence, and for nutrient use through an integrated breeding programme that also select for N and P use efficiency together. This process offer the advantage of including any new genotype in the breeding chain at any time, while a new genotype can emerge at any stage that are suitable for various target environments. This program will be more resource abundant, including beneficial gene flow, which is otherwise not the case in targeted breeding programmes for individual stress resistance.