Category: Breeding

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Assuming genebanks

Most crop geneticists agree that enrichment of the cultivated gene pool will be necessary to meet the challenges that lie ahead. However, to fully capitalize on the extensive reservoir of favorable alleles within wild germplasm, many advances are still needed. These include increasing our understanding of the molecular basis for key traits, expanding the phenotyping and genotyping of germplasm collections, improving our molecular understanding of recombination in order to enhance rates of introgression of alien chromosome regions, and developing new breeding strategies that permit introgression of multiple traits. Recent progress has shown that each of these challenges is tractable and within reach if some of the basic problems limiting the application of new technologies can be tackled.

That’s from Breeding Technologies to Increase Crop Production in a Changing World, part of the recent Science special feature on food security. Sure, the challenges of use are tractable. But what if those germplasm collections are inadequate in their coverage, accessibility, management or funding? As ever, genebanks are pretty much taken for granted in these sorts of discussions.

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Getting breeders to focus

Really, who’d be a breeder. Everybody’s telling you what to do all the time. There are those famous “climate-ready” varieties everybody says they need. Plus on top of that, every single-issue lobby group is also making its own demands for tailor-made varieties. The organic or conservation agriculture crowd want varieties adapted to those conditions. People who think the future is mixed crop-livestock farming want dual-purpose varieties. And so on. What’s the poor plant breeder to do?

Well, she might read a new paper in Food Security for a start. Waddington et al. have identified the top ten production constraints for six major staples in 13 farming systems in sub-Saharan Africa, South Asia and East Asia and the Pacific, based on a survey of over 600 experts. They call their paper “Getting the focus right.”

The survey found significant yield gaps for smallholder farms, which were largest for sorghum, cowpea and chickpea, and large in the marginal, drier systems, particularly in Sub-Saharan Africa. All categories of production constraint—abiotic, biotic, management and socio-economic—were important contributors to yield gaps. A great diversity of specific constraints was reported for the crops in the different systems. The specific production constraints that were most severe and widespread for wheat and rice involved the deficiency, high cost and poor management of N fertilizer, soil fertility depletion, inadequate water management and drought stress. Weeds, soil degradation and drought were the most severe constraints for sorghum. Various insect pests and diseases and the high cost of their control were the major constraints for the legumes. Marketing and finance problems, and some specific biotic constraints, were the main concerns for cassava. The diversity of these important production constraints offer the agricultural research and development community an array of opportunities for solutions.

Some of these opportunities will have to do with improved agronomic practices, no doubt. But that will still leave a lot of work for breeders, in particular in the CGIAR system, for whose Generation Challenge Programme the work described in the paper was done. It will be interesting to see to what extent the varieties they develop over the coming years address the challenges identified in this paper. But by the time the next cycle of assessment of improvement programmes comes around, the constraints will have changed. Who’d be a breeder.