Rapid-Cycle Plant Breeding Systems are the Key to Climate Change Adaption in Agriculture

Plant breeding is the primary mechanism for adaptation of cropping systems to climate change.  Most discussion of its role in adaptation has focused on discovering alleles with large effects on heat and drought tolerance.  These are important, but phenology and stress tolerance are usually polygenic in architecture. Adaptation will result from applying modern breeding methods for maximizing genetic gains for quantitative traits.  These include rapid breeding cycles, high selection intensity, managed-stress phenotyping, and multi-location testing that adequately samples the target population of environments.  Bteeding programs are needed that produce a steady stream of improved varieties, with breeding cycles of no more than five or six years, as well as seed systems that quickly replace varieties. Farmers in the developing world should be using varieties that have been developed in the current climate, or roughly in the last 10 years.  Seed systems must aggressively replace obsolete varieties. Commercial seed systems in temperate regions achieve this via competitive seed markets and a high level of trust of farmers in new varieties recommended by seed companies, but the situation is very different in the developing world, where many varieties in widespread use were introduced in the late years of the Green Revolution, and have never been replaced.  These varieties were developed in a climate different than today’s, placing farmers at risk.   The strengthened and accelerated public sector breeding systems needed for climate change adaptation must be supported by freer international exchange of elite germplasm.