Rapid breeding and varietal replacement are critical to adaptation of cropping systems in the developing world to climate change.
Rapid breeding and varietal replacement are critical to adaptation of cropping systems in the developing world to climate change.
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DOI：
10.1016/j.gfs.2017.01.008
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发表时间：
2017-03
期刊：
影响因子：
--
通讯作者：
Das B
中科院分区：
文献类型：
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作者：
Atlin GN;Cairns JE;Das B
植物育种是作物系统适应气候变化的关键机制。许多关于气候变化育种的讨论都集中在对耐热性和耐旱性有重大影响的基因上，但物候学和抗逆性是高度多基因的。因此，适应主要是通过快速循环育种不断调整许多位点的等位基因频率，从而提供稳定的增量改良品种流。这将需要获得来自其他地区的优质种质，缩短育种周期，以及能够充分采样目标环境群体的多地点测试系统。为小农服务的育种和种子系统的目标应该是确保他们使用过去10年开发的品种。品种的快速更替必须得到积极推广新品种和积极淘汰过时品种的支持。温带地区的商业种子系统通过竞争性种子市场实现了这一点，但在发展中国家，大多数作物没有竞争性商业种子系统提供服务，许多品种可以追溯到绿色革命结束时（1970年代末，第二代现代水稻和小麦品种被广泛采用）。这些过时的品种是在与今天不同的气候下开发的，使农民处于危险之中。为降低这一风险，需要加强育种体系，实现更自由的优良品种国际交流、短育种周期、高选择强度、大范围表型分型和基因组技术支持的准确选择。政府需要鼓励品种发布和传播系统，以不断取代过时的品种。作物品种的持续更替对适应气候变化至关重要。采用温带商业种植系统的农民，由于品种更替迅速，得到了最好的保护。育种计划需要不受限制地获得来自现在面临未来气候的地区的优质品种。为了实时适应气候变化，需要快速有效的育种周期。发展中国家的农民正面临育种和品种更换周期缓慢的风险。
Plant breeding is a key mechanism for adaptation of cropping systems to climate change. Much discussion of breeding for climate change focuses on genes with large effects on heat and drought tolerance, but phenology and stress tolerance are highly polygenic. Adaptation will therefore mainly result from continually adjusting allele frequencies at many loci through rapid-cycle breeding that delivers a steady stream of incrementally improved cultivars. This will require access to elite germplasm from other regions, shortened breeding cycles, and multi-location testing systems that adequately sample the target population of environments. The objective of breeding and seed systems serving smallholder farmers should be to ensure that they use varieties developed in the last 10 years. Rapid varietal turnover must be supported by active dissemination of new varieties, and active withdrawal of obsolete ones. Commercial seed systems in temperate regions achieve this through competitive seed markets, but in the developing world, most crops are not served by competitive commercial seed systems, and many varieties date from the end of the Green Revolution (the late 1970s, when the second generation of modern rice and wheat varieties had been widely adopted). These obsolete varieties were developed in a climate different than today's, placing farmers at risk. To reduce this risk, a strengthened breeding system is needed, with freer international exchange of elite varieties, short breeding cycles, high selection intensity, wide-scale phenotyping, and accurate selection supported by genomic technology. Governments need to incentivize varietal release and dissemination systems to continuously replace obsolete varieties. Continuous turnover of crop varieties is critical to climate change adaptation. Farmers in commercial temperate cropping systems, with rapid varietal replacement, are best protected. Breeding programs need unfettered access to elite varieties from regions now facing their future climate. Rapid and effective breeding cycles are needed to deliver climate change adaptation in real time. Farmers in the developing world are at risk from slow breeding and varietal replacement cycles.