Rapid breeding and varietal replacement are critical to adaptation of cropping systems in the developing world to climate change

Abstract

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.

Closing the global ozone yield gap: Quantification and cobenefits for multistress tolerance

“…For example, varieties that use less water per unit of carbon fixed will have higher yield under drought conditions (Rebetzke, Condon, Richards, & Farquhar, ) as will those with “stay‐green” characteristics during water stress (Jordan, Hunt, Cruickshank, Borrell, & Henzell, ). Whilst it is widely recognized that rapid breeding programmes will have a vital role to play in adaptations of crops to climate change (Atlin, Cairns, & Das, ), selection of traits for tolerance of one abiotic stress, tropospheric (ground level) ozone pollution, is currently omitted from such breeding programmes (Ainsworth, ; Frei, ). This is happening even though field experiments from nine countries representing three continents have shown that reducing ozone concentrations back to pre‐industrial levels would give an average wheat yield benefit of 8.4% globally (Pleijel, Broberg, Uddling, & Mills, ), a figure that is matched by modelling based on the stomatal uptake of the pollutant (Mills, Sharps et al., ).…”

Cuestiones Ambientales y Seguridad Alimentaria en el Cantón Guano, Ecuador

“…De acuerdo a Noboa et al (2012), en el caso de la agricultura se evidencia impactos directos que inciden en el rendimiento de los cultivos y en los ciclos de crecimiento de las especies agrícolas, ocasionados principalmente por la variación de la temperatura y la presencia de algunas plagas e insectos que perjudican el normal desarrollo de los cultivos. Esto se relaciona con lo expuesto por Atlin (2017), que señala que el objetivo de los sistemas nacionales de semillas debería ser garantizar que la edad media de las variedades en los campos de los agricultores sea inferior a 10 años, tanto para asegurar que las ganancias genéticas se entregan constantemente a los agricultores y para mantenerse a la par con los efectos del cambio climático. Según Zamora et al, (2015), menciona que el crecimiento de la actividad humana está afectando la existencia de las comunidades bióticas al generar importantes pérdidas de especies y graves niveles de contaminación ambiental que se traducen en cambios drásticos en el funcionamiento y constitución de la biósfera.…”

Revisiting rice breeding methods – evaluating the use of rapid generation advance (RGA) for routine rice breeding

“…new races, pathotypes or biotypes), rice breeders need to consider adopting faster breeding methods to modernize their programmes and specifically to increase the rate of genetic gain, while also minimizing operational costs (Atlin et al, 2017). RGA is one of many effective methods that can allow rice breeders and geneticists some 'quick wins' to modernize quickly, and with a simple re-allocation of existing resources currently being spent on expensive pedigree selection schemes.…”

“…shorter the length of time of the breeding cycle), the higher the genetic gain, assuming the variables in the numerator remain the same (Fehr, 1984;Moose & Mumm, 2008). It is generally considered that one of the simplest ways to increase genetic gain is to reduce the time of the breeding cycle (Atlin et al, 2017;De La Fuente et al, 2013).…”