Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6375277 | Field Crops Research | 2013 | 7 Pages |
â¢Variety trial yields were used as a proxy for potential yield.â¢Genetic progress over the past ca. 30 years largely linear and substantial for winter wheat, spring barley, starch potato and sugar beet.â¢Differences between variety resistances were found in sugar beet.â¢Farm yields could not always keep pace with the combined genetic and year effects (G Ã E Ã M) in variety trials, suggesting a widening yield gap.â¢Also, significant year (climate and/or management) effects were found in variety trials.
Crop yields are a result of interactions between genetics, environment and management (G Ã E Ã M). As in the Netherlands differences between potential yield and actual farm yields (yield gaps) are relatively small, progress in genetic potential is essential to further increase farm yields. In this paper we study the progress in yields of newly released varieties in official Dutch variety trials as a proxy for the progress in genetic yield potential, i.e., yield under absence of water and nitrogen limitation and pests and diseases. The use of yields from variety trials as a proxy for genetic yield potential is justified as these are well managed and because water is hardly limiting under Dutch climate-soil conditions. We compared the genetic yield progress of winter wheat (Triticum aestivum L.), spring barley (Hordeum vulgare L.), ware and starch potato (Solanum tuberosum L.) and sugar beet (Beta vulgaris L.) over the past ca. 30 years (ca. 1980-2010) with the developments in on-farm yields over the same period. GenStat 14th edition was used to perform modified joint regression analyses (mjra) and residual (or restricted) maximum likelihood (reml) analyses of yields in order to separate year (i.e., climate and/or management) effects from variety effects. Genetic progress in yield has been linear with ca. 100 and 60 kg haâ1 yearâ1 (15% moisture), respectively, for winter wheat and spring barley, 580 kg haâ1 yearâ1 payment weight for starch potato, and, partly non-linear for sugar beet, i.e., 80-170 kg sugar haâ1 yearâ1 depending on resistance type of the varieties. We also analyzed significant year effects (corrected for genetic progress) for most crops in the variety trials, which point at an effect of climate (environment) and/or management in addition to the genetic effect. Farm yields of winter wheat, spring barley and starch potato have increased linearly over the last decades, with ca. 90, 70 and 320 kg haâ1 yearâ1 (in the same units as above). Increase in sugar yields on farms was concave (20-230 kg haâ1 yearâ1) and spectacular over the last 10 years. For ware potatoes the genetic yield increase was only 20 kg dry matter haâ1 yearâ1 and reliable farm statistics for dry matter yields are lacking. We conclude that for the main crops in the Netherlands genetic progress in yield potential of varieties newly released over the past three decades has been substantial and largely linear. Farm yields for these crops also continued to increase, at approximately the same rates, but could not always keep pace with the combined genetic and year effects (G Ã E Ã M) in variety trials, suggesting a widening yield gap.