Unfolding the potential of wheat cultivar mixtures: A meta-analysis perspective and identification of knowledge gaps
Unfolding the potential of wheat cultivar mixtures: A meta-analysis perspective and identification of knowledge gaps
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DOI：
10.1016/j.fcr.2017.09.006
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发表时间：
2018-05-15
影响因子：
5.8
通讯作者：
Enjalbert, J.
中科院分区：
文献类型：
--
作者：
Borg, J.;Kiaer, L. P.;Enjalbert, J.
增加作物的生物多样性是农业生态学的一个关键杠杆，旨在通过生态过程和法规取代化学投入。品种混合是增加作物内多样性的一种直接方法，但迄今为止，农民对这种方法的利用率很低，咨询服务也不鼓励这种方法。基于Kiaer等人（2009）开发的方法，我们实现了小麦品种混合物的荟萃分析。在120篇关于小麦的出版物中，我们选择了32篇研究，通过计算超高产，即品种混合物与其纯林组分品种的加权平均值相比的生产力差异，分析了可能决定小麦混合物成功或失败的各种因素。分析强调了3.5%的显著全球超高产，在疾病压力较大的情况下，发病率达到6.2%。播种密度和地块大小对过产率没有影响。在高病压条件下，每增加一个组分品种，增产幅度可达3.2个百分点。抗病性或物候异质的杂交组合比同质的杂交组合分别增产5.3%和3.3%，而高度异质的杂交组合比同质的杂交组合增产不多。Overyielding在19805年和19905年达到最高值，这反映了在此期间以疾病为重点的研究占主导地位。我们的研究结果证实，品种混合是一种潜在的方式来增加产量相对于纯品种，特别是在低农药种植制度。文献表明，由于缺乏有助于混合品种的一般规则，混合做法受到阻碍。为了设计这样的规则，需要（1）实现操纵品种性状异质性的新实验，（2）通过实验确定混合性能的生态机制，（3）开发新的模型，以测试和分析这些机制。
Increasing the biodiversity of cropped plants is a key leverage for agroecology, aiming to replace chemical inputs by ecological processes and regulations. Cultivar mixtures are a straightforward way to increase within-crop diversity, but they have so far been poorly used by farmers and they are not encouraged by advisory services. Based on the methodology developed by Kiaer et al. (2009), we achieved a meta-analysis of cultivar mixtures in wheat. Among the 120 publications dedicated to wheat, we selected 32 studies to analyze various factors that may condition the success or failure of wheat mixtures by calculating overyielding, i.e. the difference in productivity of a variety mixture compared with the weighted mean of its component varieties in pure stand. The analysis highlighted a significant global overyielding of 3.5%, which reached 6.2% in condition of high disease pressures. Overyielding was not affected by seeding density or plot size. Under high disease pressure, over yielding increased by 3.2% point per added component variety. Overyielding was respectively 5.3% and 3.3% higher for mixtures heterogeneous in disease resistance or phenology than for homogeneous ones, and did not vary when considering height. Overyielding reached its highest values in the 19805 and 19905, which reflects the predominance of disease-focused studies during this period. Our results confirm that cultivar mixtures are a potential way to increase yield relatively to pure varieties, especially under low pesticide cropping systems. Literature suggests that mixture practice is impeded by the lack of general rules that could help to mixing varieties. To design such rules it is needed to (1) achieve new experiments manipulating the heterogeneity in variety traits, (2) determine experimentally the ecological mechanisms underlying mixture performance and (3) develop new models allowing testing and analyzing these mechanisms.