Intercropping cereals with faba bean reduces plant disease incidence regardless of fertilizer input; a meta-analysis
Ecological intensification of agriculture calls for ecological mechanisms to replace anthropogenic inputs. Cereal/legume intercropping increases yields due to species complementarities, it produces high protein food and feed, and it reduces the need for artificial N fertilizer because legumes fix N biologically. In addition, intercropping has the potential to suppress plant diseases, but its efficacy for disease suppression in cereal/legume mixtures has not been well characterized quantitatively. Here we conducted meta-analysis to quantify the disease suppressive effect of intercropping cereals with legumes at different levels of N fertilizer. Intercropping reduced disease incidence (measured by the odds ratio of disease occurrence) by 45% on average. This reduction was significant (P < 0.01) for four out of six studied pathogens: yellow rust (Puccinia striiformis f.sp. tritici) and mildew (Blumeria graminis) in wheat (Triticum aestivum), and chocolate spot (Botrytis fabae) and Fusarium wilt (Fusarium oxysporum) in faba bean (Vicia faba). Disease reduction was marginally significant for yellow rust in barley (Puccinia striiformis f.sp. hordei) (P < 0.10) and not significant for bean rust (Uromyces fabae). The reduction in disease incidence was greatest during the early stages of epidemics. N fertilizer strongly increased the incidence of powdery mildew of wheat, but it did not affect the incidence of the other diseases and it did not affect the effectiveness of intercropping as a management strategy for disease control. While nitrogen input increased powdery mildew incidence in both sole and intercropped wheat, the incidence was lower in the intercropped than sole wheat at all levels of N input. The disease suppressive effect of intercropping on wheat powdery mildew or any other disease was not affected by the amount of nitrogen fertilizer. The results show that intercropping has a substantial and consistent effect on disease incidence in cereal/faba bean mixtures across studies, but is not sufficient to provide complete disease control. Intercropping is therefore best used as a component in an integrated approach for managing plant diseases.
KeywordsIntercropping Disease control Meta-analysis Nutrient management
We are grateful for the financial support from the key project of the Ministry of Science and Technology of China (grant number 2016YFE0101100), the National Natural Science Foundation of China (NO. 31210103906), the Chinese National Basic Research Program (2015CB150405), and the European Union’s Horizon 2020 Programme for Research & Innovation under grant agreement n°727217 “ReMIX”.
YD and CZ did the literature search, extracted data and conducted the analysis. CZ, YD, YY, DM and WW designed methods for statistical meta-analysis and interpreted results. All authors contributed to formulation of research aims and overall approach, discussed outcomes and approved the submission. CZ, YD, DM and WW wrote the paper.
Compliance with ethical standards
Conflict of interests
The authors declare no conflicts of interests.
- Agresti A. 2002. Categorical data analysis. Wiley. 2nd edition.Google Scholar
- Bedoussac, L., Journet, E., Hauggaard-Nielsen, H., Naudin, C., Corre-Hellou, G., Jensen, E. S., Prieur, L., & Justes, E. (2015). Ecological principles underlying the increase of productivity achieved by cereal-grain legume intercrops in organic farming. A review. Agronomy Sustainable Development, 35, 911–935.CrossRefGoogle Scholar
- Borenstein, M., Hedges, L. V., Higgins, J. P. T., & Rothstein, H. R. (2009). Introduction to meta-analysis. Wiley.Google Scholar
- Keesing, F., Belden, L. K., Daszak, P., Dobson, A., Harvell, C., Holt, R. D., Hudson, P., Jolles, A., Jones, K. E., Mitchell, C. E., Myers, S. S., Bogich, T., & Ostfeld, R. S. (2010). Impacts of biodiversity on the emergence and transmission of infectious diseases. Nature, 468, 647–652.CrossRefPubMedGoogle Scholar
- Li, C. Y., He, X. H., Zhu, S. S., Zhou, H. P., Wang, Y. Y., Li, Y., Yang, J., Fan, J. X., Yang, J. C., Wang, G. B., Long, Y. F., Xu, J. Y., Tang, Y. S., Zhao, G. H., Yang, J. R., Liu, L., Sun, Y., Xie, Y., Wang, H. N., & Zhu, Y. Y. (2009). Crop diversity for yield increase. PLoS One, 4(11), e8049. https://doi.org/10.1371/journal.pone.0008049.CrossRefPubMedPubMedCentralGoogle Scholar
- Lithourgidis, A. S., Dordas, C. A., Damalas, C. A., & Vlachostergios, D. N. (2011). Annual intercrops: An alternative pathway for sustainable agriculture. Australian Journal of Crop Science, 5, 396–410.Google Scholar
- Lv, Z. X., Yu, X. P., Heong, K. L., & Hu, C. (2005). Effects of nitrogenous fertilization in rice fields on the predatory function of Cytorhinus lividipennis Reuter to Nilaparvata lugens stål. Acta Entomologica Sinica, 48, 48–56 (In Chinese).Google Scholar
- Pelzer, E., Bazot, M., Makowski, D., Corre-Hellou, G., Naudin, C., Rifaï, M. A., Baranger, E., Bedoussac, L., Biarnès, V., Boucheny, P., Corrouée, B., Dorvillez, D., Foissy, D., Gaillard, B., Guichar, L., Mansard, M., Omon, B., Prieur, L., Yvergniaus, M., Justes, E., & Feuffroy, M. (2012). Pea-wheat intercrops in low-input conditions combine high economic performances and low environmental impacts. European Journal of Agronomy, 40, 39–53.CrossRefGoogle Scholar
- R Core Team, 2015. R: A language and Environment for Statistical Computing. Foundation for Statistical Computing, Vienna, Austria.Google Scholar
- Zadoks, J. C., & Schein, R. D. (1979). Epidemiology and plant disease management (p. 427). Oxford: Oxford University Press.Google Scholar
- Zhang, S., Luo, H. G., Zhang, Q. D., Xu, Y. Y., Zou, C. H., Guo, M. L., He, S. M., Fang, X. W., Zhang, J. X., & Chen, Q. Z. (2008). Effects of nitrogen and potassium fertilizer applications on yield and occurrence of major diseases and insect pests of rice. Journal of Huazhong Agricultural University, 27, 732–735 (In Chinese).CrossRefGoogle Scholar
- Zuur AF, Ieno EN, Walter NJ, Saveliev AA & Smith GM. 2009. Mixed effects models and extensions in ecology with R. Springer, 574 pp.Google Scholar