Enhancing In-crop Diversity in Common Bean by Planting Cultivar Mixtures and Its Effect on Productivity

Abstract

Common bean (Phaseolus vulgaris L.) is the most important food legume crop worldwide. Canadian beans, especially large seeded cultivars of Andean origin, have relatively narrow genetic diversities. Establishing crops with mixtures of cultivars instead of pure lines is a simple, cost effective way to increase genetic diversity in the field. A number of studies have demonstrated the benefits of mixture cropping over monocropping in controlling disease, increasing water use efficiency, and increasing yield stability. The objective of this study was to determine the effects of increasing in-field diversity, by using mixtures of bean cultivars instead of monocultures, on productivity. The feasibility of growing bean cultivar mixtures in southern Ontario environments was confirmed with a small pilot study that was conducted with four bean cultivars and restricted number of mixtures at two locations in 2017. Mixture performance experiments were performed with seven diverse bean genotypes at two Ontario locations [Woodstock and Elora (two planting dates) research stations] as pure stands and all possible binary mixtures (planted in alternate rows or as completely random mixtures) in 2018. Conventional plot-based above ground crop data were collected. Mixing efficiencies were calculated from the yield data using a relative yield of the mixture (RYM) index. Diallel analysis was used to identify general mixing ability of cultivars and specific mixing abilities of mixtures. Significant differences among seven bean cultivars and their mixtures were identified in all three environments for all analyzed traits. The results indicated multiple benefits of planting mixtures compared to monocultures A number of mixtures overyielded component cultivars grown in pure stands; they had higher yields, RYM index values >1 and positive specific mixing abilities (for yield) in both types of biblends. The research has the potential to provide a theoretical basis for the use of precision agriculture tools to plant fields with mixtures instead of monocultures. It could lead to greater in-field diversity in the crop and in the above and below ground ecosystems that might provide greater buffering capacity and resiliency to the cropping system as well as increased ecosystem services.

Approaches and Advantages of Increased Crop Genetic Diversity in the Fields

“…Germplasm exchange and repatriation based on climate analog tools are also very effective to obtain higher production and conservation of diversity in the fields. Multiple approaches might be good to use even in a single landrace for producing higher benefits as well as to accelerate their conservation on-farm [14,15]. For increasing diversity, farmers' practices are, relatively, better than modern agricultural practices.…”

“…Selection responses in such narrow genetic diversity are almost negligible. Because of the lack of buffering capacity, these varieties are vulnerable to both biotic and abiotic stresses [15,20] and there are many cases of a complete failure of production in many crops. In addition.…”

Approaches and Advantages of Increased Crop Genetic Diversity in the Fields

“…Germplasm exchange and repatriation based on climate analog tools are also very effective to get higher production and conservation of diversity in the fields. Multiple approaches might be good to use even in a single landrace for getting higher benefits as well as to accelerate their conservation on-farm (Hufnagel et al 2020, Reinprecht et al 2020.…”

“…Selection response in such narrow genetic diversity is almost negligible. Because of the lack of buffering capacity, these varieties are vulnerable to both biotic and abiotic stresses (Lin 2011, Reinprecht et al 2020 and there are many cases of complete failure of production in many crops. Insect pollinators prefer to visit fields where diversity is high both at intra and inter-varietal levels.…”

Examination of Different Sporidium Numbers of Ustilago maydis Infection on Two Hungarian Sweet Corn Hybrids’ Characteristics at Vegetative and Generative Stages

“…Successful crop production depends on many factors, such as crop type [ 1 ], variety [ 2 ], and environmental factors [ 3 ], including climatic conditions [ 4 ], soil [ 5 ], and water [ 6 ]. Biotic and abiotic stresses also affect yield [ 7 ].…”