Cultivar mixtures: a meta‐analysis of the effect of intraspecific diversity on crop yield

Reiss, Emily R.; Drinkwater, Laurie E.

doi:10.1002/eap.1629

Cited by 216 publications

(200 citation statements)

References 82 publications

(158 reference statements)

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“…The benefits of cultivar/varietal mixtures for increasing yield and reducing yield variability are small but consistent (Reiss & Drinkwater, ). Most mixture studies have focussed only on yield and have not considered the mechanisms which deliver the benefits; the main exception has been studies looking at reduced disease transmission (Newton et al ., ).…”

Section: Discussionmentioning

confidence: 90%

“…One partial solution to the need to maintain or boost agricultural productivity, whilst maintaining biodiversity, is the use of cultivar mixtures (Barot et al ., ). These have been demonstrated to show yield benefits in comparison to cropping with single varieties (Kiær et al ., ; Borg et al ., ; Reiss & Drinkwater, ). Using mixtures also reduces the year to year variation in yield (Smithson & Lenne, ; Reiss & Drinkwater, ), increasing the reliability of farmer incomes, and reduces the need for fungicide treatments as mixtures delay or reduce disease transmission (Newton et al ., ).…”

Section: Introductionmentioning

confidence: 99%

“…These have been demonstrated to show yield benefits in comparison to cropping with single varieties (Kiær et al ., ; Borg et al ., ; Reiss & Drinkwater, ). Using mixtures also reduces the year to year variation in yield (Smithson & Lenne, ; Reiss & Drinkwater, ), increasing the reliability of farmer incomes, and reduces the need for fungicide treatments as mixtures delay or reduce disease transmission (Newton et al ., ). Whilst the agronomic benefits of growing crop mixtures have been studied, there has been less focus on the interactions of crop mixtures with the weed community, though the suppressive impacts of crops on weeds is noted as one of the potential causal drivers of the yield gain in planting cereal mixtures (Kiær et al ., ).…”

Section: Introductionmentioning

confidence: 99%

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Increased crop diversity reduces the functional space available for weeds

et al. 2019

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Summary There is a drive to improve the sustainability of agricultural systems including the biodiversity component. Cultivar mixtures offer yield benefits from the same land area, but the mechanisms behind this overyielding have not been completely worked out. One potential mechanism is improved competition with weeds. We use an experimental approach of varying barley (Hordeum vulgare L.) genotypic and phenotypic diversity to test the hypothesis that increases in diversity have an impact on weed growth strategies and community assembly, or if responses are driven by barley performance. There was no effect of increasing barley mixture diversity on weed traits, either in terms of species means or the community‐weighted mean. However, Functional Richness of the weed community decreased with increasing barley mixture diversity mainly as a result of reduced specific leaf area Functional Richness. This pattern was driven by a reduction in species richness of the weed community rather than by reduced variation within species. Whilst barley phenotype had different impacts on weed traits, there were no specific mixtures of phenotypes or genotypes that had consistent effects on community assembly or weed species responses. The competitive exclusion of weed species could have agronomic and environmental benefits, through better targeting or less frequent use of herbicides. Growing crop mixtures is one of many strategies available to improve agricultural sustainability and resilience, and one that has clear benefits.

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Section: Discussionmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Increased crop diversity reduces the functional space available for weeds

et al. 2019

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“…Previous studies have shown effects of plant genotypic diversity on productivity (Cook‐Patton et al. , Reiss and Drinkwater ), herbivore spatial distribution (Utsumi et al. , Zytynska et al.…”

Section: Introductionmentioning

confidence: 99%

Pest suppression in cultivar mixtures is influenced by neighbor‐specific plant–plant communication

Dahlin

Rubene

Glinwood

et al. 2018

Ecological Applications

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Increased plant genotypic diversity in crop fields can promote ecosystem services including pest control, but understanding of mechanisms behind herbivore population responses to cultivar mixtures is limited. We studied aphid settling on barley plants exposed to volatiles from different cultivars, aphid population development in monocultures and two-cultivar mixtures, and differences in volatile composition between studied cultivars. Aphid responses to one cultivar in a mixture were neighbor-specific and this was more important for pest suppression than the overall mixture effect, aphid colonization patterns, or natural enemy abundance. Aphid populations decreased most in a mixture where both cultivars showed a reduced aphid-plant acceptance after reciprocal volatile exposure in the laboratory, and reduced population growth compared to monocultures in the field. Our findings suggest that herbivore population responses to crop genotypic diversity can depend on plant-plant volatile interactions, which can lead to changes in herbivore response to individual cultivars in a mixture, resulting in slower population growth. The impact of plant-plant interaction through volatiles on associated herbivore species is rarely considered, but improved understanding of these mechanisms would advance our understanding of the ecological consequences of biodiversity and guide development of sustainable agricultural practices. Combining cultivars in mixtures based on how they interact with each other is a promising strategy for sustainable pest management.

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“…Thus, we expect genetic diversity at kin recognition systems in cultivated species to be much lower, if any, in elite varieties (Murphy, Swanton, Van Acker, & Dudley, ). Still, if polymorphism has been maintained, genetically based kin recognition may explain conflicting results among studies of variety mixtures within species (Reiss & Drinkwater, ; Smithson & Lenné, ) and the outcome of competition among varieties depending upon their genetic similarity at the kin recognition loci. Here, we did not find evidence that plants could direct helping toward relatives in durum wheat landraces from traditional agrosystems, where genetic diversity is still present at the field and individual levels (this study, Muller et al unpublished).…”

Section: Discussionmentioning

confidence: 99%

Preferential helping to relatives: A potential mechanism responsible for lower yield of crop variety mixtures?

Fréville

Roumet

Rode

et al. 2019

Evolutionary Applications

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Variety mixtures, the cultivation of different genotypes within a field, have been proposed as a way to increase within‐crop diversity, allowing the development of more sustainable agricultural systems with reduced environmental costs. Although mixtures have often been shown to over‐yield the average of component varieties in pure stands, decreased yields in mixtures have also been documented. Kin selection may explain such pattern, whenever plants direct helping behaviors preferentially toward relatives and thus experience stronger competition when grown with less related neighbors, lowering seed production of mixtures. Using varieties of durum wheat originating from traditional Moroccan agrosystems, we designed a greenhouse experiment to address whether plants reduced competition for light by limiting stem elongation when growing with kin and whether such phenotypic response resulted in higher yield of kin groups. Seeds were sown in groups of siblings and nonkin, each group containing a focal plant surrounded by four neighbors. At the group level, mean plant height and yield did not depend upon relatedness among competing plants. At the individual level, plant height was not affected by genetic relatedness to neighbors, after accounting for direct genetic effects that might induce among‐genotype differences in the ability to capture resources that do not depend on relatedness. Moreover, in contrast to our predictions, shorter plants had lower inclusive fitness. Phenotypic plasticity in height was very limited in response to neighbor genotypes. This suggests that human selection in crops may have attenuated shade‐avoidance responses to competition for light. Future research on preferential helping to relatives in crops might thus target social traits that drive competition for other resources than light. Overall, our study illustrates the relevance of tackling agricultural issues from an evolutionary standpoint and calls for extending such approaches to a larger set of crop species.

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Cultivar mixtures: a meta‐analysis of the effect of intraspecific diversity on crop yield

Cited by 216 publications

References 82 publications

Increased crop diversity reduces the functional space available for weeds

Increased crop diversity reduces the functional space available for weeds

Pest suppression in cultivar mixtures is influenced by neighbor‐specific plant–plant communication

Preferential helping to relatives: A potential mechanism responsible for lower yield of crop variety mixtures?

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