A functional agrobiodiversity approach to improve organic wheat production

AMBROGIO COSTANZO , PAOLO BÀRBERI - ‘Building Organic Bridges’, at the Organic World Congress 2014

Farm Table says:

This work allows to unravel the potential of different agrobiodiversity use strategies to improve organic wheat production.

Introduction

Wheat is the leading crop for human nutrition in most temperate regions worldwide. Current yields are reported to be stagnating and dependent on external input supply. In organic wheat growing, where environmental variation cannot be buffered through external inputs supply, changes in breeding and cropping systems design are necessary to ensure adequate and stable yields. The use of crop agrobiodiversity is thought to favour sustainable plant production but there is an evident gap between scientific evidence and current agricultural practice.

This works aimed to clarify the impact of different categories of crop agrobiodiversity on wheat production and related agroecosystem services.

  • ‘functional identity’, i.e. the availability of adequate cultivars adapted to local environments and cropping systems,
  • ‘functional composition’, i.e. the co-presence of complementary functional groups
  • ‘functional diversity’, i.e. the use of genetically heterogeneous cultivars

Review of the Results

Crop agrobiodiversity is an asset to improve organic and low-input wheat production, but a clear framework is necessary to translate scientific evidence into practice. Here they presented results from a field experiment on common wheat, focusing on cultivar identity, genetic heterogeneity and on the inclusion of legume living mulch. This experiment provided insights on how to improve yield, yield stability, and weed reduction through adequate cultivar choice and diversification of the crop stand.

They concluded that selecting cultivar identities adapted to local macroclimate is crucial in enhancing yields, but this is not limited to modern pedigree cultivars. Old cultivars are, for example, better weed suppressors, and genetically diverse populations may better buffer climatic unpredictability. Living mulches do not always reduce wheat yield but may reduce weed abundance.

Cultivar local adaptation emerges as the most important determinant of yield performance. However, broadening cultivar choice and system management options would be crucial in the perspective of reducing external inputs, optimizing ecological processes and adapting cropping systems to climate change.

The main outcomes are that:

  • modern commercial cultivars adapted to local conditions are the highest yielding, while old, tall local cultivars are the best weed-suppressive
  • including a certain amount of genetic heterogeneity can buffer unpredictable environmental variation
  • including a legume living mulch can help suppress weeds.

However, the strategies analyzed in this work need to be optimized.

• The use of different cultivar types, e.g. modern vs. old, should be embedded into local agroecosystems and societal needs.

• Functional diversity strategies, as the use of heterogeneous populations, need further testing, and the creation and wider distribution of CCPs for different climatic regions. This would, in turn, require innovations in seed regulation, which currently forbids trade and exchange of heterogeneous seeds.

• Functional composition effects, like those addressed by intercrops and living mulches, need improved component choice and technical optimization of the system through adequate sowing densities and management tactics.

They are currently working on optimizing wheat cultivar mixtures through a functional composition approach, to facilitate the choice of component cultivars based on the combination of key phenotypic traits.

 

2014 - Italy - AMBROGIO COSTANZO , PAOLO BÀRBERI - ‘Building Organic Bridges’, at the Organic World Congress 2014
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