Focus on Agro-Ecology: Varieties for Sustainable Agriculture

Likewise conventional farming, Agro-Ecology aims to supply agriculture products at the highest yields and the best quality.

But agro-ecology's mission includes preserving the ecosystems in the fields, rivers and nearby environment. By definition, agro-ecology is based on increasing the services provided by crops (SEMAE Report, 2022) :

📌 Production remains the primary objective of agricultural systems

📌 Preserve biodiversity, plant species and varieties ; promote favorable interactions of plants with living organisms that can contribute to their development.

📌 Improve soil conservation and regeneration by planting species that stimulate biological activity and increase the biomass produced to increase the storage of soil organic matter.

📌 Conservation of resources and energy (reduction of fossil fuel consumption).

“The development of plant cover crops and service plants are potential levers for maintaining soil capital and limiting water evapo-transpiration; improving soil water storage, pest management, CO2 capture, weed management and soil fertilization.” Olivier Lucas, RAGT

Agro-ecology, as a discipline, integrates four major challenges: Socially, it promotes the maintenance of farms and salaried employment, thanks to resilient systems. Secondly, it contributes to economic improvement by stabilizing farmers' incomes through economical practices. On a societal level, it meets the demand for virtuous production methods and supports territorial development.

Our article focuses mainly on the fourth challenge, the environmental role of an agriculture that preserves biodiversity, restores soils and reduces the impact of agriculture.

1.    The contribution of varietal selection to agro-ecology

Genetic improvement and varietal creation are central to the evolution of cropping systems and will continue to be so if the agro-ecological transition is to succeed.  

The massive use of inputs has steered breeding towards objectives that are highly focused on productivity and quality requirements for industrialists. This has resulted in varieties adapted to artificial environments and spread over vast geographical areas (SEMAE Report, 2022).

Agro-ecology involves diversifying growing conditions and using a minimum of inputs and therefore less artificial environments, which favors an increase in Genotype x Environment (GxE) interactions and calls for the adaptation of varieties to local practices and conditions (Fontaine et al., 2021).

"Interactions between plants and their environment are of particular importance in agro-ecology", especially interactions between varieties and micro-biota. This is leading to a wider diversification of varieties and improved characterization. (CTPS Scientific Committee, 2021)

The agro-ecological transition today requires a multiplication of breeding axes to move plant breeding away from the dominant concept of homogeneity, of the single or pure variety adapted to all environments. It is therefore necessary to evaluate a variety within its production system, and thus to combine genetic improvement, agronomy and all the resources for the management and protection of agro-ecological practices (CTPS Scientific Committee, 2021).

1.1.          Varietal selection schemes

The need for multi-services and varieties adapted to local conditions has consequences for the breeding profession, which is adopting different breeding methods: (CTPS Scientific Committee, 2021)

• Recourse to genomic selection (Crossa et al., 2021)and speed-breeding (accelerate cycles and integrate genotype x environment interactions into these methods).
• Increase the genetic diversity available for breeding programs by intensifying pre-breeding, making better use of genetic resources(Allier et al., 2020).
• Develop new variety selection methods better adapted to species and variety associations (Sampoux et al., 2019).
• Election of "variety populations" incorporating a heterogeneous genetic mix, whose intra-varietal variability should enable adaptation to farmers' environments and practices (van Franck et al., 2020).
• Integrate environmental diversity into selection and evaluation processes, by better characterizing the preferred environments for varieties under selection (current and future environments) and anticipating the impact of climate change.

"Seed companies will have to manage more different varieties, for more species, fewer sales per variety, and will have to better advise farmers on the favorable environmental conditions for each variety." CTPS Scientific Committee, 2021

1.2.          What varietal characteristics to select?

In agro-ecology, favorable characteristics for each species are chosen based on the services provided at the scale of the cropping system. Here are a few varietal characteristics useful for the agro-ecological transition of cropping systems (CTPS Scientific Committee, 2021).

• Efficient plant nutrition, soil fertility and reduced dependence on synthetic fertilizers: Ability to capture and return mineral elements, to colonize the soil, thus improving soil structure and limiting soil erosion. Ability to store carbon and enrich soil with organic matter (root and above-ground biomass not exported, etc.).
• ‍Bio-aggressor regulation: Ability to repel insects, host and attract parasitoids, regulate weeds.
• ‍Adaptation to agro-ecological practices:Aptitude for species or variety associations, tolerance to mechanical weeding,response to bio- control products, tolerance to no-till practices.

2.    Example of varieties adapted to agro-ecological systems

🌾 Wheat

AgriObtentions selects 15 species, mainly self-pollinated. Recently, the INRAE / Agri Obtentions varietal innovation program has focused on the creation of soft wheat varieties adapted to sustainable agriculture (INRAE,2021). AgriObtentions is the only French seed company to offer two organic wheat varieties in the French catalog.

🥔 Potatoes

For the potato species, the mandatory entry criterion for the "Adapted variety to agroecology" label is resistance to mildew. The creation of this label, controlled by the Ministry of Agriculture, is designed to make the French variety catalog more attractive. The French catalog currently features 6 agro-ecological PDT varieties registered over the last 4 years (Journal La pomme de Terre Française, N°648, p47).

3.    Information processing to select agro-ecological varieties

The evaluation of varieties for the agro-ecological transition requires a more detailed characterization of their behavior under different conditions, of the way they interact with their environment and make the most of different environmental components and cultivation practices.  

To deliver relevant information on varieties in their agro-ecological systems, we need to develop a software package for managing agro-ecological variety selection data. Such software would centralize and analyze data from different sources, including cultivation experiments carried out by variety breeding companies.

This software is designed to meet three challenges:

• Characterize agro-ecological cropping systems, criteria of interest for agro-ecology, and environments, so that they can be taken into account in the decision-making system for agronomic "systems" trials;‍
• Accelerate varietal creation(by reducing the length of selection cycles) to increase intra-species genetic variability and offer varieties better adapted to varied terroirs; ‍
• Quantify the beneficial environmental and economic impacts for farmers, to encourage the adoption of agro-ecological practices.

The software for agro-ecological varietal selection must be much more than a simple tool for managing phenotypic, genetic, and environmental data. It will be a precursor of change in agricultural systems towards agro-ecology through varietal solutions, thus contributing to the widespread adoption of agro-ecological practices and to the sustainability of our agriculture.

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