Gas sampling next to tomato cultivars
Cultivar diversity of processing tomato increases ecosystem functions and services.
This project focused on the understanding of some of the ecological processes that are related to increasing intra-specific diversity, i.e., cultivar mixtures, in an organic processing tomato field. Understanding the multifunctionality of biodiversity is necessary in agroecosystems for evaluating pros and cons of alternative management practices. The processes under study were:
- plasticity of a given cultivar 'AB2' under different community composition with other processing tomato cultivars
- resource utilization
- stability over different environmental stresses
- efficiency on N utilization as a limiting nutrient in organic systems
Plant diversity was manipulated temporally and spatially: mustard cover crop vs. no cover crop (fallow) in winter, and planting of mixtures with 1, 3 or 5 tomato cultivars in summer, comparing a monoculture with the farmer's best choice for a high-yielding cultivar with mixtures of it and other high-yielding cultivars in the region. Soil N, soil microbial biomass, crop nutrient uptake, canopy light interception, disease, GHG emissions, and biomass were measured.
Results show that the mustard cover crop reduced soil nitrate in winter and also during the tomato crop, which was associated with decreased growth and canopy development. The ‘choice cultivar’ (i.e. farmer’s best choice) showed plasticity depending on the mixture, tending to have higher biomass production in mixtures. All cultivar mixtures had fairly similar yield and shoot biomass. This study shows the complexity of cultivar mixture interactions for achieving the greatest benefit for ecosystem functions and services, and thus mixtures require greater understanding of cultivar plasticity and phenological and physiological trait diversity.