Linking Plant Production Traits with Performance In Organic Systems

Ease of establishment, vigor, plant canopy development, nutrient and water use efficiencies, and resistance to pests are traits that help determine the suitability of vegetable crops and varieties for commercial production.  These traits are critically important in organic vegetable production, where most synthetic fertilizers and pesticides are prohibited and ecological-based management is standard.  This project sought to  determine the correlation between these traits, singly and cumulatively, on vegetable crop performance across a range of organic production environments. We tested eight varieties of corn, eight varieties of potato, and nine varieties of carrot on certified organic and organic-in-transition fields across a precipitation gradient ranging from North Dakota (semiarid) to Wisconsin (subhumid), and on soils ranging from residual and coarse-textured (loamy sand), to geologically young and fine-textured (clay).  Significant differences in variety performance existed for all crops.  Data that were collected indicated several trends: (1) variety ranking with respect to yield changed across North Dakota and Wisconsin environments (i.e., there was a genotype by environment interaction); (2) crop yield improved as plant stand density increased, above-ground vegetative growth increased, or mid-season weed density decreased; (3) weed numbers and/or density declined as crop stand density, biomass, or plant height increased, and; (4) insect feeding damage increased as macronutrient concentrations in crop tissue increased.  Further research is needed to continue to evaluate these factors for a larger number of crops in order to provide information regarding these crucial production characteristics to organic growers.