Performance of Dry Bean Genotypes Grown under Organic and Conventional Production Systems in Michigan

Abstract

The lack of data on the performance of dry bean (Phaseolus vulgaris L.) cultivars grown under organic management systems in Michigan prompted the evaluation of 32 diverse dry bean genotypes in side‐by‐side trials under organic and conventional production systems. Trial sites were located in grower fields in Gratiot County, in 2007 and 2008 and in Tuscola County in 2009 and at the Kellogg Biological Station in Kalamazoo County, in all 3 yr. The conventional plots were treated following standard acceptable management practices including application of granular fertilizer at planting and use of chemical seed treatments and foliar sprays to control pests. For the organic treatments certified organic land was used and only approved methods for organic production were followed. Rhizobium inoculant was applied to seeds in the organic treatment before planting. Yields were 20% higher in conventional systems than in the organic systems over all locations. Seed classes that yielded well in the organic system included pink‐, small red‐, and black‐seeded genotypes and these classes also had the highest accumulation of seed N (36%). Some genotypes appear better suited to organic production than others; however, those genotypes performing poorly under the organic system also performed poorly under conventional system. Overall genotypes of Andean origin performed 25% lower than genotypes of Middle American origin in either organic or conventional systems. Older cultivars, such as the heirloom navy bean Michelite, commonly believed to be better suited to organic production, did not perform as well as modern commercial cultivars.