Are specific testing protocols required for organic onion varieties? Analysis of onion variety testing under conventional and organic growing conditions

• Published in: Euphytica 2012-03, Vol.184 (2), p.181-193
• Main Authors: Lammerts van Bueren, E. T., Osman, A. M., Tiemens-Hulscher, M., Struik, P. C., Burgers, S. L. G. E., van den Broek, R. C. F. M.
• Format: Article
• Language: English
• Subjects: Agricultural management; Agrochemicals; Agronomy. Soil science and plant productions; Airborne microorganisms; Biological and medical sciences; biologische landbouw; Biomedical and Life Sciences; Biotechnology; breed differences; Cultivars; Disease resistance; experimental design; Farming; farming systems; Fertility; Fundamental and applied biological sciences. Psychology; Fungicides; Genetics and breeding of economic plants; Herbicides; Leaves; Life Sciences; Onions; Organic farming; Organic fertilizers; Organic wastes; Pesticides; Plant Genetics and Genomics; Plant Pathology; Plant Physiology; Plant Sciences; Planting density; proefopzet; Rankings; rassenproeven; Rassenproeven, rassenlijsten; rasverschillen; Research projects; Selective breeding; Testing equipment; uien; Varietal selection. Specialized plant breeding, plant breeding aims; Variety Testing, Variety Lists; variety trials; Vegetables; Weed control
• ISSN: 0014-2336; 1573-5060
• DOI: 10.1007/s10681-011-0545-4

Organic growers need information on variety performance under their growing conditions. A 4-year onion variety research project was carried out to investigate whether setting up a variety testing system combining conventional and organic variety trials is feasible and efficient rather than organizing separate variety trials under the two management systems. During 4 years commercial onion cultivars were tested at a certified organic and a non-organic location. Both systems were managed without chemical pest, disease and sprouting control, but differed in fertility management (organic manure in autumn versus synthetic fertilizer), soil cultivation and weed management (mechanical weeding versus application of herbicide). Management system significantly affected plant density, thickness of neck, and proportion of small and large bulbs. Variety × management system interactions were significant for bulb uniformity, earliness, proportion of large bulbs, dormancy and relative storage success but did not change the ranking of the varieties. We conclude that organic growers can profit from a more conscious variety choice when conventionally fertilised trials would refrain from using pesticides, fungicides, herbicides and sprout inhibitors. However, this would require an adaptation of the management protocol in such a way that trials might no longer represent conditions of conventional farmers. Furthermore, assessments of leaf erectness, disease resistance to downy mildew and leaf blight should be included in the protocols for organic use. We advocate better communication between breeders and growers on specific variety characteristics contributing to improving yield stability under low-input, organic growing conditions.