2019 ASHS Annual Conference

Day-neutral strawberry production has increased dramatically in the last decade but few varieties have been developed for cooler, temperate regions such as western NY. Most commercial varieties were developed for annual production systems utilizing fumigation for soil pest management and have little or unknown resistance to soil borne pests and poor adaptation to semi-perennial production in heavy soils. The development of new varieties suitable for these conditions is of great interest to regional growers and may be of value in other areas as soil fumigation restrictions increase. However, the expression of day-neutral flowering of some varieties is inconsistent under cool, long day conditions followed by cool, short day conditions as is typical during the late summer and early fall in western NY. Breeding day-neutral varieties for these conditions necessitates the blending of germplasm from multiple geographic locations with unpredictable results. A total of 37 populations developed by combining multiple day-neutral varieties from California and the EU as well as the eastern U.S. heirloom variety ‘Tribute’ from the USDA with Cornell short-day varieties and other germplasm of mixed day-neutral/short-day genetic background were grown in a modified plasticulture system under low tunnels for 2-years in un-fumigated ground. Seeds were germinated after pre-treatment in the greenhouse under long days in the spring and transferred to plug trays for growth. Plugs were transferred to the field in early summer with low tunnels installed shortly after planting to enhance growth and provide weather protection into the fall for flower and fruit development. The plants were rated in September of the planting year as well as the following September to determine the best combinations for producing day-neutral genotypes for evaluation. Plants were covered with straw in mid-December of the planting year for winter protection and uncovered in mid-March the following spring for the second season of growth. Heritability and general and specific combining ability was calculated for the populations. Day-neutral flowering in the planting year ranged from 4% to 85% with a mean of 46% of the plants producing flowers in different populations. In the second season, the range was 17% to 82% with a 47% mean. ‘Verity’ and ‘Amandine’ from the UK and France, respectively, transmitted day-neutrality when combined with Cornell germplasm at a higher rate, 60-65%, than ‘Albion’ and ‘Seascape’ from California at 40-50% but all combinations produced many day-neutral types for evaluation.