Royce S. Bringhurst and Victor Voth at the University of California-Davis (UC-Davis) revolutionized the strawberry industry in 1979 with the release of their first “day-neutrals” ‘Aptos’, ‘Brighton’, and ‘Hecker’ ( Bringhurst and Voth, 1980 ). These
James F. Hancock, Patrick P. Edger, Peter W. Callow, Thomas Herlache and Chad E. Finn
James R. Ballington, Barclay Poling and Kerry Olive
late fall and winter) or extended-season cropping options (e.g., outdoor summer and early fall day-neutral strawberries). By way of background, the majority of strawberry producers in the southeastern United States and mid-Atlantic states currently
Thomas M. Sjulin
Day-neutral cultivars of the cultivated strawberry are very important in California's commercial strawberry industry. Since the introduction of the first successful day-neutral cultivar Selva in 1983, the cultivated area of day-neutral cultivars
Daniel Rowley, Brent L. Black, Dan Drost and Dillon Feuz
), but length of fruiting season is limited by photoperiod and temperature ( Durner et al., 1984 ). Alternatively, day-neutral cultivars are insensitive to photoperiod and continue to flower as long as temperatures are between 4 and 29 °C ( Hancock and
Kelly Gude, Cary L. Rivard, Sara E. Gragg, Kimberly Oxley, Petros Xanthopoulos and Eleni D. Pliakoni
revenue. Furthermore, yields of day-neutral cultivars are typically higher than those of June-bearing cultivars because of the extended harvest season ( Lantz et al., 2010 ; Rowley et al., 2011 ). In the high-elevation region of Utah with summer
Lisa W. DeVetter, Huan Zhang, Shuresh Ghimire, Sean Watkinson and Carol A. Miles
, which predominately uses remontant/perpetual-flowering (i.e., day neutral) cultivars grown in annual plasticulture systems ( California Strawberry Commission, 2017 ). Strawberry production in the Pacific Northwest (PNW), specifically Oregon and
Bernard Gagnon, Yves Desjardin and Roger Bédard
Abbreviations: DN, day-neutral; LT 50 , lethal temperature for SO% of flower buds; TNSC, total nonstructural carbohydrates. 1 Graduate student. 2 Research assistant. 3 Profcssor. We are grateful to the Agriculture Canada Research Station in Ste
Neil O. Anderson and Peter D. Ascher
Commercial garden and greenhouse chrysanthemums [Dendranthema ×grandiflora (Ramat.) Kitam. (syn. Chrysanthemum xmorifolium Ramat.)] are facultative short-day plants for flower bud initiation, obligate short-day plants for flower bud development, and are categorized into short-day response groups. Flower initiation can be delayed by high night temperatures. Recent research has identified true day-neutral genotypes. The purpose of this investigation was to test environments for selecting genotypes that are both day-neutral and heat-delay insensitive. One greenhouse and 18 garden genotypes were selected. A series of environments were used to select for day-neutral genotypes and then differentiate between these genotypes for heat delay insensitivity: short days, long days/red light, long days/far red light and high temperatures, and natural day lengths under field conditions. Day-neutral selections from these environments were then grown in a fifth environment of long days/continuous far red and red light with high temperature. Data were collected on the number of days to first and third flower, long day leaf number, stem length, number of strap-shaped leaves subtending the terminal flower, internode lengths, number of nodes with axillary branching, and flower bud development of the first to the sixth flowers. Genotypes required 3 to 8 weeks for complete flower bud initiation/development. Flowering responses in the first four environments were highly significant for both the first and third flowers. Genotypes ranged from obligate short-day to day-neutral for the first six flowers. Three day-neutral genotypes were selected that differed significantly for all traits in the fifth environment; flower bud development with the first six flowers occurred with only one genotype, 83-267-3. Broad sense heritability estimates ranged from h2 = 0.75 for number of nodes with axillary branching, h2 = 0.79 for long day leaf number and number of strap-shaped leaves, to h2 = 0.91 for stem length. An ideotype for day-neutral and heat-delay-insensitive garden chrysanthemums was developed for use in breeding programs.
M. Lamarre and M.J. Lareau
During 1993 and 1994, the day-neutral strawberry cultivar Tribute was subjected to two rates of N (50 and 100 kg–ha–1), four rates of K (0, 60,120, and 180 kg–ha–1), and three rates of Mg fertilization (0, 25, and 50 kg–ha–1) from June to September through trickle irrigation. The objective of this experiment was to determine the best N, K, and Mg fertilization rates in the production of day-neutral `Tribute' strawberry. The N treatments had no significant influence on yield and fruit size for the two years. We observed the same situation for K as for N. For Mg treatments, fruit size was increased by adding 25 kg–ha–1 during the first picking in 1993, and they had no effect in the second year. For both years, the Mg had no effect on the yield.
Day-neutral strawberries have the potential to fruit throughout the growing season as long as maximum air temperatures do not exceed 32.2 °C for extended periods. Appropriate temperatures for season-long production of day-neutrals occur in the southern Appalachians at 900 m elevations and above. Replicated studies were conducted at Laurel Springs (900 m elevation) in northwestern N.C. in 2002–04 to determine the most promising combinations of mulch types, planting dates and cultivars. Plasticulture establishment recommendations were followed and white/black plastic mulch compared to black. Dormant plants were established 15 Apr., 1 May, or 15 May at 12 × 12 inch spacing in 2002; plug plants on 30 Oct. 2002 at 12 × 12 inches and overwintered under rowcovers for 2003; and plug plants on 25 Sept. 2003 or 23 Oct. 2003 at 18 × 12 inches and overwintered under rowcovers for 2004. Plants came from commercial sources. Aromas, Diamante, Everest, and Seascape were included in 2002; Diamante, Everest and Seascape in 2003; and Everest and Seascape in 2004. Harvest season lasted 11 weeks in 2002, 12 weeks in 2003, and 10 weeks in 2004. Only main effects were statistically significant. White and black plastic mulch yields were significantly higher than black two years out of three. Fall planting resulted in earlier onset of production and higher yields in most cases. Planting date was important; for fall planting, midto late September was superior to October planting, and for spring planting, middle to late April was superior to mid-May. A plant spacing of 18 inches between plants in rows and 12 inches between rows was important to avoid crowding when planting in fall. Everest and Seascape had the best overall performance.