High tunnels can facilitate production of ripe colored bell peppers (Capsicum annuum) in locations with short growing seasons by extending the length of the growing season and protecting fruit from biotic and abiotic stressors. We grew 10 cultivars of bell pepper over 3 years in a high tunnel in Durham, NH. Yields of marketable colored fruit ranged from 1576 to 2285 g/plant in 2015, from 1194 to 1839 g/plant in 2016, and 1471 to 2358 g/plant in 2017. Significant differences in marketable yield among cultivars existed only in 2015 and 2017. Of the 10 cultivars evaluated, those developed for controlled environments produced greater marketable yields than those developed for production in the field or unheated tunnels (P < 0.0001). The seasonal production patterns were similar among cultivars in all 3 years: a single peak in production occurred between 159 and 175 days after seeding, followed by much lower but steady production until frost ended each growing season. Our results demonstrate that reasonable yields of colored bell peppers can be produced in high tunnels in locations with short growing seasons. We suggest that further work may be needed to identify optimal pruning and canopy management strategies to maximize yields and fruit quality.
Rebecca Grube Sideman
Clifton A. Martin and Rebecca Grube Sideman
Winter sprouting broccoli [WSB (Brassica oleracea var. italica)] is a biennial crop that is typically planted in the fall and harvested in the spring in the United Kingdom. To evaluate their suitability as an early spring crop in the northeastern United States, 10 cultivars of WSB were grown in replicated experiments inside an unheated high tunnel over 2 years in Durham, NH. Results showed that the use of a secondary low tunnel covered with heavy rowcover (1.25 oz/yard2) significantly increased winter survival, yields, and earliness of all WSB cultivars. Cultivars differed in terms of days to maturity, yields, and shoot quality. For September planting dates, broccoli shoots were harvested from March to early May. Across cultivars, days to harvest range from 190 to 216 days in 2008–09, and from 209 to 238 days in 2009–10. Season-long yields ranged from 150 to 238 g/plant. The cultivars, Santee, Red Spear, White Sprouting Early, and Late White Star, were among the highest yielding cultivars that produced attractive and tender shoots, spanning the entire harvest season. Our experiments established that fall plantings of WSB may be overwintered in an unheated high tunnel for a spring harvest in USDA Hardiness Zone 5 sites.
Kaitlyn M. Orde and Rebecca Grube Sideman
Day-neutral strawberry (Fragaria ×ananassa) cultivars show promise for extending the fruiting season and increasing production in the northeastern United States, but published research on cultivar yield in the region is lacking. Furthermore, few studies have investigated the effects of low tunnels on yield, fruit, and plant characteristics. We evaluated eight day-neutral cultivars (Albion, Aromas, Cabrillo, Monterey, Portola, San Andreas, Seascape, and Sweet Ann) on open beds and under low tunnels in two separate experiments conducted in 2017 and 2018. Cultivars began producing ripe fruit within 10 weeks of planting in both years, and continued producing fruit without interruption for 20 weeks (2017) and 18 weeks (2018). Annual total yield ranged from 234.9 to 497.8 g/plant and marketable yield ranged 126.4 to 389.1 g/plant, depending on cultivar and year. Cultivar significantly affected the percent marketable yield, late season yield, fruit size, soluble solids content (SSC), runner emergence, and plant size. Except for the cultivar Sweet Ann, low tunnels did not increase season-long marketable or total yield, but did increase the percent marketable yield for all cultivars in 2017, and most cultivars in 2018. Furthermore, marketable yield was significantly greater under low tunnels than open beds during 6 late-season weeks in 2018. Fruit SSC was greater under low tunnels in 2018, and low tunnels reduced runner emergence for certain cultivars. Season-long average air temperatures were higher under low tunnels, but the greatest temperature differences occurred when low tunnels were closed. We demonstrate that day-neutral cultivars can produce high annual yields in New England, but that cultivar selection is paramount.
Rebecca Grube Sideman, Amanda Brown, Ruth Hazzard and Heather Bryant
High demand for local produce year-round has led growers in the northeastern United States to experiment with fall planting of bulbing onion (Allium cepa) for spring harvest. Over two seasons, we evaluated survival, bolting, and bulbing of several cultivars of fall-planted onion in two sites in New Hampshire. Plants were seeded in August and September, and transplanted in September and October into raised beds covered with black plastic mulch. Low tunnels covered with 1.25-oz/yard2 rowcover and one layer of 6-mil-thick clear polyethylene were installed over the plants in late fall. Harvest dates ranged from 19 Apr. to 6 June in 2012, and from 22 May to 2 July in 2013. All onion cultivars showed high percentages of survival (65% to 100%). Cultivar, planting date, and the interaction between the two had a significant effect on the percentage of bolting and bulb diameter at harvest. In general, those planted later exhibited lower percentages of bolting and slightly smaller bulbs at harvest. Our work demonstrates that it is possible to harvest large bulbed onions in May and June in the northeastern United States in U.S. Department of Agriculture (USDA) hardiness zones 4B and 5B using low-tunnel season extension technology. This may provide additional marketing opportunities for growers in cold climates.