We evaluated the performance of several sweetpotato (Ipomoea batatas) cultivars grown on raised beds covered with biodegradable black mulch in New Hampshire. Six cultivars were evaluated over 4 years, and an additional four cultivars were evaluated in 2 or 3 years. Cultivars showed significant differences in marketable yield, percent cull, and percent small roots. The cultivars Covington and B94-14 Beauregard consistently produced high yields, whereas Vardaman consistently produced the lowest yields. ‘Georgia Jet’ exhibited variable performance, with marketable yields among the highest in 1 year and the lowest in another, largely because of a high percentage of cull roots due to severe cracking. Yields measured in our study compare favorably with average U.S. yields, with several cultivars producing over 400 50-lb bushels/acre in all years in which they were grown. In a 2-year study with the cultivar Beauregard, biodegradable mulch increased overall yields (marketable, cull, and small roots) as compared with bare ground production on raised beds. However, the percentage of culled roots was higher in mulch treatments, primarily due to breakage during digging, and the observed increases in marketable yields were not statistically significant.
Nicholas D. Warren, Rebecca G. Sideman and Richard G. Smith
Tomato (Solanum lycopersicum) growers select cultivars based on a range of performance criteria. Currently, however, information regarding tomato cultivar performance in high tunnels is lacking. We conducted a tomato cultivar trial in an 1800-ft2 plastic-covered high tunnel in Durham, NH, with 15 indeterminate cultivars using organic fertilizers and pesticides. Tomatoes were grown in-ground in a randomized complete block design (n = 4) using raised beds with plastic mulch and drip irrigation. Marketable and unmarketable yield, several yield components, and susceptibility to two common diseases, leaf mold (Fulvia fulva) and powdery mildew (Oidium lycopersici or Leveillula taurica), were evaluated over a 3-year period. Differences between cultivars existed in all areas of interest, and year-to-year variation in performance was noteworthy in this experiment. ‘Geronimo’ consistently had among the highest yields, ‘Arbason’ and ‘Massada’ produced many individual fruit, and several cultivars including Rebelski, Massada, and Geronimo showed no signs of disease. Some cultivars such as Conestoga appeared susceptible to several different physiological disorders while others were relatively robust against this type of marketable yield reduction. Because we assessed multiple yield and quality variables and observed apparent trade-offs in several of these, we used radar plots to summarize and communicate the performance of each cultivar in an intuitive and comparable manner. Based on these data, several tomato cultivars appear particularly well suited for high tunnel production in northern New England.
Nicholas D. Warren, Richard G. Smith and Rebecca G. Sideman
Living mulch systems allow cover crops to be grown during periods of cash crop production, thereby extending the duration of cover crop growth and associated beneficial agroecosystem services. However, living mulches may also result in agroecosystem disservices such as reduced cash crop yields if the living mulch competes with the crop for limiting resources. We examined whether the effects of an Italian ryegrass [Lolium multiflorum (Lam.) Husnot]–white clover (Trifolium repens L., cv. New Zealand) living mulch on broccoli (Brassica oleracea L. var. italica) yield and yield components were dependent on fertilizer rate in field experiments conducted in Durham, NH, in 2011 (Expt. 1) and 2012 (Expt. 2). Drip-irrigated broccoli was grown under a range of organic fertilizer application rates in beds covered with plastic, with and without a living mulch growing in the uncovered, interbed space. Broccoli yields were similar in the living mulch and bare soil controls under the highest rates of fertilizer application in Expt. 1. In Expt. 2, living mulch reduced broccoli yields from 28% to 63%, depending on fertilizer rate. Differences in leaf SPAD values suggest that yield reductions were attributable, in part, to competition for nitrogen; however, other factors likely played a role in determining living mulch effects. Despite yield reductions, the living mulch reduced the prevalence of hollow stem in broccoli in Expt. 1. Organic fertilizer may have inconsistent effects on broccoli yields in living mulch systems.
Kaitlyn M. Orde, Connor Eaton and Rebecca G. Sideman
Fall planting of spinach (Spinacia oleracea L.) into high tunnels for harvest from late fall through early spring is widely practiced in the northeastern United States, but replicated studies focusing on this production system are lacking. The objectives of our study were to understand the effect of fall planting date (PD) and cultivar on yield and soluble solids content (SSC) of spinach. Three cultivars (Regiment, Space, and Tyee) were transplanted in unheated high tunnels in Durham, NH, in 2014–15 (Year 1) and 2015–16 (Year 2) at six different fall dates: 20 Sept., 30 Sept., 9 Oct., 19 Oct., 30 Oct., and 9 Nov. Five additional cultivars (Carmel, Corvair, Gazelle, Emperor, and Renegade) were included at the third date (9 Oct.) to compare yield and SSC among cultivars during winter months. A randomized complete block design with four replications was used for all experiments. Year and fall transplant date had a significant effect on total yield. Total yield of Year 2 was nearly double that of Year 1 for all PDs and cultivars. In both years, total yield decreased with later planting, such that yield from the 20 Sept. date was greater than a minimum of three of five subsequent PDs, depending on year. Total yield in spring (January through April) did not differ among the first four PDs in Year 1 or among any dates in Year 2, suggesting that a wide range of PDs will work well for those primarily interested in spring harvests. Combined analyses of the data from both years showed no significant differences in total yield among the eight cultivars planted only on 9 Oct. However, of the three cultivars grown at all PDs, Regiment produced significantly higher yields than Tyee. Harvest date, cultivar, and harvest date × cultivar affected leaf and petiole sap SSC in both years. SSC was most strongly negatively correlated with air and soil temperatures at a 10-day interval in Year 1 (R 2 = 0.61 and 0.64, respectively) and a 7-day interval in Year 2 (R 2 = 0.78 and 0.69, respectively). ‘Gazelle’ and ‘Emperor’ contained among the highest SSC in both years. Our work demonstrates total yield is highly dependent on fall PD and the growing conditions of a given year.