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- Author or Editor: Robert F. Heyduck x
- HortTechnology x
In a two-part study, we examined the effect of sowing date and harvest schedule on the yield of spinach (Spinacia oleracea) grown during the winter in 16 × 32-ft-high tunnels in northern New Mexico. Each part of the study was conducted for two growing seasons and took place between 2012 and 2015. In Study A (2012–13 and 2013–14), spinach was sown four times at roughly 2-week intervals (mid-October, early November, mid-November, and early December) and plant density (plants per square foot), plant height (centimeters), and yield (grams per square foot) were measured for three harvests in mid-January, mid-February, and mid-March. The earliest sowing date had the least-dense stands, and plant density increased with each subsequent sowing. The two earliest sowing dates had significantly higher season-long yield than the later two sowings. In Study B (2013–14 and 2014–15), all plots were sown in mid-October, but harvest schedule treatments were staggered such that harvests began at 9, 11, 13, or 15 weeks after sowing and continued at irregular intervals. Treatment 2, with harvests beginning after 11 weeks, had the greatest season-long yield, slightly greater than when harvests began at 9 weeks, and significantly more than when harvest began 13 weeks or later. More importantly, a staggered harvest schedule can provide spinach weekly for direct marketing opportunities.
We examined the effect of harvest schedule on the yield of ‘Red Russian’ kale (Brassica napus ssp. napus var. pabularia) grown during the winter in 16 × 32-ft high tunnels in northern New Mexico. We conducted the study for two growing seasons: 2013–14 and 2014–15. All plots were sown on 16 Oct. and harvested four times according to four harvest schedules: A) 8, 16, 20, and 24 weeks after sowing; B) 10, 17, 21, and 25 weeks after sowing; C) 12, 18, 22, and 26 weeks after sowing; and D) 14, 19, 23, and 27 weeks after sowing. The first harvest of each treatment was the greatest, averaging 216 g/ft2, compared with 88, 109, and 104 g/ft2 for harvests 2, 3, and 4, respectively. Season total yield of treatments B, C, and D (harvests beginning at 10, 12, and 14 weeks after sowing) yielded significantly more than treatment A, but only in year 2, when delayed growth resulted in very low yields for treatment A at harvest 1. Considering the entire 240-ft2 cropped area of the high tunnel, staggered harvests of 60 ft2 at a time can yield 2.6 to 17.5 kg per harvest or up to 124 kg over an entire season. Although we examined the yield of mature leaves, harvests could possibly begin earlier than in this study for “baby” kale or salad mixes, and the area harvested could be tailored to plant growth stage and market demand.