The effects of black and white plastic mulch on soil temperature and yield of crisphead lettuce in southern New England

Abstract

Annually, Americans consume an average of 24.5 lb of lettuce (Lactuca sativa) per capita, more than half of which is head lettuce. This study examined the impacts of using black and white-on-black polyethylene mulches on three crisphead lettuce cultivars for spring production in the open field, with data collected on the soil temperature and lettuce yields. Black polyethylene, white-on-black polyethylene, and bare ground were compared for effects on soil temperature, lettuce yields, and lettuce head height and diameter. Mean soil temperatures at a 5 cm depth were 18.9 °C under black polyethylene, 17.7 °C under white-on-black polyethylene, and 17.1 °C in bare ground plots. Changes in the lettuce canopy size presented a similar trend over the growing season in all treatments. Both mulch type and cultivar significantly (P < 0.01) affected the canopy growth in head lettuce. Lettuce on black polyethylene mulch grew significantly (P < 0.01) faster than lettuce on white-on-black polyethylene or bare ground. However, the black and white-on-black mulches produced similar yields, averaging 5.76 and 5.71 kg·mˉ2, respectively. Meanwhile, bare ground plot yields were significantly (P < 0.01) lower at 4.57 kg·mˉ2. Cultivar rank order was consistent across treatments, and Crispino and Garmsir at 5.82 and 5.47 kg·mˉ2 fresh weight had significantly higher yields than Nevada at 4.75 kg·mˉ2 (P < 0.01).