The effect of layers of high tunnel covering and soil mulching on tomato fruit quality

BACKGROUND: High tunnels (HT) and plastic mulch can increase yield, extend growing seasons, protect plants from harsh weather conditions, and produce more marketable and attractive tomatoes. However, plastic covering reduces solar radiation, which may affect the quality of tomatoes. This study investigated the effects of single-layer versus double-layer HT and plastic mulch versus bare soil on the quality of fully ripe tomato fruits. The study was conducted over 2 years (2021 and 2022). The fruit color (L*, a*, and b*), vitamin C, pH, total titratable acid (TTA), total soluble solids (TSS), and lycopene content of the two tomato cultivars (Brandywine and Rebelski) were quantified. RESULTS: The results showed that quality parameters varied with the plastic layers of HT, plastic mulch, and planting year. The double-layer HT only showed a slight but significant influence on the color of tomatoes of both cultivars in the same year (P < 0.05). Brandywine tomatoes grown in the double-layer HT had significantly lower pH and lycopene content than those grown in single-layer HT, regardless of mulching. The effect of plastic layers on TTA, TSS, and lycopene depended on whether the soil was mulched. Tomatoes grown on bare soil had higher TTA and TSS values than those grown on mulched soil in double-layer HT. Tomatoes grown in single-layer HTs had significantly higher vitamin C content than those in the double-layer HT for both cultivars regardless of mulching. CONCLUSION: This study demonstrates that double-layer HT is unnecessary for the improvement of the overall quality of tomatoes.