Fresh-marketable tomato yields enhanced by moderate weed control and suppressed fruit dehiscence with woodchip mulching

The plastics have recently been recognized as serious global environmental hazards, because they do not decay in nature. The use of plastic film for mulching imposes various environmental risks in agroecosystems. The replacement of plastics with organic materials for mulching has been suggested to enhance the sustainability of agroecosystems. However, whether woodchip mulch can be used for annual crops needs to be verified, and it is still rarely used in vegetable fields. We examined the effects of mulberry woodchip mulches on tomato fruit yields over two successive years. Setting three treatments, including woodchip mulch, weed-free and weedy (i.e., unweeded) treatments, we compared the amounts of fresh-marketable and unmarketable tomato fruits. The yields of fresh-marketable tomato fruits in the woodchip mulch treatment were significantly higher than those in the weed-free treatment and comparable to those in the weedy treatment. The yields of unmarketable dehiscent tomato fruits in the weed-free treatment were significantly highest among the treatments. The woodchip mulches moderately suppressed the weed density, while the weeds that did occur grew large, preventing strong sunlight exposure and dehiscence of tomato fruits. The replacement of plastics by woodchips is a possible alternative, facilitating climate change mitigation and adaptation with agroforestry practices.