Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/26/1997
Publication Date: N/A
Interpretive Summary: Many tomato growers place plastic mulch on the soil to conserve water, control weeds, and keep fruit clean. Our goal was to develop a mulch that would keep those desirable characteristics and also reflect a light color that would further improve yield. In cooperation with a mulch manufacturer, we developed a red plastic that reflected a high amount of far-red light up to the growing plants. The far-red acted through a natural growth regulator, phytochrome, within the plants to direct more new growth to the developing fruit. Tomato productivity over the new red plastic was compared with the widely used black plastic in a 2-year field study. Number and size of early crop tomatoes were consistently greater over the red mulch. The colored mulch technology is licensed to Sonoco Products Co., and the red plastic is now available to growers.
Technical Abstract: Plastic mulches are frequently used by tomato (Lycopersicon esculentum) growers to conserve water, control weeds, and keep fruit clean. We hypothesized that changing the color of mulch to reflect a higher far-red to red light ratio would keep those benefits and also improve tomato yield. Photodegradable and nondegradable forms of red plastic mulch were developed under a cooperative research and development agreement (CRADA). Number, size, and total fruit yield over the red plastic mulches were compared to those over the widely used black plastic under the same management conditions. Photodegradable red mulch (placed over a layer of black plastic) resulted in significant increases in fruit yield while it was intact, but dropped to that of the black control after the red plastic degraded. Nondegradable red plastic resulted in significant yield increases. Yield responses over the red mulch were the same whether it was placed directly over soil or over a layer of black plastic which blocked light from the soil surface. Soil temperatures were very similar below the red and the black mulches. We conclude that tomato yields increased because of reflected far-red light and its action via phytochrome. However, the red mulch had to remain intact during the entire season to be most effective.