Bell Pepper Plant Development over Mulches of Diverse Colors

Abstract

Mulch surface color affected the growth of bell pepper (Capsicum annuum L.) plants, the amount and quality of upwardly reflected light, and the soil temperatures under the mulch. Of the surface colors evaluated (black, red, yellow, and white), plants grown over red mulch were the tallest. The darker (black and red) mulches reflected less total light and more far-red (FR) relative-to-red (R) light, and soil temperatures recorded in the afternoon and evening were warmer than under the yellow and white mulches. Plant growth responses to mulch surface color were also observed when soil temperature differences among the mulch color treatments were minimized by placing insulation boards between the mulch surface and the soil. Sensitivity of young pepper plants to a high or low FR: R light ratio was demonstrated by exposing plants to 15 minutes of FR or 15 minutes of R light at the end of the photosynthetic period each day for 14 consecutive days in a controlled environment. Plants that received the FR (high FR: R ratio) were 51% taller than plants exposed to R (low FR: R ratio) light treatments. The similar responses of pepper plants to differences in FR: R ratios associated with mulch color and end-of-day light treatments provide evidence that pepper plant growth is affected by relatively small changes in light environment induced by the surface color of the mulch.