Effect of mulch surface color on root-knot of tomato grown in simulated planting beds

The effect of different-colored polyethylene mulches on quantity and spectr a of reflected light, plant morphology, and root-knot disease was studied i n tomato (Lycopersicon esculentum) grown in simulated planting beds. Tomato plants were inoculated with Meloidogyne incognita at initial populations ( Pi) of 0, 1,000, 10,000, or 50,000 eggs/plant, and grown in a greenhouse fo r 50 days over white, red, or black mulch. Soil temperature was kept consta nt among the mulch treatments by placing an insulation barrier between the colored mulch and the soil surface. Soil temperature varied less than 0.5 d egrees C between soil chambers at solar noon. Tomatoes grown over white mul ch received more reflected photosynthetic light and had greater shoot weigh ts (27%), root weights (32%), and leaf area (20%) than plants grown over bl ack mulch. Plants grown over red mulch received a higher far-red-to-red rat io in the reflected light. Mulch color altered the plant's response to root -knot nematode infection by changing the distribution of mass in axillary s hoots. At high Pi, axillary leaf area and leaf weight were greater in tomat o grown over white mulch than when grown over red mulch. The root-gall inde x was lower for plants grown over white mulch than similar plants grown ove r red mulch.