The effect of different colored polyethylene mulches on quantity and s
pectra of reflected light, plant morphology, and root-knot disease was
studied in field grown staked tomato (Lycopersicon esculentum). Sprin
g versus fall experiments were conducted in 1987 and 1988 near Florenc
e, South Carolina. Tomato plants were inoculated with Meloidogyne inco
gnita at initial populations (Pi) of 0, 10, 50, 100, and 200 (X 10(3))
eggs per plant, and grown for 60 days over white, red, and black poly
ethylene mulch. White reflected more total light, more blue and a lowe
r far-red to red ratio than red, whereas black reflected less than 5%
of any color. Soil temperatures were warmer under black and red mulch
than under white. Plants grown with white mulch had greater shoot, ste
m, and leaf weights, and leaf area than plants grown over black mulch
(P less than or equal to 0.004). Plants grown with red mulch also had
greater shoot, leaf, and stem weights, and leaf area, than plants grow
n over black mulch (P less than or equal to 0.068). Treatment interact
ions were observed for root weight (mulch color X Pi, P less than or e
qual to 0.001) and root-gall indices (season X mulch color X Pi, P les
s than or equal to 0.001). Reductions in shoot weights with increasing
Pi coincided with increases in root weight. Linear and quadratic coef
ficients (absolute values) of the regressions (shoot and root weights
on Pi), based on standardized data, were not different (P = 0.05) with
in each color. Although shoot and leaf biomass and leaf area varied am
ong mulch colors, the relationship between biomass or area and Pi was
described by quadratic equations for plants grown over white mulch and
black mulch but not red mulch (P less than or equal to 0.057). The li
near and quadratic coefficients of the equations (leaf area, leaf weig
ht or stem weight on Pi) did not differ among tissues (P = 0.05) withi
n a mulch color when calculations were based on stanadard values.