EFFECT OF CORN-INDUCED SHADING AND TEMPERATURE ON RATE OF LEAF APPEARANCE IN REDROOT PIGWEED (AMARANTHUS-RETROFLEXUS L)

Leaf development and expansion are important factors in determining th e outcome of crop-weed interference. The comparative effects of temper ature and corn canopy-induced shading on the rate of leaf appearance ( RLA) of redroot pigweed were quantified in this study. Growth cabinet results indicated a linear increase in RLA with increased temperature. Weed RLA was predicted utilizing both this function and field tempera ture data. The ratio of observed to predicted RLA of redroot pigweed g rown in field experiments decreased in 1990 and 1991 as shading increa sed with increased corn density and delayed weed planting date. Result s indicated that RLA is substantially affected by canopy-induced shadi ng in addition to temperature.