Effect of Shade on Giant Foxtail

Abstract

Field studies were conducted with giant foxtail(Setaria faberiiHerrm.) under shade intensities of 0, 30, 60, 70, 80, and 98%. Seed weight, dry weight of plant tops exclusive of seed, and total dry weight per plant decreased linearly with increasing shade intensities. These decreases were due primarily to decreases in number of leaves, number of stems per plant, and number of heads per plant. Height of main culm was less affected than other morphological characteristics. Shading affected the length of internodes but had little influence on number of internodes on the main culm. The amount of shade required to control giant foxtail completely, once it is established, appears to be above 95%. Expressed as 2-year means, plants grew to as much as 135 cm, had as many as 188 leaves, 41 stems, and 31 heads, and produced 73 g of dry matter per plant including 6 g of seed. Maximum number of seeds per head was 1405.