LEAF AZIMUTH IN STRIP-INTERCROPPED CORN

In strip-intercropping conditions where rows of corn (Zea mays L.) are subjected to widely different levels of radiation interception and of water and nutrient competition, leaf azimuthal direction may be an im portant determinant of yield. Observations of ear leaf direction were made on two outside rows and one middle row of a corn strip grown with small-grain cereal and soybean [Glycine max (L.) Merr.] strip-intercr ops in four trials with north-south rows in Ontario and Michigan. The objectives were to assess if row position within the strip and seed or ientation at planting affect leaf azimuth and to find out if ear leaf azimuth and yield are related, In only one of the four trials was ther e a correlation between yield and the frequency of ears from ear leave s pointing in a specific direction (west). In both locations, row posi tion affected the proportion of ear leaves in a direction perpendicula r to the row and toward the inside of the strip rather than toward the outside in the case of border rows, When seed orientation at planting was controlled, 60 to 74% of ear leaves (leaves 11 or 12) developed i n the same direction as the embryo orientation or opposite this orient ation, Random orientation of the seed resulted in random ear leaf azim uths, except in a very dry growing season, when leaf azimuthal directi ons were mostly parallel to row direction, minimizing interception of radiation. This suggests that leaf azimuth could be an indicator of wa ter deficit.