ROLE OF FOLIAGE HABIT IN THE COMPETITION BETWEEN DIFFERENTLY SIZED PLANTS IN CARROT CROPS

The length of the tallest leaf on a plant varied considerably within each of 3 carrot crops, and in each crop there was a high positive correlation between shoot height and root weight. Lowering the petiole angle of carrot leaves greatly reduced the ability of plants to compete against untreated neighbors, but did not affect growth when all plants were treated similarly. Cutting treatments which produced a more uniform shoot height for all plants, allowed small plants temporarily to overcome the dominance of their larger neighbors. Similar cutting temperatures applied in a field experiment reduced crop growth and variation in root weight. Shoot height difference is an important component of inter-plant competition in carrot crops and hence is a source of root-weight variation.