Leaf Angle, Leaf Area, and Corn (Zea mays L.) Yield1

Abstract

AbstractSince canopy structure can be an important factor in determining the productivity of a plant community, these studies were undertaken to determine the influence of upright leaves, at various leaf area indexes (LAI) on the grain yield of highly productive, field‐grown corn (Zea mays L.).Leaf area index was varied by changing plant population density. Leaf angles of the upper leaves were manipulated by mechanical means to change the leaf angle from roughly 45° to 10° or 15° from the vertical.The response to upright leaves depended upon the LAI. At low LAI (below 3 or 4), upright leaves tended to decrease grain yield. At high LAI (5 and above), upright leaves tended to increase grain yield. The optimum LAI (population) for grain yield was always lower with the normal canopy structure than with upright leaves. When canopy types were compared for maximum yield (i.e. each considered at its optimum LAI), upright leaves outyielded the normal by only 0.4, 5.7, and 5.8% in 1968, 1969, and 1970, respectively. These slight yield differences are not statistically significant and occurred with LAI above those commonly found under conditions of commercial corn production in Indiana.These results suggest that an upright leaf canopy similar to that tested would not be beneficial at present in Indiana or similar corn producing areas. If varieties are developed with a higher LAI at the population giving maximum yield and/or in an environment‐management situation capable of supporting a higher LAI, upright leaves might increase grain yield significantly.