Transpiration Efficiency of Grain Sorghum and Maize under Different Planting Geometries

摘要

The Texas High Plains are classified as a semiarid region, but have many characteristics of an arid region. Hence, in this region there is a need for technologies that can sustain crop production under limited water conditions. Planting geometries ofgrain sorghum (Sorghum bicolor L. Moench) and maize (Zea mays L.) were modified to determine the effect of space between plants on transpiration efficiency and its relation to yield parameters. Three planting geometries—clump (3 plants adjacent to eachother), cluster (3 maize or 6 sorghum plants in clusters), and control (plants equally spaced) were studied in a greenhouse. The effect of plant geometry on transpiration efficiency (TE) was not significant, but there was a clear trend that the closer the plants were to each other, the greater the TE. The amount of water were required to produce 1 g biomass was 216, 223, and 231 for plants of equal population growing in clump, cluster, and equally spaced geometries, respectively, indicating a modification in microclimate. The clump treatments appeared to be about 2°C cooler, and the relative humidity was about 3% higher than the control plants during part of the day in sorghum study 1. These findings suggest that under limited water conditions there may be ways to manipulate plant growth by plant geometry. However, TE is only one of several factors that affects crop yield, particularly in grain crops. Thus, a package ofcomplementary technologies must be implemented to enhance bio-mass production and grain yield in dryland areas.