Canopy temperature, yield, and harvest index of corn as affected by planting geometry in a semi-arid environment

Selection of an appropriate planting geometry is important for determining crop yield under water-limited conditions. Four studies, consisting of six experiments, were conducted to investigate the feasibility of alternative planting geometries for sustainable corn (Zea mays L.) production on a commercial scale. Clump (three plants clustered), cluster (five plants clustered), and skip-row (one row planted, one row skipped) geometries were tested against the commonly used evenly spaced planting within the row (ESP) geometry under limited irrigation and/or dryland conditions. Among the four studies, harvest index (HI) for alternative geometries was significantly higher (9-18%) in three of them compared to ESP. Aboveground biomass and grain yield showed mixed results. Although kernel weight for alternative geometries was significantly higher (2-10%) in all studies, grain yield was significantly higher only when kernel number was also higher for alternative geometries. Decreased HI in ESP was mainly due to more tillers because tillers increased vegetative mass, but did not contribute to grain yield. Plants in ESP had 0.57-1.81 tillers plant−1, but the plants in cluster geometry had only 0.22-0.48 tillers plant-1. Canopy temperature (CT) between planting geometries was compared in two studies, where plants in ESP had higher CT (32.2-39.4 °C) than those in clusters (30.7-38.5 °C). Although alternative geometries did not always increase the yield, decreased tillers, reduced CT, and increased HI and kernel weight associated with the alternative geometries may help to reduce corn production risk under water-limited environments.