Effects of Row Spacing and Plant Population on Physiology, Water Use Efficiency, Growth and Yield of No-till Dryland Soybean.

Drought is the main abiotic factor limiting soybean yield in the semi-arid region of the Northern Great Plains of the USA. Agronomic practices that conserve soil moisture will be highly useful to realize a sustainable higher soybean yield under no-till dryland condition. Row spacing and plant population are two important agronomic parameters that affect resources use efficiency, thus the growth and yield of every crops including soybean. This experiment was conducted to determine an appropriate row spacing and plant population that has favorable effects on physiology and growth, and increases water use efficiency and yield of soybean grown under no-till dryland condition. Soybean was seeded using an ultra-narrow precision research plot seeder that maintained row spacing of 19, 38, 57, and 76 cm as main plots, and plant population of 90, 120, 150, and 180 thousand as sub-plots. The sub-plot size was 6 m X 4.5 m. The effects of treatments and their interaction on soil moisture collected with a neutron probe; canopy temperature, leaf chlorophyll, NDVI, and plant height collected remotely by sensors; and yield data are presented.