Influence of row spacing on growth, light and water use by sorghum

Abstract

SUMMARYGrain sorghum (Sorghum bicolor L. Moench) was grown in Texas in 1985 at a constant population density of c. 6·6 plants/m2 in rows 0·5, 1·0 and 1·5 m apart and with the soil profile at field capacity at planting time. Dry matter production and yield were least at the widest spacing, principally because of a reduction in number of tillers. Dry matter accumulation was in direct proportion to the amount of light intercepted and largely independent of spacing between rows, with a conversion coefficient of 1·71 g dry matter/MJ energy intercepted. The most widely spaced crop used less water but not in proportion to the extent that ground cover was reduced. Water use efficiency was also less in the most widely spaced crop, probably because of heat advection from the bare soil between rows.