Effect of sowing rate on grain yield, kernel weight, and grain protein percentage of barley (Hordeum vulgare L.) in northern New South Wales

Abstract

The effect of sowing rate (10-110 kg/ha) on the grain yield of barley (Hordeum vulgare L.) was determined from a total of 20 field experiments conducted in northern New South Wales from 1983 to 1986. Effects of sowing rate on kernel weight and grain protein percentage were also determined from 12 experiments conducted in 1985 and 1986. Two barley varieties were tested each year. In all years fallow plus winter rainfall was equal to or greater than average. Grain yield increased with higher sowing rates in most experiments, with the response curve reaching a plateau above 60-70 kg/ha. For 13 of the 40 variety x year combinations, grain yield fell at the highest sowing rates. Only in an experiment where lodging increased substantially with higher sowing rates was there a reduction in yield at a sowing rate of 60 kg/ha. The average sowing rate for which 5 kg grain was produced per kg of seed sown was 63 kg/ha. Grain protein percentage usually fell, and kernel weight invariably fell, with increasing sowing rate. Increasing sowing rates from the normal commercial rate of 35 kg/ha to a rate of 60 kg/ha typically increased grain yields by 100-400 kg/ha, decreased kernel weight by 0.4-2.0 mg, and decreased grain protein by up to 0.5 percentage points. In no case was the grain weight reduced to below malting specifications. It was concluded that sowing rates for barley in northern New South Wales should be increased to about 60 kg/ha.