Effects of seed ageing on growth and yield of spring wheat at different plant-population densities

Abstract

When seed samples of spring wheat ( Triticum aestivum L., cv. Timmo) were aged they showed delayed field emergence and slower seedling growth. However, their subsequent relative growth rate was not deleteriously affected and, at a low plant-population density, on one occasion there was even evidence of some compensatory increase in growth rate, though not sufficient to overcome the disadvantages of poor initial seedling growth. Since poor seed vigour mainly affected early growth, it was argued that its deleterious effect would be minimised at high population densities where the potential advantage of high-vigour seeds would be partially counteracted by earlier competition. Experiments carried out over a wide range of population densities supported this proposition. They also showed that, if direct effects of poor vigour seed on yield through reduced establishment are avoided by adjusting sowing rates so that recommended rates of establishment are achieved, then there will probably be little or no effect of seed vigour in final yield, providing normal germination in the laboratory test is 85% or more, and sowing in the spring is not delayed. However, if these conditions are not met, then significant yield reductions can be expected which could not be overcome by increasing sowing rate.