The effect of parent plant nutrition on seed size, viability and vigour and on germination of wheat and triticale at different temperatures

Seed was obtained from two adjacent trials of wheat (cv. Avalon) and triticale (cv. Lasko) harvested in 1990. The treatments consisted of factorial combinations of five levels of spring nitrogen (50, 100, 150, 200 and 250 kg N ha^-1) with fungicide treatments designed to control foliar diseases. Seed was graded by size into different fractions. Application of foliar fungicides to the parent plant increased the proportion of large seed in wheat but not in triticale. Fungicide application had no effect on seed vigour (quantified as the value of K; after controlled deterioration), final germination, median germination time (t₅₀) or rate of germination. Parent plant nutrition altered the proportions of seed in different size categories in triticale and wheat. In laboratory germination tests, final germination of wheat increased with seed size. Large (> 3.0 mm diameter) wheat seed from plots receiving 50 kg N ha“¹ had a lower final germination than large seed from plots which had received greater amounts of nitrogen, but t₅₀ and K; were similar for all nitrogen levels. In triticale, the higher the seed weight, the higher the final germination, the faster the rate and the higher the Ki. Final germination, t₅₀ and K;, were all positively correlated with the amount of nitrogen received by the parent plants. Parent plant nutrition had no effect on the response to temperature of final germination, t₅₀, or rate of germination for large or small seeds of both wheat and triticale.