Dependence of Yields of Wheat Varieties on their Leaf Area Durations

Abstract

In a field experiment three wheat varieties: autumn-sown Cappelle Desprez, Prestige, both autumn-sown and spring-sown, and spring-sown Jufy I, each supplied with 0.5 or 1.0 cwt nitrogen/acre (6₃ or 126 kg/ha), had grain yields nearly proportional to their Leaf Area Durations (D) during grain development. Squarehead's Master had a smaller grain yield relative to its total D, but with 0.5 cwt N/acre the ratio of its grain yield to D of parts above the flag leaf node (D_F) was similar to the other varieties. The difference in this ratio between varieties was less when D_Fwas calculated from anthesis than from ear emergence to ripening. Squarehead’s Master with 1.0 cwt N/acre had a smaller ratio of grain yield to D_F than other treatments, implying less grain per ear relative to D_Y per shoot, perhaps because of lodging, or because factors limiting size of ears restricted their ability to accept all the assimilate the shoots could produce with this amount of N.