Leaf emergence and tillering in barley and wheat

Abstract

A scheme to relate leaf emergence and tillering is described. It assumes that 3 phyllochrons elapse between the emergence of a leaf and the tiller in its axil (phyllochron interval) and that leaves emerge at the same rate on all shoots. These assumptions were examined in several varieties of wheat and barley sown on 4 different dates in each of 3 seasons. It was found that the phyllochron interval was generally about 3 but that it tended to be longer in the coleoptile tillers and the 1st secondary tiller. There were significant differences in the rate of leaf emergence amongst shoots. In spite of these considerations observed tiller production measured on a main shoot leaf number basis agreed well with the predicted production. The main shoot leaf number at which tillering ceased was correlated with total number of leaves on the main shoot. These results indicate that rate of tillering will vary with rate of leaf production and that genetic variation in rate of leaf production may be used to predict and select for different tillering patterns.