Published online by Cambridge University Press: 27 March 2009
1. A study of the length of the rachilla in barley shows that it is a varietal character, although strongly affected by environmental factors.
2. Rachilla length as a varietal character is affected by the density of the ear and the type of hairs or bristles borne on the rachilla.
3. In six-row barleys the length of the rachilla of the lateral spikelet is greater than that of the corresponding median spikelet.
4. In the absence of any of the complicating factors mentioned above, rachilla length is inherited as a straightforward quantitative character with an intermediate F1 and no signs of segregation in the F2. The number of major factors when the extremes of length are hybridized appears to be in the neighbourhood of four.
5. Hybridization of “Archer” and “Chevallier” type parents has given “dominance” of length and a possible heterotic effect. Long rachilla in these crosses appears to be linked with the “Chevallier” rachilla type.