FLOWERING BEHAVIOUR, COMPATIBILITY AND MAJOR GENE DIFFERENCES IN HOLCUS LANATUS L.

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Abstract
Summary: Holcus lanatus is wind‐pollinated. Anthesis occurs twice a day if weather conditions are favourable, the first time between 5 and 9 a.m. and the second between noon and 4 p.m. G.M.T. The two florets composing the spikelet each produce anthers but the upper may sometimes be hermaphrodite and can then develop a caryopsis.Self‐compatibility varies from low to very low, and plants of high self‐fertility, not uncommon in other species, have not been found. The I1 progenies frequently contain mutant seedlings, and of these a lethal yellow and a lethal pale green are described. Neither type developed anthocyanin even when genes for its production were present. The possible reasons for this are discussed.The great majority of uncultivated (wild) plants are anthocyanin‐positive. The purple colour is especially prominent along the veins of the sheaths and forms a diagnostic character. Failure to produce anthocyanin is a result of homozygosity for recessive allelomorphs at either of two loci. The non‐anthocyanin plants occasionally found fall, therefore, into two groups which can be genetically designated CCrr and ccRR.A number of other qualitative differences were studied, including a new mutant dark green dwarf. This has very short broad leaves and crowded tillers, resulting in a rosette‐like plant about 6 cm in diameter. In all instances the differences were controlled by a single gene.Although H. lanatus shows much variability in the degree of hairiness, a truly glabrous plant has not yet been found.