Lateral Spikelets Research Articles

Radiation induced reversions of a waxy allele in barley

Barley plants homozygous for the waxy allele were irradiated around meiosis of the pollen mother cells with 25 r, 100 r and 400 r of γ-rays and the frequencies of reversions from the waxy phenotype to the wild type of the pollen were analysed. The relation between mutation frequency and dose was found to be exponential, which suggests that the mutations were caused both by point mutations and chromosomal aberrations, possibly deletions. A separate analysis of mutation frequencies of pollen from central and lateral spikelets was made. The lateral spikelets, which develop more slowly, gave higher frequencies of mutants than the central spikelets.

The origin of cultivated barleys: A discussion

Two hypotheses were considered by De Candolle (1883) for the origin of the cultivated six-rowed tough-rachis barleys (Hordetain vulgare): first, that the sixrowed barleys arose in early prehistoric agriculture from the two-rowed Hordeumn distichon, in which the wild brittle-rachis H. spontaneum was included; and second, that the six-rowed barleys may have been derived from a wild six-rowed form. It is obvious that De Candolle was in favor of tihe former hypothesis because a wild six-rowed barley was then unknown. This would mean that H. spontaneum, which had been described by Koch ( 1848), was considered as the ancestor of all cultivated barleys. The term six-rowed is applied in this paper to all barleys with fertile lateral spikelets irrespective of density of the spike. Another term often used in the same sense is many-rowed. Since De 'Candolle, different students of the phylogeny of the cultivated barleys have supported each of these hypotheses, although with slight variations (cf. Aberg, 1940). From the morphological point of view, Schiemann (1932) concluded that the two-rowed barleys were reduced forms and formulated the hypothesis that a wild six-rowed brittle-rachis type should be considered as the ancestor of the cultivated

MORPHOLOGICAL ANALYSIS OF THE MAIZE EAR

THE FEMALE INFLORESCENCE, or ear, of Zea mays L. has been the subject of much research, but there has never yet been offered a wholly acceptable explanation of its morphology. In order to provide a sound basis for a study of variation in cobs of Indian corn or maize (Nickerson, 1953), the problem has been reinvestigated. Whether or not the interpretation here advanced is correct, the facts themselves must be considered in any explanation of maize ear morphology. In their classic work, Mangelsdorf and Reeves (1939) summarized botanical opinion on maizeear morphology up to that time. They pointed out that maize had a perfect-flowered ancestry, and that monoecism has developed by abortion of pistillate organs in the upper inflorescences and of staminate organs in the lower ones. They also emphasized the essential homology of ear and tassel, a fact already recognized by Collins (1912) and Weatherwax (1918), and further strengthened by the work of Anderson (1944), Anderson and Brown (1948), Laubengayer (1949), Reeves (1950, 1953), and Bonnett (1953). Mangelsdorf and Reeves (1939), Reeves (1950, 1953), and Reeves and Stansel (1940), agreed with Weatherwax (1935, 1950) that the origin of both ear and central spike results from reduction of branches of a panicle to one pair of spikelets for each member. Bonnett (1940, 1948, 1953) showed that lateral spikelet initials were homologous with branch initials in maize, and pointed out that in the ear they are subtended by ridges similar to leaf initials in barley, oats and wheat. Stephens (1948) stated that paired spikelets of maize may be regarded as greatly reduced branches, and showed that this reduction is not peculiar to either tassel or ear but is a cumulation of processes initiated in the vegetative phase. The conclusion which can be drawn from these investigations is that the maize ear arose phylogenetically by a telescoping and reducing of parts already present in the maize progenitor. This concept of suppression, condensation, telescoping or aggregation can be identified in some of its minor aspects throughout the maize plant, and extension of it to previously unconsidered units provides the key to understanding much of the heretofore puzzling morphology of the ear. Anderson (1944) noted that condensation is

Inheritance of Reduced Lateral Spikelet Appendages in the Nudihaxtoni Variety of Barley1

Agronomy JournalVolume 34, Issue 3 p. 211-221 Article Inheritance of Reduced Lateral Spikelet Appendages in the Nudihaxtoni Variety of Barley1 Warren H. Leonard, Warren H. Leonard The writer wishes to express his appreciation for helpful suggestions received during the course of this study from Dr. F. R. Immer, Professor of Agronomy and Plant Genetics, University of Minnesota, and from Dr. D. W. Robertson, Agronomist, Colorado Experiment Station.Search for more papers by this author Warren H. Leonard, Warren H. Leonard The writer wishes to express his appreciation for helpful suggestions received during the course of this study from Dr. F. R. Immer, Professor of Agronomy and Plant Genetics, University of Minnesota, and from Dr. D. W. Robertson, Agronomist, Colorado Experiment Station.Search for more papers by this author First published: 01 March 1942 https://doi.org/10.2134/agronj1942.00021962003400030002xCitations: 6 1 This material is taken from a thesis presented to the faculty of the Graduate School of the University of Minnesota in partial fulfillment of the requirements for the degree of doctor of philosophy. The data all were obtained at the Colorado Experiment Station at Fort Collins, Colo. Published with the approval of the Director of the Experiment Station as Scientific Series Paper No. 129. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume34, Issue3March 1942Pages 211-221 RelatedInformation

The inheritance of rachilla length in barley

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.