Experiment Station Record, Volume 92, January-June, 1945 Page: 32
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32 EXPERIMENT STATION RECORD [Vol. 92
Jour. Sci., 18 (1944), No. 4, pp. 457-469, ills. 9).-The so-called strophiole of
sweetclover seeds was found to be the place in the hilum where the vascular connection
occurs between the seed and the, funiculus. At this' place the light line and
associated structures related to hardness are interrupted by the vascular elements,
which afford a passageway to water. The endosperm, consisting mainly of two
gelatinous layers, completely envelops the embryo and, owing to its water retention,
is well adapted to protect the embryo against excessive water loss and temperature
fluctuation. By its force of imbibition it greatly accelerates the water flow into
the seed and to all distal parts; by its pressure, exerted in swelling, it plays a major
role in opening the seed coat.
Studies of the germination of sweetclover seeds indicated the strophiole to be
the natural place of initial water absorption during this process. Seeds naturally
soft or softened artificially or by weathering blackened and began swelling first at
the strophiole when immersed in osmic acid solution. On the other hand, hard
seeds almost without exception showed no blackening at this point until softened
by some means, whereupon they behaved as the naturally soft seeds. Samples of
hard seeds scarified not too harshly by hand were softened in proportion to the
number of seeds with blackening at the strophiole; the effectiveness of scarification
thus lay in making the strophiole permeable to water. In seed samples cleaned and
scarified by commercial houses, nearly all soft seeds showed blackening and water
absorption at the strophiole, though many of them also blackened and absorbed
water at various other places where the seed coat had been mutilated by the processing.
The coats of soft seeds stored outside deteriorated rather rapidly. Blackening
of the micropyle occurred in some seeds, both hard and soft, but no case was
observed in which water was absorbed through the micropyle. The cuticularized
layer, domes, and light line constituted an almost .continuous barrier to water
absorption, being interrupted only at the micropyle and strophiole. At the micropyle,
the Malpighian layer closes together so tightly that, with associated structures, it
renders the region watertight.
Vegetative development of inbred and hybrid maize, M. E. PADDICK (Ioza
Sta. Res. Bul. 331 (1944), pp. 373-399, illus. 12).-Corn plants of the inbred strains
La and Pr and the hybrid strains La X Pr and, Pr X La were studied during
germination, when the third, fifth, tenth, and fifteenth leaves were unrolling, and
at vegetative maturity. The hybrids ,developed faster, as shown by the speed of
initiation of successive leaves and whorls of roots, made greater over-all growth as
indicated by much larger immature leaves of comparable position on plants of the
same age, and had larger comparable plant parts, e. g., leaf blades, at maturity.
Hybrid plants appeared to have excelled also in extent of development, producing
from 20 to 22 leaves compared with 18 or 20 for inbreds. Mature hybrid and
inbred plants differed most strikingly in leaves formed after the twelfth or thirteenth,
which were much heavier, longer, and wider on the hybrids. Since these
leaves developed during tassel formation and rapid culm elongation, on the inbred
plant they may have been subject to an inhibiting influence not so effective on the
hybrid plants. Hybrid vigor appeared as a factor accelerating growth activities
of the plant and carrying them beyond a point common in less vigorous inbreds.
Cytogenetic studies with polyploid species of wheat.-II, Additional chromosomal
aberrations in Triticum vulgare, E. R. SEARS. (U. S. D. A. coop. Mo.
Expt. Sta.). (Genetics, 29 (1944), No. 3, pp. 232-246, illus. 2).-Eleven of the
17 of 21 possible nullisomics obtained in Chinese Spring wheat (designated I to XI)
were found to involve chromosomes homologous to those of the emmer or tetraploid
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U.S. Department of Agriculture. Agricultural Research Administration. Office of Experiment Stations. Experiment Station Record, Volume 92, January-June, 1945, book, 1947; Washington D.C.. (digital.library.unt.edu/ark:/67531/metadc5064/m1/45/: accessed August 19, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.