Experiment Station Record, Volume 93, July-December, 1945 Page: 20
xiii, 941 p. ; 24 cm.View a full description of this book.
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20 EXPERIMENT STATION RECORD [Vol. 93
A cyto-taxonomic study of the North American species of Melica, W. S.
BOYLE. (Univ. Calif.). (Madrono, 8 (1945), No. 1, pp. 1-26, illus. 3).-It is now
recognized that a clear understanding of the taxonomy of any group of plants
will be greatly facilitated by a knowledge of the cytology and breeding behavior
of the species in question. This study is an attempt to apply such data with the
evidence from morphology and geographic distribution in defining the specific lines
and probable relationships of the North American species of melicgrass or
oniongrass.
An ecological study of four species of sumac in relation to development and
growth on eroded soil, I. L. BOYD (Kans. Acad. Sci. Trans., 47 (1944), No. 1, pp.
51-59, illus. 7).-Tbe four species-Rheus arpmatica, R. copallina, R. glabra, and
R. typhina-were chosen for studies involving adaptation to the soil and climatic
conditions, growth rate, spread by root sprouts, and value in erosion control and
tannin production. From the results of these observations and experiments it is
concluded that the favorable responses by the smooth sumac (R. glabra) warrants
its use both in erosion control and as an economic tannin-producing plant.
Nitrogen fixation in leguminous plants.-IV, The influence of reaction on the
formation of root nodules in Medicago and Trifolium, H. L. JENSEN (Linn. Soc.
N. S. Wales, Proc., 68 (1943), pt. 5-6, pp. 207-220).-In continuation (E. S. R.,
91, p. 653), these studies of nodule formation on seedlings grown in agar media
differing in reaction indicated pH 5.3-5.4 to be the critical range for Medicago;
in several species of Trifolium nodule formation was seen at pH 4.5 and even at4.2.
When once formed, nodules could continue to fix N at pH values too low
for their formation de novo. When alfalfa and subterranean clover were-grown
in various sand and soil media at approximately pH 5-7.5, as a rule fewer and
bigger nodules were produced with increasing acidity; this effect varied considerably
in different tests, but on the whole was more pronounced in the alfalfa.
Both plants formed nodules in natural soil at pH 4.9-5, whereas sand acidified
with H2SO4 appeared very unfavorable to nodule formation. The yield of alfalfa
was reduced below pH 6; that of clover was little affected. The dry matter
yields and N percentages of the plants, as well as the number and size of nodules,
apparently depended not only on the pH value, but also on the composition of the
growth substrate. The relative weight of the nodule substance was constantlyand
the actual weight frequently-increased at acid reactions. There was evidence
of an inverse correlation between the N-fixing efficiency of the nodules and
the H-ion concentration of the growth substrate.
The internal reaction of root .nodules was found to be pH 5.55-6.32 (average
pH 5.92); the root tissues were on the whole slightly more acid. No significant
correlations were observed between the pH values in nodules, roots, and growth
substrates-the last being approximately 5-8. In roots of young seedlings of alfalfa
and subterranean clover the reaction appeared to vary in the same direction
as that of the growth substrate, but remained within the limits of pH 5.5-6.1.
Generally, the influence of the soil reaction on nodule formation appeared to differ
from that on the subsequent N-fixing activity, and the latter was subject to wider
pH limits, i. e., the free-living Rhizobia were more sensitive to acid reaction than
the N-fixing complex of plant + Rhizobia.
Einfluss von Vitamin B1 auf Wachstum und Ertrag verschiedener Kulturpflanzen
[Influence of vitamin B1 on the growth and yield of various crop
plants], L. GISIGER (Landw. Jahrb. Schweiz, 58 (1944), No. 1,. pp. 54-66, illus. 6;
Fr. abs., pp. 65-66).-In the pot experiments reported, thiamine failed to show any
favorable influence on the development of sunflower, corn, wheat, flax, or bean
plants; similar yields were obtained with or without added thiamine. Since this
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U.S. Department of Agriculture. Agricultural Research Administration. Office of Experiment Stations. Experiment Station Record, Volume 93, July-December, 1945, book, 1947; Washington D.C.. (https://digital.library.unt.edu/ark:/67531/metadc5063/m1/33/: accessed April 23, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.