George Harlan Dungan.

The influence of plant injury and the root rot diseases upon the physical and chemical composition of corn grain online

. (page 3 of 3)
Online LibraryGeorge Harlan DunganThe influence of plant injury and the root rot diseases upon the physical and chemical composition of corn grain → online text (page 3 of 3)
Font size
QR-code for this ebook


in actual content of starch. There is evidently a physical difference
in these two types of corn which represents a qualitative dissimilarity
as well as a quantitative chemical one.

These results suggest that the "starchy" condition may be induced
or accentuated by many ecological factors. Interference with the usual
translocative processes, brought about by breaking the stalks, in-
creased materially the proportion of soft starch in the endosperm.
Premature harvesting doubtless produces the same effect. The injury
to the shanks which greatly increased "starchiness," produced an effect
not unlike that of complete removal of the ear from the plant. The
modification of the plant's metabolism caused by infection with the
corn root rot organisms also increased the "starchiness" of the grain,
and the root rot diseases are associated with both hastened and de-
layed maturity of the grain. It would seem that even slight altera-
tions from the optimum environment, either of parasitic or climatic
factors and possibly edaphic factors, may have a distinct effect upon
the quality of the grain.

Snyder 33 ' 34 explains that the light weight of the apparently
"starchy" wheat grains is due to a lower than average degree of matur-



1026] INFLUENCE OF PLANT INJURY ON COMPOSITION OF CORN 277

ity, as evidenced by their high nitrogen, phosphoric acid, and potas-
sium content.

Roberts and Freeman 2fl draw the conclusion that it is the presence
of air-vacuoles that gives to yellow-berry wheat its "starchy" appear-
ance and its uniformly low specific gravity. They support their reas-
oning by stating that the specific gravity of starch is 1.53, sugar 1.60,
and cellulose 1.53, whereas gluten, which is greater in amount in the
horny grain, has a specific gravity of only 1.297. An increased amount
of a substance having a lower specific gravity would not of itself in-
crease the specific gravity of the whole. Hence, it was assumed that
the lesser specific gravity was due to air-vacuoles.
, Cobb 4 ' 5 and Lyon and Keyser 23 point out that the starch granules
in soft wheats are larger in diameter than those of horny wheats. Even
tho the horny wheat varieties contain some large-sized starch gran-
ules, their relative number is much less than in the softer varieties.
Cobb 5 also notes that "whenever the starch grains are large, the cells
containing them are also large." Lyon and Keyser 23 working with
yellow-berry in wheat, state that "the protoplasmic network of the
cells in the sections from the very horny kernels showed only an oc-
casional vacuole. Sections from the markedly yellow kernels showed
very much more numerous and larger vacuoles."

Hackel 11 attributes the filling up of the intervals between starch
grains to albuminoids. The analyses of Hopkins, Smith, and East 14
sup'port this view by showing that the horny starch of the corn grain
contains 2.3 percent more protein than the white starch of the same
grain. Their data also show that the horny starch contains slightly
more oil.

An investigation into the nature of the starch in horny and in
"starchy" corn would seem to offer a very promising approach to the
explanation of the real difference between these. distinct types of dent
corn. Tanret, 36 from a study of starches in oats, bananas, wheat, chest-
nuts, beans, lentils, maize, barley, peas, apples, rice, buckwheat, rye,
and potatoes, concluded that the starches from these various sources
are not only dissimilar chemically, but that they react differently to
physical and other agents. Since the various grains and fruits con-
tain different kinds of starch, it is probable that there may be man}
different kinds of starch within the same grain, and when the propor-
tions of these vary the character of the grain is changed.

That there is a difference either in the ease with which starch is
hydrolized or in the activity of the dissolving enzym is indicated by
the consistently superior quantity of soluble starch and dextrins in
the horny corn over the "starchy" corn during germination. This
property is in all probability responsible for the greater vigor of corn
seedlings from the horny seed. 13



278 BULLETIN No. 284 [December,.

The immediate problem confronting the research worker in this
field appears to be not so much the question of what factors tend to
favor the development of the "starchy" character of corn grain, but
what "starchiness" really is as contrasted with horniness, the influence
which this condition has upon the metabolic processes incident to
seedling production, and the ease or difficulty with which seedlings are
infected by fungi.

In view of the fact that the difference between horny and
"starchy" is not one of quantity of starch, it would seem desirable to
discontinue the use of the term "starchy" as descriptive of that type
of corn and to substitute an adjective which is accurately descriptive
of the condition. A number of words suggest themselves, but cannot
be used because they have previously been adopted to describe other
conditions. While "soft" is often used to carry a meaning the opposite
of horny, common usage has led to the very general application of the
term to immature corn having an unusually high percentage of mois-
ture. The adjective "mealy" would be a good term to substitute for
"starchy," but it has been used by Mangelsdorf 24 to designate a par-
ticular type of endosperm in which practically all the material of
which it is composed is soft starch. The term "floury" is therefore
suggested by the author as the most nearly appropriate word for de-
scribing corn grain which has a relatively large quantity of soft starch
in the endosperm. "Floury" connotes the qualities of flour; namely,
light or pale-colored, soft, and powdery. "Floury" corn, then, wo'uld
be maize grain that is made up largely of material having a pale color
and a soft and friable texture. The distinction between "floury" corn,
as it is understood here, and the flour, or soft, corn of the tropics
should be kept in mind. "Floury" corn is corn of the dent type pos-
sessing a relatively high proportion of soft starch in the endosperm,
whereas flour corn is a separate and distinct type of corn, the grains of
which are very large and the endosperms of which contain no horny
material.



CONCLUSIONS

The results of these investigations indicate that the character
of the starch in the endosperm of corn grain may be influenced to
a perceptible degree by the environment in which it is produced. The
inoculation of the seed with certain organisms capable of causing;
the corn root rot disease alters the physiology of the plant produced
by such seed, resulting in the development of grain containing a
greater percentage of floury starch than that produced by plants from
uninoculated seed. Injury of the plant, such as the breaking of the
shanks and stalks, before the grain is completely mature causes an.



1926} INFLUENCE OF PLANT INJURY ON COMPOSITION OF CORN 279

increased proportion of white starch in the grain of such plants. If,
however, the shank be broken when the ear is in a very immature
condition, a grain possessing a waxy rather than a floury endosperm
may result.

Seedlings produced by corn possessing a relatively large quan-
tity of soft starch in the endosperm are not so vigorous as are those
from horny corn, owing to the fact that the floury starch is less
rapidly hydrolyzed to a soluble condition than the horny starch.

In general, horny corn contains as much starch as, and fre-
quently more than, floury corn of the same variety, but the specific
gravity of floury corn is much lower than that of horny corn.

A quantitative determination of the water absorbed by different
lots of corn under the same conditions furnishes a good index as to the
comparative amounts of soft starch contained in the samples.

ACKNOWLEDGMENTS

Grateful appreciation is expressed to Doctor E. J. Kraus, Department of
Botany, and to Doctor J. G. Dickson, Department of Plant Pathology, both of
the University of Wisconsin, for the interest they have taken in this problem
and for the many helpful suggestions which they have given during the progress
of the investigational work and in the preparation of this manuscript. Dr. W.
E. Tottingham, of the Department of Agricultural Chemistry, also of the Uni-
versity of Wisconsin, has assisted by suggesting proper chemical methods, and to
him sincere thanks are extended.



LITERATURE CITED

1. APPLBMAN, C. O.

1924. Some chemical aspects of sweet corn drying. Md. Agr. Exp. Sta.
Bui. 267, 287-298.

2. BLISH, M. J.

1920. Effect of premature freezing on composition of wheat. Jour. Agr.
Res. 19, 181-188.

3. BUSHEY, ALFRED

1924. Some chemical characteristics of soft corn. S. Dak. Agr. 'Exp. Sta.
Bui. 210, 713-718.

4. COBB, N. A.

1904. Universal nomenclature for wheat. To prepare sections of ripe wheat
grain. Agr. Gaz. N. S. Wales 15, 359-360.

5.

1904. Universal nomenclature for wheat. Structure of the flour-cells. Agr.
Gaz. N. S. Wales 15, 509-513.

6. CURTISS, C. F., AND PATRICK, G. E.

1893. A study of ripening corn. Iowa Agr. Exp. Sta. Bui. 23, 874-880.

7. DOOLITTLE, R. E., HOOVER, G. W., MAC!NTIRE, W. N., PATTEN, A. J. Ross, B.

B., AND SALE, J. W.

1925. Official and tentative methods of analysis of the association of offi-
cial agricultural chemists. Assoc. Off. Agr. Chem., Washington, D. C.

8. DUNCAN, GEORGE H.

1924. Some factors affecting the water absorption and germination of seed
corn. Jour. Amer. Soc. Agron. 16, 473-481.

9. ECKERSON, SOPHIA H.

1917. Microchemical studies in the progressive development of the wheat
plant. Wash. Agr. Exp. Sta. Bui. 139, 3-21.

10. jFAILYER, G. H., AND WlLLARD, J. T.

1891. Composition of certain plants at different stages of growth. Kan.
Agr. Exp. Sta. Bui. 32, 229-232.

11. HACKEL, EDWARD

1890. The true grasses. Henry Holt & Co.

12. HEADDEN, W. P.

1916. A study of Colorado wheat. Colo. Agr. Exp. Sta. Bui. 219, 3-131.

13. HOLBERT, JAMES R., BURLISON, W. L., KOEHLER, BENJAMIN, WOODWORTH, C.

M., AND DUNCAN, GEORGE H.

1924. Corn root, stalk, and ear rot diseases and their control thru seed
selection and breeding. 111. Agr. Exp. Sta. Bui. 255, 239-478.

14. HOPKINS, C. G., SMITH, LOUIE H., AND EAST, EDWARD M.

1903. The structure of the corn kernel and the composition of its different
parts. 111. Agr. Exp. Sta. Bui. 87, 77-112.

15. HORNBERGER, R., AND RAUMER, E. VON

1882. Chemische Untersuchungen iiber das Wachsthum der Maispflanze.
Landw. Jahrb. 11, 359-523.

16. HUME, A. N., CHAMPLIN, MANLEY, AND LOOMIS, HOWARD

1914. Selecting and breeding corn for protein and oil in South Dakota.
S. Dak. Agr. Exp. Sta. Bui. 153, 59-80.

17. INCE, J. W.

1916. Composition of the maize plant. N. Dak. Agr. Exp. Sta. Bui. 117,
3-32.

18. JONES, W. J. JR., AND HUSTON, H. A.

1914. Composition of maize at various stages of its growth. Ind. (Purdue)
Agr. Exp. Sta. Bui. 175, 599-630.

280



INFLUENCE OF PLANT INJURY ON COMPOSITION OF CORN 281

19. KEDZIE, R. C.

1893. Composition of clawson wheat at different periods of ripening. Mich.
Agr. Exp. Sta. Bui. 101, 2-12.

20. KENT, D. A., PATRICK, G. E., EATON, E. N., AND HEILEMAN, W. H.

1893. When to cut corn. Iowa Agr. Exp. Sta. Bui. 21, 778-787.

21. LfiCLERC, J. A.

1906. The effect of climatic conditions on the composition of durum wheat.
U. S. Dept. Agr. Yearbook, 199-212.

22. LINK, K. P., AND TOTTINGHAM, W. E.

1923. Effects of the method of desiccation on the carbohydrates of plant
tissue. Jour. Amer. Chem. Soc. 45, 439-447.

23. LYON, T. L., AND KEYSER, ALVIN

1905. Nature and causes of yellow berry in hard winter wheat. Nebr. Agr.
Exp. Sta. Bui. 89, 23-36.

24. MANGELSDORF, P. C.

1922. Heritable characters of maize mealy endosperm. Jour. Heredity 13,
359-365.

25. MCDOWELL, R. H.

1895. Wheat-cutting at different dates. Nev. Agr. Exp. Sta. Bui. 30, 1-7.

26. ROBERTS, H. F., AND FREEMAN, G. F.

1908. The yellow berry problem in Kansas hard winter wheats. Kan. Agr.
Exp. Sta. Bui. 156, 1-35.

27. SAUNDERS, CHAS. E.

1921. The effects of premature harvesting on the wheat kernel. Sci. Agr.
1, 74-77.

28. SCHWEITZER, P.

1889. Study of the life history of corn at its different periods of growth.
Mo. Agr. Exp. Sta. Bui. 9, 3-78.

29. SHAFFER, P. A., AND HARTMAN, A. F.

1921. The iodometric determination of copper and its use in sugar analysis.
Jour. Biol. Chem. 45, 349-390.

30. SHUTT, FRANK T.

1904. The effect of rust on the straw and grain of wheat. Wallace's Farmer
29, 1502.

31.

1908. Wheat. Canada Expt. Farms Rpt., 135-143.

32. SMITH, CLINTON D.

1898. Some experiments in corn raising. Mich. Agr. Exp. Sta. Bui. 154,
259-288.

33. SNYDER, HARRY

1904. Glutenous and starchy wheats. Minn. Agr. Exp. Sta. Bui. 85, 179-188.

34.

1905. Glutenous and starchy grains. Minn. Agr. Exp. Sta. Bui. 90, 219-225.

35. STOA, T. E.

1924. The early harvest of rusted Marquis wheat. Jour. Amer. Soc. Agron.
16, 41-47.

36. TANRET, M. CHARLES

1914. Sur la pluralite des amidons. Compt. Rend. Acad. Sci. (Paris) 158,
1353-1356.

37. TOOLE, E. H.

1924. The transformations and course of development of germinating
maize. Am. Jour. Bot. 11, 325-350.

38. TROST, JOHN F.

1922. Relation of the character of the endosperm to the susceptibility of
dent corn to root rotting. U. S. Dept. Agr. Bui. 1062, 1-7.



UNIVERSITY OF ILLINOIS-URBANA






1 3

Online LibraryGeorge Harlan DunganThe influence of plant injury and the root rot diseases upon the physical and chemical composition of corn grain → online text (page 3 of 3)