/t M ■ i i] ot in Issued November 25, 190i U. S. DEPARTMENT OF ACxRICULTURE, Bl REAL 1 (>F PLANT [NDUSTRY— Circular No. 16. B. T. GALLOWAY, Chli i ol Bureau. A NEW BASIS KOI! BARLEY VALUATION AM) IMPROVEMENT. ALBERT MANN. Expert in Charge "i Special Barley Investigations. ! Cir. 10 08 US DEPOSITORY BUREAU OF PLANT INDUSTRY. Physiologist and Pathologist, and Chief of Bureau, Beverly T. Galloway. Physiologist and Pathologist, and Assistant Chief of Bureau, Albert F. Woods. Laboratory of Plant Pathology, Erwin F. Smith. Pathologist in Charge. Investigations of Diseases of Fruits, Morton B. Waite, Pathologist in Charge. Laboratory of Fortst Pathology. Haven Metcalf, Pathologist in Charge. Cotton and Truck Diseases and Plant Diseast Survey, William A. Orion. Pathologist in Charge. Plant Lift History Investigations, Walter T. Swingle, Physiologist in Charge. Cotton Breeding Investigations, Archibald D. Shamel and Daniel N. Shoemaker, Physiologists in Charge Tobacco Investigations, Archibald D. Shamel. Wightman W. Garner and Ernest 11. Mathewson, in Chargi Corn Investigations, Charles P. Hartley, Physiologisl in charge. Alkali mill Drought Resistant Plant Breeding Investigations, Thomas II. Kearney, Physiologist in Charge. Soil Bacteriology and Water Purification Investigations, Karl K. Kellerman, Physiologisl in Charge Bionomic Investigations of Tropical and Subtropical Plants, Orator F. Cook. Bionomist in Charge. Drug and Poisonous Plant Investigations and Tea Culture Investigations, Rodney ll. True, Physiologisl in Charge. Physical Laboratory, Lyman J. Briggs, Physicist in Charge. crop Technology and Fiber Plant Investigations, Nathan A. Cobb, Crop Technologist in Charge. Taxonomic and Rangt Investigations, Frederick V. Covillc. Botanist in Charge. Farm Management Investigations, William J. Spillman, Agriculturist in Chargi'. Grain Investigations, Mark Alfred Carle ton, Cerealist in Charge. Arlington Experimental Farm. Lee C. Corbett, Horticulturist in Charge. Vegetablt fisting Gardens. William W. Tracy, sr., Superintendent. Sugar-But Investigations, Charles O. Townsend. Pathologist in Charge. II estern Agricultural Extension Investigations, Carl S. Scofield, Agriculturist in Charge. Dry-Land Agriculture Investigations, E. Charming Chilcott. Agriculturist in Charge Pomological Collections, Gustavus B. Brackett, Pomologist in Charge. Field Investigations in Pomology, William A. Taylor and G. Harold Powell, Pomologists in Charge. Experimental Gardens and Grounds, Edward M. Byrnes, Superintendent. Fonigii Seed and Plant Introduction, David Fairchild. Agricultural Explorer in Charge. Forage Crop Investigations, Charles V. Piper, Agrostologist in Chargi Seed Laboratory, Edgar Brown, Botanist in Charge. Grain Standardization. John D. Shanahan. Crop Technologist in Charge. subtropical Laboratory and Gardi a . Miami. Fla.. P. .1. Wester, Gardener in Charge Plant Introduction Garden, Chico, Co'., W. W. Tracy. jr., Assistant Botanist in Charge South Texas Gardt n . Brownsx illi . Tex. , Edward C. Green, Pomologist in Charge. Farmers' Cooperative Demonstration lie/;.. Seaman A. Knapp, Special Agent in charge. Seed Distribution (directed by chief of Bureau), I. isle Morrison. Assistant in General Charge. Editor, J. E. Rockwell, Chief Clerk, James E. Jones. i it 16] 2 B. P. I.— 401. A NEW BASIS FOR BARLEY VALUATION AND IMPROVEMENT. INTRODUCTION. In planning for the improvement of barlej crops there are among many other things two of great importance: (1) The means of clearly recognizing the best grades of barley and (2) the knowledge of what factors or qualities in barley ii is especially desirable to improve. A great many tests for distinguishing different grades of barlej have been in use. Of these the simpler ones, and therefore those thai should l>e most useful, have not been found to be reliable, ('(in- clusions based upon such external signs as color, fineness and wrin- kling of hull, smooth or toothed condition of the uerves, long or shorl haired basal brush, and size and shape of grain are serviceable, but have proved so inaccurate that it is evident the} cannot be depended upon as a basis for scientifically accurate conclusions. 'The test made h\ cutting the grain across so as to see the relative mealiness of it> starch contents i> also verj unsatisfactory, because there are two different hut similar appearing states of glassiness, one that injures the malting qualities of the grain, while the other has no such effect. Even the more difficult ami expensive chemical analyses leave much t<> he desired. For example. the\ indicate the percent- age of nitrogen contained in a sample, hut distinguish with great difficulty between the different kinds of nitrogenous contents; and, what is --till more unfortunate, though the} accurately determine the chemical composition of a given sample the\ have no testimony to offer showing why one variety has more of a certain substance than another, where the dilferent constituents aie located in the grain, or how superior grades of barlej ma\ he recognized and -till better grades developed. Therefore, although chemical analysis in barley determinations is indispensable, there is greal need for a trustworthy si met ural test . In undertaking the improvement of American barleys the Bureau of Plant [ndustry therefore decided to attempt the solution of some [Cir. 16] 4 A NEW BASIS FOR BARLEY VALUATION AND IMPROVEMENT. of these questions along new lines. Mr. David F aire! did has believed for some time that a thorough study of the internal structure of the barley grain should afford better knowledge than that hitherto secured of the location of the various constituents of the grain and especially of the location within the grain of those energies that bring about the changes included in the artificial process called malt- ing and the 1 natural process called germination. The valuable dis- coveries made by Dr. N. A. Cobb in his morphological studies of wheat a strengthen the belief that the functions of barley, included in its malting processes, however complicated, are referable to some structural parts as their source and are correlated with deiinite organs. The writer therefore undertook a careful study of the internal mechanism of the barley grain as to the structural changes that take place during its successive steps in malting. To do this, modifications in laboratory technique have had to be worked out and methods discovered that would give the best results in killing, fixing, sectioning, staining, etc., this refractory material so as to fit it for microscopic study. The object of this article is merely to give a brief sketch of the work so far accomplished and to announce a new basis for barley valuation. The first task undertaken was to investigate anew the work per- formed by the different parts of the grain. This was necessary because, although an enormous amount of study lias been given to this subject, there is no unity of opinion to be found in the reports published. To take an example: it has long been known thai the peculiar part of the embryo barley plant called the scutellum is an absorbing organ, which seizes upon the food supply stored in the resl of the grain and transfers it to the growing parts, the young root sys- tem and the stem. The shape and position of this organ suggesl such a use to even an untrained observer, its broad, flat surface is pressed close against the large, stored-up mass of starch, called the endosperm, which forms the bulk of the grain; anil when germination, or its modified form called malting, has been going on for three or I'oui' days it is easy to see that the starch endosperm, especially that portion lying nearest the scutellum, is disappearing and that at the same time the embryo plant has commenced growth. It is evident that the scutellum is absorbing the starch ami transferring it to the plant. But this can not be effected without certain preliminary changes. The walls of the starch-containing cells must firsl be broken down and the starch grains must then be changed into a liquid state l>\ conversion into sugar, dextrin, or some such soluble correlative before t he scutellum can absorb this supplj and convey it to the plant. a Published by the Department of Agriculture of New Smith Wales under the title " I traversal Nomenclature of Wheat." r. 101 \ M-.w BASIS FOR BARLEY VALUATION \M> [MPROV] MINI. 5 Ii i- therefore importanl to know where the ferments or enzymes necessary to bring about these changes are secreted. Are the} the producl of tin' scutellum, making it thereby not onhj an absorbing l)ii t a secreting organ ' < >r are thej located elsewhere? This i- one of the questions about which there is much diversity of opinion. Some investigators bold thai the necessary enzymes, diastase and cytase, ;iii' to In' found in tin 1 cells of the starch endosperm itself, and that if. as is probable, the scutellum also secretes these enzymes ii is supple- mentary to the stored-up supph of the starch cells. Other- believe all or a considerable part of the supph is secreted 1>\ the cells of the aleuroD layer, which invests the entire starch endosperm excepl ;it i he end of the grain occupied by the plantlet. Certain authors hold that both this layer and the scutellum supph these ferments. Ii was such discordanl testimony on this and other point- that made necessary at the outsel a thorough stud) of the morphology of the barlej grain so a- to fix, a- far a- possible, the location- of these import ant fund ion-. These investigations have proved that the enzymes already men- tioned, the diastatic and cytatic starch ferments, are wholly the producl of t he scutellum and are secreted by its outer la) <•:■. called t he epithelial layer; that although a minute t race of t hem is to he found in the starch cell- (as in ail starch-containing tissue), it plays so slight a part in the normal -tarch conversion that it is practically negligible; that, furthermore, the aleuron layer has nothing whatever to do with this process. The scutellum can therefore he called the "malting organ" of the barley grain and it> epithelial cells the "malting glands." This organ, together with the size and quality of the endo- sperm, is therefore of the highest importance in all quegtions concern- ing the food value, malting value, ami germinating value of barle] . I>\ a comparative study of this important organ in the leading vari- eties of cultivated barley, it was soon discovered that it> shape varies u r reatl_\. At least two distinct types exist, with main inter- mediate forms- one ver\ broad, almost circular in outline, covering tlu 1 lower end and reaching well over the shoulders of the grain sei fig. 1); the other narrow . elongated, with nearly parallel -ide- and rounded or pointed tip (see fig. 2). The broad scutellum i- generally nearly ilat or so slightlj convex on it- inner surface that it lies in a shallow depression of the -larch endosperm, while the narrow scutel- lum is thick and tongue shaped and is sunken quite deep into the endosperm. Compare the depression shown on the left in figure I with that in figure '_': also tin' two scutellums. Corresponding differences, though less strongly contrasted, were found to exisl in the size and shape of the epithelial cell- clothing the inner surface of these two types y^( scutellum. The broad, shallow 16] 6 A NEW BASIS FOR BARLEY VALUATION AND IMPROVEMENT. form has decidedly narrow and elongated cells, on an average live to six times as long as broad; those of the other type are shorter and relatively thicker, averaging three to four times as long as broad. It is easy to understand how the former will have a greater secreting power than the latter, since the number of cell units in a given space will be greater without any loss in the capacity of each cell. A fact of especial importance is that the broad, circular, slightly convex type of scutellum having long, narrow epithelial cells is found to be characteristic of the best grades of malting barley, while the narrow, deep-sunken type, with short and broad epithelial cells, is characteristic of barley inferior for malting purposes. A Fig. 1. — High-grade Swedish pedigree barley. Tin' hulls and outer membranes have been mim\ ed to show the ideal form of scutellum. Grain on the right entire; on the left with the scutellum removed, leaving a broad, shallow depression; scutellum in the center, seen from under side. Magnified 8 diameters. good example of 1 his fad is seen in figure ■'!. The value of this correla- tion is twofold: (1) It furnishes a means of recognizing the grade of any variety of barley by a test that is unquestionably more reliable than the external earmarks hitherto relied upon, such as character of the hull, basal bristle, shape of the grain, etc. For in the case of these external tests we have nothing more than an accidental and somewhat inconstant coincidence between form and physiological quality, while in the case of the-scutellum we deal with a strictly vital correlation, a necessary and therefore (ixed relationship between the organ and the malting efficiency. In the matter of its use the SCUtellum tesl is almost as easy as the above-mentioned external [Clr. 16] A NEW BASIS FOR i;\l;U\ VAL1 \TI<>\' AND IMPROVEMENT. i tests, the general build of this organ being easily made out 1>.\ merely removing the outside hull- of the grain. Tin- is readily done even when the barley is dry, though it is better to soak the sample for a fe\n bours. The examination of the epithelial layer is also a comparatively simple operation. A longitudinal section of a well-soaked grain, freed from it- hulls, can be quickly made with a razor or -harp knife, and the microscope will then reveal the general form of this important glandular tissue. Of course, better sections can be secured with a microtome. Some of the new freezing micro- tomes are not >>nl\ cheap hut are easilj operated. The one used iu these investigations will enable a grain investigator to prepare excellent sections in five to eight minutes, and such sections give a Pro. 2, Low-grade barley sold on the Milwaukee market. Crop of 1907 The hulls and outer membranes have been removed to show the poor form of scutellum. Grain on the right entire; on the left with scutellum removed, leaving a narrow, deep-sunken depression; scutellum in the n from under side. Magnified 8 diameters. far better image of the starch body it- texture, mealiness, glassi- ness, etc. than the crude method of cross-cutting the grain now practiced l>\ grain buyers and malt experts. ll i- tO he -ceil hv the foregoing that the lir-t e— eiltial for barley improvement mentioned at the head of this article, namely, the mean- of recognizing the best grades of barley, is supplied by the structural differences of the scutellum. The -ccnnd essential mentioned, a knowledge of what factor- in barley it is especially desirable to imprcn e, is also closelj connected with the function- of the scutellum, for evidently an\ improvement in malting barley must include an improvement in the malting organ. Other factor- are without doubt involved, the quality of the starch [Cir. U.] — — ^_^_ < "^^™ o> u ^^==co oc u_ «a^^^0O u_ =^04 o 189 >- h- *— * (/) ^____^_ f^| IE — ^ / ^^^^™ 8 A NEW BASIS Fdi; BARLEY VALUATION AND [IMPROVEMENT. endosperm, the percentage of nitrogen, etc, as well as some very weighty agricultural considerations having to do with yield, stiffness of 'straw, etc. But whatever other elements of quality enter into our work of Ameri- can barley improve- ment, the scutellum, as the most potential part of the barley grain, is likely to he one. How far this is ca- pable of modification is at present unde- termined. But the opinions of those ex- perimenters in grain breeding both here ami in Europe who •have been consulted on this point agree that there is no a priori reason why this particular form of plant structure should not be as plastic and capable of improve- ment as any other. The general success in plant breeding, ac- cording to modern methods, leads us to expect that in our work of barley improvement now going on at St. Anthony Park, Minn., we shall secure results of distinct value to American agriculture. Fig.3.— Malted barlry from Pilsen, Aus1 ria. Thegrainon the right ha: ill- sprout removed to show the ideal form of scutellum. Magnified S diameters. Approved : James Wilson, St cretary of Agi icultun . Washington, I). ('.. September 24, 1908. [Cir. 10] o