Imágenes de páginas
PDF

• * Fruit oblong, narrow, laterally compressed, somewhat acuminate. I / / / / -fr. sat. durum, 3. 7V. Polonicum L. A very striking species, with large, compressed, mostly blue-green spikes. Spikelets appearing as if cut off trans versely, because the third and fourth flowers scarcely reach to thj point of the two lower ones; flowering glumes compressed, navicular, many-nerved, awned; fruit 8-12 mm. long.

METHOD OF DESCRIBING WHEAT VARIETIES.

198. Half Grown Plant In The Field. Each student should be given a printed or typewritten sheet as indicated below and requested to describe two or more varieties of wheat growing in the field by underscoring the adjective which most nearly applies to the condition found.

1. Color: light green; medium green; dark green; light yellowish green; medium yellowish green; dark yellowish green; light gray green; medium gray green; dark gray green.

2. Leaf blade: average length of ten blades .

3. Leaf blade: average width of maximum dimensions of ten blades **

4. Leaf blade: erect; ascending; drooping.

5. Leaf blade: smooth; rough; downy.

6. Leaf blade: veins prominent; veins not prominent.

7. Leaf blade: end tapering; end wit. !:bs parallel.

8. Leaf sheath: green; green shading t p role.

9. Ligule: 2.5 mm. long; 2 ran. long: . nun. long.

10. Ligule: white; purple.

11. Auricles: white; green; white with p- rple tips; purple.

12. Auricles: hairy; partly hairy; smooth.

Note: The above practicum and those following are intended to teach a method of describing wheat varieties as first proposed by Cobb and published by Scofield, The student should be referred to The Description of Wheat Varieties, by Carl S. Scofield. U. S. Dept. of Agr., Bu. of PI. Ind. Bui. 47

199. Mature Plant In The Field. Each student should be given k printed or typewritten sheet as indicated below and requested to describe two or more varieties of wheat growing in the field by underscoring the adjective which most nearly applies to the condition found.

1. Height: average of ten culms to tip of apical gloom, not counting awn

if any . ,

2. Vigor of plant: strong; medium; weak.

3. Diameter below spike: average of ten culms .

4. Depth of furrows below spike: furrowed; medium; smooth.

5. Upper part of culm: solid; semi-solid; hollow.

6. Wall of culm: thick; medium; thin.

7. Color of culm: light yellow; yellow; purple; bronze. & Foliage: scanty; medium abundant.

9. Rust: leaves, per cent ;culms, per cent .

10. Smut: loose, per cent ;stinking, per cent .

11. Spike: erect; leaning; nodding.

12. Spike: beardless; partly bearded; bearded. 13. Shattering: badly; medium; none.

200. Mature Dried Plant In Laboratory. Give each student a printed or typewritten sheet as indicated below and request a description of two or more varieties from dried samples by underscoring the adjective which most nearly applies to the condition found. If opportunity to study varieties in the field is lacking, some of the items given in (199) may be included here.

1. Length of spike: average of five spikes from base of lower spikelet to tip of

apical flowering glume, not counting awn, if any .

2. Compactness of spike: very open; open; medium; compact; crowded.

3. Shape, side view: tapering towards apex; tapering both ways; uniform;

clubbed.

4. Shape, end view: square; flattened with spikelet; flattened across spikeLt.

5. Sterile spikelets: No. .

6. Awns: length .

7. Awns: slender; medium; stout.

8. Awns: parallel; spreading; widely spreading.

9. Awns: deciduous; partly deciduous; persistent

10. Awns: light yellow; yellow; brown; black.

11. Spikelet: spreading widely; spreading; narrow.

12. Spikelet: number of grains .

13. Basal hairs: long; medium; short; wanting: white; brown.

14. Outer glume: light yellow; yellow; bronze; black.

15. Outer glume: hairy; partly hairy; smooth.

16. Width of outer glume: broad; medium; narrow.

17. Length of outer glume: long (as flowering glume); medium; short .

18. Attachment of outer glume to rachilla: firm; medium; weak.

19. Beak of outer glume: long; medium; short.

20. Shoulder of outer glume: broad; medium; narrow: square; sloping; round.

201. The Grain. Give each student a printed or typewritten sheet as indicated below and request a description of two or more varieties by underscoring the adjective which most nearly applies to the condition found.

1. Density: very hard; hard; medium; soft; very soft.

2. Appearance of cross-section: very horny; horny; dull; starch.

3. Weight: of 100 average seeds in duplicate (a) (b) .

4. Ratio of length to width: divide length of twenty-five grains by width of

twenty-five grains with crease down ,

5. Shape: straight; curved; pear-shaped.

6. Plumpness: plump; medium; shrivelled.

7. Cheeks: flat; plump; angular. 8. At tip: pointed; blunt.

9. At base: pointed; blunt .

10. Crease: deep; medium; shallow: wide; medium; narrow.

11. Brush: large area; small area: long hairs; short hairs.

12. Color of grain: light yellow; yellow; clear amber; dull amber; clear red; dull red.

202. Classification Of Varieties Of Common Wheat. Take preferably fifty varieties of either spring or winter wheat in sheaf and in grain. A desirable plan is to have one thousand grains of each variety in glass vials one inch in diameter and six inches high, taking care to have the vials of clear glass and uniform diameter. The difference in the size of grains can be noted at a glance and all other characters as easily observed as in larger samples.

[graphic]

An agronomy laboratory, showing materials ready for the study of varieties of wheat

Require the student to classify them into eight groups as follows:

( Grains red

Bearded

Beardless

Glumes white

Glumes bronze

Glumes white

Glumes bronze

Grains white
Grains red
Grains white
i Grains red
'Grains white
'Grains red
Grains white

The student should note what differences, if any, exist between varieties of the same group as for example in smoothness or hairiness of glumes, and length of straw; and in what cases the varieties are probably synonymous. (89) A written report concerning the best ten varieties as shown by Stations testing varieties in question may be required. Definite references to proper bulletins should be furnished each student.

203. Relation Of Color, Hardness, Size, Specific Gravity And ConTent Of Gluten.—

1. Take five varieties of wheat varying as widely as may be in different qualities mentioned, as for example, Fultz, Gold Coin, Rudy, Turkey, Kubanka.

2. Note color and hardness.

3. Find weight of 500 grains.

4. Fill a 50-gram picnometer with benzene and weigh on balance sensitive to 1 mgm. Add twenty grams of wheat and weigh. Add weight of wheat to weight of picnometer and benzene and subtract last weight, which will give weight of volume of benzene equal to volume of grains of wheat. Divide this difference by the specific gravity of benzene, which will give the weight of a volume of water equal to the volume of grains of wheat. To determine the specific gravity of the wheat, divide twenty grams of wheat by the weight of an equal volume of water.

5. To find the relative size of grains, divide the weight of five hundred grains by their specific gravity.

6. To determine content of gluten, take thirty grams of ground wheat, work with water in a round bottomed glass vessel with spatula, and wash off starch after gluten has gotten into a sticky mass,and continue to wash until there is no appearance of starch grains being carried off. To be sure that all the starch is freed from gluten, test washings with potassium iodide; blue color shows the presence of starch. Work mass of gluten in fingers until all water that will run off has been expelled. Weight will give amount of moist gluten. Place in drying oven at no" C until constant weight is obtained. Weight will give amount of dry gluten. At same time find weight of dry matter in ten grams of ground wheat. Calculate per cent of moist and dry gluten from data obtained.

If there is not time or facilities to carry out No. 6, the instructor may determine the content of gluten in advance and allow the student to compare Nos. 2 to 5, rubber (tube) J with the results thus obtained.

204. Quality Of Flour.—Furnish each student with a sample of high grade and low grade flour and have him determine the following:

1. Character of granulations: Note under a high power microscope (172) whether flour particles are round sired—any size cloth can or angular.

be inserted; 8, wire clamp 2_ size 0f partides; By means of apparatus tfeholdine apparatus in place. vised by Snyder, determine the amount of flour in twenty-five grams that will pass through bolting cloth Nos. 9 to 20.

[graphic]

Snyder's apparatus for de.
termining the granulation
of flour. I, Erlenmeyer
flask; 2, suction connec-
tion; 3, rubber cork; 4,
adapter;
packing, making air-tight
joint; 6, section of brass
crucible overlapping sec-
tion 7; between these two
parts bolting cloth is
placed and removed as de-

3. The color test: Place samples of flour on plate of glass and determine color by means of a series of colored glass slabs.'

4. The baker's sponge test: Place in a wide pint porcelain bowl one hundred grams of flour. Dissolve five grams of sugar and five grams of compressed yeast in sixty-five grams of water and stir with steel spatula into flour. Continue to add water and knead until proper consistency is obtained. Note quantity of water required to give equal consistency in both samples. Place dough in cylinders about four inches in diameter graduated into c. c.'s. Set tube in water at 900 F. and determine time required to rise to full height and maximum volume attained. If time permits, allow second rise to occur and note time and maximum volume. The first rise takes about an hour and a half to two hours and the second rise from an hour to an hour and a half. If the per cent of gluten has been determined (203), calculate volume to each gram of gluten.2

205. Collateral Reading.

The Basis for the Improvement of American Wheats. By Mark Alfred Carleton. U. S. Dept. of Agr., Div. of Veg. Phys. and Path. Bui. 24, pp. 63-83.

The Structure of the Wheat Grain. By Charles E. Bessey. Neb. Bui. 32, pp. 100-114.

William C. Edgar: The Story of a Grain of Wheat, pp. 111-131. New York: D. Appleton & Co.

Plant Breeding. Willet M. Hays. U. S. Dept. of Agr., Div. of Veg. Phys. and Path. Bull. 29, pp. 44-54.

Grain Elevators. By N. A. Cobb, Dept. of Agr., Sidney, New South Wales, Misc. Pub. 452.

• These can be purchased of Eimer & Amend, New York. * For further details see Minn. Bui. 62. (1899), pp. 346-352.

[graphic]
« AnteriorContinuar »