Abstract
1. The germination of non-after-ripened juniper seeds under ordinary conditions is very low, amounting to 1 per cent. 2. These seeds are protected by a semipermeable and thick coat which makes up 75 per cent by weight of the entire seed. Acids enter very slowly, while bases, silver and mercury salts, enter rapidly. While the coat serves as a protection against fungal attack and prevents water-imbibed seeds from expanding and rupturing the tissues before after-ripening is accomplished, it takes little or no part in the dormancy or after-ripening of the seed. 3. Food material in the resting seed is stored in the form of fats and proteins, with traces of glucose but no starch. The resting seed endosperm has a PH value of about 5, while that of the embryo is about 8. 4. Although some forcing agents changed the respiration and catalase activity of seeds, it was not possible to force the germination of non-after-ripening juniper seeds by high temperature, alternating temperature, wounding, warm bath, dry air, removal of coats, treatment with hydrogen peroxide, mercuric chloride, ether, carbon dioxide, oxygen, light, soil, dilute acids, dilute bases, nitrates, suphates, or strong acids. 5. Freezing and thawing as such has no forcing action on the germination of juniper seeds, neither does it hasten after-ripening. Freezing and thawing produces marked chemical changes in this seed, but these changes, as has been outlined, are quite different from those occurring during after-ripening. Seeds ready to germinate (after the coat is cracked and their water content increased to 52 per cent) are killed by an exposure to -5⚬ C. 6. The juniper seed has a dormant embryo that must after-ripen before germination. After-ripening occurs at temperatures between 0±1⚬ C. and 10⚬ C., although fastest at about 5⚬ C. 7. The changes that accompany after-ripening of the juniper seed at 5⚬ C. were found to be as follows: (1) rather rapid and complete imbibition, followed by a steady slow decrease in water content during after-ripening or until near germination; (2) increased H+ ion concentration, especially of the embryo; (3) an increment of titratable acid; (4) a steady and enormous increase in the degree of dispersion of the stored fat; (5) decrease in the amount of stored fat and protein, with an increase of sugar content and the first appearance of starch; (6) the translocation of food in the form of fat or fatty acids from endosperm to embryo; (7) a seven-fold increase in the amino acid content, and a complete disappearance of histidine from the endosperm; (8) an increase of soluble proteins, with a marked hydrolysis of the stored proteins: (9) slight growth of embryo; (10) very slight increase of the respiration intensity; (11) increased respiratory quotient; (12) decreased intramolecular respiration; (13) a doubling of the catalase activity; and (14) the rise in vigor of seeds as shown by their resistance to fungal attack. 8. In conjunction with after-ripening at 5⚬ C., desiccation seems to be the only promising means of shortening this after-ripening period. 9. The time at which the hypocotyl breaks through the nucellus was fixed as the end of after-ripening and the beginning of germination. 10. Neither the resting nor the after-ripened juniper seeds yield more than about 1 per cent germination at temperatures above 15⚬ C. Seeds after-ripened at 5⚬ C., then placed at 10⚬ C., germinate slower than those left at 5⚬ C. When after-ripened seeds are transferred from 5⚬ C. to temperatures above 15⚬ C. they are thrown into a state of secondary dormancy. Hence these seeds require a low temperature for germination as well as for after-ripening, and therefore no seed should be transferred to higher temperatures until germination has started. If these seeds are given sufficient time they will germinate, even at 0 ±1⚬ C. 11. Subsequent to after-ripening and germination at 5⚬ C., the best temperature for seedling development is 15⚬ C. 12. The development of chlorophyll in the juniper seed and seedling was found to be independent of light, but conditioned by the temperature range. Seedlings grown at temperatures of 0 ±1⚬ C. or 30⚬ C. never developed chlorophyll. Anthocyanin development in seedlings seems to depend upon relative temperature and carbohydrate supply. 13. A more complete chemical analysis of these seeds at different stages of development will be given in a later paper.
Abstract from the paper’s OpenAlex record, shown for indexing and research. Copyright remains with the authors or the publisher. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 20
Claim · model-written summary
Non-after-ripened juniper seeds germinated at 1% under ordinary conditions.
Verbatim
e0“The germination of non-after-ripened juniper seeds under ordinary conditions is very low, amounting to 1 per cent.”
Claim · model-written summary
The seed coat is semipermeable and accounts for 75% of seed weight.
Verbatim
e0“These seeds are protected by a semipermeable and thick coat which makes up 75 per cent by weight of the entire seed.”
t0“Juniperus”
Claim · model-written summary
Acids entered the coat slowly relative to bases and salts.
JuniperusOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Acids enter very slowly, while bases, silver and mercury salts, enter rapidly.”
t0“Juniperus”
Claim · model-written summary
The coat played little or no role in seed dormancy or after-ripening.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“it takes little or no part in the dormancy or after-ripening of the seed.”
t0“Juniperus”
Claim · model-written summary
Resting seeds stored fats and proteins, traces of glucose and no starch.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Food material in the resting seed is stored in the form of fats and proteins, with traces of glucose but no starch.”
t0“Juniperus”
Claim · model-written summary
Resting seed endosperm had pH about 5 versus about 8 in the embryo.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The resting seed endosperm has a PH value of about 5, while that of the embryo is about 8.”
t0“Juniperus”
Claim · model-written summary
Listed forcing agents failed to induce germination of non-after-ripened seeds.
- Taxon
- junipere0
- Treatment
- high temperature, alternating temperature, wounding, warm bath, dry air, removal of coats, treatment with hydrogen peroxide, mercuric chloride, ether, carbon dioxide, oxygen, light, soil, dilute acids, dilute bases, nitrates, suphates, or strong acidse0
- Outcome
- germinatione0
- Direction
- not possiblee0
Not reportedComparator
Verbatim
e0“it was not possible to force the germination of non-after-ripening juniper seeds by high temperature, alternating temperature, wounding, warm bath, dry air, removal of coats, treatment with hydrogen peroxide, mercuric chloride, ether, carbon dioxide, oxygen, light, soil, dilute acids, dilute bases, nitrates, suphates, or strong acids.”
Claim · model-written summary
Freezing and thawing did not force germination or hasten after-ripening.
Not reportedComparator
Verbatim
e0“Freezing and thawing as such has no forcing action on the germination of juniper seeds, neither does it hasten after-ripening.”
Claim · model-written summary
Seeds ready to germinate were killed by exposure to −5°C.
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Seeds ready to germinate (after the coat is cracked and their water content increased to 52 per cent) are killed by an exposure to -5⚬ C.”
t0“Juniperus”
Claim · model-written summary
Juniper seeds have a dormant embryo requiring after-ripening.
Verbatim
e0“The juniper seed has a dormant embryo that must after-ripen before germination.”
Claim · model-written summary
After-ripening occurred from about 0 to 10°C and was fastest around 5°C.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“After-ripening occurs at temperatures between 0±1⚬ C. and 10⚬ C., although fastest at about 5⚬ C.”
t0“Juniperus”
Claim · model-written summary
Water content decreased slowly after rapid imbibition during after-ripening.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“rather rapid and complete imbibition, followed by a steady slow decrease in water content during after-ripening or until near germination”
t0“Juniperus”
Claim · model-written summary
Embryo hydrogen ion concentration increased during after-ripening.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased H+ ion concentration, especially of the embryo; (3) an increment of titratable acid”
t0“Juniperus”
Claim · model-written summary
Stored fat dispersion increased during after-ripening.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a steady and enormous increase in the degree of dispersion of the stored fat”
t0“Juniperus”
Claim · model-written summary
Stored fat and protein declined during after-ripening.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“decrease in the amount of stored fat and protein, with an increase of sugar content and the first appearance of starch”
t0“Juniperus”
Claim · model-written summary
Amino acid content increased sevenfold.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a seven-fold increase in the amino acid content, and a complete disappearance of histidine from the endosperm”
t0“Juniperus”
Claim · model-written summary
Soluble proteins increased with hydrolysis of stored protein.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“an increase of soluble proteins, with a marked hydrolysis of the stored proteins”
t0“Juniperus”
Claim · model-written summary
Catalase activity doubled during after-ripening.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a doubling of the catalase activity”
t0“Juniperus”
Claim · model-written summary
Resting and after-ripened seeds germinated at no more than about 1% above 15°C.
Verbatim
e0“Neither the resting nor the after-ripened juniper seeds yield more than about 1 per cent germination at temperatures above 15⚬ C.”
Claim · model-written summary
Seed and seedling chlorophyll development depended on temperature but not light.
Verbatim
e0“The development of chlorophyll in the juniper seed and seedling was found to be independent of light, but conditioned by the temperature range.”