Proceedings of the Iowa Academy of Science Volume 25 Annual Issue Article 30 1918 The Germination of Some Trees and Shrubs and Their Juvenile Forms L. H. Pammel C. M. King Let us know how access to this document benefits ouy Copyright ©1918 Iowa Academy of Science, Inc. Follow this and additional works at: https://scholarworks.uni.edu/pias Recommended Citation Pammel, L. H. and King, C. M. (1918) "The Germination of Some Trees and Shrubs and Their Juvenile Forms," Proceedings of the Iowa Academy of Science, 25(1), 291-340. Available at: https://scholarworks.uni.edu/pias/vol25/iss1/30 This Research is brought to you for free and open access by the Iowa Academy of Science at UNI ScholarWorks. It has been accepted for inclusion in Proceedings of the Iowa Academy of Science by an authorized editor of UNI ScholarWorks. For more information, please contact [email protected]. Pammel and King: The Germination of Some Trees and Shrubs and Their Juvenile Forms THE GERMINATION OP SOME TREES AND SHRUBS AND THEIR JUVENILE FORMS. L. H. PAMMEL AND C. M. KING. (Contribution JVo. 2 on Germination of the Woody Plants.) Ill the proceedings of the Iowa Academy of Science, 1917, we published a paper on the germination and the juvenile forms of some oaks, mostly species native to Iowa. In this paper some of the literature on the subject was given. C. S. Sargent1 has touched on the germination of many of the species of North America, in some cases in detail. Germination of exotic species is described by Tubeuf.- It seemed well, therefore, to continue observaticns on the germination of Iowa species, and a few not native to the state axe included. Little specific seems to be known about the vitality of tree and shrub seeds. The state ments made are usually quite general. The species here studied were treated as to seed bed conditions in two ways. One lot of seeds was placed in good greenhouse soil in the fall (1917) and stratified in a cold frame, from which they were removed to the greenhouse in March, 1918. The second lot was planted in an open place covered with two inches of soil and leaves. Air temperature records were kept throughout the season. soil tem perature records were kept in the fall until the ground was frozen, and again during the opening of the growing period of 1918. Show3 calls attention to the need of testing every lot of seed, these tests to be co-ordinated with actual germination in the nursery. His paper describes a series of tests of seeds of yellow' . pine. Jeffrey pine and incense cedar. He considers live factors influencing germination; 1. temperature of soil; 2. character of soil; 3. amount of light; 4. amount of water, and 5. depth of cover. The last three factors can be quite well standardized : character of soil is predetermined ; temperature is consequently the variable. The germination of the three conifers is more rapid and complete in fertilized soils and slowest in clay. He finds that mean temperature does not apply strictly to germina tion. An examination of greenhouse germination shows that after two days with the same mean the germination increases iSllva of North America, various volumes. Tubeuf, K. Samen, Fruchte u. Keimlinge. Berlin, 1891. Published'Show, by UNIS. B., ScholarWorks,The Relation 1918 of Germination in the Greenhouse and Nursery ; 1 Jour, of Forestry, 1C, pp. 319-328. Proceedings of the Iowa Academy of Science, Vol. 25 [1918], No. 1, Art. 30 292 IOWA ACADEMY OF SCIENCE VOL. XXV, 1918 with increase between extremes. Thus if 'he temperature is constant at 60' F. on one day and varies from 50° to 70° P. with a mean of 60° on another, germination is highest following the latter. The practice in testing seed in greenhouses is to hold air tem perature to a minimum of 50° F. An examination of thermo graph sheets and germination records indicates that minimum air temperatures down to 32° F., the freezing point, do not retard germination and in fact appear to accelerate it unless they are prolonged. Seed in the nurseries is of course sub jected to a wider variation in temperature than in the green house, but it is difficult to say that this results in slower germi nation. It is probable, though not proved, that the accumulated temperatures above 40° F. control germination. The author dis cusses the vitality of seeds of the three conifers. He finds that in the case of Jeffrey pine, seed several years old may be used. In case of yellow pine the germination- percentage falls off after two 'years. Seeds of incense cedar fall to 33 per cent the second year, and have practically no germination after the third year. Three years tests on over forty lots of seed of sugar pine gave no consistent or reliable results. The author finds it important to know the average rapidity of germination so that enough young plants be produced before the necessary time for transplanting. lie finds in his tests that northern seed is more rapid and shows less variation than southern seed. He believes that for planting the percentage of effective germination should be determined for each species ; as for instance, he has found it in the case of yellow and Jeffrey pines to be about 50. Gifford4 discusses germination distributed over a period of time; as in white pine, some grow the first year, many the sec ond year, a few the third year. With regard to geographical conditions; the farther north and the higher the altitude, the smaller the seed and the smaller the percentage of germination, although the quantity produced is often immense. The author quotes from Rafn determination of germination percentage of many species, which indicate how variable is the value of seeds on the market. Of the general statements which we find the following ma>' serve the purpose of this paper. John Nisbet5 quotes from Ne>' '(iifford, J.. Practical Forestry, pp. 102. 106, 111. 112. https://scholarworks.uni.edu/pias/vol25/iss1/303British Forest Trees and Their Silvicultural Characteristics and 'Treat- 2 irent, 48. Pammel and King: The Germination of Some Trees and Shrubs and Their Juvenile Forms GERMINATION OF TREES AND SHURBS 29:5 on the germination in percentage of seeds as sold by seedsmen : birch 10; alder 15; elm 20; hornbeam 50; oak 60; chestnut 60; maple 50; beech 60. K. Gayer and H. Mayr6 state that in spite of care there is some loss in the vitality of seeds. Robinia was found to ger minate 75 per cent; oak 69; beech 27; elm 26: birch 25. Harrington Moore finds "In fir there ar.? indications of a periodicity of reproduction which is of considerably more im portance than that due to the seed supply. * ••' * and that these conditions are largely controlled by the forest itself.'' STANTOX HILLSIDE SEED PLOT, OCTOBER, 1917. SOIL. TEMPERATURES OCTOBER 15 TO NOVEMBER 24. Precipitation during this period, 1.3!i inch. 8:00 A. M. 12:00 M. 5:00 P. M. Day Deg. C. Deg. C. Deg. C. Oct. 15 16 11. 14. 20. 17 14. 14. 14.5 18 12.5 . 10.5 19 6. 7. 7.5 20 7.5 7.5 21 4. 22 4.5 7. 15. 23 5. 6. !). 24 . 3.5 7. 8. 25 6. 7. 9. 26 6.5 6.5 6.5 27 5.5 6. 6. 28 29 3.5 3. 3. 30 0. 3. 3.25 31 2.5 3. 3.5 Nov. 1 2.5 a. 5. 2 3. 4. 7. :', 5. 7.5 10. 4-> 6.5 8.5 10. 6 6.5 10. 11. 7 10.5 7 12 8 8.5 9.5 11 9 8 10 10.5 10 9 10 11 12 8 9.5 9.5 13 8 9.5 10 14 7 8.5 10 15 R R.5 11.5 16 7 10.5 17 18 19 5 5.5 8 Published3Die Forstbenutzuns by UNI ScholarWorks,545 See Zurich1918 Samenkontroll Station. 1S76-1S94. 3 Reproduction in the coniferous forests of northern Neiv KnglanJ. Bot. Gazette 64. pp. 149-158. Proceedings of the Iowa Academy of Science, Vol. 25 [1918], No. 1, Art. 30 294 IOWA ACADEMY OF SCIENCE VOL. XXV, 1918 Day i:00 A. M. 12:00 M. 5:00 P. M. Deg. C. Deg. C. Deg. C. Nov. 20 7 8 10 21 8 9.5 9 2-2 23 '3.5 24 3.5 4. JO snow storm C. M. King, Observer SOIL, TEMPERATURE IN STRATIFIED BED SOUTH OF GREEN HOUSE, NOVEMBER 14 TO NOVEMBER 30, 1917. S:30A. M. 3:30 P.M. Day Deg. C. Deg. C. Nov. 14 " 15 1 15 " 16 3 14 " 17 4 13 " 18 " 19 " 20 6 14 " 21 s 11 " 22 1 2 " 23 1 " 24 7 " 25 " 26 29 30 W. Jeffrey, Observer TEMPERATURE AND MOISTURE RECORDS, AMES. F. S. Wilkins, Observer. Ti'mp. Deg. K. Temp. Deg. F. Day Mas. Min. Mean Preci p Day Max. Min. Mean iPrecip October, 1 73 32 Vovember, 1 40 29 1917 2 30 43 1917 2 56 21 3 62 49 3 66 29 4 73 49 4 63 35 5 56 40 5 65 34 6 64 25 6 68 30 7 57 40 7 69 30 8 49 23 8 45 36 9 fi6 36 9 57 35 10 55 34 10 55 40 22 11 51 31 11 59 40 12 47 27 12 44 37 13 51 12 13 42 34 14 T6 46 14 i6 28 15 n 40 15 58 26 https://scholarworks.uni.edu/pias/vol25/iss1/3016 65 37 16 67 32 4 17 72 48 17 61 31 Pammel and King: The Germination of Some Trees and Shrubs and Their Juvenile Forms GERMINATION OP TREES AND SHRUBS 296 Temp.