Table 1 shows the results obtained from treated nuts of ten species of Juglans when they were planted in the open field, in soil in the greenhouse or in moist sphagnum in the greenhouse. While some variation in germination is observed, most of the species gave a good germination under all treatments. The field planted seeds were somewhat slower in appearing above the soil surface than those planted in the greenhouse. This delay may have been caused by the cold rainy weather soon after planting. The firmness of the soil, a clay loam, may also have retarded the emergence of the seedlings.
The germination percentages are based upon lots of 100 nuts except in a few species in which only 50 nuts were used. Differences in the percentage of germination obtained from various plantings of the same species are slight in most species. Even the larger differences in germination obtained in a few species cannot be considered significant but probably indicate variations in the quality of the original lots used.
Summary
Walnuts husked soon after harvest, before they are completely air-dried, and stored in moist peat at 1 to 3° C. for five to six months have their dormancy broken and remain viable for at least three months thereafter. This treatment is effective for all ten species tested. It is probably effective for all species of Juglans. This method of handling the nuts has the advantage over outdoor stratifying or autumn planting which often result in much damage or loss of nuts from the activities of rodents.
Table 1. Germination of nuts of Juglans spp. after stratifying in
peat over winter, at 1-3°C.
| Per cent germination | |||||
|---|---|---|---|---|---|
| Kind | Source | Date entered in storage | Planted in soil in greenhouse April 15 | Planted in field April 24 | Planted in sphagnum June 2 |
| nigra | (Cornell) Ithaca, N. Y. | Oct. 1 | 70 | 80 | 68 |
| nigra | (Cayuga) Ithaca, N. Y. | Oct. 1 | 100 | — | 80 |
| cinerea | —Ithaca, N. Y. | Oct. 1 | 60 | 44 | 8 |
| regia | (Sorrentina) Chico, Calif. | Nov. 9 | 66 | 48 | 8 |
| regia | (Franquette) Chico, Calif. | Nov. 9 | 80 | 36 | — |
| regia | —Chico, Calif. | Nov. 9 | 75 | 46 | — |
| Sieboldiana | —Ithaca, N. Y. | Oct. 1 | 100 | 40 | — |
| honorei | —Chico, Calif. | Dec. 18 | 60 | 55 | 46 |
| pyriformis | —Riverside, Calif. | Nov. 9 | 10 | 54 | 31 |
| rupestris | —Alpine, Texas | Oct. 1 | 40 | 83 | 50 |
| major | —Riverside, Calif. | Nov. 9 | 90 | 92 | 66 |
| californica | —Pomona, Calif. | Nov. 9 | 62 | 84 | 91 |
| californica | quercina —Chico, Calif. | Dec. 18 | — | 18 | 25 |
| hindsii | —Riverside, Calif. | Nov. 9 | 50 | 56 | 52 |
References—
1. Brown, Babette I. Injurious Influence of Bark of Black Walnut Roots on Seedlings of Tomato and Alfalfa. Northern Nut Growers Association, 1942: 97-101. 1943.
2. Barton, Lela V. Seedling Production in Carya ovata. Juglans cinerea and Juglans nigra. Contr. Boyce Thompson Inst. 8: (1) 1-5. 1936