1. The optimum sugar concentration for germination of Corylus pollen is around 25% by weight in 1.5 per cent agar at 25° C.
2. Forcing the catkins at a low temperature (4° C.) and at high relative humidity (80%) favors the development of a high percentage of viable pollen.
3. The catkins contain some substance which when added to the germination media inhibits pollen germination and causes abnormal types of germination.
4. Preliminary results on pollen storage indicate that Corylus americana pollen can be stored for eight months or more in a viable condition at 0° C. with a range of 30 to 40% relative humidity. Juglans Sieboldiana pollen can be stored at 0° C. at 40 to 60% relative humidity. Whether or not pollen stored for this length of time would be effective in plant breeding should be tested by actual trial. The supposition based upon studies with other pollens is that germination tests are a reliable indication of the effectiveness of pollen in fertilization.
Storage and Germination of Nuts of Several Species of Juglans
W. C. Muenscher and Babette I. Brown
Cornell University, Ithaca, N. Y.
While working on the general problem of the possible toxic effect of the roots of species of Walnut (Juglans) upon other plants we have had occasion to germinate the nuts to produce seedlings for experimental use.[1] The storage treatment employed previous to planting the nuts provided a successful method of supplying viable nuts. The simple treatment used, a modification of that suggested by Barton,(2) is briefly described and the results that may be obtained are indicated in a report of some germination data from the plantings of 1943.
The nuts were harvested after they had fallen from the trees and were stored in a cool place as soon as possible thereafter until the time when the husks were removed. Those harvested at Ithaca were put in cold storage at once; those harvested in California or Texas were delayed a few weeks during shipment. The husked nuts were stratified between layers of moist peat 2 cm. thick in two-or five-gallon crocks. The uppermost layer of nuts was covered with peat to a depth of about 10 cm. The nuts were placed in a cold room at 1 to 3° C. in late autumn and left until they were planted, between April 15 and June 2. Nearly all species used germinated well after about five to six months of cold storage.