Treesearch

Deep-freezing of pine pollen offers a means of prolonging its storage life. Early work showed that pollen could be frozen without losing its viability. A study was started in 1958 at the Institute of Forest Genetics at Placerville to determine how long frozen pollen of several pines would remain viable. This paper reports in vitro germination and in vivo seed production by pollens stored at -20ºC. up to 5 years.

Vacuum-drying, followed by storage in vacuo or in an inert gas, is effective for storing pollen of many species. It permits storage at room environments without rigid controls of either temperature or humidity, an advantage that becomes paramount during long-distance transfers of pollen when critical storage conditions are impossible to maintain. In the study reported here, the objectives were to learn if vacuum storage is effective for yellow-poplar (Liriodendron tulipifera L.) pollen and to determine optimum rehydration conditions.

The study of internal seed structure by radiography requires techniques which will give good definition. To establish the best procedures, we conducted a series of experiments in which we manipulated the principal controllable variables affecting the quality of X-radiographs: namely, focus-to-film distance, film speed (grain), exposure time, kilovoltage, and milliamperage. The results presented here will eliminate the need for repetition by others interested in moving directly to research applications of X-radiography. A few examples will illustrate the interpretation of detail and perhaps...