A Method for testing seed viability of some coniferous trees in Korea

This study was conducted to examine the possibility of determining the internal characters of four coniferous tree seeds (Pinus densiflora, Pinus koraiensis, Pinus rigida and Larix leptolepis) by X-ray photography, to examine the influence of seed (embryo-endosperm) quality on germination, and to compare the seed germinability between by tetrazolium method and by X-ray contrast method. X-ray photography was a useful tool to measure the embryo and endosperm development of the conifer seeds. The different stages of embryo and endosperm development observed on the photographic plates were classified into 5 embryo-classes (0, I, II, III and IV) and 2 endosperm-classes(A and B). The seeds of Larix leptolepis and Pines rigida were classified into 4 embryo-classes and 2 endosperm-classes. Pines densiflora seeds mostly consisted of III-A and IV-A classes. Many of Larix leptolepis seeds were empty. The seeds of Pinus densiflora and Pinus rigida exhibited mostly IV-A class and those of Pinus koraiensis mostly III-A class. The degree of embryo-endosperm development affected the germinability. The higher was the embryo-endosperm class the better was the germinability of the seed. The seeds belonged to embryo class II were germinated slower than those to classes III and IV. The germination capacity of endosperm class A was better than that of endosperm class B. The results compared between X-ray contrast and tetrazolium methods for examining germinability indicated that the germination values obtained by X-ray contrast method were more closely related to those in an incubator than to those obtained from the tetrazolium method The tetrazolium method was reliable for the rapid determination of seed germinability if treated properly. However, the X-ray contrast method was more precise, simpler and quicker than tetrazolium method for examining seed germinability. Thus, the X-ray contrast method is recommendable to examine seed viability for these four coniferous species.