Abstract
Studies on the hybridization in the genus Pinus have been conducted at the Kamigamo Experimental Forest Station of Kyoto University since 1960. The object is to clarify the crossability in interspecific pollinations among species and the growth characteristics of F1 and F2 hybrids produced. This paper deals with the crossability in 120 combinations among species of hard pines in the genus Pinus. Results are summarized as follows: 1) F1 hybrids were obtained in nine combinations, these being Pinus thunbergii PARL. (as seed parent) ×P. densiflora S. et Z., ×P. massoniana LAMB., ×P. luchuensis MAYR, ×P. tabulaeformis CARR., ×P. khasya ROYLE, and ×P. taiwanensis HAYATA, P. densifiora (as seed parent) ×P. thunbergii, P. taeda L. (as seed parent) ×P. rigida MILL., and P. rigida (as seed parent) ×P. taeda. 2) Putative hybrids were obtained in nine combinations, these being P. densiflora (as seed parent) ×P. massoniana, ×P. tabulaeformis, and ×P. taiwanensis, P. massoniana (as seed parent) ×P. densiflora and ×P. thunbergii, P.virginiana MILL. (as seed parent) ×P. rigida and ×P. clausa (CHAPM.) VASEY, and P. muricata D. DON (as seed parent) ×P. rigida and ×P. pungens LAMB. 3) The relationships from these results of crossability tend to coincide with the taxonomic relationships in the genus Pinus reported by LITTLE and CRITCHFIELD.
