Objective This study aimed to compare the efficiency of embryogenic callus among four spruce species, namely Picea species, Picea abies, P. likiangensis, P. glauca, and P. mariana, and to provide a basis for screening efficient induction media suitable for different species and genotypes.

Methods Based on the cones from five seed lots representing the four species, cone size was measured, and the developmental stages of zygotic embryos were observed. Embryogenic callus induction trials were conducted, and histochemical staining was subsequently performed to characterize the structure of induced callus.

Results Cone size differed significantly among the four species, following the order: P. abies > P. likiangensis > P. glauca > P. mariana. Zygotic embryo development varied markedly both among species and among individual trees within the same species, ranging from the early embryonic stage to the mature embryonic stage. Analysis of induction rates revealed that P. likiangensis exhibited the highest interspecific induction rate (20.16%). Among the different seed lots, the first lot of P. abies and the fifth lots of P. likiangensis and P. glauca showed the highest induction rates. Histochemical staining further confirmed that calli induced from all four species exhibited typical embryogenic characteristics, including densely arranged, highly active cells in the embryonal head region and extensively vacuolated cells in the suspensor region.

Conclusion The four tested Picea species exhibited significant differences in cone size, with P. abies producing the largest cones. P. likiangensis demonstrated the highest induction efficiency, while all four species successfully produced callus with definitive embryogenic structures. These results provide a useful reference for optimizing embryogenic callus protocols across diverse Picea species.