Ovule and seed development in Pinus radiata: postmeiotic development, fertilization, and embryogeny

Abstract

Development of ovule tissues in Pinus radiata after meiosis, fertilization, and embryogeny is comparable with that of other pines, but P. radiata takes longer to develop. Fertilization occurs 15 months after pollination and morphological embryo maturity is reached 5 months later. In ovules harvested in spring after meiosis, a curved band of small cells with dense cytoplasm extends from the chalazal end of the ovule to the vascular tissue of the ovuliferous scale. It is interpreted as a procambial strand, which in the next year, differentiates basipetally into elongated, thick-walled cells with degenerated nuclei.