Embryo growth and dormancy in seeds of six Hosta species native to Korea

Abstract

Although it has been speculated that Hosta seeds have an underdeveloped embryo and morphological (MD) or morphophysiological dormancy (MPD), no detailed studies have been carried out to definitively confirm this suggestion. Our first purpose was to determine if embryos of six Korean species of Hosta (H. capitata, H. clausa, H. jonesii, H. minor, H. venusta and H. yingeri) grew inside the seeds prior to germination (i.e., were underdeveloped) or did not do so (i.e., were fully developed). Our second purpose was to identify the class of dormancy found in these seeds by examining germination during incubation at 15 and/or 25 C. The initial embryo : seed ratio in seeds of the six Hosta species was between 0.78 and 0.85, and embryos elongated by 9.6 to 17.5% prior to germination. Seeds of H. capitata, H. clausa, H. venusta and H. yingeri germinated to ≥65% in light and darkness at 15 and 25 C within 30 days, those of H. minor germinated to ≥80% in light and darkness at 25 C and to 24% in light and 50% in darkness at 15 C, and those of H. jonesii germinated to 100% in light at 25 C. We conclude that embryos in seeds of these six Hosta species are underdeveloped at maturity. Because high percentages of H. capitata, H. clausa, H. venusta and H. yingeri seeds germinated at cold and warm temperatures within 30 days, they have MD. On the other hand, seeds of H. minor germinated to high and low percentages at warm and cold temperatures, respectively. Thus, some seeds have MD and others may have MPD. K E Y W O R D SHosta, Korea, morphological dormancy, morphophysiological dormancy, underdeveloped embryos

Dormancy-release and germination improvement of Korean bellflower (Campanula takesimana Nakai), a rare and endemic plant native to the Korean peninsula

“…Generally, when seeds with an underdeveloped or undifferentiated embryo are dispersed from parent plants, MD or MPD is demonstrated, and the seeds may germinate or not within 30 days under suitable environmental conditions. These dormancy types require sufficient time for embryo development and radicle protrusion [ 18 , 34 ]. If seed germination occurs within 30 days, it is determined as MD, and if seed germination does not occur within 30 days or pretreatments such as cold and/or warm stratification or phytohormones are required, it is determined as MPD [ 16 , 35 ].…”

“…sufficient time for embryo development and radicle protrusion [18,34]. If seed germination occurs within 30 days, it is determined as MD, and if seed germination does not occur within 30 days or pretreatments such as cold and/or warm stratification or phytohormones are required, it is determined as MPD [16,35].…”

Embryo growth and seed germination of four taxa of Narcissus (section Pseudonarcissi) conserved under non‐recalcitrant seed conditions in germplasm banks

“…At the end of each month, the germination percentage was recorded for each seed lot. These data were referred to as the numbers of viable seeds, namely, those whose embryo and endosperm were white and firm (Ryu et al, 2019). Twenty‐five healthy seed embryos were evaluated.…”