Embryo Development, Seed Germination, and the Kind of Dormancy of Ginkgo biloba L.

Jing Feng,Yongbao Shen,Fenghou Shi,Chengzhong Li

doi:10.3390/f9110700

Jing Feng, Yongbao Shen + Show 2 more

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https://doi.org/10.3390/f9110700

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Abstract

The embryos of Ginkgo biloba L. are generally reported to undergo after-ripening and be underdeveloped at the time of dispersal, which suggests that the seeds have morphological dormancy (MD) or morphological physiological dormancy (MPD). The aim of this work is to determine whether embryos of a G. biloba population are well-developed at the time of seed dispersal, and whether the seeds are dormant or not. From 8 September, which was the 140th day after flowering (140 DAF), seeds were collected separately from trees (T) and the ground (G) every 10 days until 7 December (230 DAF), resulting in a total of 10 samples. The changes in vertical diameter, transverse diameter, fresh weight, water content, and embryo length during seed development were measured. Simultaneously, the effects of different temperatures (15, 25, 30, and 35 °C) on seed germination, dormancy, and germination characteristics of G. biloba seeds were studied. Results showed that the embryos of G. biloba seeds were well developed and had no morphological dormancy. On 18 September (150 DAF), embryos were visible with a length of 2.5 mm. On 7 December (230 DAF), at the time of seed dispersal, their length was 17.1 mm. The germination percentage of the isolated embryos and seeds increased as the delay in seed collection increased, but there was no significant difference between T and G (p > 0.05). On 7 December (230 DAF), the germination of the isolated embryos reached 98%, indicating that the embryos were nondormant. Without pretreatment, seed germination was 82.57% within four weeks at 25 °C. Furthermore, the germination test at different temperatures showed the highest germination percentage at 30 °C (84.82%). Obviously, the G. biloba seeds were nondormant. The mean germination time (MGT) of the seeds at 30 and 35 °C was significantly lower than that of the seeds at 15 and 25 °C, and the speed of germination (SG) was significantly higher than that of the seeds at 15 and 25 °C. Although there was no significant difference in the seed-germination percentage between 30 and 35 °C, a portion of the seeds (9.5%) rotted at 35 °C. Therefore, 30 °C was the most favorable germination temperature for G. biloba seeds. This is the first study that reports G. biloba seeds with no dormancy.

Highlights

Both spore and seed plants undergo growth and reproduction stages throughout their lives.The whole process comprising the sequential, regular cycle of these two stages is called the life history or life cycle
The process of embryo development can be divided into three stages: proembryo development, embryonic differentiation, and late embryonic development
Yu et al [39] reported that the seed germination of G. biloba at 25 ◦ C was higher than that at 15 ◦ C, and the respiration rate at 15 ◦ C was significantly lower than that at 25 ◦ C. In this experiment, when the temperature was 35 ◦ C, the initial germination time of G. biloba seeds was earlier than that at 30 ◦ C, the germination percentage was lower than that at 30 ◦ C. These results indicate that the higher temperature caused significant damage to the seeds, which succumbed to mildew and rotted during germination

Summary

Introduction

Both spore and seed plants undergo growth and reproduction stages throughout their lives.The whole process comprising the sequential, regular cycle of these two stages is called the life history or life cycle. The life history of seeds begins with flowering and pollination, proceeds through fertilization, development, maturation, scattering, dormancy, and, germination. This series of steps translate to a delicate, unique, and inter-related life course [2]. Ginkgo pollen matures in late April and begins to pollinate; fertilization does not occur immediately. At the beginning of September, the color of the ginkgo’s sarcotesta changes from green to yellow or orange and white powder appears, signifying the maturity of Ginkgo biloba seeds [3]. The harvest period starts in about late September or earlier, but the embryo is still underdeveloped at this time.

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