Subjects: Other Disciplines >> Synthetic discipline submitted time 2023-03-28 Cooperative journals: 《中国科学院院刊》
Abstract： Plant resources are the basis of human survival and development. Due to human and natural disturbance, plant diversity is facing a serious threat. Ex situ conservation is an important way to remove the threat. Botanical garden and germplasm bank are the main institutions of ex situ conservation. A total of 105 634 species of plants have been ex situ protected in the global botanical gardens, accounting for about 30% of the global total, and more than 40% of the threatened species have been protected. More than 3 million crop germplasm resources have been collected in more than 500 germplasm banks around the world. China’s botanical gardens ex situ protected more than 20000 native plants, accounting for about 60% of the total species; the National Crop Germplasm Bank and resource nurseries preserved more than 500000 germplasm resources. While strengthening plant conservation, ex situ plant protection institutions have carried out a lot of scientific research and resource utilization. In order to promote the ex situ conservation of plant diversity and green development, this study also reviewed the research progress of ex situ conservation of plants, and put forward some suggestions on strengthening ex situ conservation of plants in China.
Subjects: Biology >> Botany >> Applied botany submitted time 2018-09-07 Cooperative journals: 《广西植物》
Abstract： Parakmeria omeiensis, a small evergreen tree in Magnoliaceae, is a great ornamental plantwithnicefragranceandorangeseedcoats.In ordertoexplain thereasonsforthelowseed-set -ting rate of P. omeiensis in natural condition and determine the optimum pollinating time. The floral character were studied through field observation in Mount Emei, the type of breeding system was estimated by out-crossing index (OCI), the pollen-ovule ratio (P/O), pollen viability and the stigma receptivity,And the artifical pollination experiments were carried out. The results were as follows：(1) The florescence of P . omeiensis was from late April to mid-late May. Male plants bloomed 3-4 d earlier than female plants, and their florescence were overlapped. (2) Bisexual flowers with pistils and stamen were actually female in reproductive function, 1-2 carpels remained on the male flower of some male plants.The selective abortion of either pistil or stamens led to sex differentiation. so P . omeiensis belongs to Cryptic dioecy. (3) The flowering process followed six stages from spathe dehiscence, tepal dehiscence, spreading, fully blooming, the second spreading to flowers withering, it took 4 d. (4) The viability of pollen in male flowers was 92.8% during the first spreading,and then it descended greatly after 2 d. The stigmas of bisexual flowers were strong receptivity when all tepals were spreading,while some stigmas were receptive after blooming. (5) The out-crossing index (OCI) was 5 and pollen/ovule was 2.14x104, which indicated that P . omeiensis should be classified as an allogamous plant. (6) The artificial pollination revealed the self-pollination phenomenon did not existed and no apomixis phenomenon, The fruit-setting rate and seed-setting rate were significantly higher than that of natural pollination. In conclusion, the breeding system of P . omeiensis was obligate cross-pollination which requires pollinators, and its fruit-setting rate was limited by pollinators and the short pollination time under natural conditions. The results can promote for protecting the resourcesP .omeiensis
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