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Response of Leaf Amino Acids of Understory Shrubs to Nitrogen Addition in Primary Forest and Secondary Forest of Mt. Jianfengling

LI Xiuping, AN Lihua, NI Xiaofeng, JI Chengjun

Acta Scientiarum Naturalium Universitatis Pekinensis 2021, 57 (4): 660-670. DOI: 10.13209/j.0479-8023.2021.043

Abstract （607）

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In order to further understand of the plants response and adaptation mechanism to nitrogen addition in primary and secondary tropical montane rain forests, the authors conducted a nitrogen addition experiment in the primary and secondary forests in Mt. Jianfengling respectively, setting three nitrogen addition treatments (0, 50 and 100 kg N/(ha·yr)) in each forest, to explore the effects of enhanced nitrogen addition on amino acid content in leaves of understory shrubs. The results showed that when no nitrogen was added, the contents of total amino acids and hydrolyzed amino acids in primary forest and secondary forest were not significant, while the content of free amino acids in primary forest was significantly higher than that in secondary forest. When middle nitrogen was added, the response of leaf amino acid content of understory plants in secondary forests was higher than that in primary forests. When high nitrogen was added, there was no significant difference in the response of hydrolyzed amino acids of understory shrubs in primary forest and secondary forest, but the response of free amino acids in understory shrubs in primary forests was higher than that in secondary forests.

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Leaf Stomatal Traits of Woody Plants and Their Response to Nitrogen Addition in Typical Forests in Eastern China

JIANG Xingxing, ZOU Anlong, WANG Yuanyuan, ZHOU Xuli, JI Chengjun

Acta Scientiarum Naturalium Universitatis Pekinensis 2018, 54 (4): 839-847. DOI: 10.13209/j.0479-8023.2018.003

Abstract （568）

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The stomatal traits of eighteen dominant woody plants in the Nutrient Enrichment Experiments in Chinese Forests (NEECF) were compared. The results showed that the lifeform affects stomatal features of the woody plants significantly (P<0.05). There is a visible latitudinal pattern of stomatal traits of dominant woody plants in eastern China and MAT, MAP, PET are important influent factors. All woody plants’ stomatal traits have significant correlation. The stomatal length and density showed negative correlation, and the stomatal conductance increased with increasing stomatal length and decreased with increasing stomatal density. Woody plants of different climate zones and lifeform showed diverse response with nitrogen addition.

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RAPD Analyses of Fagus Species in China

JI Chengjun,SHEN Haihua,FANG Jingyun,XIE Changfu,FAN Yongjun

Acta Scientiarum Naturalium Universitatis Pekinensis

Abstract （639）

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Random amplified polymorphic DNA (RAPD) technique was applied to assess six Fagus species in China. Fifty-six of eighty tested arbitrary primers generated obvious bands with size ranging from 250 to 3050bp. An index of genetic similarity(F)was calculated and the value of (1-F) was used to evaluate genetic distances between species to construct dendrogram. The result suggested that three species，F.pashanica, F.hayaatae and F.hayatae var.zhejiangensis, had closer relationship and should be clustered into a single species. This was in good agreement with our morphological work. Based on RAPD markers,we suggested that Chinese beech species should be divided into four species, F.longipetiolata, F.engleriana, F.lucida and F.hayaatae (including F. pashanica and F.hayatae var.zhejiangensis).

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Ultrastructural Studies on Megasporogenesis in Triticum aestivum L.

LI Ling,JI Chengjun,YOU Ruilin

Acta Scientiarum Naturalium Universitatis Pekinensis

Abstract （602）

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Ultrastructural changes of the megasporogenesis of Triticum aestivum L were studied. During the meiotic process of megasporocyte, the ribosome population diminished greatly in prophase I and restored in metaphase I; plastids and mitochondria turned unclear (dedifferentiation) in prophase I and recovered their normal structures (redifferentiation) in metaphase I. All these proved that cytoplasmic reorganization took place during the megasporogenesis of Triticum aestivum. It was also found that the nuclear envelope disappeared earlier at the micropylar end than that at the chalazal end. The speed of the programmed cell death were different in three nonfunctional megaspores at the micropylar end and their relationships with the neighboring cells were also different. The biological significance was discussed about these phenomenon.

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Cytological Studies on the Formation of Female Gametophyte and Development of Archegonia in Ginkgo Biloba

JI Chengjun,YANG Xiong,LI ZhengliLee CL

Acta Scientiarum Naturalium Universitatis Pekinensis

Abstract （815）

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Following approximately a dozen of multiple divisions of producing about 2000 nuclei, the cell wall of the female gametophyte of Ginkgo biloba began to form centripedally. The archegonial initials could be distinguished from the peripheral cells at the micropyle end of the female gametophyte before the completion of the wall formation where the cell wall had reached the center of the gametophyte. Usually there were two archegonia in a female gametophyte which developed asynchronously at first, and gradually developed in concert. Great structural and morphological changes in the neck cell and the central cell took place during the archegonial development. The two neck cells of the archegonium divided to form four neck cells before fertilization, this division happened prior to the division of the central cell, but at times they divided synchronously. The initiation and development of archegonia in Gingko, compared with those of cycads, were liked to be more primitive at the evolutional level.

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