Abstract:Magnoliaceae is a widespread family in tropical, subtropical and warm-temperate regions, especially in East and Southeast Asia, southeast of North America,Central America and the north part of South America.There are 15 genera and about 246 species in the world, 11 genera and 99 species in China. East and Southeast Asia is the centre of recent distribution of Magnoliaceae.According to the evolutionary tendency of the characters and the geographical distribution of this family, we propose a new system by dividing it into two subfamilies, Magnolioideae and Liriodendroideae Law;wo tribes,Magnolieae and Michelieae Law, five subtribes,Manglietiinae Law, Magnoliinae,Alciman driinae Law,Elmerrillinae Law,Micheliinae; and fifteen genera.Based on the evidence of fossil records and modern distribution of Magnoliaceae,it is reasonable to presume that this family1was possibly originated from southwest region of China in very early Cretaceous and radiated from there, and its dispersal routes might be 1. from Southwest China through Japan, Far East of Russia, Bering land bridge, to North America;2.From Southwest China through Old Qinling mountain area,West Siberia, Europe, Greenland, to North America, and then to South America;3.From South China through Indo-China,Malay Peninsula, to New Guinea. The formation of disjunct distribution between East Asia and North America was due to the glaciation during the late Tertiary and Quaternary Periods. Most magnoliaceous plants were extinguished in Europe and the west of North America, with the exception of some plant refuges. The Magnoliaceae in South America was distributed from NOrth America about in Miocene.

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Abstract:Five taxa of Euphorbiaceae from southern China are described.Acalypha wui H.S.Kiu and Trigonostemon wui H.S.Kiu are new species, which grow on limestone hills in the west part of Guangdong Province.Claoxylon subsessiliflorum Croiz.and Euphorbia reniformis B1.are new records for China.Euphorbia heterophylla Linn.is a naturalized weed in China,and E.epilobiifolia W.T.Wang is treated as synonym of E.heterophylla.

Abstract:In the present paper,a new Flora Index i. e.Fij=(Lij/Cj)/(Li/C)is specially designed to resolve the comparative study on numerous regional floras,and its noral geographical and mathematical significance has been disscussed in detail.At last,the seed plant flora of Dujiangyan city and other 13 regional seed plant floras in China are shown to be examples by using floral index.

Abstract:With permanent field surverys on long-term site,in 1980 and 1994,the population structure changes and community structure changes in Pinus massoniana community in Dinghushan within 14 years'succession process were studied. The results showed that tree species number increased from 4 to 7.The composition structure of community was optimizing. The species diversity and evenness of community were increasing,i.e.the Shannon-Wiener index increased from 0.58 to 1.60,the evenness index from 0.29 to 0.69,while Simpson index decreased from 0.83 to 0.38.In the process of 14 years'succession, the population structures of dominallt species in community had been changed.Although Pinus massoniana, the pioneer species of community happening,was still dominant,its declining trend was obvious. Zonal climax community forming species, such as Schima superba,were greatly developed.The community was changing into mixed forest acceleratedly.

Abstract:Study on the dynamics of nutrient elements returned to the forest floor from litterfall in a subtropical rain forest of Hexi in Fujian Province showed that the contents of elements in various fractions of litterfall fluctuated within a year, and the weighted'average contents of elements were in the order N>K>Ca>Mg>P(Ca=Mg for fruit, Ca>K for branch). The annual flows of N, P, K, Ca, Mg and ash from litterfall were 87.41, 3.82,40.80,28.81, 15.32 and 284.57kg hm-2, respectively. The pool amounts of N, P, K, Ca and Mg in residues on the floor were 54.83, 2.45, 9.69, 17.0 and 9.25kg hm-2, respectively. The residence time of the five elements on the floor was 0.61, 0.61, 0.23, 0.56 and 0.53 year, respectively.

Abstract:Soil available nitrogen in Dinghushan monsoon evergreen broadleaf forest assessed by using ion exchange resin bags showed significantly seasonal variations depending on diffferent forms of available nitrogen and on different depths of the soil.Ammonium(NH4+-N)was found to be the major form of the available nitrogen, and nitrate (NO3--N) in the soil at 10-20cm depth was significantly higher than that at 0-10cm depth (p=0.05), however,ammonium in the soil at 10-20cm depth tended to be lower than that at 0-10cm depth.

Abstract:The paper reports a new finding that Fe++ with high concentrations (0.44-7.16mmol/L)is another effective stimulating factor other than the reported ones like CO2,ethylene,etc.Under submergence,4 out of 19 tested chemicals, at the same concentration of 1.79mmol/L,inhibited the seedling growth of rice, only FeSO4 significantly stimulated it, and the other ones had no effeCt. In aerobic condition,this stimulation still occur, but with a smaller extent. No obvious genotype difference was observed in the response to ferrous ion,which might imply that this stimulation behavior is one of the ways for rice to adapt flooded condition. High concentration of ethylene had a similar stimulative effect like Fe++ on the seedling growth of rice. This finding may probably help to improve the seedling establishment in the direct seeding, in which germinated seeds are sowed under flooded soil surface.

Abstract:The effect of calcium on vigor of Zea mays L. seeds was studied. When seeds were treated with 0-10mmol/L concentrations of CaCl2, the germination percentage and vigor of seeds were increased. As Ca2+ concentration was more than 10mmol/L,the effects on seed viability and vigor decreased. The reasons that Ca2+ raised germination percentage and vigor of seeds might be due to the enhancing activities of amylases in embryo and endosperm,and the accelerating mobilization of stored reserves,e.g.starch and soluble proteins in endosperm. During seed germination, the exogenous EGTA and EDTA could drop seed vigor, but this inhibitory effect was partially removed by the addition of 2.5 and 10mmol/L Ca 2+.

Abstract:In this paper, changes of endogenous ABA content in different parts of the peanut seed (Arachis hypogaea L.)development and germination in vitro were studied. The results showed that there were distinct differences in changes of endogenous ABA content among tissues of testa, cotyledon and embryonic axis in peanut seed development and germination in vitro. There existed C40 path of endogenous ABA synthesis in the testa and the cotyledon,but C15 path in the embryonic axis. During treatment of precocious maturation and precocious germination, endogenous ABA content decreased drastically in the testa, cotyledon and embryonic axis. There was a correlation between changes of endogenous ABA content and vigor index of peanut seed.

Abstract:Twenty to 100mg L-1 resorcinol(Res)stimulated the formation of adventitious roots in hypocotyl cuttings of mung beau.Mixtures of the resorcinol with 20mg L-1IBA showed more effective than IBA or Res alone in promoting adventitious root formation.The essential role of Res in promoting adventitious rootS was in relation to the increasing activities of IAA oxidase and polyphenol oxidase in the early stages of root regeneration.ten to 100 mg L-1 salicylic acid(SA)inhibited adventitious root formation and decrea...

Abstract:The application of chlorophyll fluorescence technique played a more and more important role in the study of responses of plants,including algae,to various environmental stresses over the last 10 years.The minireview discribed the works and development in this field,including the characteristics for fluorescence,the changes in induced fluorescence involving a complex physiological content under various stresses, especially light stress and events in vivo and mechanism among the dissipation of excessive excitation in photosynthetic apparatus. The problems and perspective in basic and applied environmental researches were discussed.