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Of Rhododendron (Rhododendron L.) is a genus of Ericaceae plants (Ericaceae), the Hunan Province Rhododendron plants rich in resources. Our system research and study on the basis of the inspection of specimens and literature, the the Rhododendron plants resource types, records the characteristics and distribution of the wild 38 kinds of Hunan Rhododendron ornamental plants, four kinds of high ornamental value antlers azalea (R. latoucheae) , of Rhododendron fortunei (R.fortunei), wool and cotton azalea (R. moulmainense) and riverbank azalea (R. rivulare), soil characteristics and photosynthetic characteristics, the results show that: (1) Hunan Rhododendron plant species of 58 species (including 1 variant), which found group Rhododendron (Rhodeden-dron orbiculare) and Iwatani azalea (Rhododendron rupivalleculatum,) a new distribution of species. Hunan rhododendron species distribution center in southwestern Hunan region, the species diversity was progressively increased distribution pattern with elevation the vertical distribution center at an altitude of 800 ~ 1500 m, horizontal distribution center in north latitude 27 ° ~ 25 ° between longitude 108 ° ~ 114 °, azalea subgenus elevation gradient largest span, for altitude 50 ~~ 2000 m. (2) four kinds of rhododendrons, different levels (0 ~ 15,16 ~ 30,31 ~ 45cm) of soil moisture in the range of 21.02 to 21.95, in which the highest antlers cuckoo average moisture content; showing soil bulk density with soil depth low to high trends were 1.335 g/cm3, 1.3425 g/cm3, 1.42 g/cm3. Soil organic matter content riverbank cuckoo table highest soil (0 ~ 15 cm), 85.25 g / kg, a minimum of 16 ~ 30 cm of antlers cuckoo level of organic matter, 19.17 g / kg; average total N content of 0.52 g / kg, 0 ~ 15 cm cotton wool cuckoo highest level reached 1.07g/kg, rhododendron and the riverbank azalea N in wool and cotton significantly higher than average levels of antlers azaleas and Rhododendron fortunei. P, K, Mg average content were 0.17,3.58 and 1.95 g / kg; soil trace elements content of the order: Fe gt; Mn gt; Zn gt; Ni gt; of Cu gt; Pb gt; Co. gt; Cr. (3) different rhododendron genus net photosynthetic rate there is a big difference in the highest net photosynthetic rate antlers cuckoo, the lowest cotton wool cuckoo, a difference of 2.214μmol · m-2 s-1. 4 Rhododendron in descending order of net photosynthetic rate of plants antlers cuckoo riverbank azalea, Rhododendron fortunei, wool and cotton cuckoo. 4 cuckoo species, antlers azalea and riverbank cuckoo transpiration rate maximum, minimum cuckoo transpiration rate in cotton wool, a difference of 0.802 mmol · m-2 · s-1. Transpiration rate of the different species in descending order of antlers rhododendron, the riverbank azalea, Rhododendron fortunei, wool and cotton cuckoo, compared to the sort of net photosynthetic rate is basically the same. Intercellular CO2 concentration antlers cuckoo smallest wool and cotton cuckoo 115.07μmol · m-2 · s-1. 4 Hunan Rhododendron net photosynthetic rate (Pn) showed a typical diurnal variation of difference \The bimodal curve showed higher photosynthetic capacity and production potential adaptation in Hunan and subtropical regions development and application and promotion.
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