Breeding Technology And Application Of Two Native Shrubs Species In The Coastal Shelterbelt On Hainan Island

Because of the Casuarina equisetifolia plantation as coastal shelterbelt on Hainan island had some defects such as with single tree species, it has been tried to introduce some other arbor species into the C. equisetifolia plantation to construct mixed forest to increase tree species diversity in recent years. In this study for increasing the vertical levels in the C. equisetifolia plantation it was tried to introduce two local shrubs species Pandanus tectorius and Clerodendrum inerme to construct coastal shelterbelt with multi-species and multi-layers to enhance its ecological function by making full use of coastal native shrub resources. It was investigated the distribution and resources of P. tectorius and C. inerme on the coasts of Hainan island. It was studied the techniques of seedling and cuttage breeding for the two shrubs species and the growth of the seedlings which were planted with mixed planting in the C.equisetifolia plantation. The study results were as follows.1. After the investigation of native shrub species distributed on the coasts in the12 coastal cities or counties around Hainan island, the location and the resources of P.tectorius and C. inerme were made clear. C. inerme plants were found in 27 sites of the all 79 investigation sites, and more plants in Wenchang city on the east coast of the island. P. tectorius plants were found in all the investigation sites.2. In the study on the seedling technique for P. tectorius, three treatment factors germination media, seed soaking way and seed soaking time were designed to treat the seeds. It was found the shortest germination starting time was 52.0 days appeared in the combination treatment with seeds soaked in water for 5 days and sowed in river sand. The germination rate was 57.78% in the treatment with seeds sowed in sea sand without soaking and was 54.44% in the treatment with seeds soaked in water for five days and sowed in river sand, which were higher than other treatments. Therefore the sea sands and river sands are appropriate germination media for higher germination rates of P. tectorius. In the study on cuttage breeding for P. tectorius the cuttings were treated by ABT1, IBA and NAA with different concentrations. It was found thatthe highest survival rate of P. tectorius cuttings apperaed in the treatment with100mg·L-1NAA.3. In the study on the cuttage breeding for C. inerme, cuttings collected form the coasts in Hiakou city in the north, Wanning city in the east and Changjiang county in the west of Hainan island, treated by ABT1, IBA and NAA and planted in the different media of red soil, river sands and mixure of red soil and river sands with equal volume. The highest survival rate was 68.80% appeard in the treatment with cuttings from Changjiang treated by IBA-100mg?L-1 and planted in red soil. The maximum rooting number was 27.33 appeared in the treatment with cuttings from Wanning treated by ABT1-100mg?L-1 and planted in river sands.4. The two shrubs P. Tectorius and C. Inerme were grown in mixed planting way in C.equisetifolia plantation near the edges. They had kept the higher survival rates before the super-typhoon Rammasun on July 18, 2014 and Kalmaegi on September 15,2014 attacked the research field. The survival rate of P. tectorius had been higher than95.56% and that of C. Inerme higher than 91.11%. The typhoons badly damaged the research field and the survival rates of the two shrubs declined to 48.89% for P.tectorius and 64.44% for C. Inerme. The heights and base diameters of the shrubs maintained steady growth. The relationship between the survival rate, plant height and base diameter and the environmental factors such as light intensity, soil nutrients and so on were quite complicated for the two shrub species.5.The two shrubs P. Tectorius and C. Inerme which were grown in mixed planting way in C. equisetifolia plantation were quite different in the diurnal change of photosynthesis characteristics. For the same species the diurnal changes of Pn, Cond,Ci and Tr had some differences among treatments with different fertilizing amount in the soil. For C. Inerme the diurnal change of Pn showed a “ single-peak curve” in winter and a “double-peak curve” with the "midday depression of photosynthesis" in other three seasons. For P. Tectorius the diurnal change of Pn showed an inverted "V" type in winter, while it showed a gradual decline pattern without a "midday depression of photosynthesis" in other three seasons. The diurnal change patterns of Pn,Cond, Ci and Tr were different between the two shrub species. However for the same species they had similar trend among the treatments with different fertilizing amount in the soil, and the photosynthesis characteristics had some differences among different seasons. There were some correlations between photosynthesis characteristics and the environmental factors such as light intensity, soil nutrients and so on.