A Study On Breeding Of Local Tree Species Of Terminalia Catappa And Hernandia Nymphiifolia And Planting The Trees In Hainan Coastal Shelterbelt Of Casuarina Equisetifolia

In order to overcome the shortcomings of current coastal shelterbelt of Casuarina equisetifolia L. on Hainan Island, it was tried to introduce local tree species in it to construct a shelterbelt as mixed forest with multiple tree species and then to form local vegetation as shelterbelt gradually. In this study the resources and distribution of the local tree species of Terminalia catappa L. and Hernandia nymphiifolia(Presl)Kubitzki on the coasts of Hainan Island were investigated. It was studied the seed morphological characteristics, seedling breeding and the growth of the seedlings of the two species mixed planting in the shelterbelt of C. equisetifolia. The main results were as follows.1. The resource and distribution of T. catappa and H. nymphiifolia were systematically investigated. One investigation site was set in almost every coastal town in 12 coastal cities or counties on Hainan Island where there was vegetation distribution and transportation was available. The sites were with the length about 500 m along the coastline and the width about 100 m.The city or county with the sites of T. catappa distribution accounted for 83.3% of the coastal city or county, and there were most sites with T. catappa distribution in Wenchang city. The city or county with the sites of H. nymphiifolia distribution accounted for16.7% of the coastal city or county, and there were most sites with H. nymphiifolia distribution in Qionghai city.2. The seed production was apparently different among the four provenances of T.catappa. The seed setting rates were in the order of Tanmen port > Dongzhai port > Shimei bay > Mulan port, but the seed healthy rates were in the order of Dongzhai port > Tanmen port > Shimei bay > Mulan port. The phenotypic traits of fruit pits andseeds of T.catappa were significantly different among the four provenances. The broad-sense heritability(h2) was higher in the range of 87.65% to 98.76%. The seed setting rate of H. nymphiifolia was 76%.The coefficient variation of weights of fruit pits and seeds were larger in the range of 17.13% to 13.95% among the seven phenotypic traits of H. nymphiifolia.3. When the seeds of T.catappa treated by means of soaking in plant growth regulator of 25, 50 and 100 mg·L-1 of naphthalene acetic acid(NAA), it began to germinate after 23 days. The germination rate increased firstly and then decreased with NAA concentration increasing. The best treatment was 50 mg·L-1 of NAA with the average germination rate of 50.54%. When the seeds were treated by soaking in 25, 50 and 100 mg·L-1 of gibberellin(GA3), the germination rates decreased with the concentration of GA3 increasing. So it could significantly promote the seed germination rates by treatments of plant growth regulator. When the fruit pits of T.catappa were broken, the seeds germinated after 19-60 d. The seeds in intact fruit pits from Mulan port germinated 8 days later than other treatments. The germination rates of the seeds with broken fruit pits were higher(with the highest value of 61.1%) than those with intact fruit pits(with the highest value of 50%). The rate, power and index of seed germination were in the order of Tanmen port> Shimei bay> Mulan port. Furthermore, there were some seed significant correlation between seed phenotypic traits and germination characters of T.catappa.When the seeds of H. nymphiifolia were treated by means of soaking in 100 mg·L-1 of NAA and GA3, the germination rates increased by 58.33% and 64.28% respectively. The seeds germinated 36 days and 21 days earlier than the control respectively. Survival rate and the average number of lateral buds of H. nymphiifolia cuttings had apparently change in thetreatment combinations of different soil mediums, different types and concentrations of plant growth regulators. After 90 days of cutting planting, the survival rate of cuttage was highest as 85.19% in the mixed soil with red loam and river sand(volum ratio 1:1), which was better than that in red loam soil. Treatments with NAA and IBA were obviously better than that with ABT1, and the treatment with 200mg·L-1plant growth regulator was better than others. So the suitable treatment combinations for cuttings of H. nymphiifolia were mixed soil with red loam and river sand(volum ratio 1:1) and 200mg·L-1 NAA or 50 mg·L-1IBA.4. The results of effects of C. equisetifolia leachates on growth and physiological and biochemical characteristics of T. catappa seedlings showed as follows. The leachates of root, litter and rhizosphere soil reduced the survival rates of seedlings and significantly affected the height and the biomass of leaves and roots of T. catappa seedlings. All the three types of leachates significantly reduced the net photosynthesis(Pn), stomatal conductance(Ccond), intercellular CO2 concentration(Ci), transpiration rate(Tr), but significantly increased the water use efficiency(WUE) of the seedlings after 15-45 days since treatment beginning. The seedlings growth period of 60 days, all the three leachates significantly increased the cell membrane penetrability and proline content(Pro), but the root leachate significantly increased the stomatal conductance, intercellular CO2 concentration, superoxide dismutase in leaves and catalase in roots of T. Catappa. The litter leachates increased the stomatal conductance and transpiration rate, and they also reduced peroxidase content. The root leachates decreased apparent photosynthetic quantum and chlorophyll content of seedling at the beginning of the growth.5. The results of study on the effects of drought stress and allelopathy on growth, photosynthesis and physio-biochemical characteristics of T. catappa seedling showed asfollows. The drought stress and litter leachates affected the survival rate and the height growth of T. catappa with the seedling growing. It significantly reduced the numbers, areas, water content and biomass of leaves after 60 days’ dual stresses. It also significantly reduced the net photosynthesis(Pn), stomatal conductance(Ccond), transpiration rate(Tr) and apparent photosynthetic quantum, but intercellular CO2 concentration(Ci) decreased early and increased later in the 15 days and 60 days.The water use efficiency(WUE) of the seedlings and the stomatal limitation value significantly increased, which might be the main reason to cause the decline of photosynthesis of seedlings. The dual stresses also increased the cell membrane penetrability and the activity of peroxidase(POD) in roots and leaves, as well as the activity of superoxide dismutase(SOD) in leaves. Analysis of variance indicates that there was interaction, which was antagonistic to certain extent, between the drought stress and allelopathy of C. equisetifolia litter leachates on the growth, photosynthesis and physio-biochemical characteristics of T. catappa seedlings.6. The seedlings of T. catappa and H. nymphiifolia were mixed planting in the central area of C. equisetifolia shelterbelt. One kind of organic fertilizer with different amount(500g,250 g,and 125g) was added in the planting hole as base fertilizer, and the control group was without base fertilizer. The survival rates of four treatments of H. nymphiifolia seedlings remained above 93.3%, but the seedlings were damaged with the survival rate below 50% by super-typhoon Rammasun and Kalmaegi. Also the survival rate decreased of seedlings of T. catappa. As the seedlings were broken by super-typhoon, the seedling height of H. nymphiifolia was decreased in fifteenth months. Meanwhile, the height of seedling of T. catappa decreased.7. After the planting holes were added organic fertilizer with different amount, the soilnutrient content of ammonium nitrogen, nitrate nitrogen, available phosphorus and available potassium near by the base of the plant were obvious changed. Soil nutrient content in summer was higher than that in winter, and the nutrient content in rainy season was higher than that in dry season. Furthermore, soil available nutrient content of T. catappa and H. nymphiifolia were positively correlated with environmental factors.8. Among the treatments with four doses of organic fertilizer,the diurnal changes of Pn of H. nymphiifolia showed "a single peak curve", but in fifteenth and eighteenth months, the diurnal change of H. nymphiifolia showed "double-peak curve" with a "midday depression of photosynthesis". And also the seedlings of T. catappa had the same phenomenon. Photosynthesis characteristics of mixed planting two species were seasonal change in this study, and varied among different dose treatments of organic fertilizer. The photosynthesis characteristics of mixed planting two species were positively correlated with light intensity, soil temperature, soil moisture, soil available phosphorus, available potassium, total P and total K.