| Cerbera Manghas is one of the native species in Hainan Island, growing on coastal zone.It has characteristics of wind resistance, tolerance of soil depletion and saline-alkaline soil,strong natural regeneration ability, etc. This project mainly involved in the investigation ofCerbera Manghas germplasm resource, its breeding characteristics, and mixed-speciesplantation technology to provide theoretical basis for the selection, utilization anddevelopment of alternative tree species for Casuarina equisetifolia shelterbelts in HainanIsland.Based on the Google Earth map, the investigation zones of Cerbera Mangha germplasmresource was determined. Cerbera Manghas germplasm resource of five cities and counties inNorthern Hainan Island, including Haikou, Wenchang, Qionghai, Dengmai and Lingao, wereinvestigated with the combination of on-site survey and typical sample plots, in order tounderstand general distributions and population characteristics of Cerbera Manghasgermplasm resource in the zones mentioned above. L8(27) thogonal experiment design for thegermination of Cerbera Manghas seeds was adopted to analyze the influences of growthhormone(A), hormone concentration(B), soil matrix(C) and light conditions(D) on seedgermination and seedling/sapling growth of Cerbera Manghas. In tissue culture, explants ofCerbera Manghas were taken from stems with axillary buds and tender leaves; leaf callus andstem germinations were induced by exploring means of sterilization and anti-brown stain, andat the same time, different culture media used. The treatment factors designed in Cerberamanghas mixed experiment were different Casuarina equisetifolia stands, water retentionagent added and Casuarina equisetifolia litters added. Three kinds of Casuarina equisetifoliastands were considered, including young, medium, mature and over-mature forests. Themixed species plantation was designed to evaluate the suitability of Cerbera Manghasgrowing in Casuarina equisetifolia forests, by observing its survival rates, growing traits andphysiological indexes.The main results were as following:(1) Cerbera Manghas germplasm resource:population distributions of Cerbera manghas were not discovered in Lingao, Chengmai andQionghai, but found in Haikou and Wenchang coastal zones. The total distribution areas of Cerbera manghas were up to177.04hm2, the total distribution densities were437.56trees/hm2. Cerbera manghas mainly distribute in Haikou, and distribution areas were up to150.03hm2, accounting for84.74%of the total areas; only a small amount was distributed inWenchang. In investigating zones, large patches of Cerbera Manghas were not discovered,just loosely and sparsely distributed. In Haikou, Cerbera Manghas mainly distributes nearHouwei village, with the areas of106hm2. In Wenchang, it mainly distributes in Leda villageand Shanya village. The better stands structure of Cerbera Manghas was in Leda village ofWenchang, the worst was in Mupai village. The largest numbers of inflorescence of CerberaManghas were found in Houwei village of Haikou, the largest numbers of seeds of CerberaManghas were found in Leda village and are best area to collect seeds. In Houwei village, thenumbers of saplings were the largest, and indicated the strongest natural regeneration abilities.Shanya village showed the less numbers of seeds.(2) Cerbera Manghas seeds germination:Among the eight treatment combinations in orthogonal tests, the germination rates of2(A1B1C2D2) were the highest, with averaging70%, and the germination periods of it was theshortest. Results from range analysis and variance analysis showed that among the fourinfluencing factors mentioned above, different growth hormones had the biggest effects onseed germination rates. Germination rates of seeds with GA3treatment were obviously higherthan those with SA treatment. Combined with other factors, such as the period of seedtreatment, etc. the combination of No.2in orthogonal tests was the best way for CerberaManghas seeds to germinate.(3) Cerbera Manghas tissue culture and inducinggermination: The best disinfection treatment for leaves was to disinfect7minutes with0.1%L mercury.0.1%L mercury was used for stems to be disinfected for twice continuously, with7minutes for the first time and5minutes for the second time. Both acticarbon and VC canreduce the browning rates and levels. When the concentrations of acticarbon was up to1g/L,the browning rates was in the lowest (37.8%). when VC concentration was up to1.5g/L, thebrowning rates was in the lowest (48.9%). In the two methods, the anti-browning result of theformer was much better. The best medium of inducing leaves to generate calluses was MS+2,4-D5mg/L, culturing in dark conditions, in which the induction rates can be up to40.91%.The medium of MS+2mg/L2,4-D+0.5mg/L6-BA can have the best results in making stemsswell. The combination of medium MS+2mg/L6-BA+0.4mg/L NAA＋0.5mg/L GA3was the one that can induce stems to germinate in the fastest speed.(4) The mixed species plantationresults of Cerbera Manghas: Among the three kinds of Casuarina equisetifolia forests, thesurvival rates of Cerbera Manghas saplings were up to88.9%in mature and over-matureCasuarina equisetifolia forests, obviously higher than those in young and medum ageCasuarina equisetifolia forests. The lowest survival rates were in young age Casuarinaequisetifolia forests. Among the three treatments, the treatments with Casuarina equisetifolialitters added indicated the best growing of Cerbera Manghas saplings. Among the three kindsof Casuarina equisetifolia forests, the strength order of photosynthetic capacity was asfollows: mature Casuarina equisetifolia forests＞medum age forests＞young age forests.Chlorophyll contents in mature forests were the highest, with up to47.62mg.m-2, while it wasthe lowest in the young age forests, with only33.98mg.m-2. Among the three kinds ofCasuarina equisetifolia forests, the crown densities were the largest in mature andover-mature forests, so illuminance was the weakest, but the survival rates of CerberaManghas were relatively higher and growing situations were reletively better, which indicatedthat Cerbera Manghas in sapling stage have the biological characteristics of shade lovingenvironment.In conclusion, the mixed plantation of Cerbera Manghas and Casuarina equisetifoliashowed characteristics of high afforestation survival rates, high seed germination rates, goodgrowing traits and even naked seedlings can be survival easyly. Furthermore, CerberaManghas have advantages of strong natural regeneration ability, tolerance of soil depletionand saline-alkali soil, and wind resistance, etc. It’s the best companion tree species that can beplanted with Casuarina equisetifolia shelterbelts growing on sandy coasts. However, thedistributions of natural resources of Cerbera Manghas was limited, amounts small, andheavily destroyed by man interference. It is suggested to the responsible departments thatsome measures will be taken to protect the population of it. |
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