The Cultivation Techniques And Drought-tolerance Research On Pithecellobium Dulce And Prosopis Chilensis

This research is mainly on the introduced species-Pithecellobium dulce and Prosopis chilensis. Firstly, this study analysed the breeding, afforestation and management of introduced species in the field at Yimin countryside at Panzhihua city in Sichuan province and Taoyuan countryside at Yongsheng county in Yunnan province. Then, cutting propagation, fertilizer and water adjustability experiments on the introduced species were conducted in the greenhouse of Chinese Academy of Forestry. Furthermore, the drought resistant physiological were compared to the main native tree species- Dodonaea viscose in the field. Through this research, the cultivation techniques and drought-tolerance ability of P. dulce and P. chilensis were concluded, which provided the theoretical base and technical measures for vegetative rehabilitation in dry-hot valley of China. The results were summarized as follows:(1) The best germination percentage of P. dulce and P. chilensis were 55.00% and 62.50% when treated with sulphoric acid(98%) for 30 min and 15 min, respectively. By sown in plastic bags, the height and collar diameter of P. chilensis were remarkable significantly increased. The common flushes applies fertilizer can remarkable significantly increase the height and collar diameter of P. dulce'bareroot seedlings, significantly increase the height of P. chilensis'bareroot seedlings, but the collar diameter of P. chilensis'bareroot seedlings, the height and collar diameter of P. chilensis'containered seedlings were not sigficantly influenced. Between the last ten days of June and the first ten days of July, P. dulce'bareroot seedlings were mainly grew in collar diameter while P. chilensis'containered seedlings were mainly grew in height. Field estabilishment were conducted with containerized transplants in polyethylene bags. The most growth amount of height and collar diameter of P. dulce and P. chilensis is between July and October after field establishment. Both of the two species showed negative height growth in dry season especially between March and May. It's interesting that the height recovered rapidly in rainly season.(2) Different kind of hormone and different concentration both have effect on the rooting of the cuttings, such as the rooting percentage, the number of the rooting and the length of the longest rooting. The low concentration of hormone has plus effect on the rooting of the cutting, while the high has the minus. The effect of rootage by using combinations of various hormones was better than by using only hormone treatment. Good rooting percentage was observed with 60.00% of P. dulce'untreated cuttings after 2 months while IBA2000ppm+NAA2000ppm treatment significantly increased its to 90.00%. The rooting percentage was only 5.00% of P. chilensis'untreated cuttings after 2 months, but IBA1000ppm treatment remarkable significantly increased its to 57.50%.(3) The two introduced species were able to acclimate to a wide range of nitrogen and phosphorus environments, but the response trend to nitrogen and phosphorus levels in P. dulce was more prositable than in P. chilensis. With an increase in nitrogen levels, the root mass ratio and root mass/crown mass of P. dulce significantly decreased. Under a wide range of nitrogen levels, the total biomass of P. dulce significantly increased, but decreased significantly at over 0.1g·kg-1soil nitrogen levels. With an increase in phosphorus levels, the root mass ratio and root mass/crown mass of P. chilensis decreased, but the total biomass significantly increased. No matter with an increase in nitrogen levels or with an increase in phosphorus levels, the specific leaf area of P. dulce increased and height, leaf nitrogen conntent, leaf phosphorus content, net photosynthetic rate significantly increased. The total biomass and height of P. chilensis significantly increased while the root mass ratio and root mass/crown mass decreased.(4) The water adjustability experiments showed that the two species'water use efficiency of non-irrigated plants to irrigated plants increased with the drought period and obtained the highest value about seven days before the over of drought period, which was 3-4 times to irrigated plants. The net photosynthetic rate and stomatal conductance of P. dulce.and P. chilensis reached values close to zero after 53 days and 60 days when the soil water content droped to 3.71% and 3.63%, respectively. P. dulce.and P. chilensis can rapidly and totally recoverd after irrigated. We conclude that the two introduced species presented good tolerance to water and good capacity to recover the physiological performance related to photosynthesis, suggesting substantial physiological plasticity during the juvenile phase for those tree species. (5) The meteorological data indicated that Panzhihua is drought than Yongsheng The net photosynthetic rate, transipiration, stomatal conductance, CO2 compensation point and leaf relative water content of P.dulce, P.chilensis and D.viscose in Panzhihua decreased compared to Yongsheng, while the water use efficiency, leafδ13C value and leaf nitrogen content increased. No matter in net photosynthetic rate, stomatal conductance, water use efficiency, or in leaf relative water content, P.chilensis behave best in stomatal conductance adjustable ability, water-keeping ability, osmotic adjustable ability and drought-tolerance ability. The 3 species had the same transipiration adjustable ability. With the growth, the leafδ13C value of P. dulce.and P. chilensis can increase.