Mutual Influence Between Santalum Album And Its Host On Water And Nutrient

Few plants are so medicinally, culturally, and economically important as the Santalum album Linn., commonly known for its aromatic heartwood oil. Since the late 1990s, the international demand market for Santalum album heartwood and value-added products is gradually increasing, and over-harvesting and illegal poaching of native stands have led to a steady decrease in the wood availability of Santalum album, which leading to the rising prices. In our country, the demand for wood, handicraft and additional product of Santalum album is sharply increasing year by year with the continuous improvement of people’s living standard, and there is a saying "Money comes easily, but sandalwood is hard to find" in the market. In order to achieve sustainable artificial silviculture in China, it is essential to make a better understanding of the pattern of water and nitrogen demand, selection and configuration of the host, irrigation and fertilization management of Santalum album. Detail investigations on the physiological responses to different water and nitrogen supply in association with hosts and non-host, and N, C transfer between Santalum album and its host were poorly understood and needed to be determined. The aim is to elucidate the role of the host Kuhnia rosmarnifolia in physiological responses of the hemiparasitic tree Santalum album at different water and nitrogen regimes, and then make a better understanding of the pattern of water and nitrogen demand to achieve sustainable artificial silviculture of Santalum album in China. Moreover, we also studied the N, C transfer between Santalum album and its host.Main conclusions are as follows:(1) Improvement of water and nitrogen supply (It’s 70%RWC and 300 mg nitrogen application rate per seedling in our study,) or with host planted is conducive to the growth of Santalum album roots and absorption of nutrients N, P, K, which expressed by total root length, surface area and dry mass increasing. There is a significant promoting on mean diameter of the roots.(2) Improvement of water and nitrogen supply (It is 50%RWC and 300 mg nitrog en application rate per seedling in our study) or with host planted is conducive to imp rove the protective enzyme CAT activity and reduce the MDA content in leaves of San talum album. Therefore, the degree of membrane lipid peroxidation of leaves reduced a nd dry biomass improved.(3) Improvement of water and nitrogen supply (It is 50%RWC and 300 mg nitrogen application rate per seedling in our study) is conducive to improve Fm, Fv/Fm, Yield, rETR, Pn, Gs and Tr, that is, to improve the photosynthetic performance of Santalum album.(4) High water supply and high nitrogen supply can not replace the role of the host for Santalum album. In the cultivation of Santalum album, the most important thing is to do a good job of the host configuration and management, and at the same time, increasing of water supply and nitrogen fertilizer supply are conducive to grow better of Santalum album.(5) The WUE1 and δ13C overall increased with the increase of nitrogen application rate, and increases at first and then decreases with the increase of water content of substrate, which reached the highest at 50%RWC. WUEI and δ13C significantly reduced when host planted.(6) Santalum album could absorb nitrogen efficiently from host and transfer N to its ogans quickly. Nitrogen transfer rate exspressed significant difference when different nitrogen application rate treatments, that is, nitrogen transfer rate are high when nitrogen application rate are low, nitrogen transfer rate are low when nitrogen application rate are high. At low nitrogen application rate treatment (0 mg nitrogen application rate per seedling), NdFF% is strong whether overground part or underground part (overground part> underground part); Nitrogen fertilizer distribution rate was similar as NdFF%.(7) When the root of Santalum album and it’s host Kuhnia rosmarnifolia both in the same NH4+ concentrations, the absorbtion ability of Kuhnia rosmarnifolia to NH4+ is higher than Santalum album. This study detected that surface cells of haustorium also have certain absorption function to the outside NH4+ for the first time, which was different from previous reports about two functions of haustorium.(8) The two-way exchange of inorganic nitrogen source existed in the parasitic system between Santalum album and its host Kuhnia rosmarnifolia, so did the two-way exchange of photosynthetic organic carbon in this study though this exchange was extremely weak. The distribution rule of photosynthetic organic carbon was similar to the transfer and distribution of inorganic nitrogen in Santalum album.(9) After parasitic relationship was build between the Santalum album and Dalbergia in the field, the chlorophyll fluorescence parameters of Fm’, Fv’/ Fm’, rETR would been significantly improved under light adaptation; Photosynthetic capacity would be reduced of Dalbergia after parasited by Santalum album.15N isotope tracing results indicated that N element could transfer to Santalum album from Dalbergia, but it was not detected from Santalum album to Dalbergia during the trial period.