| Rattan is a group of climbing plants belonging to the family of Palmae, occurring naturally in different forests in tropical and subtropical areas. As its habitat implying, rattan grows well when water supply is plentiful. It was also reported that water is the most important factor controlling rattan growth. However, the productivity of rattan plantations is reduced for occurrence of deficiency of water or drought inevitably caused by green-house gas emission, changes of climate and season, sites and human activities. How to minimize the decrease of productivity caused by water deficiency or drought is the essential for rattan plantation industry. Intensive management and other sylviculture methods can resolve the problem to some extent,but it is hard and expensive. To select the drought resistance species with a high water use efficiency is the alternative way which resolve the problem without intensive management or other sylviculture actions. This paper is to select such sought-after rattan species by comparisons of drought resistance and water use efficiency of Daemonorops margaritae, Calamus simplicifolius and C. tetradactylus, which are widely used rattan species. Completely randomized block designs was used in the experiment of studying drought resistance of three rattan species, with soil water content 45.0±5%, 57.5±5%, 70.0±5%, 82.5±5% and 95.0±5% of field capacity. The data about recruitment leaf, length of plant part above ground-level, length of root and biomass of each seedling were measured and processed by analysis of variance and tested by q test. The results showed that significant difference occurred in the length of D. margaritae above ground plant and the length of C. simplicifolius root when the soil water content decreased from 95.0±5% to 82.5±5% of field capacity, so did other indices when soil water content decreased further to 70.0±5%. However, differences were not significant in any indices of C. tetradactylusseedlings growing under different water regimes. It was concluded from above that drought resistance of D. margaritae seedlings is similar to that of C. simplicifolius seddlings, but both are inferior to that of C. tetradactylus seedlings. Another experiment was carried out to investigate seedlings grown with two water regimes, one was to water seedlings everyday to keep soil moisture, the other was not to water at all. The results showed that C. tetradactylus seedlings watered everyday died as well as those not watered at all, and even the number of dead seedlings grown with water was higher than that of dead seedlings grown without water. D. margaritae seedlings grown without water had a higher mortality than C. simplicifolius seedlings. Thus together with results from the last paragraph, it was concluded that the seedlings of C. tetradactylus was more tolerance to water drought than the seedlings of C. simplicifolius and D. margaritae, D. margaritae seedlings was less tolerance to water drought than C. simplicifolius seedlings. Water use efficiency of three rattan species was studied as following. Firstly, indices of chlorophyll a/b, ratio of stomata on topsurface to that on below surface, PEPCase, PPDK and isotopic carbon ratio were assayed and the results showed that the three rattan species were plant with C3 photosynthesis pathway, which was the basis for employing isotopic carbon ratio in comparing water use efficiency between rattan species. Secondly, based on the experiment conducted for comparison of drought resistance, the isotopic carbon ratio of both the leaves and roots of seedlings, the biomass and its consumption of water of the seedlings were recorded and assayed, the results showed that water use efficiency of C. simplicifolius seedlings was a little higher than that of D. margaritae, but both were larger than that of C. tetradactylus. Both isotopic carbon ratio of leaves and roots were relevant positively to the water use efficiency of rattan seedlings, however, the isotopic carbon ratio of leaves was...
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