Study On Water-Consumption Characteristics And Drought-Resistance Mechanism Of Four Artermisia Species In Loess Plateau

In order to reveal the mechanism of vegetation succession in the process of ecological restoration, Artemisia scoparia Waldst. et Kit., Artemisia giraldii Pamp., and Artemisia gmelinii Web.ex Stechm., as three dominant species during early succession in the Loess Plateau, while Artemisia annua L. as conventional species, were selected to study water consumption, growth characteristic, water physiology, anti-oxidative characteristic and leaf anatomy of seedling pot-cultured under 3 different soil water content: CK (water content with 75% of field water capacity), medial water stress(ms55%), severe water stress(ss35%). The three different levels of soil water content were set by artificially controlling the soil moisture. At last, these indexes was used to make a comprehensive evalution of drought adaption for four Artemisia species under severe water stress, expecting to find the characteristic of drought resistence of four Artemisia soecies respectively. The main results are as follows:1. The characteristic of water consumption of four Artemisia species were different. Water consumption characteristic were similar for each Artemisia species under three different water stress. The quantity of water consumption for four species in days, ten-day and monthly periods showed that the ck >ms>ss. The comparative peak value of water consumption in days occured on June and July,2009; that of water consumption in ten-day periods were in early June,ealy July, and end of July,2009. The majority of water consumption for 4 Artemisia species were in June and July,2009. Water consumption for four species in a day showed one-peak curve. The four species have different characteristic of water consumption under one level of water stress. A. scoparia,A. giraldii and A. gmelinii hanve similar values and peak values of the days,ten-day periods and month water consumpution under CK, that is different from A. annua. The quantity of water consumption of the four species in this growing season Under CK showed that A. scoparia>A. gmelinii> A. giraldii> A. annua.. Under medial water stress, the curves of A. scoparia and A. gmelinii in days, ten-day periods were almost overlap. It was non-significant difference between the total water consumption of A. gmelinii and A. scoparia under medial water stress, and the value of former two species were higher than the A. scoparia's; the total water consumption of A. annua is the lowest among the four soecies. It was significant difference among the water consumption curve of the four species under severe water stress, and the total values showed that A. scoparia>A. gmelinii>A. annua.>A. giraldii.2. The growth characteristics of four Artemisia species were difference in the growing season. The biggest growth raete of four species was in the early and middle ten days of May,2009, and stop to stretching at end of July,2009. The stem length of the four species were showed that the CK>the medial water stress>the severe water stress. The dry weight of the four species under water stress showed that A. scoparia>A. giraldii>A. gmelinii>A. annua.. The different rate of root to shoots of the four species indicated that the water stress had obviously different affection on photosynthetic product distribution, the degree of affection displayed that A. scoparia>A. annua.>A. gmelinii>A. giraldii. The water stress had obviously affected on the changes of WUE of the four species. The different changes of root morphology among the four species under water stress revealed that the capacity of adaption to drought among the four species were difference .3. It had difference physiology changes among the four Artemisia species treated by water stress. The different descending rate of RWC of the four species displayed the different undertaking level of water stress.The result suggested that A. scoparia>A. annua and A. giraldii>A. gmelinii. The method of membership function was chosed to calculate the values of the WSC rising rate of four Artemisia under water stress, and the results displayed that A. annua's WSC content was easy to affect by water stress while A. gmelinii was less easy to affect. And we used same calculating method to evaluate the value of anti-oxidative system of the four species under water stress. Finally, the outcome was that A.annua>A.giraldii>A.scoparia>A.gmelinii.4. The anatomy characteristics of four Artemisia species were difference. A.gmelinii is transutional form; A.giraldii and A.scoparia are Ring-palisade and A.annua is Bifacial leaf. A.gmelinii has no trichome on upper leaf surface and more trichome on lower leaf surface. But more corneum layer thickness is existed on upper leaf surface. The most stomas of A.gmelinii and A.annua were found on lower leaf surface, and the cell was compacted. A.giraldii and A.scoparia's corneum layer thickness are smaller than the A.gmelinii's , but bigger than the A.annua's. The stomas and trichome were found on upper and lower leaf surface of A.giraldii and A.scoparia. But the trichome of A.giraldii on upper leaf surface is rare.The anatomy characteristics showed that A.gmelinii's leaf has the most drought-resistence capacity among four Artemisia species , and A.annua's leaf is not that better.5. Four Artemisia species have respective characteristics to drought resistence, we can not conform the drought-resistence capacity of the four species just from one single respect. We made a comprehensive evaluation by 28 kinds of indexes and the result reveals that the capacity drought-resistence of the four species is A.giraldii>A.gmelinii>A.scoparia>A.annua.