| Species in Ceratoides are semi-shrub xerophytes distributed in arid and semi-arid area. They have great potentialities to ecological restoration and high value to being used as forage. However researches on their physiological characteristics related to drought adaptabilities were not sufficient, yet. Therefore, it is necessary to reveal more properties in order to increase efficiency in the ecological practice and to promote using in pasturage. Experiment site was in Huhhot, Inner Mongolia, PRC. Species in Ceratoides were main material. Field and potted trials were adopted. Drought adaptive characteristics were tested mainly on dehydration resistance (DRe) of detached branchs and transpiration rate (TR). A new method called Turning Point (TP) was suggested. TP was the eigenvalue of Logistic Equation. The DRe differences among plants could be well differentiated by TP. The DRe., i.e. water retention, represented by TP, was used as a major index to identify the ability of plant drought tolerance. It was showed that C.arborescens Ecotype Wu was generally the most drought tolerant one except lower than C.arborescens Ecotype XJ which was the maximum in May, bore comparison with Zygophyllum xanthoxylum by estimating seasonally; C.latens Ecotype NX was significantlly lower than C.arborescens Ecotype Wu, the result was contrary to being known; C.arborescens Ecotype Kerqin was significantlly lower than Wu; XJ, the maximum in May, showed no else great difference to NX; C.lanata was high in April and not high afterwards, however its phenological phase presented visible changes as compared with the original life patterns in western America. Diurnal and seasonal changes in TR of Ceratoides spp. displayed typically a single peak. TR was higher and response was more sensitive to environmental factors in Ceratoides spp. and Caragana korshinski than in Z. xanthoxylum and Calligonum rubicundum. TR ability was put in step-down order for Ceratoides spp. according to the general area under the TP lines: C ewersmanniana, Kerqin, NX, XJ, Wu. TR response to environmental factors exhibited a cycle appearance, which was called Hysteresis by cited literature. Important discovery came out after the cycle was analysed. The cycle could be Single or Complex one. There were further two different types of Upper Start and Under Start. Sensitivity Increase or Decrease could occur at any section of the cycle. The Increase and Decrease appeared alternately. All of those effects resulted in diverse response patterns. A new conceptCircular Response was brought forward to renew Hysteresis. On the basis of new concept, TR response to environmental factors could be well identified by sectioning analysis. For Ceratoides spp., TR Circular Response was obvious, and both diurnal and seasonal rhymes were clear, variance among plants was distinct. Because of the complicacy of Circular Response, further research and discussion on relationship between Circular Response and plant drought tolerance was needed. In ported trials, Wu gave the minimum TR of all plants, and its diurnal maximum TR persisted stability the most within the range of soil moisture 20.4%-6.4%.; NX lowered its TR and shrank its high-low lines after had experienced irregular wet-drought hardening period during culturing; Kerqin performed a plasticity as compared to field; C. lanata also stood the most stability but on the basis of middle-high maximum TR level; TR by Caragana korshinski was high when soil water was abundant, but was lowest for lack of water (6.4%). Moderate soil moisture (10.4%) accelerated TR. In the detached leaf test, TR within 12 minutes after leaf detached exhibited a irregular wave. Average TR (ATR) had a a slight increase at prophase then declined. Trend of liner ATR presented well controling TR property.
|
PDF Full Text Request