Research On Cutting Propagation And Stress Resistance Of Oreocharis Auricula

Oreocharis auricula belongs to Gesneriaceae family. It is a herb with a high potential for garden use because of its remarkable flowers, leaves and shapes. In this paper, the cutting propagation, as well as shade tolerance and drought resistance of Oreocharis auricula were studied in order to provide theoretical basis and technique guide for the introduction, cultivation and application in the future. The results are as follows:(1) Cutting propagationWith different methods of leaf cutting, exogenous hormones, mediums and seasons, the cutting propagation of Oreocharis auricula was studied. The findings indicate that the best way of cutting propagation for Oreocharis auricula is entire leaf cutting. Different exogenous hormones with their concentration have some positive impact on the cutting propagation of Oreocharis auricula; the best exogenous hormone is ABT6, and the best concentration is 300 mg·L-1. Vermiculite is the most suitable medium for Oreocharis auricula. In terms of spring and winter, spring is the better season for Oreocharis auricula's cutting.(2) Shade toleranceThe effects of shading on growth characteristics, diurnal variations of net photosynthesis, and chlorophyⅡcontents of Oreocharis auricula were determined under three different shading gradient levels (30,50,75% shading). The results indicate that with the increase of shading, leaf area shows an increasing trend. 75% shading treatment is more suitable for accumulating organic matter and promoting plant growth. The diurnal variations of net photosynthetic rate (Pn) cures of Oreocharis auricula presented two peaks. The first peak of Pn appeared at 9 AM, and the second peak of Pn appeared at 5 PM, showing that the shade plant has "midday depression" apparently. The contents of chlorophy II under shading treatment are increasing significantly. Also the ratio of chlorophyⅡa/b is decreasing, which shows shade plants' general features.(3) Drought resistancePhysiological indexes and chlorophyⅡfluorescence characteristics of Oreocharis auricula were determined after 25d's drought treatment. The results show that the leaves lost nearly 50% of water within 4h; Membrane permeability increased with the adding of the drought degree; in the activity of protective enzymes, the general trends of SOD and POD's activities were similar, that is, fluctuation within a narrow range first, next on the rise and then on the decline. They reached the peak after 20d's being pressed, and the content of MDA showed the trend of rising, falling and rising again. After the lasting drought, there have been great changes on chlorophyⅡfluorescence parameters. According to the experiment, all indexes could be used to determine drought resistance of Oreocharis auricula, and it is considered preliminarily that 25d's drought stress could cause them drought injury.