| Lilium pumilum DC. and Lilium cernuum Kom. are the perennial herbaceous bulbous plants, which belong to the Lily of the Liliaceae, with high ornamental value. The experiment focused on the Lilium collected from Kaoshan town of Kaiyuan in Liaoning province. Explore the impact of simulated drought environments and artificial shade conditions on the growth and physiological characteristics of two lilium pecies. Results as follows:1The impact of drought stress on plant growth and physiological characteristics1.1The impact of plant growth Drought stress had no significant effect on plant height and stem diameter growth, However, plant height/stem diameter ratio increased with the severity of drought stress, and the L. pumilum significantly higher than control. Drought stress resulting L. cernuum’s leaf area, leaf fresh weight and dry weight significantly even more significantly lower than the control. L. pumilum’s leaf area and leaf fresh weight had no significant difference with control, but dry weight were significantly higher than control,or even more.1.2Impact on the content of photosynthetic pigments The content of Chlorophyll decreased, but the variation is not exactly the same. L. pumilum had a large decline in Chlorophyll a, and L. cernuum had a large decline in Chlorophyll b. The impact of drought stress on the carotenoid content, L. pumilum showed a downward trend, L. cernuum had an upward trend, but no significant difference with the control.1.3Impact on the protein content and SOD activity of leaf Compared with the control, the soluble protein content of L. pumilum increased with the increasing degree of drought stress, L. cernuum showed the trend first and then decreased. Changes of SOD activity, the L. pumilum decreased first and then increased, and the lowest value was in45%treatment, the maximum was in the35%treatment. In contrary, L. cernuum’s maximum was in the45%treatment, and the minimum was in the35%treatment.1.4Impact on the anatomical structure of leaves Leaf thickness, down-epidermis thickness, thickness of palisade tissue and spongy tissue thickness of two lilium species increased first and decreased, and was lower than that of the control, ratio of palisade tissue/spongy tissue was higher than the control, the density was lower than the control.2The impact of shading on plant growth and physiological characteristics2.1With the increase of the shading, plant height, plant height/stem diameter, leaf area and leaf fresh weight of two lilium species were higher than the control. On the contrast, leaf dry weight/leaf fresh weight was lower than the control, and the L. cernuum changed by a big margin. 2.2The content of chlorophyll a, chlorophyll b and chlorophyll a+b increased compared with the full light environment. Chlorophyll content of L. pumilum gradually increased, and the L. cernuum first increased and then decreased with the increase of the shading degree.2.3Soluble protein content in the shade treatments was higher than control. SOD activity of L. pumilum first increased and then decreased with the increase of the shading degree, L. cernuum decreased gradually.2.4Effects of shading on photosynthetic characteristics Net photosynthetic rate of two lilium species appeared bimodal curve in the full light and50%shade conditions (9:00and15:00), and accompanied by a "lunch break" phenomenon. L. cernuum was also bimodal curve in75%and90%shade conditions, but appeared differently from the above (11:00and13:00). Net photosynthetic rate of L. pumilum peaked at13:00. The compensation point and light saturation point of two lilium species were lower than the control, while the net photosynthetic rate was higher than the control. Among treatments, the compensation point, light saturation point and the net photosynthetic rate decreased with the increase of the shading degree.2.5Impact on the anatomical structure of leaves In the shading conditions, up-epidermis thickness of of two Lilium species decreased, while down-epidermis thickness increased. Comparing with the control, Leaf thickness, palisade and spongy tissue, as well as CTR and SR of L. pumilum increased, while the L. cernuum decreased.Comprehensive analysis, L. pumilum had a stronger ability to adapt to drought and light intensity than L. cernuum. |
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