Study On The Photosynthetic Characteristics Of 4 Lycoris Species

Lycoris plant belongs to the Amaryllidaceae which has more than 20 in the world.Lycoris is not only used in horticulture but also with high value of medicinal and nutritional health care due to its beautiful appearance and rich in lycorine. This paper studied on photosynthetic characteristics and chlorophy fluorescence characteristics of Lycoris aurea Lycoris chinensis Lycoris longituba and Lycoris radiata.By exploring the best optimal method for measuring the light response curves and comparing the differences between this four Lycoris species under different temperature conditions.It aims at finding out suitable cultivation temperature for Lycoris plants and afford some basic scientific data for the mass production of Lycoris plants.The results showed that:(1)The most suitable way for measuring the photosynthetic light response curve of Lycoris plants is set intensity from low to high and induct leaves at each light intensity for 3min, then decrease light intensity from high to low and record the net photosynthetic rate data.(2)The photosynthetic light response curve of 4 Lycoris species under different temperature are not identical. Lycoris aurea has the highest net photosynthetic rate at 25 while Lycoris chinensis has the highest net photosynthetic rate at 20.Lycoris longituba has the highest net photosynthetic rate at 30 while Lycoris radiate has the highest Pn value at 10. Lycoris aurea has the minimum light saturation point at 30;Lycoris longituba has lower light saturation poin at low temperature(5-15)while Lycoris radiata has low light saturation point at high temperature(20,30); light saturation point of Lycoris chinensis is higher than other 3 Lycoris species shows that Lycoris chinensis has strong light ability. Lycoris aurea and Lycoris radiata both have lower light compensation point that confirm to the characteristics of shade plants; Lycoris chinensis and Lycoris longituba have higher compensation point which related to its intermediate requirements of illumination intensity and high temperature.(3)The maximum net photosynthetic rate of each Lycoris species has reached is under the temperature which the apparent quantum efficiency is highest either. Changes of light compensation point is proportional to the changes of AQY value. Lycoris radiate is a typical Autumn leaf plant,the most suitable temperature of photosynthesis measurement is consistent to its required environmental temperature in field.Although Lycoris aurea is autumn leaf plant, but the optimum temperature has measured is higher than that in field. Lycoris chinensis and Lycoris longituba are spring leaf plants,the optimum temperature measured in the experiment compared with the ambient temperature is slightly higher in spring.(4)The stoma conductance curves of these 4 plants under different temperatures are consistent to their photosynthetic rate curves and transpiration rate curves.The curves of Ci in contrast to the first three. The leaf water deficit when the temperature is too high which will lead to partial stoma temporarily shut down and net photosynthetic rate decreased, which is caused by a “stoma” factors; The stoma conductance and intercellular CO2 concentration of Lycoris chinensis are higher at 15 but the net photosynthetic rate is low, may be affected by the “non-stoma” limiting factors.Therefore, the net photosynthetic rate of Lycoris plants is affected by stoma and non-stoma factors.(5)Water use efficiency of 4 plants increased with the rising light intensity between 5 and 20. The 4 kinds of plant water use efficiency compared to other temperature is lower at 25-30.Because the temperature is high and air relative humidity is low, leaf transpiration becomes strong and plants can use less water.(6)In this experiment, Lycoris radiate maintains higher Fv/Fm under low temperature(5-15) shows that Lycoris radiate has strong ability of light energy utilization and photosynthetic electron transport. The other three species of Lycoris plants have lower Fv/Fm but higher F0 and NPQ at 5-15.With the increase of temperature, Fv/Fm has increased.It suggests that low temperature damage in photosynthetic is reversible, leaf dissipates excess light energy through the heat.4 plants have the lowest Fv/Fm under 30 show that high temperature decreased light energy conversion efficiency of PS reaction center and photo inhibition appeared.The light conversion efficiency of Lycoris radiata under low temperature is the highest, while the other 3 plants can maximize the potential of light utilization at 20-25℃.