基于光响应机理模型的3种草本植物 光合特性差异解析

利用植物光响应机理模型,比较了大狼把草(Bidens frondosa)、山莴苣(Lactuca indica)和酸模叶蓼(Polygonum lapathifolium)光合特性的差异。结果表明,大狼把草和酸模叶蓼在中、高光强部分的电子传递速率(J)明显高于山莴苣,并且在高光强部分二者没有出现明显的光抑制,而山莴苣则光抑制较明显。大狼把草和酸模叶蓼在各光强下的净光合速率(P_n)也明显高于山莴苣。3种植物成熟叶片叶绿素的含量依次是大狼把草>酸模叶蓼>山莴苣,类胡萝卜素含量依次为酸模叶蓼>大狼把草>山莴苣。山莴苣的叶绿素含量虽然最少,但它的捕光色素分子本征光能吸收截面(σ_ik)最大; 与之相反,大狼把草的叶绿素含量最多,但σ_ik最小,酸模叶蓼的叶绿素含量和σ_ik则介于二者之间。大狼把草和酸模叶蓼的最大电子传递速率(J_max)明显高于山莴苣,二者是通过增加有效光能吸收截面,以及缩短τ_min值提高电子传递速率。相对于山莴苣,大狼把草和酸模叶蓼具有更高的最大净光合速率(P_n,max)、光饱和点(I_sat)和暗呼吸速率(R_d)。大狼把草更高的非光化学猝灭系数(q_NPQ)有利于热耗散,避免光损伤。酸模叶蓼更高的类胡萝卜素含量,在耗散过剩的激发能上具有积极作用,有助于植物体免受高温、高光、干旱等逆境伤害。综上所述,相较于山莴苣,大狼把草和酸模叶蓼应该对环境胁迫有更好的耐受性和适应性。

Differences of photosynthetic characteristics based on a mechanistic model of light-response for three herbaceous plants

A mechanistic model of light-response of photosynthesis was used to compare the differences of photosynthetic characteristics for Bidens frondosa, Lactuca indica and Polygonum lapathifolium. The results showed that the electron transport rates of B. frondosa and P. lapathifolium were significantly higher than that of L. indica under middle and high light, and neither appeared photinhibition under high light, whereas L. indica appeared photinhibition significantly. Net photosynthetic rate(P_n)of B. frondosa and P. lapathifolium were higher than that of L.indica under different light intensity. Chlorphyll content of three plants mature leave listed as B. frondosa>P. lapathifolium>L.indica, and P. lapathifolium>B. frondosa>L.indica for carotenoid content. Although chlorphyll content of L. indica was the lowest, its eign-absorption cross-section(σ_ik)was the maximum. On the contrary, chlorphyll content of B. frondosa was the highest, and its σ_ikwas the lowest. Chlorphyll content of P. lapathifolium and σ_ik were between the other two species. The maximum electron transport rates of B. frondosa and P. lapathifolium were significantly higher than that of L. indica, which improved their electron transport rates through increasing the effective light absorption cross-section of photosynthetic pigments(σ_ik')and decreasing the minimum average life time of photosynthetic pigment molecules in the excited state(τ_min). Compared with L.indica, B. frondosa and P. lapathifolium had higher the maximal net photosynthetic rate(P_n,max), light saturation point(I_sat), and dark respiratory rate(R_d).The higher NPQ of B. frondosa was helpful for thermal dissipation, and avoiding light damage. The higher arotenoid content of P. lapathifolium exerted positive effects on dissipating excess excitation energy, which was contributed to its avoid of the stress damage as high temperatures, high lights and drought. In conclusion, compared with L. indica, B. frondosa and P. lapathifolium might have better tolerance and adaptablity under environmental stress.