Chin J Plan Ecolo ›› 2007, Vol. 31 ›› Issue (1): 129-137.doi: 10.17521/cjpe.2007.0016
• Research Articles •
SHI Sheng_Bo; LI He_Ping; WANG Xue_Ying; LI Hui_Mei; HAN Fa
Aims The Qinghai-Tibet Plateau is characterized by high elevation, thin atmosphere and high solar transparency. Strong solar radiation is a major stress factors during the growing season. Means of defense and dissipation of strong solar radiation rarely have been explored. Our objective is to determine solar utilization and dissipation characters in two native alpine plants, Anisodus tanguticusand Rheum tanguticum.
Methods We used data obtained from a portable pulse amplitude modulation fluorometer (FMS_2, Hansatech Co., UK) to explain the characteristics of utilization and dissipation and components of non-photochemical quenching.
Important findings Strong solar radiation could cause the photoinhibition of photosynt hesis, but this constitutes reversible destruction to PSⅡ reaction center in both alpine plants. Quenching analysis of chlorophyll fluorescence indicated that A. tanguticus could dissipate more excess excitation energy in PSⅡ antennae through non-photochemistry progress than R. tanguticum, as the fraction of energy utilized in photochemistry was decreasing. Dark relaxation kinetics analysis showed that “fast" component qNf was the main fraction of qN, then “slow" component qNs. “Middle" component qNm was lower than qNs, but it had an increasing tendency accompanied increased light at noon, which indicated that qNm still played an important role in non-photochemical quenching. Diurnal variations of NPQS and qNs were similar in the two plants; the same as qNf, rapidly relaxing quenching NPQF was also the main component in non-photochemical quenching NPQ, and both NPQF and qNf were significantly higher in A. tanguticus than in R. tanguticum (p<0.05). The fraction of light energy absorbed in PS Ⅱ antennae, which is utilized in PSⅡ photochemistry (P), was significantly lower in A. tanguticus than in R. tanguticum (p<0.01), but the fraction that was dissipated thermally (D) was significantly higher in A. tanguticus than in R. tanguticum (p<0.01). The midday depression of the excess excitation that was neither utilized in photosynthetic electron transport nor dissipated thermally (Excess) showed that there was a light stress acclimation in the two alpine plants. The study indicates relatively lower proportion of P and qP in A. tanguticus than in R. tanguticum and the higher fraction of D and NPQ and qN, so actual photochemistry efficiency ΦPSⅡ was lower in A. tanguticus than in R. tanguticum. Higher level of NPQ and qN mainly results from the NPQF and qNf, as well as NPQS and qNs in A. tanguticus compared to R. tanguticum.
SHI Sheng-Bo, LI He-Ping, WANG Xue-Ying, LI Hui-Mei, HAN Fa. UTILIZATION AND DISSIPATION OF STRONG SOLAR RADIATION IN TWO ALPINE PLANTS, ANISODUS TANGUTICUS AND RHEUM TANGUTICUM[J].Chin J Plan Ecolo, 2007, 31(1): 129-137.
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