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Scientia Silvae Sinicae ›› 2015, Vol. 51 ›› Issue (10): 134-141.doi: 10.11707/j.1001-7488.20151017

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A Comparative Study on Photosynthetic Characteristics and Photoprotective Mechanisms between Torreya grandis cv. ‘Merrilli’ and Torreya grandis

Chen Jiani1, Liao Liang2, Huang zengguan1, Dai Wensheng1, Yu Weiwu1, Hu Yuanyuan1, Wu Jiasheng1   

  1. 1. The Nurturing Station for State Key Laboratory of Subtropical Silviculture, Zhejiang Agriculture and Forestry University Li'an 311300;
    2. Yandang forest farms of yueqing city Yueqing 325614
  • Received:2015-05-05 Revised:2015-09-06 Online:2015-10-25 Published:2015-11-10

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Abstract: [Objective] This paper investigated the differences in photosynthesis characteristics and photo-protection mechanisms between Torreya grandis cv. 'Merrilli' and T. grandis by comparing the characteristics of gas exchange, leaf nitrogen content and chlorophyll fluorescence of the flat young leaves (young leaves) and fully grown leaves (mature leaves) of two species. [Method] We measured the light response curve, photosynthetic pigment content, leaf nitrogen content and chlorophyll fluorescence parameters of young leaves (10 days after budding) and mature leaves (50 days after budding) of T. grandis 'Merrilli' and T. grandis (15 years old) in a natural forest. [Result] The, young leaves of T. grandis 'Merrilli' had significant lower Amax, LSP and higher SLW than that of the young leaves of T. grandis, and the relative difference value was 40.3%, 33.1% and 29.7%, respectively (P≤0.05). However, the mature leaves of T. grandis 'Merrilli' had significantly higher Amax, LSP and SLW than those of T. grandis, and the relative difference value was 26.3%, 40.9% and 44.8%, respectively (P≤0.05). Furthermore, T. grandis cv. 'Merrilli' had significantly higher leaf nitrogen content than those of T. grandis, and the content was about 32.5% and 44.9% higher in young and mature leaf, respectively (P≤0.05). However, the PNUE in T. grandis cv. 'Merrilli' were about 54.9% and 12.8% lower in young and mature leaf compared to those of T. grandis, respectively. The Pn and Gs in young or mature leaves both of T. grandis and T. grandis cv.'Merrilli' measured at midday (at 13:00 pm) were all distinctly lower than those in the morning (at 9:00 am), the relative difference value of Pn was 33.7%, 26.8%, 35.1% and 44.4% (P≤0.05), and the relative difference value of Gs was 27.7%, 23.5%, 38.7%, 45.0% (P≤0.05), respectively. No significant changes in Ci (P≥0.05) were observed. The young leaves of T.grandis cv. 'Merrilli' had significant higher quantum yield of △pH- and xanthophyll-regulated thermal dissipation (Y(NPQ),), and Car/Chl and Chl a/b ratios (P≤0.05). The mature leaves of T. grandis cv. 'Merrilli' had significant higher quantum yield of fluorescence and light-independent constitution thermal dissipation (Y(NO)) than T. grandis (P≤0.05). [Conclusion] The results indicate that young leaves of T. grandis cv. 'Merrilli' (with lower Amax and LSP compared to T. grandis) mainly dissipate the excess energy through increasing Y(NPQ) and Car, and decreasing Chlb content under high irradiance (at 13:00 pm). The mature leaf of T.grandis cv. 'Merrilli' (with higher Amax and LSP) also needs to increase the Y(NO) to dissipated the excess energy. Significant lower PNUE in leaves of T.grandis cv.'Merrilli' reminds us to pay more attention to the use of nitrogen fertilizer in future.

Key words: gas exchange, chlorophyll fluorescence, young leaf, mature leaf, photoprotection

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