ข้อมูลงานวิจัย

พืช

Photoprotection of evergreen and drought-deciduous tree leaves to overcome the dry season in monsoonal tropical dry forests in Thailand

การปกป้องแสงของใบไม้ยืนต้นและไม้ผลัดใบที่แห้งแล้งในป่าเขตร้อน ประเทศไทย

Tree physiology

Dry Dipterocarp Forest; Dry Evergreen Forest

2014/2557

2017-2010

บทความ

ฉบับสมบูรณ์

พืชพรรณ

Chlorophyll; Fluorescence; D634functional Type; Leaf Phenology; Photoinhibition

In tropical dry forests, uppermost-canopy leaves of evergreen trees possess the ability to use water more conservatively compared with drought-deciduous trees, which may result from significant differences in the photoprotective mechanisms between functional types. We examined the seasonal variations in leaf gas exchange, chlorophyll fluorescence and the amounts of photosynthetic pigments within lamina of the uppermost-canopy leaves of three drought-deciduous trees (Vitex peduncularis Wall., Xylia xylocarpa (Roxb.) W. Theob., Shorea siamensis Miq.), a semi-deciduous tree (Irvingia malayana Miq.) and two evergreen trees (Hopea ferrea Lanessan and Syzygium cumini (L.) Skeels) in Thailand. Area-based maximum carbon assimilation rates (Amax) decreased during the dry season, except in S. siamensis. The electron transport rate (ETR) remained unchanged in deciduous trees, but decreased during the dry season in evergreen and semi-deciduous trees. In the principal component analysis, the first axis (Axis 1) accounted for 44.3% of the total variation and distinguished deciduous from evergreen trees. Along evergreen trees were characterized by a high Stern-Volmer non-photochemical quenching coefficient (NPQ), high xanthophyll cycle pigments/chlorophyll and a high de-epoxidation state of the xanthophyll cycle, whereas the deciduous trees were characterized by a high ETR, a high quantum yield of PSII ((Phi)PSII = (Fm - F)/Fm) and a high massbased Amax under high-light conditions. These findings indicate that drought-deciduous trees showing less conservative water use tend to dissipate a large proportion of electron flow through photosynthesis or alternative pathways. In contrast, the evergreens showed more conservative water use, reduced Amax and ETR and enhanced NPQ and xanthophyll cycle pigments/ chlorophyll during the dry season, indicating that down-regulated photosynthesis with enhanced thermal dissipation of excess light energy played an important role in photoprotection. Trees with different water uses and leaf lifespans appear to employ different photoprotective mechanisms to overcome the unfavorable dry-season drought. Our data may suggest that future changes in precipitation will strongly impinge on forest structure and functions.

Ishida, A., Yamazaki, J. Y., Harayama, H., Yazaki, K., Ladpala, P., Nakano, T., ... & Puangchit, L. (2014). Photoprotection of evergreen and drought-deciduous tree leaves to overcome the dry season in monsoonal tropical dry forests in Thailand. Tree physiology, 34(1), 15-28.

Atsushi Ishida(อัตสึชิ อิชิดะ) Duriya Staporn(ดุริยะ สถาพร) Emiko Maruta Hisanori Harayama(ฮิซาโนริ ฮารายามะ) Jun-Ya Yamazaki(จุนยะ ยามาซากิ) Kenichi Yazaki(เคฮิ ยาซากิ) Kenichi Yoshimura(เคฮิ โยชิมูระ) Ladawan Puangchit(ลดาวัลย์ พวงจิตร) Minaco Adashi(มินาโกะ อะอาชิ) Phanumard Ladpala(ภาณุมาศ ลาดปาละ) Samreong Panuthai Sapit Diloksumpun(สาพิศ ดิลกสัมพันธ์) Takahisa Maeda(ทาคาฮิสะ มาเอดะ) Takashi Nakano(ทาคาชิ นากาโนะ)