[Responses of Nicotiana tabacum morphology and photosynthetic physiology to reduced ultraviolet-B radiation].
By the method of canopy film-covering to reduce UV-B radiation, this paper studied the responses of the morphology and photosynthetic physiology of Nicotiana tabacum cultivar K326 at its physiological, technical, and physiological-technical transitional maturity stages in high-elevation tobacco-growing area of Yunnan. Three treatments were installed, i.e., reducing 75.74% (T1), 70.08% (T2), and 30.39% (T3) of natural solar UV-B radiation. Reducing UV-B radiation increased the stem height and the internode distance of K326 significantly, with the larger values in T2. Comparing with those under natural UV-B radiation condition, the leaf net photosynthetic rate (Pn), assimilation capacity (AC), water use efficiency (WUE), intrinsic water use efficiency (WUEi), photosynthetic pigments (PP) and flavonoids (FL) contents, and specific leaf mass (SLM) in T1 and T2 all decreased, with larger decrement in T2. The factors affecting the Pn in T, and T2 were stomatal and non-stomatal, and the latter was the main one. The major reason of the lower WUE in T1 and T2 was due to the increase of transpiration rate (Tr) caused by low stomatal regulation capability. In T3, the Pn, AC, WUE, WUEi, and PP increased but the FL and PP decreased to the lowest levels at physiological and transitional maturity stages, and the PP degradation rate was faster at the technical maturity stage.
College of Agronomy and Biotechnology, Yunnan Agricultural University, Kunming, China. angellsf1987@163.com
Chu
C
Zhong
Yi
Y
Wang
Zong-yu
ZY
Chen
Zhuo-ya
ZY
Dong
Kan
K
Yan
Shao-fen
SF
Jian
D000531:Altitude; D002681:China; D010788:Photosynthesis / Q000502:physiology / Q000528:radiation effects*; D014026:Nicotiana / Q000033:anatomy & histology* / Q000502:physiology / Q000528:radiation effects*; D014466:Ultraviolet Rays / Q000009:adverse effects*