PARAHELIOTROPIC LEAF MOVEMENT IN SIRATRO AS A PROTECTIVE MECHANISM AGAINST DROUGHT-INDUCED DAMAGE TO PRIMARY PHOTOSYNTHETIC REACTIONS - DAMAGE BY EXCESSIVE LIGHT AND HEAT
PARAHELIOTROPIC LEAF MOVEMENT IN SIRATRO AS A PROTECTIVE MECHANISM AGAINST DROUGHT-INDUCED DAMAGE TO PRIMARY PHOTOSYNTHETIC REACTIONS - DAMAGE BY EXCESSIVE LIGHT AND HEAT
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DOI：
10.1007/bf00407082
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发表时间：
1984-01-01
期刊：
影响因子：
4.3
通讯作者：
BJORKMAN, O
中科院分区：
文献类型：
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作者：
LUDLOW, MM;BJORKMAN, O
干旱、超光和超热对杏叶初级光合反应的损害。简历。通过测量77 K（-196度）下叶绿素荧光发射动力学来评估Siratro。C)。叶片的准向日性运动保护受水分胁迫的“Siratro”叶片免受过度光（光抑制）、热以及过度光和高叶温的相互作用的损害。当叶片被限制在水平位置时，发生光抑制，并且随着暴露于高水平太阳辐射的时间增加，光抑制损伤的程度增加。严重抑制后叶片死亡，但叶片逐渐从中度损害中恢复。这种干旱引起的光抑制损害似乎与叶片水势低而不是叶片电导低更密切相关。暴露于叶片温度约42度。即使在黑暗中，C也会对光合系统造成损害，叶片在48度时死亡。42. c。和48.度。热损伤程度随暴露时间的增加而增加，但从中度热损伤恢复需要几天时间。直接热损伤的阈值温度随生长温度的升高而升高，但不受水分胁迫历史和当前叶片水分状况的影响。在< 42度时未发生直接热损伤。但在水分胁迫下，随着叶片温度的升高，光抑制作用在31℃~ 42℃范围内增强。C和增加光子通量密度，直到完全的阳光值。因此，水分胁迫明显使光合系统易发生光抑制，而高叶温加剧了这种光抑制损害。在自然发生“Siratro”的气候条件下，在没有向日向叶片运动的情况下，干旱期间光抑制损伤可能比直接热损伤更频繁地发生。
Damage to primary photosynthetic reactions by drought, excess light and heat in leaves of M. atropurpureum DC. cv. Siratro was assessed by measurements of chlorophyll fluorescence emission kinetics at 77 K (-196.degree. C). Paraheliotropic leaf movement protected water-stressed ''Siratro'' leaves from damage by excess light (photoinhibition), by heat, and by the interactive effects of excess light and high leaf temperatures. When the leaves were restrained to a horizontal position, photoinhibition occurred and the degree of photoinhibitory damage increased with the time of exposure to high levels of solar radiation. Severe inhibition was followed by leaf death, but leaves gradually recovered from moderate damage. This drought-induced photoinhibitory damage seemed more closely related to low leaf water potential than to low leaf conductance. Exposure to leaf temperatures > 42.degree. C caused damage to the photosynthetic system even in the dark and leaves died at 48.degree. C. Between 42.degree. and 48.degree. C the degree of heat damage increased with the time of exposure, but recovery from moderate heat damage occurred over several days. The threshold temperature for direct heat damage increased with the growth temperature regime, but was unaffected by water-stress history or by current leaf water status. No direct heat damage occurred at < 42.degree. C, but in water-stressed plants photoinhibition increased with increasing leaf temperature in the range 31.degree.-42.degree. C and with increasing photon flux density up to full sunlight values. Thus, water stress evidently predisposes the photosynthetic system to photoinhibition and high leaf temperature exacerbates this photoinhibitory damage. Under the climatic conditions where ''Siratro'' occurs in nature, but in the absence of paraheliotropic leaf movement, photoinhibitory damage would probably occur more frequently during drought than would direct heat damage.