Chin J Plan Ecolo ›› 2010, Vol. 34 ›› Issue (12): 1439-1447.DOI: 10.3773/j.issn.1005-264x.2010.12.010
• Research Articles •
JIA Shi-Fang1,2, LI Cong-Feng1,3, DONG Shu-Ting1*, ZHANG Ji-Wang1
Aims Our objective was to investigate the light-adaptive physiological mechanism of maize on shading stress after anthesis, in order to provide theory behind evidence for high and stable yield in summer maize. Methods In a field experiment, we used common corn (Zea mays) (TY2) to analyze changes of photosynthetic performance, chlorophyll fluorescence parameters, xanthin circle and light partition in maize in the process of shading and recovery stages under (a) shading 55% (+S) 1–20 d after pollination and (b) natural illumination in field condition (–S). Important findings The net photosynthetic rate and light saturation point of ear leaves declined rapidly, because the chlorophyll content, soluble protein content and PEPCase and RuBPCase activities in ear leaves markedly decreased after shading. Under shading, the maximal photochemical efficiency (Fv/Fm) and the actual photochemical efficiency (ΦPSII) significantly declined, but non-photochemistry quenching (NPQ) increased. The ΦPSII of ear leaves increased in early recovery, which indicated that the sudden exposure to natural light significantly enhanced the photosynthetic electron transport rate, according with its photosynthetic rate and carbon metabolism activity of maize ear leaves. After shading, the size of xanthin circle sink in ear leaves was not significantly different, but the de-epoxidation state of xanthin circle (A + Z)/(V + A + Z) increased after shading. The distribution of light energy in photochemical reaction was lower, but the antenna dissipation rate of light energy increased significantly. On the other hand, the dissipation of excess light energy in the recovery process mainly depended on non-photochemical reactions. The PSII primary photochemistry activity of maize decreased under after shading and recovery in early stage, which limited electron supply of photosynthetic carbon metabolism and re- strained the photosynthesis. Then the energy dissipation mostly relied on the xanthin circle increased. The light protective mechanism of maize leaves improved in adaptation to the natural light, and photosynthetic capability gradually recovered after illumination switch.
JIA Shi-Fang, LI Cong-Feng, DONG Shu-Ting, ZHANG Ji-Wang. Physiological mechanism of shading stress on photosynthetic efficiency in summer maize (Zea mays)[J]. Chin J Plan Ecolo, 2010, 34(12): 1439-1447.
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