To cope with a highly heterogeneous light environment, photosynthesis in plants can be regulated systemically. Currently, the majority of studies are carried out with various plants during the vegetative growth period. As the reproductive sink improves photosynthesis, we wondered how photosynthesis is systemically regulated at the reproductive stage under a vertically heterogeneous light environment in the field. Therefore, changes of light intensity within canopy, chlorophyll content, gas exchange, and chlorophyll a fluorescence transient were carefully investigated at the graining stage of maize under various planting densities. In this study, a high planting density of maize drastically reduced the light intensities in the lower canopy, and increased the difference in vertical light distribution within the canopy. With the increase of vertical heterogeneity, chlorophyll content, light-saturated photosynthetic rate and the quantum yield of electron transport in the ear leaf (EL) and the fourth leaf below the ear (FLBE) were decreased gradually, and the ranges of declines in these parameters were larger at FLBE than those at EL. Leaves in the lower canopy were shaded artificially to further test these results. Partial shading (PS) resulted in a vertically heterogeneous light environment and enhanced the differences in photosynthetic characteristics between EL and FLBE. Removing the tassel and top leaves (RTL) not only improved the vertical light distribution within the canopy, but also reduced the differences in photosynthetic characteristics between the two leaves. Taken together, these results demonstrated that maize plants could enhance the vertical heterogeneity of their photosynthetic function to adapt to their light environment; slight changes of the photosynthetic function in EL at the graining stage under a vertically heterogeneous light environment indicated that the systemic regulation of photosynthesis is weak at the graining stage.

WU Han-yu;QIAO Mei-yu;ZHANG Wang-feng;WANG Ke-ru;LI Shao-kun;JIANG Chuang-dao

Key Laboratory of Plant Resources,Institute of Botany,Chinese Academy of Sciences,Beijing 100093,P.R.China;Key Laboratory of Oasis Eco-Agriculture,Xinjiang Production and Construction Corps/College of Agronomy,Shihezi University,Shihezi 832003,P.R.China;Institute of Crop Sciences,Chinese Academy of Agricultural Sciences/Key Laboratory of Crop Physiology and Ecology,Ministry of Agriculture and Rural Affairs,Beijing 100081,P.R.China

农业科学学报（英文）

[1]WU Han-yu;QIAO Mei-yu;ZHANG Wang-feng;WANG Ke-ru;LI Shao-kun;JIANG Chuang-dao-.Systemic regulation of photosynthetic function in maize plants at graining stage under a vertically heterogeneous light environment)[J].农业科学学报（英文）,2022(03):666-676

FLBE,tassel

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