Responses of the photosynthetic characteristics of summer maize to shading stress

Abstract

AbstractThe vast majority of the energy and substance required for maize growth and development and related metabolic processes come from the photosynthesis of leaves. Over the past 60 years, the amount of solar radiation reaching the earth's surface has decreased significantly, reducing the photosynthetic rate of crops and leading to a significant reduction in yields. However, (1) the effects of shading stress on stomatal characteristics, electron transport efficiency of summer maize leaves and (2) the adaptability of summer maize to low light are still unclear. In order to investigate this problems, maize hybrid Denghai605 (DH605) was used as the experimental materials, and two treatments of shading (shading degree is 60%) and CK (natural light as control) were set in the field. The results showed that shading stress resulted in chloroplast dysplasia, and the overall performance of the two photosystems was reduced by 27.85%. The number of stomata per unit area decreased by 15.6% and the proportion of stomatal opening decreased by 73.1% after shading, which resulted in a significant 27.7% reduction in intercellular CO2 concentration. Shading significantly reduced photosynthetic rate by affecting stomatal characteristics and electron transport, and the former was the main influencing factor. The decrease in carbon assimilation capacity resulted in insufficient assimilate supply and significantly reduced grain allocation ratio, resulting in a significant yield reduction of 57.5%. However, in the low‐light environment, the expression of chlorophyll‐binding protein in the leaf of summer maize was upregulated, the content of Lhcb1 protein of the light harvesting pigment protein complex II (LHCII) was increased, and the content of photosynthetic pigment, especially chlorophyll b, was increased, which increased the absorption and capture of blue light, improved the efficiency of light energy utilization, and was a stress manifestation of summer maize adapting to shading stress.