Leaf Morphological Structure And Photosynthetic Characteristics Of Maize Plants In The Condition Of Light Heterogeneity On Different Sides

The anatomical structural development and photosynthetic performance of plant leaves are not only affected by their own light environment,but also by the light environment of other parts,that is,light-dependent systemic regulation.In the maize-soybean strip intercropping,maize are generally grown in heterogeneous light.In this study,two maize cultivars with different physiological characteristics were selected to study the effect of heterogeneous light of the plant on the photosynthetic performance and anatomical structure of newly developed leaves.The differences of two cultivars in response to light-dependent systemic regulation were analyzed.It provides a theoretical basis for the breeding of maize cultivars and optimization of field allocation in the maize-soybean strip intercropping.The results showed that the photosynthetic performance of the newly developed leaves of the two cultivars was significant different under heterogeneous light.The photosynthetic rate（P_n）was increased in Rong Yu 1210（RY）and decreased in Zhong Dan808（ZD）.The analysis of leaf anatomical structure,fluorescence parameters and photosynthetic characteristics shows that the main reason for the difference in P_nwas the systematic regulation of the bundle sheath cells and carbon assimilation.The level of key photosynthetic enzymes and the operation of malate were responsible for the carbon assimilation of the two cultivars maize.In addition,the photosynthetic performance of leaves also depends on the systematic regulation of carbohydrate output.In ZD,the relative area of vascular bundle sheath cells(S_BSC)was reduced,which was disadvantage to the Calvin-Benson cycle.The supply of assimilation force reflected in ETR was decline,and the carbon assimilation process involved by the enzyme was weakened.In addition,due to the reduction of the relative area of vascular tissue(S_VB),the ability to carbohydrates output in the newly developed leaves was limited,resulting in excessive accumulation of starch,which subsequently causes a limitation of carbon assimilation and ultimately reflected in the P_n.In RY,the S_BSCwas unchanged,while the Chl a+b content was increased.The supply of assimilation force was increased,and the carbon assimilation process in which the enzyme participates was enhanced.On the other hand,the ability of carbohydrates export was enhanced,which was supported by structural development.This study indicated that the photosynthetic performance of C₄plant leaves under heterogeneous light depends mainly on the systemic regulation of photosynthetic carbon assimilation capacity and carbohydrate output.