不同品种(系)马铃薯叶片光合机构对遮阴的响应OA

Twenty-five potato varieties(lines)were subjected to 75%shading for three weeks during the tuber bulking stage.The photosynthetic response mechanism to low-light stress was investigated by analyzing the rapid chlorophyll fluorescence induction kinetics of leaves.Furthermore,principal component analysis and the membership function method were employed to comprehensively evaluate the shade tolerance of the tested materials.Shading significantly reduced the SPAD values and yield(except for'E Malingshu 2')but increased plant height in all varieties.Additionally,shading increased the maximum photochemical efficiency(Fv/Fm)and the photosynthetic performance index(PIabs).Under shading conditions,the number of electron transporters(Sm)on the PSII receptor side and the QA reduction rate(Mo)showed no significant changes among most of the test varieties.Meanwhile,the electron transfer capability of QA was enhanced,as indicated by an increased degree of active reaction center opening(ψo)at 2 ms.Although shading decreased the number of active PSII reaction centers per unit area(RC/CS),the absorbed light energy(ABS/CS)remained stable,while the captured light energy(TRo/CS)varied among most of the test varieties.The energy for electron transport(ETo/CS)increased.This is beneficial for maintaining photosynthetic electron transport efficiency under low light and represents an adaptive response to low light stress.Principal component analysis was conducted on the shade tolerance coefficients of 17 indicators,including SPAD value,yield,plant height,Fv/Fm,PIabs,ψo,φEo,RC/CS,ETo/CS,etc.Four principal components with a cumulative contribution rate exceeding 85%were extracted.Combined with the membership function method for comprehensive evaluation,'E Malingshu 15'(comprehensive score:0.804 5),'E Malingshu 12'(0.757 5),and'E Malingshu 7'(0.733 0)were identified as varieties with strong comprehensive shade tolerance.This study reveals the photosynthetic adaptation mechanism of potato to low-light stress and provides a scientific basis and material foundation for the screening and breeding of shade-tolerant varieties.