渗透胁迫对小麦幼苗根系呼吸的影响

用PEG—6000调节培养液的渗透势,研究了渗透胁迫对小麦幼苗根系呼吸作用的影响。在-0.5 MPa的溶液中根总呼吸强度显著降低,不同苗龄根的反应差异明显;随胁迫加强呼吸强度随之降低;根系ATP含量减少。在胁迫初期呼吸废物对呼吸强度的降低无补偿作用,而在后期(72 h后)则可提高呼吸强度。 中度水分胁迫下,HMP支路活性上升,EMP-TCAO途径活性降低;抗氰呼吸活性增大,而对氰敏感的系统活性减低;细胞色素氧化酶活性显著低于对照。

Effects of Osmotic Stress on the Respiration of Wheat Roots

The aim of this studying. is to elucidate theeffects of osmotic stress on the respiration ofyoung wheat root grown in solution with differentosmotic potentials. The results showed thattotal respiratory intensity of roots treated in--0.5MPa osmotic solution decreased signifi-cantly. The responses of various age rootsto stress were different. The respiratory inten-sity decreased with the graduately decreasing ofthe osmotic potential of solution. ATP contentin roots decreased, and the activity of cytchromeoxidase was much lower than that of control.However, the respiratory quotient remainedunchanged. Within 72 h after beginning of thestress there we no effect of respiratory substrateon the respiration of stressed roots and after 72 h,the respiration. was increased greatly by addingsubstrate. The respiratory pathway changedunder osmotic stress. while roots were treat-ed with -0.5 MPa solution, the activities ofHMP pathway and CN-resistant electrontransport system increased, and the activities ofEMP-TCAC pathway and CN-sensitive systemdecreased. The experimental results showed that the os-motic stress had direct and great effects on thecrop roots respiration, and the decrease of respi-ration intensities was caused by the osmotic stressin wheat roots.