【摘要】 用小麦（农大183品种）幼苗的叶片作为材料,测定其在光照初期叶绿素营光₆₈₅的时间进程的变化。在不同温度影响下发现萤光衰变在一定范围内随温度上升而加速,且有萤光强度再度上升的现象,这一现象称为第二波。第二波的出现与温度有一定的关系,在45 ℃温度中经过10分钟处理后,萤光衰变现象消失,经过衰变后的叶片放入黑暗后可以恢复其萤光强度,其恢复的程度与在黑暗中放置的时间成比例。用抑制剂进行试验得到以下结果:迭氮化钠、氰化钾及DNP对第一波无甚影响,而对第二波有抑制作用;丙二酸对第一波的下降有很大的影响,而对第二波完全没有抑制作用;琥珀酸及延胡索酸对丙二酸的抑制有恢复作用。所以很可能第一波的下降与三羧酸循环有一定关系,而第二波则可能与细胞色素系统及磷酸化有联系。更多还原

【Abstract】 Excised leaves of wheat （var.Lungta 183） previously kept in the dark for 30 minutes were illuminated with light of wave lengths shorter than 525 mμ and the time course of their fluorescence decay was followed at 685 mμ for up to 6 minutes （or longer） in respect to temperature and certain metabolic inhibitors. The intensity of fluorescence decreased from an initial maximum to a lower constant level within a few minutes with a clearly defined second peak （Fig.2）.The higher initial intensities may be restored by periods of darkness,so that the decay process can be repeated by periods of illumination following periods of darkness （Fig.3）. Within the temperature range studied （2-45℃） the rate of fluorescence decay as well as the time of appearance and amplitude of the second rise were temperature dependent （Fig.2）.An increase in temperature hastened the first two items,while the amplitude of the secondary rise had a negative temperature coefficient （Fig.2）.No peak appeared at 2° even after prolonging the experiment to 15 minutes,and in leaves which were subjected to 45° the decay as well as the second rise were abolished （see Chow et al,1963）. The behaviours of the fluorescence decay and that of the second rise toward metabolic inhibitors are different.In general,the former is sensitive to those affecting the TCA （tricarboxylic acid） pathway of carbohydrate oxidation and the latter to those for electron transfer and phosphorylation.Sodium azide (10^-4 to 10^-2 M) has no effect on fluorescence decay （Fig.5）.DNP （2,4-dinitophenol） and KCN partially inhibit the process at higher concentration (5×10^-3M) and are without effect at lower (10^-4M) concentrations （Fig.4）.On the other hand,the second peak was significantly inhibited by Na-azide,KCN and DNP,and the inhibition was proportional to concentration (5×10^-3M to 10^-4M). Malonate was without effect on the second rise （Fig.6）,but it significantly inhibited (at 5×10^-2M) the fluorescence decay （Fig.6,1）.This inhibition was reversed by addition of succinate （Fig.6,2） or fumarate （Fig.6,3）. It is concluded from these experiments that two light-dependent enzyme catalyzed reactions are related to the phenomenon of fluorescence decay in these wheat leaves.One of these,the second rise,is affected by azide and DNP,and may therefore be concerned with electron transfer and phosphorylation,and the other,which is malonate sensitive,may be concerned with the TCA pathway of carbohydrate metabolism.更多还原