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了解菜心光能利用效率的规律性,可为具优良光合性状菜心品种的选育提供参考。据此,本研究选用在二份耐热性强和二份耐热性弱的菜心品种作为研究对象,探讨了这些品种的叶绿素荧光参数的日变化规律。结果表明:随着光强和温度的上升和下降的日变化,四份菜心材料的初始荧光(Fo)、相对可变荧光(VJ)和单位反应中心热耗散能量(DIo/RC)出现先升后降的趋势,而最大荧光(Fm)、光能转化效率(Fv/Fm)、光化学性能指数(PIABS)则出现先降后升的情况;除Fo的最大峰值在四份材料中均在13:00时外,耐热性强的材料其余参数的最大或最小峰值出现在光照强度最大的13:00时且变化幅度较小,而在耐热性弱的材料中这些值的变化幅度大且出现在日最高温度的14:00。另外,随着光强和温度的降低,各荧光参数又逐渐向初始水平恢复,但耐热性强的菜心品种的恢复速率高于耐热性弱的菜心品种。这一结果表明叶绿素荧光参数可考虑作为评价菜心材料耐热性强弱的一个参考指标。
To understand the regularity of the utilization efficiency of Brassica campestris can provide reference for the breeding of Brassica campestris with excellent photosynthetic characteristics. In this study, two cabbage varieties with high heat tolerance and two low heat tolerance were selected as research objects to study the diurnal variation of chlorophyll fluorescence parameters of these varieties. The results showed that the initial fluorescence (Fo), relative variable fluorescence (VJ) and the unit energy of reaction center (DIo / RC) of four cabbage materials appeared with the diurnal variation of light intensity and temperature rising and falling. (Fm), light energy conversion efficiency (Fv / Fm), and photochemical performance index (PIABS) first decreased and then increased. In addition to the maximum peak value of Fo in all four materials At 13:00, the maximum or minimum peak of the remaining parameters of the heat-resistant material appeared at 13:00 with the largest light intensity with a small change, whereas in the less heat-resistant material, the magnitude of the change Large and appears at the highest temperature of 14:00. In addition, with the decrease of light intensity and temperature, the fluorescence parameters gradually recovered to the initial level, but the recovery rate of Brassica campestris species with higher heat tolerance was higher than that of Brassica campestris species with low heat tolerance. This result shows that chlorophyll fluorescence parameters can be considered as a reference index to evaluate the heat resistance of Brassica parachinensis.