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以2龄枳砧纽荷尔脐橙为材料,镁胁迫4个月后测定不同处理组叶片的叶绿素荧光参数,研究镁缺失和过量胁迫对纽荷尔脐橙不同叶龄叶片叶绿素荧光日变化特性的影响研究.结果表明:不同叶龄叶片的ΔFv′/Fm′、rETR和NPQ日变化与外界光强、叶表光强、叶表温度呈极显著相关关系,而与外界温度和湿度无显著相关性.随着叶龄的增大,镁缺失导致叶片ΔFv′/Fm′的降低趋势增大,显著大于镁过量;镁缺失和过量均导致不同叶龄叶片rETR日变化能力显著降低,且前者的不利影响显著大于后者;镁缺失和过量均导致不同叶龄叶片NPQ日变化呈显著增大趋势,且镁缺失程度越大NPQ增加越显著.由此可知,镁过量对纽荷尔脐橙不同叶龄叶片光合荧光特性的影响显著小于镁缺失,对植株光合作用的胁迫不显著,而在夏季高温、高光条件下镁缺失易导致老龄叶片发生光伤害,加速叶片衰老和脱落.
Chlorophyll fluorescence parameters of leaves of different treatment groups were determined after 4 months of magnesium stress by using Newhall navel orange (Trifolium pratense) 2-day-old. The effects of magnesium deficiency and excessive stress on the diurnal variation of chlorophyll fluorescence of leaves of Newhall navel orange at different leaf ages were studied The results showed that the daily variation of ΔFv ’/ Fm’, rETR and NPQ of leaves with different leaf age had significant correlations with the outside light intensity, leaf light intensity and leaf surface temperature, but not with the outside temperature and humidity With the increase of leaf age, the decrease of ΔFv ’/ Fm’ caused by magnesium deficiency increased significantly, which was significantly higher than that of magnesium. Both magnesium deficiency and excess caused the rETR diurnal variation ability of leaves at different leaf ages significantly decreased, The effect of magnesium deficiency was significantly greater than the latter; magnesium deficiency and excessive lead to different leaf age NPQ diurnal changes showed a significant increase trend, and the greater the extent of magnesium deficiency NPQ increased more significantly.Thus, magnesium overdose of Newhall navel orange leaf age The photosynthetic fluorescence characteristics of leaves were significantly less than that of magnesium, which did not affect the photosynthesis of the plants. However, under the conditions of high temperature and high light in summer, magnesium deficiency easily led to light damage of aged leaves and accelerated leaf senescence and Fall.