低钾胁迫对不同效应型大豆光合特性及叶绿素荧光参数的影响

Effect of Low Potassium Stress on Photosynthetic and Chlorophyll Fluorescence Parameters of Two Soybean Varieties with Different K-efficiency

以钾高效大豆品种九农15和低效品种GD8521为材料,在溶液培养条件下研究低钾胁迫对其叶绿素含量、光合特性及叶绿素荧光参数等生理指标的影响,从光合物质生产方面探讨不同效应型品种对低钾胁迫的耐性机制。结果表明:在低钾胁迫下,高效品种的叶绿素a、b及a+b总含量与对照之间没有差异,但叶绿素a/b值较对照显著提高,而低效品种的叶绿素a及a+b总量较对照显著降低,叶绿素b的含量及a/b值没有显著变化;低钾胁迫下高效品种仍保持较高的光合速率,但气孔导度和胞间CO2浓度则显著低于对照,低效品种的各参数下降幅度远大于高效品种,处理间均达到极显著差异;随着供钾水平的降低,高效品种叶绿素荧光各参数中仅Fv显著增加,而低效品种F0、Fm、Fv、Fv/Fm、Fv/F0等参数的变化均达到显著或极显著水平;低钾胁迫下低效品种反应中心耗散的能量较多,用于电子传递的能量减少,而高效品种处理间无明显变化。由此可见,在低钾胁迫下高效型品种仍能保持较高的叶绿素含量,尤其是叶绿素a的比例显著提高,其光合电子传递过程受低钾胁迫的影响也较小,因而能保持较高的光合生产能力,而低效品种受低钾胁迫时各参数则发生显著变化,导致光合生产能力降低。

In former thesis, difference of photosynthetic ability due to low K stress between two kinds of K- efficiency varieties had been reported in soybean,but the internal change and factors led to this difference hadnt been found. So in this experiment, we selected two soybean varieties with different K-efficiency as material, in order to study the effect of low potassium on chlorophyll（Chl） contents, photosynthesis characteristics and chlorophyll fluorescence parameters, so as to probing into tolerant mechanism of different K-efficient varieties on low potassium stress. The plants were grown in modified 1/2 Hoagland＇s solution with two different levels of K （K0.5 and K30 ）- Results showed there was no difference in Chl contents （a, b and a ＋ b） between low potassium stress and CK for K-efficient variety,but the ratio of Chl a/b increased significantly. For K- inefficient variety, the content of Chl a and （ a ＋ b） greatly decreased in low potassium stress, and there were no change in content of Chl b and ratio of Chl a/b. Photosynthetic rate（ Pn ） of K- efficient variety in low potassium level was similar to that of CK, but the CO2 concentration（Ci） in the cell and stomatal conductance（ 6;, ） in low K level were much lower than that of CK. For K- inefficient variety, the decreases of Pn, Ci and Gs were all significant. The differences of F0, Fm, Fv/Fm and Fv/F0 between two K levels werent significant for K-efficient variety,while the changes of these parameters were significant difference for K- inefficient variety, including the change of Fv. Except for that, the ratio of energy dissipated by reaction center increased in low K stress for GD8521, and the ratio of transfer energy decreased at the same time, while those change of Jiunong 15 were tiny. So we can concluded that a relatively high content of Chl a, b and（ a ＋ b）, especially the increase of Chl a content, resulted in a high ability of photosynthesis,the effective transfer of photosynthetic electron was another factor in maintaining the ability,while the significant changes of those parameters led to decrease of photosynthesis ability for K-inefficiency variety.