喷施硝酸镧对脐橙叶片渗透调节物质的影响

为了探明稀土元素镧对脐橙叶片渗透调节的影响,本研究以2年生‘纽荷尔’脐橙为试验材料,采用0 mg/L(CK)、50 mg/L、150 mg/L和300 mg/L硝酸镧溶液喷施脐橙叶片,分别于喷施后0、2、4、8、12、24 h采集植株中上部当年生嫩叶,测定渗透物质可溶性糖、可溶性蛋白与游离脯氨酸含量。结果表明：不同生长时间,脐橙叶片(CK)可溶性蛋白含量积累先升高后降低,可溶性糖和游离脯氨酸含量积累持续降低;喷施不同浓度硝酸镧溶液后,脐橙叶片游离脯氨酸含量的积累趋势发生改变。当喷施50 mg/L和150 mg/L的硝酸镧时,可同时促进脐橙叶片中可溶性糖、可溶性蛋白与游离脯氨酸含量的积累;当浓度提高到300 mg/L时,叶片可溶性糖和游离脯氨酸含量的积累明显高于其他处理,但可溶性蛋白含量的积累明显受到抑制。由此可见,喷施硝酸镧后,脐橙叶片通过主动积累可溶性糖、可溶性蛋白与游离脯氨酸来适应和调节细胞渗透胁迫;由于渗透物质种类的不同,导致促进其含量积累的适宜浓度存在差异,其中适宜可溶性蛋白含量积累的浓度为≤150 mg/L;适宜可溶性糖和游离脯氨酸含量积累的浓度为≥300 mg/L。研究结果可为进一步研究稀土元素对脐橙渗透物质影响的作用机理及生理代谢的调控提供参考依据。

Effect of Lanthanum Nitrate Spraying on Osmotic Regulating Substance Accumulation in Navel Orange Leaves

To investigate the effect of rare earth element lanthanum on osmotic regulation of navel orange leaves, the two-year-old ‘Newhall’ navel orange trees were used as the test material, and 0 mg/L (CK), 50 mg/L, 150 mg/L and 300 mg/L lanthanum nitrate solutions were sprayed on the navel orange leaves. Subsequently, the young leaves of the middle and upper part of the plant were collected at 0 h, 2 h, 4 h, 8 h, 12 h and 24 h after spraying. Finally, the content of soluble sugar, soluble protein and free proline in the samples were determined. The results showed that the soluble protein content in navel orange leaves (CK) increased first and then decreased at different growth time, while the content of soluble sugar and free proline continued to decrease. The accumulation trend of free proline content in navel orange leaves changed after spraying lanthanum nitrate solution with different concentrations. When the concentration of lanthanum nitrate was 50 mg/L and 150 mg/L, the accumulation of soluble sugar, soluble protein and free proline in navel orange leaves were promoted simultaneously. When the spraying concentration was increased to 300 mg/L, the accumulation of soluble sugar and free proline content in leaves was significantly higher than that of other treatments, but the accumulation of soluble protein content was significantly inhibited. Therefore, it could be concluded that navel orange leaves could adapt to regulate cell osmotic stress by actively accumulating soluble sugar, soluble protein and free proline after spraying lanthanum nitrate. Due to the varieties of osmotic substances, the appropriate concentration that promotes its content accumulation is different, wherein the appropriate concentration of soluble protein content accumulation is ≤ 150 mg/L, and the appropriate concentration of soluble sugar and free proline content accumulation is ≥ 300 mg/L. The results could provide reference for further research on the functional mechanism of rare earth elements on osmotic substances and the regulation of physiological metabolism.