氮源对甘蔗锰毒的效应研究

Effects of Nitrogen Sources on Manganese Toxicity in Sugarcane

【目的】探究氮源对甘蔗锰毒的影响。【方法】采用水培试验方法研究氮源对锰毒胁迫下甘蔗幼苗黄化、锰吸收及分配和叶片光合及光合荧光特性的影响。【结果】在锰胁迫下甘蔗幼苗锰含量增加而叶片叶绿素含量(SPAD值)显著降低。氮源影响植株对锰的吸收和幼苗黄化:氮源为硝酸盐的植株在0.5 mmol/L 锰溶液中培养后叶片SPAD值显著降低、幼叶明显黄化,而锰对氮源为铵盐的植株SPAD值的影响不显著;锰处理后不同氮源间锰在老叶-新叶和叶片-叶鞘间的分配以及锰在细胞汁液中的分配率差异不大,但氮源为铵盐的植株锰吸收量及锰含量均显著低于氮源为硝态氮的植株;不同氮源处理间植株对锰的吸收量及锰含量的差异随着锰处理浓度(0、0.1、0.2 mmol/L)的增加而加大,叶片SPAD值的差异则随着处理时间(0~21 d)延长而加大。与此相似,氮源为铵盐的植株在锰处理后叶片光合速率、蒸腾速率、气孔导度、实际光合效率、光化学淬灭系数较高而调节性能量耗散的量子产量较低。【结论】铵态氮可以有效降低甘蔗幼苗的锰毒黄化。

【Objective】The study was to explore the effects of nitrogen(N)sources on manganese(Mn)toxicity in sugarcane.【Method】Effects of N sources on leaf chlorosis, plant Mn absorption and distribution, and leaf photosynthetic and fluorescence characteristics in sugarcane seedlings were studied through the hydroponic tical.【Result】Under excessive Mn stress, Mn content in sugarcane seedlings increased significantly while leaf chlorophyll content (SPAD value)decreased significantly. Mn absorption of the plant and the seedling chlorosis affected by N sources were indicated as follows: the decrease in leaf SPAD value and seedling chlorosis were shown in the plants exposed to 0.5 mmol/L Mn solution with nitrate as the N source, while Mn had no significant effect on the plants with ammonium as the N source. There was no significant difference in Mn ratio in elder leaves to young leaves, Mn ratio in young leaves blade to the sheath and Mn distribution in leaf cell saps between the seedlings with different N sources after Mn treatment, however, Mn absorption and Mn contents of plants with ammonium source were significantly less than those of the plants with nitrate source. The differences in plant Mn absorption and content and the difference in leaf SPAD values between the plants with different N sources tended to increase with the increase of Mn treatment concentration(0, 0.1, 0.2 mmol/L)and Mn treatment time (0-21 d), respectively. Similarly, the plants with ammonium source had higher leaf photosynthetic rate, transpiration rate, stomatal conductance, actual photosynthetic efficiency, photochemical quenching coefficient and lower quantum yield of regulatory energy dissipation.【Conclusion】Mn-induced chlorosis in sugarcane seedings could be effectively alleviated by ammonium application.