低钾胁迫下不同低钾耐性大豆光合特性及保护性酶的差异

Photosynthetic characteristics and protective enzyme activities of different low K-tolerance soybean varieties under low potassium stress

田间试验选用耐低钾和低钾敏感的大豆品种各2个,研究低钾胁迫下不同品种光合特性及活性氧代谢的差异。结果表明,与施钾相比,低钾胁迫下,两类品种的相对叶绿素含量(SPAD值)、净光合速率(Pn)和气孔导度(Gs)均下降,但低钾耐性品种比低钾敏感品种下降的幅度小;而胞间CO2浓度(Ci)、蒸腾速率(Tr)和脯氨酸含量升高,且低钾敏感品种比低钾耐性品种升高幅度大。低钾耐性品种SOD活性在开花期低于低钾敏感品种,成熟始期又明显高于低钾敏感品种;CAT活性在开花期和结荚期低钾耐性品种都高于低钾敏感品种;成熟始期POD活性低钾耐性品种下降的幅度小于低钾敏感品种;MDA在生育中后期,低钾耐性品种明显低于低钾敏感品种。

Potassium（K） is the most important cation in plants,which plays an important role in plant growth,metabolism and yield.K-deficient soils are common world-wide,and their widespread occurrence in the crop growing regions of northeastern China has been recognized in these years.Nowadays,the occurrence of K deficiency in soybean（Glycine max L.）,the most important oil crop in northeastern China,has increased.This paper presents the responses of photosynthetic characteristics and active oxygen metabolism of four K-tolerance soybean varieties,Shennong 6（SN6） and GD1617 as tolerant and Tiefeng 31（TF31） and Tie 95068-5（T95068-5） as sensitive,to low potassium stress under field condition from seedlings to maturity stage.The results showed that the leaf net photosynthetic rate（Pn）,chlorophyll（Chl） content and stomatal conductance（Gs） of K-tolerant varieties decreased under low potassium stress,but compared with the sensitive varieties,the tolerant varieties decreased less,while intercellular CO2 concentration（Ci）,transpiration rate（Tr） and content of praline content increased with sensitive verities increased more.The SOD activities of tolerant varieties were lower than those of sensitive one at flowering stage,while higher at maturity stage.The CAT activities of tolerant varieties were significant higher than those of sensitive varieties at both flowering and podding stages.The POD activities of tolerant varieties were significantly higher than those of sensitive varieties in maturity stage.In latter stage,the contents of MDA of tolerant varieties were lower than those of sensitive varieties.