不同属性特征基质对早稻秧苗耐低温的影响

Effects of Substrates with Different Properties on Chilling Tolerance of Early Rice Seedlings

【目的】早稻育秧过程中易遭受低温冷害,引起水稻减产。因此,有必要研究不同类型的基质对早稻秧苗耐低温的影响。【方法】以水稻田自然表层土为对照,采用两种代表性基质(无土基质和发酵基质)培育早稻秧苗,在水稻出芽6 d后进行不同低温处理,3 d后测定水稻的基本理化性质指标和基因表达,明确不同基质对早稻秧苗耐低温胁迫的调节作用。【结果】1)无土基质和发酵基质容重均显著低于对照,电导率、通气孔隙、碱解氮、速效磷、速效钾和有机质含量显著高于对照;发酵基质育成的秧苗其根长、百株地上部干质量和百株根部干质量均显著高于对照,无土基质和发酵基质育成的秧苗根系和地上部的氮、磷、钾养分含量显著高于对照。2)随着温度的降低,水稻秧苗的生长和养分吸收均受到抑制。低温对发酵基质上生长的秧苗抑制作用较弱,无土基质次之,对照受抑制较强。3)在低温条件下(白天8℃/晚上4℃),无土基质和发酵基质中育成的秧苗丙二醛含量显著低于对照,说明在寒冷条件下的细胞氧化损伤较少。其中,无土基质和发酵基质育成的秧苗超氧化物歧化酶、过氧化氢酶活性,脯氨酸含量和可溶性蛋白含量均高于对照,发酵基质育成的秧苗过氧化物酶活性高于对照,无土基质育成的秧苗谷胱甘肽转移酶活性高于对照。同时,无土基质和发酵基质育成的秧苗OsCold1、OsCOIN、OsP5CS和OsSODB四个基因表达水平均显著高于对照,提高了水稻耐低温能力。【结论】以上结果表明,无土基质和发酵基质通过调控水稻秧苗的生理生化反应和相关基因表达,提高秧苗耐低温胁迫能力。

【Objective】Early rice is easy to suffer from chilling damage during seedling raising,resulting in yield reduction.Therefore,it is necessary to reveal the effects of different types of substrates on early rice chilling tolerance.【Method】To clarify the regulatory effect of different substrates on the tolerance of early rice seedlings to chilling stress,two representative substrates(soilless substrate and fermentation substrate)and paddy soil(as control)were used in present study.Six-day-old rice seedlings were subjected to different low temperature treatments,and the basic physicochemical properties and gene expression levels of rice were determined after 3 days of treatment.【Result】1)The bulk density of soilless and fermentation substrates was significantly lower than that of the control,however,the electrical conductivity,aeration porosity,and the contents of alkali hydrolyzable nitrogen(N),available phosphorus(P),available potassium(K)and organic matter were significantly higher than those of the control.The root length,shoot and root dry weight per 100 rice seedlings grown in the fermentation substrate exceeded those of the control group,and the nutrient contents(shoot and root N,P,K contents)of seedlings grown in the soilless substrate and fermentation substrate were significantly higher than those of the control group.2)With the decreasing temperature,the growth and nutrient uptake of rice seedlings were both inhibited.The low temperature exerted a slight influence on the growth of seedlings on the fermentation substrate,followed by soilless substrate,and the control was strongly inhibited.3)The MDA content in the seedlings grown in soilless substrate and fermentation substrate was significantly lower than that in the control under low temperature(day 8℃/night 4℃)treatment,indicating the lower oxidative damage induced by low temperature.The activities of superoxide dismutase(SOD),catalase(CAT),proline content and soluble protein content were higher in the seedlings grown in soilless substrate and fermentation substrate than those in the control.The peroxidase(POD)activity in the seedlings grown in fermentation substrate was higher than that of the control,and the activity of glutathione transferase(GST)was higher in the seedlings grown in soilless substrate than that in control.At the same time,the expression levels of OsCold1,OsCOIN,OsP5CS and OsSODB were significantly higher in the seedlings grown in soilless and fermentation substrate than those of the control,which improved the tolerance to low temperature.【Conclusion】The above results showed that the physiological and biochemical reactions and related gene expression were regulated by fermentation substrate and soilless substrate,leading to improved tolerance of rice seedlings to low temperature stress.