叶面喷硒对茶树叶片硒及矿质元素含量的影响

Effects of foliage spraying selenium on the selenium and mineral elements contents in leaves of tea plant

【目的】探究叶面喷硒对茶树叶片硒及矿质元素含量的影响,为硒肥的合理利用及富硒茶的安全生产提供技术支持。【方法】以亚硒酸钠(Na2SeO3)(四价硒)和硒酸钠(Na2SeO4)(六价硒)为硒源,在田间对桂绿1号茶树进行叶面喷施试验,其中,亚硒酸钠设0、5.0、25.0、50.0、100.0和150.0 mg/L 6个处理,硒酸钠设25.0 mg/L处理。分别于施肥后第6、12、18、24、30和36 d采集茶树嫩叶,分析其总硒、有机硒及Zn、K、Fe、Ca和Mg含量的变化规律。【结果】喷施5.0～150.0 mg/L亚硒酸钠和25.0 mg/L硒酸钠均可提高茶树叶片的总硒和有机硒含量,尤其以喷施25.0～150.0 mg/L亚硒酸钠和25.0 mg/L硒酸钠效果显著(P<0.05,下同);随喷施亚硒酸钠浓度的增加,茶树叶片的总硒和有机硒含量迅速升高;随采样时间的延长,总硒和有机硒含量在施肥后第6～18 d迅速降低,第24 d后趋于稳定;25.0 mg/L六价硒(硒酸钠)处理茶树叶片的总硒含量在施肥后18 d内与25.0 mg/L四价硒(亚硒酸钠)处理无显著差异(P>0.05,下同),但在施肥24 d后显著高于25.0 mg/L四价硒(亚硒酸钠)处理。各处理茶树叶片有机硒含量占总硒含量的比例保持在93.3%～96.6%,处理间差异不显著。亚硒酸钠喷施浓度为50.0 mg/L时可显著提高茶树叶片的Fe含量,浓度大于100.0 mg/L时会显著降低叶片的Zn和K含量,浓度为150.0 mg/L时显著降低叶片的Fe含量。5.0～150.0 mg/L亚硒酸钠处理和25.0 mg/L硒酸钠处理对茶树叶片的Ca和Mg含量影响不显著。【结论】叶面喷硒可明显提高茶树叶片的总硒和有机硒含量;茶树叶片吸收无机硒后大部分可转化为有机硒形态。富硒茶生产推荐使用25.0～50.0 mg/L亚硒酸钠或25.0mg/L硒酸钠,推荐采摘时间分别在施肥后12～36 d和施肥后6～36 d。

【Objective】A field plot experiment was conducted to explore effects of spraying selenium(Se)on the Se and mineral elements contents in the leaves of tea plant,so as to provide theoretical basis and technical support for reasonable application of Se fertilizer and safe production of Se-enriched tea.【Method】The tea plant(Guilüyihao)was used as experimental material and sodium selenite(Na2SeO3)(quadrivalence selenium)and sodium selenate(Na2SeO4)(sexivalent selenium)as the exogenous Se sources.A field experiment was conducted by follow application.Six levels of sodium selenite treatments were tested in this experiment as follows:0,5.0,25.0,50.0,100.0 and 150.0 mg/L,and sodium selenate treatment was 25.0 mg/L.Young leaves were sampled respectively at 6,12,18,24,30 and 36 d after fertilization,and the changes of total Se,organic Se and Zn,K,Fe,Ca,Mg contents in leaves were analyzed.【Result】The total Se and organic Se contents in leaves were increased in all of the treatments,and 25.0-150.0 mg/L sodium selenite treatments and 25.0 mg/L sodium selenate treatment had significant effects(P<0.05,the same below).The total Se and organic Se contents in leaves were rapidly increased with increasing concentrations of applied sodium selenite.During the sampling time,the total Se and organic Se contents in leaves were rapidly decreased during day 6-day 18 after the treatment,and then were stable after day 24.There were no significant differences in total Se content in tea leaves within 18 d between 25.0 mg/L sexivalent selenium(sodium selenate)and 25.0 mg/L sodium selenite(quadrivalence selenium)(P>0.05,the same as below),but total Se content in tea leaves treated by 25.0 mg/L sexivalent selenium(sodium selenate)was significantly higher than that in 25.0 mg/L sodium selenite(quadrivalence selenium)24 d after fertilization.The organic Se content in tea leaves accounted for 93.3%-96.6% of the total Se,and there were no significant differences among different treatments.The content of Fe significantly increased when spraying 50.0 mg/L sodium selenite,the content of Zn and K significantly decreased when the concentration of sodium selenite was over 100.0 mg/L,the content of Fe significantly decreased when spraying 150.0 mg/L sodium selenite.5.0-150.0 mg/L sodium selenite and 25.0 mg/L sodium selenate had no significant effects on Ca and Mg contents in tea leaves.【Conclusion】The total Se and organic Se contents in leaves can be significantly increased with the foliage spraying.Most of the inorganic Se can be converted to the safe organic Se in leaves.25.0-50.0 mg/L sodium selenite and 25.0 mg/L sodium selenate can be recommended for the production of Se-enriched tea,and the period of 12-36 d and 6-36 d after fertilization could be recommended as sampling time respectively.