高CO_(2)浓度和叶面施锌对稻米锌营养的影响

Effects of free air CO_(2) enrichment and foliar zinc application on the grain zinc nutrition of rice

水稻是全球半数以上人口的主食,增加稻米中的锌营养水平对解决人类锌缺乏至关重要。依托稻田FACE(Free Air CO_(2) Enrichment)平台,采用9个现代品种为供试材料,CO_(2)处理设置环境CO2浓度(Ambient)和高CO2浓度(增200μmol·mol-1)两个水平,锌处理设置对照(不施锌)和叶面施锌(灌浆前期喷施0.2%ZnSO_(4))处理,研究水稻糙米产量、锌浓度、锌有效性以及锌肥利用率对CO2和锌处理的响应及其品种间差异。结果表明,与Ambient相比,高CO_(2)浓度使所有品种糙米产量平均增加15.7%,但对糙米锌浓度、植酸浓度及植酸与锌摩尔比均无显著影响,不同品种和不同锌处理条件下趋势均一致;高CO_(2)浓度下扬稻6号和隆两优1988糙米籽粒锌肥利用率显著降低,而其他品种无显著变化。花后叶面施锌对糙米产量及植酸浓度无显著影响,但使糙米锌浓度平均增加37.3%,植酸与锌摩尔比平均降低29.1%,不同品种间响应幅度存在显著差异。以上数据说明,在环境CO_(2)浓度和CO_(2)浓度升高两种情形下,水稻花后叶面喷施锌肥均可显著改善稻米的锌营养水平,幅度因品种而异,而高CO_(2)浓度使部分籼稻品种的锌肥利用率显著下降。

More than half of the world′s population uses rice as a staple food,and increasing the zinc nutrition level in rice is vital to solve the problem of human zinc deficiency.In 2018,nine rice cultivars were grown at ambient and elevated CO_(2) concentrations(200μmol·mol-1 higher than ambient)in a Free Air CO_(2) Enrichment(FACE)facility installed in a paddy field.Foliar zinc application(0.2%ZnSO_(4))commenced immediately after the flowering period three times at an interval of every five days.At plant maturity,the response of the brown rice yield,grain zinc concentration,and bioavailability in different rice cultivars to CO_(2) and zinc treatment were studied,and the effect of elevated CO_(2) on zinc fertilizer use efficiency was determined.The results showed that high CO_(2) significantly increased the brown rice yield by 15.7%.However,zinc concentration,phytic acid concentration,and the molar ratio of phytic acid to zinc of brown rice were not affected by elevated CO_(2),which was the same trend observed for different rice cultivars and different zinc treatments.The grain zinc use efficiency of Indica rice cultivars YD6 and LLY1988 decreased under elevated CO_(2) levels,but other rice cultivars showed no significant changes.Foliar zinc application had no effect on the phytic acid concentration and yield of brown rice.Foliar zinc application significantly increased the zinc concentration of brown rice by 37.3%on average but significantly reduced the molar ratio of phytic acid to zinc in brown rice by 29.1%,and the magnitude of each response varied significantly among cultivars.These results suggest that the spraying of zinc fertilizer on a leaf surface after flowering significantly improve the zinc nutrient levels of rice at both ambient and elevated CO_(2) levels.Improvements varied with cultivars,but the zinc use efficiency of some Indica cultivars decreased with elevated CO_(2).