Abstract The aim of the study was to investigate the influence of potassium (K) nutrition and/or aeration of flooded soil through drainage on iron (Fe) toxicity of rice during the period of establishment. A hydroponic experiment with three Fe (0.1, optimal; 1, high; 2.5 mM, very high) and K levels (0.3, low; 2, optimal; 5 mM, high), and a soil experiment with two moisture levels [continuously flooded; alternate-wetting and drying (AWD)] and three Fe levels (16, low; 163, optimal; 490 mg Fe(II) kg−1 soil, high) was conducted. In the hydroponic experiment, high Fe supply increased tissue concentrations of Fe, phosphorus (P) and magnesium (Mg), and reduced manganese (Mn) concentrations. Particularly Fe, K and P were maintained at root surfaces in larger amounts than taken up by the roots. Growth of rice, photosynthesis, maximum quantum yield, effective quantum yield and electron transport rate were decreased at high and very high Fe concentrations while K application had no positive effect. In the soil experiment, growth and nutrient relations under increased Fe supply were similar to those observed in the hydroponic experiment. However, comparing both moisture levels showed that soil solution Fe concentration and plant growth were reduced and tissue P, Mg and Mn concentrations were increased in the AWD system compared to flooding. Therefore, the application of K or aeration of flooded soil cannot be generalized as promising strategies to alleviate Fe toxicity in rice at the initial crop establishment stage.

中文翻译：

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钾营养和水分供应对水稻幼苗铁毒性的影响

摘要 本研究的目的是研究钾（K）营养和/或通过排水对淹水土壤通气对水稻建株期间铁（Fe）毒性的影响。使用三种 Fe（0.1，最佳；1，高；2.5 mM，非常高）和 K 水平（0.3，低；2，最佳；5 mM，高）进行的水培实验，以及具有两种湿度水平的土壤实验 [连续淹没; 交替湿润和干燥 (AWD)] 和三个 Fe 水平（16，低；163，最佳；490 mg Fe(II) kg−1 土壤，高）。在水培实验中，高铁供应增加了组织中铁、磷 (P) 和镁 (Mg) 的浓度，并降低了锰 (Mn) 的浓度。特别是铁、钾和磷在根表面的保持量大于根吸收的量。水稻生长、光合作用、最大量子产率、在高和非常高的 Fe 浓度下，有效量子产率和电子传输速率会降低，而 K 的应用没有积极影响。在土壤实验中，铁供应增加下的生长和养分关系与在水培实验中观察到的相似。然而，比较两种水分水平表明，与洪水相比，AWD 系统中土壤溶液 Fe 浓度和植物生长降低，组织 P、Mg 和 Mn 浓度增加。因此，不能将钾肥的施用或淹水土壤的曝气推广为在作物生长初期减轻水稻中铁毒性的有希望的策略。铁供应增加下的生长和养分关系与水培实验中观察到的相似。然而，比较两种水分水平表明，与洪水相比，AWD 系统中土壤溶液 Fe 浓度和植物生长降低，组织 P、Mg 和 Mn 浓度增加。因此，不能将钾肥的施用或淹水土壤的曝气推广为在作物生长初期减轻水稻中铁毒性的有希望的策略。铁供应增加下的生长和养分关系与水培实验中观察到的相似。然而，比较两种水分水平表明，与洪水相比，AWD 系统中土壤溶液 Fe 浓度和植物生长降低，组织 P、Mg 和 Mn 浓度增加。因此，不能将钾肥的施用或淹水土壤的曝气推广为在作物生长初期减轻水稻中铁毒性的有希望的策略。