水钾耦合对水稻根际土壤钾空间分布及根系生长的影响

The Combined Impact of Water and Potassium on Root Growth and Potassium Distribution in the Rhizosphere of Rice

【目的】探究水钾耦合对水稻根际土壤钾空间分布及根系生长的影响。【方法】以水稻武运粳30为供试作物进行盆栽试验,设置3个水分水平(70%θf^80%θf、80%θf^90%θf、100%θf,θf为饱和含水率),3个钾素水平(混施钾素0、100、200 mg/kg),采用完全随机试验设计,测定了水稻苗期(6叶期)根系生理学指标(物质的量、根冠比)和不同土层根际含钾量。【结果】根际土壤中的水溶性钾总量与钾素水平成正比,水溶性钾量在垂直根系方向上呈降低趋势;各层含交换性钾总量与水分水平成正比,交换性钾量在垂直方向上总体呈增加趋势;根际土壤中各层缓效性钾的总量与供钾水平成正比;缓效性钾量在垂直方向上呈降低趋势;施钾能够抑制水稻苗期地上部的生长,轻度水分胁迫有助于水稻苗期根系的生长,而轻度水分胁迫下施钾有助于增大水稻苗期的根冠比;水分对苗期水稻根系干物质的积累有影响,而钾素则影响水稻苗期地上部干物质量的积累。【结论】水钾耦合效应首先是从影响根际土壤中养分的转化开始,当钾素营养被水稻根系吸收利用后,钾素开始由土壤中迁移到根系中,从而对植株及根系生长产生影响。

【Objective】Water and nutrient distributions in soil modulate root growth, and the purpose of this paper is to investigate the combined impact of water and potassium on root growth and potassium distribution in the rhizosphere of rice.【Method】Pot experiments were carried out with the variety of Wuyun japonica rice as the model plant. We examined three soil saturations： 70%θf^80%θf, 80%θf^90%θfand 100%θf, and three potassium levels： 0, 100 mg and 200 mg per pot. When the rice seedling was at the six-leaf stage, we measured the amount of dry matter, root-shoot ratio, root activity, as well as the potassium content in the rhizosphere.【Result】Soluble potassium content in the rhizosphere was proportional to total potassium content and decreased with soil depth.Along the soil profile, the slow-K content was proportional to the applied potassium and decreased with soil depth. Potassium application impeded the accumulation of above-ground biomass at early growing stage, while a slight water stress enhanced root growth and the root-shoot ratio. The experimental results revealed that soil moisture modulated root growth while potassium impacted mainly on shoot growth.【Conclusions】The onset of water and potassium is the root and they are then extended to the shoot and canopy.