不同基因型玉米适应低钾胁迫的根系响应机理

Response mechanism of the absorption of potassium in roots of different maize cultivars

钾是植物生长所必需的主要营养元素,目前土壤钾素供应不足已成为部分地区限制作物产量提高的因子之一,充分利用作物高效吸收土壤难溶性钾的能力,对提高土壤钾素和钾肥利用率有重要作用。本研究以玉米钾营养高效基因型‘豫玉23’和钾营养低效基因型‘兴农998’为供试作物,采用营养液培养方法,研究低钾胁迫对2玉米品种生长发育、根系形态、生理特性和解剖结构的影响。结果表明:与正常供钾相比,低钾处理的2玉米品种总叶面积、根干重、地上部干重、总干重、根冠比、植株钾累积吸收量均降低;根长增大,根表面积、根直径、根体积下降;吸K+能力和K+亲合力增大,根系解剖结构导管数目、木质化程度、中柱所占比例、中皮层细胞空腔直径均降低。不同基因型间存在显著差异。缺钾时,钾营养高效的‘豫玉23’生物量和钾含量均大于钾营养低效的‘兴农998’,主要在于前者具有较大的根长、根表面积和根体积,较活跃的根系活力、较强的吸K+能力,较好的根系结构,有利于低钾环境中有效地吸收钾。

Potassium（K） is a main macronutrient for crop growth.Now in some area in China K deficiency in soil has become one main factor to limit the crop yield increasing.It＇s very important for enhancing soil K nutrient and K fertilizer utilization rate to make the best of crop to absorb the insoluble K in soil.In this paper two typical K high and low use efficiency maize cultivars,such as ＇Yuyu 23＇ and ＇Xingnong 998＇,were tested under the conditions of nutrient solution culture with K sufficiency and deficiency.Plant growth and development,root morphology,root physiological characters and anatomical structure were studied.The results showed that compared with the treatment of K sufficiency,in the K deficiency treatment the total leaf area,dry weight of root,shoot and whole plant,the ratio of root to shoot,and plant K absorption were all decreased in two maize cultivars.But root length was increased.The surface area,diameter and volume of roots were dropped.K＋ absorption capacity and affinity were enhanced.In the root anatomical structures,vessels,lignification,proportion of colummals and the cortical cells cavity diameter were dropped.Comparison two maize,there had significant differences.Under the K deficiency conditon,the biomass and K accumulated content in ＇Yuyu 23＇ were higher than those of ＇Xingnong 998＇.Because in the former there had larger root length,surface area and volume,more active root activity,greater K＋ uptake and affinity capacities,better root anatomical structure,these was propitious to uptake K of roots in K deficiency.