氮磷亏缺对玉米根系水流导度的影响

Effect of Nitrogen and Phosphorus-Deficiency on Maize Root Hydraulic Conductivity

在人工气候室水培条件下 ,从单根和整株根系两个层次研究了N、P营养与玉米 (ZeamaysL .)根系水流导度 (roothydraulicconductivity ,Lpr)间的关系。结果表明 :表型抗旱的杂交种F1代户单 4号和母本天四的单根水导和整株根系水导均高于不抗旱的父本478,其中天四的单根水导最高 ,而户单 4号的整株根系水导最高。N、P亏缺均使玉米单根水导和整株根系水导降低 ,但与N亏缺相比 ,P亏缺的植株具有较高的整株根系水导和较低的单根水导。整株根系的水导更能反映植物根系的输水性能。

Under solution culture conditions, the effect of nitrogen and phosphorus-deficiency on maize(Zea mays L.)root hydraulic conductivity were studied both at the level of individual root and whole roots system using pressure chamber. The results showed that the hydraulic conductivity of roots different with genotype and nutrition condition(Fig.1), which were observed not only at individual root level, but also at whole root system level. Results of inhibition experiment with HgCl 2 and de-inhibition experiment with 2-SH-C 2H 4OH suggested that nutrition directly affect individual Lp r by affecting the properties of water channels (aquaporins) in root protoplast plasma membrane(PM)(Table 1). However, at the level of whole root system, there is not only direct effect but also indirect effect resulting from change in root morphology change(Fig.2). Compared with N-deficientous, P-deficient maize seedlings have higher whole Lp r, but lower individual Lp r. It was indicated that the two nutrient elements make different contribution to individual Lp r and whole Lp r , and the functions they performed are also different. There is not a straight-line relationship between individual Lp r and whole Lp r(r 2=0.4957,P<0.05)(Fig.3), which means when individual Lp r was increased, whole Lp r was increased at the same time, but when the individual Lp r was decreased, the whole Lp r did not decrease in a linear way. It makes the plant continuously taking up water from draught soil.The whole Lp r can well reflect the crop's capacity of absorbing water.