氮素水平对小麦根-冠生长及水分利用效率的影响

用水培方法,研究了氮素对不同抗旱特性小麦根-冠生长及其水分利用效率的影响。结果表明,氮素能显著提高叶片光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)和WUE,促进根系和地上部分生长,但根/冠比随氮素水平的增加显著降低;根体积、根容重和根系含水量随氮素水平提高均表现先升后降的趋势。本试验条件下根/冠比为0.3左右时根系含水量最高,根/冠比的增加不利于WUE的提高;随根系含水量的增加,Pn、Tr和Gs呈明显递增趋势,但Tr的增加幅度小于Pn和Gs,所以WUE随根系含水量增加而升高。在一定氮素水平下,旱地小麦品种具有较高的根/冠比、根体积和根干重,而施氮能够促进根系发育和协调根-冠生长,因此氮素能在确保整株抗旱性的前提下提高WUE。

The Effects of Nitrogen Level on the Root and Shoot Growth and Their Relationship with the Water Use Efficiency in Wheat Plants

A solution cultured simulating experiment had been conducted to study the effects of nitrogen application on the root and shoot growth and water use efficiency of two different drought-resistance spring wheat.The results showed that nitrogen application could increase leaf photosynthetic rate(Pn),transpiration rate(Tr),stoma conductance(Gs),water use efficiency(WUE),and promote the shoot and root growth,but the ratio of root to shoot(R/S) decreased as the nitrogen level increased significantly.Root volume,root bulk density and root water content increased firstly and decreased finally as the nitrogen level increased.It was indicated that the root water content was highest when Root/shoot ratio was about 0.3 in this experimental,but the higher or lower R/S was not favor to the WUE increasing.the Pn,Tr and Gs was increased with the root water content increasing,but the increscent extent of Pn was higher than Tr,so the leaf WUE increased continuously as the root water content increased.Under the rate nitrogen application,the R/S,root volume and root dry matter of dryland cultivar was higher than waterland cultivar,and reasonable nitrogen application can promote root development and harmonize the root and shoot growth,therefore,the drought-resistance capability and higher WUE in wheat plants could be obtained synchronously.