侧向垂直断根对不同根型夏玉米品种叶片光合性能及产量的影响

【目的】探明距离植株中心不同距离处根系对玉米叶片光合特性及产量形成的作用,为生产上通过筛选理想根系构型进一步提高玉米产量和资源利用效率提供理论依据。【方法】以高产夏玉米品种登海661(深根型,DH661)和郑单958(浅根型,ZD958)为材料,于大喇叭口期(V12)的植株为中心,沿行向分别在植株两侧10 cm(T-10)、20 cm(T-20)处侧向垂直断根,断根深度60 cm,以不断根处理为对照(CK),共6个处理,研究在玉米植株两侧不同水平距离处侧向垂直断根对不同根型夏玉米品种叶片光合性能及产量形成的调控作用。【结果】深根型品种DH661在距离植株10 cm范围内其根系干重(RDW)、总根长(RL)、根表面积(RSA)、根系体积(RV)分别占总体根系的83.18%,69.55%,68.74%,66.44%,浅根型品种ZD958则分别为75.19%、51.17%、53.85%、56.49%,DH661根系的分布主要集中在距离植株中心0—10 cm范围内,相对于ZD958根系在横向分布上更为紧缩。在距离玉米植株两侧10 cm及20 cm处垂直断根对于DH661各根系指标的影响较ZD958要小。断根显著影响了两玉米品种叶片的光合性能,抑制了花前叶片的生长,加速了花后叶片的衰老。两年中DH661的T-20处理在抽雄期(VT)叶绿素含量下降4.29%和6.32%,净光合速率(Pn)下降5.16%和4.66%,T-10处理降幅分别为6.37%和6.86%,6.47%和8.66%;ZD958的T-20处理降幅分别为6.52%和9.91%,6.48%和9.15%,T-10处理降幅分别为15.40%和15.01%,11.89%和15.49%。断根同时造成地上部生物量、籽粒产量显著下降,各指标的下降幅度均为T-10T-20,且对深根型品种DH661的影响显著小于浅根型品种ZD958。【结论】侧向垂直断根显著降低了两种不同根型夏玉米品种的穗位叶净光合能力、植株生物量和最终产量,降幅随着侧向垂直断根距离植株中心靠近呈显著增加趋势。两品种相比,深根型夏玉米品种(登海661)对于远距垂直断根(T-20)的响应明显弱于浅根型夏玉米品种(郑单958)。深根型与浅根型夏玉米品种从根系构型、分布和垂直断根后保留的根系功能方面相比,深根型品种根系性能更适宜纵向压缩的栽培空间,是其较浅根型耐密种植的主要原因之一。

Effect of Vertically Cutting Roots at Different Horizontal Distances from Plant on Leaf Photosynthetic Characteristics and Yield of Summer Maize with Different Root Types

【Objective】This study was conducted to evaluate the regulating effects of root in different distances to plant center on leaf photosynthetic characteristics and yield, aimed to provide theoretical supports for screening ideal root system architecture to obtain further yield increase. 【Method】Two summer maize cultivars with different root types, Denghai 661 (DH661, deep root type) and Zhengdan 958 (ZD958, shallow root type) were chosen as experimental materials. At the V12 stage, roots were cut vertically at different horizontal distance of 10 cm (T-10), 20 cm (T-20) from maize plant center at 60 cm soil depth, while no roots cutting as control (CK), to investigate the role of root in different soil profiles in regulating yield and leaf photosynthetic characteristics. 【Result】Results shows that, roots of these maize varieties were mainly located within a horizontal area 0-10 cm from the plant center and in this area, 83.13% of total root biomass, 69.55% of total root length, 68.74% of root surface area and 66.44% of root volume were located for DH661, but for the ZD958, percentage of these index were 75.19%, 51.17%, 53.85%, 56.49%, respectively. Compared to ZD958, the root distribution in horizontal of DH 661 was more compact and less impact caused by cutting root in both sides of plant in the distance of 10 cm or 20 cm to plant center. Roots excision made a prominent impact on the photosynthetic characteristics of the two maize varieties leaves, being followed by inhibiting the growth of leaves before anthesis and accelerating senescence after bloom. Root pruning reduced chlorophyll content of two maize varieties and net photosynthetic rate in two years, at tasseling stage (VT), the chlorophyll content of T-20 treatment of DH661 decreased by 4.29% and 6.32%, respectively, the net photosynthetic rate decreased by 5.16% and 4.66%, the reduced rate of T-10 were 6.37% and 6.86%, 6.47% and 8.66%. The reduced photosynthetic rate of T-20 treatment of ZD958 were 6.52% and 9.91%, 6.48% and 9.15%, in T-10 treatments were 15.40% and 15.01%, 11.89% and 15.49%. At the same time, resulted in significant root shoot biomass and grain yield decreased, the index decline was T-10 > T-20, and the deep root type of DH661 was significantly less than the shallow one ZD958. 【Conclusion】Cutting the roots vertically decreased the ability of net photosynthetic of ear leaf, shoot biomass and final yield of the two maize varieties with different root architecture significantly. The range of reduce increases when the cutting position is close to the main stem. The impact of T-20 on DH661 is obviously weaker than that on ZD958. Compare the root architecture, distribution and the root ability of two maize reserved after cutting vertically, the root performance of deep type is more adaptable to greater planting density.