夏玉米不同土层根系对花后植株生长及产量形成的影响

【目的】探明夏玉米不同土层根系对花后植株生长及产量形成的调控作用，为生产中塑造高产高效根群结构，提高籽粒产量提供理论依据。【方法】以高产夏玉米品种郑单958和登海661为材料，采用土柱栽培方式，设置3个处理（不断根处理：CK，地下40 cm处断根：T-40，地下80 cm处断根：T-80），于开花期进行断根，研究不同土层根系对地上部生长及产量形成的调控作用。【结果】0—40 cm土层根系对花后氮素积累和转运量影响最大，切断40 cm以下土层根系后植株吸收氮素能力显著降低，植株营养器官氮素向籽粒库的转运量增加。花后40 cm以下土层根系对叶片保绿性和光合性能影响显著，切断深层根系后玉米单株叶面积、叶绿素含量、净光合速率(Pn)和SOD活性显著降低，MDA含量升高，光合高值持续期缩短，单株生物量和籽粒产量显著下降；0—40 cm根系对产量影响最大，40—80 cm根系对穗粒数和千粒重有显著影响，80 cm以下土层根系对千粒重影响较为显著。【结论】高产栽培中促进根系下扎，保持深层根系活力可以防止玉米早衰，提高叶片光合能力和对氮素的吸收能力，有助于提高玉米单产。

Effect of Root in Different Soil Layers on Plant Growth and Yield Formation After Anthesis in Summer Maize

【Objective】This study was conducted to evaluate the regulating effects of roots in different soil layers on plant growth after anthesis and yield formation in summer maize，aimed to provide theoretical supports for building high efficient root systems of maize and then increase grain yield of maize.【Method】Two high yield summer maize varieties, Zhengdan 958 (ZD) and Denghai 661 (DH), were used as experimental materials, and they were planted in soil columns. Three treatments (without cutting the roots, CK; cutting maize roots at 40 cm below the surface at anthesis, T-40; cutting roots at 80 cm below the surface at anthesis) were designed to evaluate the regulating effects of summer maize roots in different soil layers on shoot growth and yield formation.【Result】 The regulation of upper roots (0-40 cm) to nitrogen uptake and translocation was most significantly. While losing function of deep roots (below 40 cm) reduced nitrogen absorption capacity, and accelerated the transportation from nutritive organs to grain kernels. Deep roots below 40 cm had significant effects on leaves staying green and photosynthetic performance. Cutting deeper roots at anthesis significantly decreased green leaf area per plant, chlorophyll content, activity of SOD and Pn, and increased the content of MDA, shortened the duration of high photosynthesis and reduced biomass of plant and grain yield significantly. Intermediate roots (40-80 cm) had notable influence on grain numbers of per ear and grain weight; however, deeper roots had more significant effects on grain weight than grain numbers per ear.【Conclusion】Cutting upper roots (0-40 cm) reduced maize yield significantly. Intermediate roots had significant influences on grain numbers per ear and grain weight; deeper roots had significant effects on grain weight than grain numbers per ear. In high-yielding cultivation, keeping deep root actively can delay leaf senescence, enhance photosynthetic performance and absorption of nitrogen, and increase grain yield.