摘要：
[Objective] In recent years,the declining trend of global solar radiation has become a limiting factor in crop production,low light is one of the most important stresses to maize growth and yield formation.This study was conducted to investigate the effects of different light intensities on the root growth and yield of summer maize under field conditions.[Method] In 2012-2014,Denghai 605 (DH605) was used as experimental material.Two treatments of both shading (S) and increasing light (L) from flowering to maturity stage during maize growth period were designed.The field experiment was conducted to explore the effects of different light on dry matter accumulation,root structure characteristics and yields of summer maize.The shading degree was 60％ and the illumination intensity of the increasing light on cloudy day could reach 80 000-10 0000 lx.One non-shading and non-increasing light treatment was used as control.[Result] Compared to CK,root characteristics and grain yield under shading decreased,while those of L increased.Results showed that grain yields in S treatment were reduced by 79％,61％ and 60％ from 2012 to 2014,compared to CK,while the yields in L treatment were increased by 13％,7％ and 15％.Yield,root/shoot ratio,root diameter,root length density,root absorption area and root active absorption area decreased,respectively,after shading from flowering to maturity stage;however,the yield,root/shoot ratio,root diameter,root length density,root absorption area and root active absorption area increased after increasing light from flowering to maturity stage.Shading had a strong impact on the development of roots in the upper soil layer,while roots in lower soil layers were less affected.Shading from flowering to maturity stage clearly decreased the photosynthetic rate,leaf pigments content,dry matter accumulation,root/shoot ratio,root length density,root absorption area and active absorption area.Overall,shading from flowering to maturity stage decreased the root morphologic and activity indices.Increasing light was beneficial to the improvement of the root of the robust growth and root activity.The root absorption areas in the 0-30 cm and 30-60 cm soil layers in L increased by 17％,18％,17％ and 21％,27％,27％ at VT+20,VT+40,and R6,respectively,compared to the control.The root active absorption areas increased by 11％,18％,17％ and 27％,33％,28％ at VT+20,VT+40,and R6,respectively,compared to the control.Increasing light made the plants could get more water and nutrients from the soil for the growth of the aerial part,increasing grain filling rate and grain yield.[Conclusion] Inlattergrowingperiod,rootcharacteristicsandgrainyielddecreasedundershading,whilethose of L increased.In order to fit rainy weather in latter period,the study suggest that adjusting plant date and optimizing management should be done to mitigate shading in this region.%[目的]近年来全球太阳辐射不断下降已经成为作物生产的一个限制性因素,弱光成为影响夏玉米生长发育和产量形成的重要非生物逆境之一.本研究旨在探讨花粒期不同光照强度对夏玉米根系生长和产量的影响.[方法]2012-2014年,大田条件下选用玉米品种登海605 (DH605)为试验材料,种植密度为67 500株/hm2,设计花粒期遮阴(S)和花粒期增光(L)两个试验处理,遮光度为60％,阴雨天气下增光的光照强度可达到8×104-10×104 1x,以自然光照作为对照(CK),研究夏玉米根系生理特性、叶片光合性能、干物质积累量及产量对花粒期光照强度的响应.[结果]本试验表明,花粒期遮阴导致玉米根系特性降低,产量降低;而补充光照有利于生育后期根系活性保持,显著提高籽粒产量.2012-2014年间,遮阴处理的产量较对照分别降低79％、61％和60％,增光处理较对照则分别增加13％、7％和15％.具体表现为花粒期遮阴处理使地上部功能叶片光合速率降低,干物质积累量减少,根冠比显著下降,根系直径和根长密度降低,根系总吸收面积和活跃吸收面积显著降低,致使夏玉米产量降低;花粒期增光处理则有利于玉米根系的健壮生长和根系活力提高,增光后根系总吸收面积和活跃吸收面积显著增加,即根系吸收能力增强,使产量显著提高.在花后20 d、40 d和成熟期,增光处理的0-30 cm和30-60 cm土层根系总吸收面积较对照分别增加17％、18％、17％和21％、27％、27％,根系活跃吸收面积分别增加11％、18％、17％和27％、33％、28％,有助于夏玉米植株从土壤中吸收更多的水分和养分来供给地上部的生长,增加穗数和千粒重,进而提高产量.[结论]花粒期遮阴导致夏玉米生育后期根系特性降低和产量降低,而增光有利于保持根系活力和提高产量.针对近年来黄淮海区域夏玉米生育后期阴雨寡照天气频发的情况,本研究建议适当调整播期,使夏玉米生育后期避开阴雨天气;通过蹲苗或者合理的水肥调控措施促进根系下扎和健壮生长,提高抗逆能力,以减轻阴雨寡照的不利影响.
