行向和种植方式对生育后期玉米叶片衰老进程的影响

Effects of row orientations and planting patterns on senescence of maize leaves at later growth stage

玉米产量的大部分来自花后的光合产物积累,花后叶片的光合和生理特性直接影响到籽粒的灌浆,而功能叶片衰老是影响产量的重要因素之一。适宜的种植方式可有效延长叶片持绿期,达到增产的效果。通过改变行向和种植模式,能够优化冠层结构,改善玉米冠层光照条件和玉米产量。本研究在吉林省春玉米种植区,分析东西垄向和南偏西20°垄向条件下,65 cm均匀垄和160 cm+40 cm组合垄距配置的种植方式对生育后期穗位叶以上叶片、穗位叶和穗位叶以下叶片的SPAD值、N含量、超氧化物歧化酶(Superoxide dismutase,SOD)和过氧化物酶(Peroxidase,POD)的活性的影响,以期明确行向和行距对玉米叶片衰老的影响。结果表明,南偏西20°行向中,前期的下部叶片和穗位叶以及后期上部叶片中SPAD值显著高于东西行向。南偏西20°行向种植下的玉米上、中、下不同部位叶片中N含量均极显著高于东西行向。南偏西20°行向中,160 cm+40 cm垄距种植下的玉米下部和上部叶片中N含量显著高于65 cm均匀垄。东西行向中,160 cm+40 cm垄距种植的玉米不同时期的穗位叶和上部叶片中SOD酶活性均明显大于65 cm均匀垄。与传统种植方式下的玉米相比,160 cm+40 cm垄距种植的玉米叶片衰老进程延缓,且衰老程度明显较低。

The maize yield mainly comes from photosynthate accumulation after tasseling,while the photosynthetic and physiological characteristics of maize leaf directly affects grain filling; thus,premature aging of functional leaf is one of the important factors affecting maize yield. An appropriate change of row orientation and planting pattern could optimize the canopy structure to improve the light condition within the canopy,and effectively extend green period of maize leaf and increase maize yield. We conducted a field experiment in Jilin Province with 2 × 2 treatments： 2 row orientations,east-to-west orientation（ EW） and northeast-to-southwest orientation（ SW20）,where the orientation was southwestern 20°; 2 planting patterns, ‘65 ＋ 65＇with 65 cm of both rows（ 65） and‘160 ＋ 40＇with 40 cm of narrow row and 160 cm of wide row. Then,we investigated,during grain filling period,the effect of row orientation and planting pattern on SPAD value,nitrogen content,superoxide dismutase（ SOD） and peroxydase（ POD） activity of leaves at different leaf positions（ leaves above ear leaf,ear leaf and leaves below ear leaf）. The results showed that SPAD value with lower and ear leaves during the early filling stage and upper leaf during the later filling stage were higher in SW20 than that in EW. Nitrogen content with different leaf positions was higher in SW20 than that in EW. As for SW20,nitrogen content with lower and upper leaves in ‘160 ＋ 40＇row was significantly higher than that in ‘65 ＋ 65＇row. As for east-to-west orientation,SOD activity with ear and upper leaves in‘160 ＋ 40＇row was higher than that in‘65 ＋ 65＇row. Compared with traditional planting pattern,treatments with 160 cm ＋ 40 cm row delayed the aging time of maize leaves and significantly slowed leaf aging speed.