【摘要】 在大田箱式土柱栽培条件下,比较了高产玉米品种登海3719和金海5号的根系特征,并以混播时地上部生物产量变化为依据,分析了根系特征与竞争能力的关系。结果表明,在氮肥供应充足条件下,登海3719单株根系生物量低于金海5号,根冠比无明显差异,其0～20cm根系分配比率大、活力高,在与金海5号根系竞争中地上部氮素积累量增加6%、生物量提高8%。不施氮时,登海3719的根冠比增加4%,金海5号增加21%,登海3719的根冠比、0～20cm根系分配比率及活力均低于金海5号,在根系竞争中氮素积累量减少8%,生物量下降2%。与金海5号相比,登海3719在氮素供应不足时,根系竞争力弱,适应低氮条件的能力较差,但在氮肥充足条件下表现吸氮能力高,竞争力强。更多还原

【Abstract】 Corn(Zea mays L.) plant density is known as a major factor determining the degree of competition between plants. Modern corn hybrids have several responses to light decline at large densities,such as keeping a erectophile plant type and elongating the maintenance of green leaves. Some researchers have pointed out that modern hybrids showed high levels in root vigor,ATPase activity,and soluble protein contents as well as the deep-vertical but narrow-horizontal distribution of roots in soils. However,the root competitive ability among cultivars that released in different years is little known. Denghai 3719 created a yield record of 21 t ha-1 in 2005. To understand the root spatial distribution and competitive ability of Denghai 3719,an experiment was conducted in rectangle tanks for comparing the roots characteristics and the biomass of aboveground part between Denghai 3719 and Jinhai 5(a hybrid widely cultivated in China as control). The cultivars were planted in two models,i.e.,two plants per tank with the same cultivar and with each plant from both cultivars. Each model treated with two nitrogen levels(0 and 7.5 g N plant-1). Under the nitrogen application condition,the two cultivars had a distinct biomass accumulation,but their root/shoot ratios were similar. Denghai 3719 took on superiority over Jinhai 5 both in the proportion and root vigor of shallow(0–20 cm) roots,as a result of an increase of nitrogen accumulation by 6% and biomass by 8% under competition,respectively. Under nitrogen deficiency,root/shoot ratio increased in both hybrids than that under nitrogen application,with Denghai 3719 and Jinhai 5 increased by 4% and 21%,respectively. Owing to the inferiority of Denghai 3719 over Jinhai 5 in respects of root/shoot ratio,and the proportion and root vigor of shallow(0–20 cm) roots under nitrogen deficiency,Denghai 3719 had a decrease in nitrogen accumulation by 8% and in biomass by 2% under competition,respectively. The results indicate that Denghai 3719 is more adapted to nitrogen-efficient environment in view of root distribution and root vigor.更多还原