Root growth in response to nitrogen supply in Chinese maize hybrids released between 1973 and 2009  

作　　者：WU QiuPing CHEN FanJun CHEN YanLing YUAN LiXing ZHANG FuSuo MI GuoHua 

机构地区：[1]Key Laboratory of Plant-Soil Interaction, MOE, College of Resources and Environmental Science, China Agricultural University, Beijing 100193, China

出　　处：《Science China(Life Sciences)》2011年第7期642-650,共9页中国科学（生命科学英文版）

基　　金：supported by the National Basic Research Program of China (Grant No. 2009CB11860);the National Natural Science Foundation of China (Grant Nos. 31071852 and 30821003);the Special Fund for Agriculture Profession (Grant No. 201103003)

摘　　要：Root growth has a fundamental role in nitrogen （N） use efficiency. Nevertheless, little is known about how modem breeding progress has affected root growth and its responses to N supply. The root and shoot growth of a core set of 11 representative Chinese maize （Zea mays L.） hybrids released between 1973 and 2009 were investigated under high N （4 mmol L^-1, HN） and low N （0.04 mmol L^-1, LN） levels in a solution culture system. Compared with LN, HN treatment decreased root dry weight （RDW）, the root： shoot ratio （R/S）, and the relative growth rate for root dry weight （RGRroot）, but increased the total root length （TRL） and the total lateral root length （LRL）. The total axial root length （ARL） per plant was reduced under HN, mostly in hybrids released before the 1990s. The number of seminal roots （SRN） was largely unaffected by different N levels. More recently released hybrids showed higher relative growth rates in the shoot under both HN and LN. However, the roots only showed increased RGR under HN treatment. Correspondingly, there was a positive linear relationship with the year of hybrid release for TRL, LRL and ARL under HN treatment. Together, these results suggest that while shoot growth of maize has improved, its root growth has only improved under high N conditions over the last 36 years of selective breeding in China. Improving root growth under LN conditions may be necessary to increase the N use efficiency of maize.Root growth has a fundamental role in nitrogen (N) use efficiency.Nevertheless,little is known about how modern breeding progress has affected root growth and its responses to N supply.The root and shoot growth of a core set of 11 representative Chinese maize (Zea mays L.) hybrids released between 1973 and 2009 were investigated under high N (4 mmol L?1,HN) and low N (0.04 mmol L?1,LN) levels in a solution culture system.Compared with LN,HN treatment decreased root dry weight (RDW),the root:shoot ratio (R/S),and the relative growth rate for root dry weight (RGRroot),but increased the total root length (TRL) and the total lateral root length (LRL).The total axial root length (ARL) per plant was reduced under HN,mostly in hybrids released before the 1990s.The number of seminal roots (SRN) was largely unaffected by different N levels.More recently released hybrids showed higher relative growth rates in the shoot under both HN and LN.However,the roots only showed increased RGR under HN treatment.Correspondingly,there was a positive linear relationship with the year of hybrid release for TRL,LRL and ARL under HN treatment.Together,these results suggest that while shoot growth of maize has improved,its root growth has only improved under high N conditions over the last 36 years of selective breeding in China.Improving root growth under LN conditions may be necessary to increase the N use efficiency of maize.

关 键 词：ROOT R/S ratio NITROGEN relative growth rate maize breeding 

分 类 号：S512.11[农业科学—作物学] S512.1