铵态氮/硝态氮对水稻铝毒害的影响

Effect of Ammonium Nitrogen/Nitric Nitrogen on Al Toxicity in Rice

由于酸性土壤中硝化反应受到抑制,NH4+-N是酸性土壤中无机氮存在的最主要的形式,故酸性土壤中Al3+经常与NH4+-N共存,但这种现象往往被忽视。因此,了解氮形态与Al3+之间的相互关系不仅有助于我们更好地理解水稻的耐铝机制,还能够为酸性土壤施肥提供理论依据。试验选用2个水稻品种武运粳7号和扬稻6号,采用水培方法,进行长期和短期观察,分析铵态氮和硝态氮对水稻铝毒害的影响。结果显示:在长期(14 d)硝态氮与铝交替处理下,铝对2个水稻品种生物量和根系形态的抑制作用明显大于长期铵态氮与铝交替处理,而且硝态氮处理下水稻根部铝浓度显著高于铵态氮处理;在短期(24 h)处理条件下,与铵态氮相比,硝态氮加重了铝对水稻根伸长的抑制,同时提高了2个品种水稻根尖的铝含量,而且铵态氮与硝态氮处理之间根尖铝含量的差异随着培养时间的推移而增大;与铵态氮相比,硝态氮增加了水稻根中其他阳离子(K+、Ca+、Mg2+和Mn2+)的浓度。因此,与硝态氮相比,铵态氮减轻了铝对水稻的毒害,降低了水稻根系对铝的累积。

In acidic soils,nitrification is depressed and ammonium nitrogen（NH4^＋-N） is the predominant inorganic N form,so Al^3＋ and NH4^＋-N often coexist in the soils.Investigating the interaction of Al^3＋ and nitrogen forms is helpful not only for well understanding the Al^3＋ resistance mechanisms of rice,but also for establishing theoretical bases of fertilization in acidic soils.In this study,two rice cultivars Wuyunjing7（Al^3＋-tolerant） and Yangdao6（Al^3＋-sensitive） were selected as materials to investigate the effects of different N forms on the Al^3＋ toxicity in rice through long-term（14 d） and short-term（24 h） experiments under hydroponic conditions.The inhibitory effects of Al^3＋ on biomass and root types of the two rice cultivars were significantly stronger in long-term NO3——N/Al^3＋ intermittent treatment than those in long-term NH＋4-N/Al^3＋ intermittent treatment,and the Al^3＋ concentration in root was higher in NO3——N treatment than that in NH4^＋-N supply.In short-term N-Al treatment,the suppression of Al^3＋ on root elongation in NO3——N/Al^3＋ treatment was more significant than that in NH4^＋-N/Al^3＋ treatment,and the Al^3＋ treatment content in root tip of rice in NO3——N/Al^3＋ treatment was improved.To maintain a charge balance on the root surface,the concentration of cations（K^＋、Ca^＋、Mg^2＋、Mn^2＋） in roots inereased when NO3——N was taken up.These results indicated that compared with NO3——N,NH4^＋-N alleviated Al^3＋ toxicity to rice and reduced Al^3＋ accumulation in the roots.