不同水分供应及氮素形态对旱作水稻铁素营养特征的影响

 为探明非充分灌溉条件下水稻铁素营养特征,设置了不同地下水埋深,模拟水分胁迫、铵态氮和硝态氮施用比例对水稻铁素养分吸收的影响,以及对8个水稻品种在水、旱作条件下分蘖期和成熟期植株样品中铁素含量进行了测定和分析比较。结果表明,在10～50cm范围内,随着地下水埋深增加其剖面各层土壤中有效性铁含量显著下降,由平均2.70mg·kg~(-1)下降到0.83mg·kg~(-1),造成水稻植株体内铁素含量下降40％以上。在非充分灌溉条件下,氮肥中硝态氮施用比例达到75％及其以上时,加剧水稻植株中铁素匮缺。与充分灌溉的处理相比,非充分灌溉条件下的武育粳3号、扬稻4号和9520等3个水稻品种,在分蘖期铁素营养吸收就受到显著不良影响,植株体内平均含铁量分别从195、197和175mg·kg~(-1)下降到99、87和95mg·kg~(-1)。在成熟期,供试8个品种水稻植株体内铁素含量均极显著低于相应的对照(水作)。

Effect of Different Water Managements and Nitrogen Forms on Characteristics of Iron Nutrition of Rice Cultivated Under Aerobic Condition

Although available iron is usually abundant for the growth of rice cultivated in waterlogged condition, but rice crop may suffer from its deficiency when cultivated in aerobic soil since the soil properties are totally different from waterlogged. Solubility of iron is very low in soils with high Eh and/or high pH. A field experiment with five different depths (10, 20, 30, 40 and 50 cm) of groundwater, and a pot-experiment with five treatments of ammonium-nitrate ratio (100/0, 75/25, 50/50, 25/75 and 0/100) were conducted to study the characteristics of iron nutrition of rice in non-full irrigation condition. Moreover, the contents of iron extracted by 1 mol.L-1 HC1 from rice plant samples of 8 cultivars from both aerobic and waterlogged cultivation were analyzed to study the effect of water regimes on iron content of rice plants. The results were as follows: ( 1) The average content of available Fe (2. 70 mg .kg-1 ) of 5 layers of the soil treated with 10-cm depth of groundwater was significantly higher than that (0 .83 mg.kg-1) with 50-cm depth of ground-water, and the iron concentration of rice plant of the former was much higher than that of the later. (2) Iron deficiency of rice became much severe when high ratio of nitrate (more than 75 percent) in nitrogen fertilizer applied at different intervals in aerobic cultivation. (3) The iron concentrations of 3 cultivars, Wuyujing 3 (99 mg.kg-1) , Yangdao4 (87 mg .kg-1 ) and 9520 (95 mg.kg-1) of rice plants cultivated in aerobic condition were significantly less than those (195, 197 and 175 mg.kg-1 respectively) in waterlogged condition at tillering stage. And even much significant differences e-xisted in the iron concentrations of different cultivars growing in the aerobic and waterlogged condition at maturity.