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在水培条件下研究了NO3 N ,NH4 N及添加HCO- 3和HEPES对豌豆铁营养的影响。与NO3 N相比 ,供应NH4 N时豌豆根系铁还原力上升较早 ,铁还原酶活性显著较高 ,铁向地上部转移较多。供应NH4 N时培养Sparkle的营养液pH下降较快 ,而培养E10 7营养液 pH受氮源形态的影响较小。对根系质外体铁的利用 ,以NH4 N为氮源时 ,两种豌豆经过 15天后都全部利用 ;供应NO3 N的E10 7能全部利用 ,Sparkle也利用了约 3/ 4 ;以HCO- 3缓冲时E10 7利用了约 3/ 4 ,而Sparkle则几乎不能利用。但是生长在HCO- 3缓冲的营养液中的豌豆根系结构完好 ,转移到低pH环境中后铁还原力不仅没有降低 ,反而比对照有所提高。HCO- 3和HEPES对豌豆铁营养的影响相似。表明HCO- 3对豌豆铁营养的影响不是破坏了根系的结构和功能 ,而主要是通过提高根际 pH值 ,抑制了根系铁还原酶活性的作用 ,从而降低了对铁的吸收利用能力。氮素形态对豌豆铁营养的影响主要是通过影响质外体 pH起作用的。
The effects of NO3 N, NH4 N and addition of HCO-3 and HEPES on iron nutrition of pea were studied under hydroponics. Compared with NO3N, the iron reduction ability of pea root supplied earlier when NH4N was supplied, iron reductase activity was significantly higher, and iron was more transferred to the shoot. The nutrient pH of Sparkle cultured in NH4N decreased rapidly, while the pH of culture E107 was less affected by the nitrogen source. Utilizing NH3N as nitrogen source, both peas were fully utilized after 15 days. E107 supplied with NO3 N was fully utilized and Sparkle also utilized about 3/4. With HCO-3 The buffer E10 7 takes about three-fourths, while Sparkle barely uses it. However, the root system of pea growing in HCO-3 buffered nutrient solution was intact. After being transferred to low pH environment, iron reducing power not only did not decrease, but increased compared with control. HCO-3 and HEPES have similar effects on pea iron nutrition. The results indicated that the effect of HCO-3 on iron nutrition of pea was not to undermine the structure and function of the root system, but mainly reduced the iron absorption and utilization ability by increasing rhizosphere pH and inhibiting the activity of root iron reductase. The effect of nitrogen form on iron nutrition in pea mainly works by affecting the apoplast pH.