作 者 ：张淼 赵书岗 耿丽平 霍红 刘文菊
期 刊 ：植物营养与肥料学报 2013年 19卷 3期 页码：577-585
Keywords:P starvation, iron plaque, crop, root morphology,
摘 要 ：采用营养液培养方法，以水稻、 小麦、 玉米和大豆为试验材料，研究了短期缺磷（2周）诱导根表沉积铁氧化物是否为水稻特有的性质，以及缺磷对不同作物根系形态及其吸收钾、 钙、 铁、 锰、 铜、 锌营养元素的影响。结果表明，供磷和缺磷处理并没有影响小麦、 玉米和大豆3种作物根系的颜色，而缺磷处理水稻根表沉积了铁氧化物而呈红（黄）棕色，且铁氧化物不均匀地富集在根细胞壁的孔隙中; 缺磷促进了水稻，小麦，玉米和大豆根系的生长，分别比供磷处理伸长了11%、 11%、 20%和11%（P<0.05）。此外，缺磷胁迫下水稻根表铁氧化物增强了钙、 铁、 锰、 铜和锌在根表的富集而成为其进入根系的缓冲层。缺磷处理水稻根中铁浓度明显高于供磷处理（P<0.05），而地上部铁的浓度仅为磷营养正常水稻植株的18%，这说明缺磷诱导的铁氧化物促进了根系对铁的吸收但抑制了铁由根系向地上部的转运。短期缺磷对其他养分在水稻根中和地上部的浓度没有明显影响。对于其他 3 种作物，短期缺磷没有明显影响钾、 钙、 铁、 锰、 铜和锌在其根表富集及在植物体内的浓度。因此，在供试的4 种作物中，由于磷胁迫诱导根表形成铁氧化物是水稻特有的性质，铁氧化物的沉积可促进铁的吸收但抑制了铁向地上部的转运，而短期缺磷并没有影响其他3种作物对钾、 钙、 铁、 锰、 铜和锌养分的吸收和转运。
Abstract:The hydroponics experiments were conducted to verify a hypothesis of the specific property of rice which iron plaque can be induced on the rice root surface under phosphorus (P) starvation and to investigate the effects of phosphorus deficiency on root morphology and concentrations of some nutrients in different crops (rice, wheat, corn and soybean). The results show that the root colors of wheat, corn and soybean are same in the nutrient solutions with P or without P, which are verified further by the Fe concentrations extracted from root surface using dithionitecitratebicarbonate (DCB) extraction method. There are no significant differences in Fe concentrations of DCB solution between the roots of wheat, corn and soybean (DCB-Fe) under P and P0 situations. Moreover, the iron plaque is observed on the rice root surface under the P starvation and distributed in the space of cell wall unevenly using microscope. DCB-Fe from rice root without P is 1.71 folds of rice root with P, and is 13.2, 6.4 and 8.6 times of those from root surface of corn, wheat and soybean under the P starvation, receptively. These results indicate it is the specific property of rice that iron plaque can be induced on the root surface when grew in nutrient solution without P supply. P starvation for 2 weeks could increase root lengths of the crops. The root lengths of rice, wheat, corn and soybean under the P starvation are increased significantly by 11%, 11%, 20% and 11% compared to those of the P sufficiency, respectively (P<0.05). The iron plaque induced by P deficiency on the rice root surface enhances the sequestration of other elements in the plaque, such as Ca, Fe, Mn, Cu and Zn, and could be a buffer or reservoir of nutrient elements into rice roots, especially for Fe. The results show that the Fe concentration in rice roots under the P starvation is higher than that of the P treatment significantly (P<0.05), while the shoot-Fe is very low with a proportion of 18% of that under the P application, which suggests iron plaque formation on the rice roots under the P deficiency inhibits the Fe translocation from roots to shoots of rice. In addition, the P starvation does influence the concentrations of other nutrients in roots and shoots of rice. For other crops, the P starvation does not the significant effects on other nutrients levels in roots and shoots. In conclusions, iron plaque induction on root surface under the P starvation is the specific property of rice, and the P deficiency for a short period does not influence the uptake and translocation of K, Ca, Fe, Mn, Cu and Zn of wheat, corn and soybean.
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