磷、砷双重胁迫对不同耐低磷水稻苗期生长及磷、砷吸收的影响

以1个耐低磷和1个低磷敏感水稻为材料,通过土培试验研究磷、砷双重胁迫对水稻苗期生物学特性及磷、砷吸收的影响,并比较不同品种之间的差异.结果表明,相同磷水平下,外加砷浓度为小于25 mg/kg时,水稻的生物量、叶宽、株高、SPAD值及磷吸收量均随砷浓度的增加而增加,当砷浓度达到50 mg/kg时开始下降,两个品种表现相同趋势.说明少量砷可以刺激水稻生长,促进磷的吸收,砷用量过多则抑制水稻的生长及磷的吸收.相同砷水平下,水稻生物学性状及磷、砷吸收量随磷用量的增加而增加,两个品种亦表现相同趋势.说明适当施磷肥可以缓解砷对水稻生长的抑制作用.上述结果表明,低浓度的磷、砷具有协同效应,高浓度的磷、砷表现拮抗作用.此外,相同磷、砷水平下,供试耐低磷水稻的生物学性状及其相对值较低磷敏感水稻大;但相对磷吸收量(除磷处理为150 mg/kg外)比低磷敏感水稻小,而砷吸收量及其相对值均比低磷敏感水稻多,这可能与二者的磷营养特性及水稻对磷和砷的竞争吸收有关.图7表1参19

Effect of P and As Couple Stress on Growth, and P and As Absorption of Different P-tolerant Rice Seedlings

One low-P tolerant rice genotype and one low-P sensitive rice genotype were used to study the effect of P and As couple stress on their growth, and P and As absorption of their seedlings planted in soil. The results showed that at the same P level, the biomass, leaf width, plant height, SPAD value and total P of the rice genotypes increased with As concentration ranging from 0 mg/kg to 25 mg/kg, and then decreased with As concentration increasing to 50 mg/kg. The two rice genotypes showed the same tendency, which means meant that a small quantity of As might stimulate rice growth and absorb more P, while 50 mg/kg As would start to suppress rice growth and P absorption. At the same As level, the biological characters and P and As absorptions of the rice genotypes increased along with increasing of P supply. So proper P supply might alleviate the inhibition of rice by As. These indicated that the low levels of As and P displayed synergistic effect, while high levels of those displayed antagonism effect. Moreover, At the same P and As levels, the biomass, leaf width, plant height and SPAD value of the low-P tolerant rice genotype and their relative values were larger than those of low-P sensitive rice genotype, but the low-P tolerant rice genotype also absorbed more As than the low-P sensitive rice genotype, indicating that the uptake capability of rice to As might be related to its P nutrient character and its competitive absorption between P and As. Fig 7, Tab 1, Ref 19