根际O_2胁迫对网纹甜瓜矿质营养吸收的影响

为探讨根际O2对网纹甜瓜矿质营养吸收的影响,采用气雾法栽培系统,研究果实发育期间根际低氧(体积分数为10%O2和体积分数为5%O2)处理对网纹甜瓜根、茎、叶和伤流液中矿质营养吸收的影响。结果表明:在网纹甜瓜果实发育期间,根际10%O2和5%O2处理不同程度地抑制根系对矿质营养的吸收和运输。根中氮质量分数先增后降,磷、钾和钙质量分数显著低于对照,根和茎中镁质量分数与对照差异均不显著。茎中氮、磷和钾质量分数在低氧处理20d时显著低于对照,茎中钙质量分数在5%O2处理期间显著低于对照,在10%O2处理期间差异不显著。叶片中氮质量分数在低氧处理20d时显著低于对照。5%O2处理期间叶中磷质量分数显著低于对照,10%O2处理20d显著低于对照。叶中钾、钙和镁的质量分数在10%O2处理期间与对照差异不显著,5%O2处理显著低于对照。根系伤流液中氮、磷、钾、钙和镁质量分数均随根际O2体积分数的降低而下降,5%O2处理下降的幅度显著大于10%O2处理。说明,在网纹甜瓜果实发育期,当根际O2体积分数降到10%O2及其以下时,植株对矿质营养的吸收及矿质营养通过木质部向地上部的运输均受到阻碍。

Effect of Rhizosphere O2 Stress on Mineral Nutrient Absorption of Muskmelon

The objective of the experiments is to investigate the effect of rhizosphere O₂ on mineral nutrient absorption of muskmelon. By the aeroponics culture system, the effects of rhizosphere hypoxia (10% and 5% O₂) stress on mineral nutrient absorption of muskmelon were studied during the fruiting periods, and 21% O₂ was served as the control. The results showed that in hypoxia treatments, the absorption and transportation of nutrition were restricted.The mass fraction of nitrogen in roots was increased first and then decreased, the mass fraction of P, K and Ca in roots were decreased significantly. The mass fraction of Mg in roots and stems had no significant difference. The mass fractions of N, P and K in stems were significantly lower than the control at 20 d of treatment. The content of Ca in stem was significantly lower than the control in treatment of 5% O₂ and the difference was no significant under 10% O₂ treatment. The mass fraction of N in leaves decreased significantly at 20 d of hypoxia stress. The mass fraction of P in leaves was affected significantly in 5% O₂ treatment. The mass fraction of P in leaves decreased significantly at 20 d under 10% O₂ treatment. The mass fractions of K, Ca and Mg in leaves were no significant difference under 10% O₂ treatment. It was significantly lower than the control in treatment of 5% O₂. The mass fraction of N, P ,K Ca and Mg in root xylem sap reduced to different degree with the decreasing of the root-zone O₂ volume fraction. It was more serious effect in 5% O₂ treatment than under 10% O₂ treatment. It was concluded that the uptake and transportation of mineral nutrient were inhibited in plant when the rhizosphere O₂ volume fraction reached 10% in fruit development period of muskmelon.