根际低氧胁迫对网纹甜瓜光合作用、产量和品质的影响

 采用气雾法栽培系统, 研究了网纹甜瓜根际低氧(10%、5% O₂ ) 胁迫对果实发育期间光合 作用及产量和品质的影响。结果表明: 低氧胁迫明显降低了叶片光合色素含量、净光合速率( P_n ) 、气孔导度(G_s ) 、胞间CO₂浓度(C_i ) 、蒸腾速率( T_r ) 以及PSⅡ最大光化学效率( F_v /F_m ) 和PSⅡ潜在活性( F_v /F_o ) , 显著提高了气孔限制值(L_s ) ; 显著降低了单株产量和果实中维生素C、蛋白质、可溶性糖及主要芳香物质含量, 提高了有机酸含量, 降低了糖酸比。说明网纹甜瓜果实发育期间根际O₂浓度降到10%及以下时, 光合作用及果实发育就会受到显著抑制, 从而导致产量和品质降低。

Effects of Root-zone Hypoxia Stress on the Photosynthesis, Yield and Quality of Muskmelon

By the aeroponics culture system, the effects of root-zone hypoxia stress (10% and 5% O₂ )on the leaf photosynthesis, fruit yield and quality of muskmelon were studied. The results showed that there were distinct decreases in the contents of photosynthesis pigments, net photosynthetic rate ( P_n ) , stomatal conductance (G_s ) , intercellular CO₂ concentration (C_i ) , transp iration rate ( T_r ) and the maximal photo chemical efficiency of PSⅡ ( F_v /F_m ) and PSⅡ potential activity ( F_v /F_o ) under the root-zone hypoxia stress as compared with the control ( 21% O₂ ). However, the stomatal limitation value (L_s ) was significantly increased. In addition, the results of yield and fruit quality showed that root-zone hypoxia stress markedly reduced the fruitweight per plant, and the contents of vitamin C, protein, soluble sugar and ratios of sugar/acid in fruit, in contrary, the content of organic acid was increased. Besides, the main aroma components detected were also declined with the decrease of the root-zone oxygen concentration. This indicated that leaf photosynthesis and fruit growth ofmuskmelon will be inhibited obviously when the root-zone oxygen concentration were lower than 10% during the fruit development, the yield and quality of muskmelon fruit decreased.