Abstract: 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.

Key words: muskmelon, root-zone hypoxia stress, photosynthesis, yield, quality