The optimal level of oxygen concentration of nutrient solution and the differences in physioecological and morphological responses with the different levels of oxygen in nutrient solution were investigated in order to establish an ideal system of soilless culture. The concentrations of oxygen in nutrient solution were regulated four levels, which were 5, 10, 20 and 40ppm. The levels of oxygen were controlled by the application of liquefied oxygen gas. The tomato cultivar `Seokwang´ which was bred for forcing culture were used for the experiment.
1. The growth of shoots were better in the 10ppm and 20ppm treatment than in the 5 or 40ppm.
2. The cluster of flower in the 20ppm treatment were Betted in the higher node than those of other treatments. The number of flowerlets were greater in the 10ppm and 20ppm treatments, and also the cluster of flower were heavier in those treatments.
3. The main and total root lengths were longer in the 10ppm and 20ppm treatments than those in the 5 or 40ppm.
4. The amount and length of root hair and the length of root hair zone from roottip to 2cm were better in the 10ppm or 20ppm, while those from 2㎝ to first rootlet were better in the roots grown at the 20ppm or 40ppm. Those above the first rootlet were better in the roots grown at the 5ppm or 40ppm.
5. The pH and EC of nutrient solution in 10ppm, 20ppm and 40ppm plots became gradually increased, but those in the 5ppm plot were decreased or constant.
6. The stomatal resistances were higher in the leaves grown at the 5ppm or 40ppm of oxygen, but the value in the 5ppm was especially low at 16 : 00 o´clock.
7. The photosynthetic activity and the root respiration became better as the concentration of oxygen got higher.
8. There were marked differences in the parameters of growth analysis; CGR, RGR, NAR, SL A, LAI, LAR, DMPR, T/R ratio, and root number/root length ratio among the treatments with different concentration of oxygen in nutrient solution.
|