ISHS Acta Horticulturae 761: XXVII International Horticultural Congress - IHC2006: International Symposium on Advances in Environmental Control, Automation and Cultivation Systems for Sustainable, High-Quality Crop Production under Protected Cultivation
EFFECTS OF POTASSIUM SUPPLY ON THE GROWTH, PHOTOSYNTHETIC CHARACTERISTICS AND QUALITY OF LETTUCE |
| Authors: | X.F. Yang, Z.L. Bie, J.L. Xu |
| Keywords: | Lactuca sativa L., potassium, hydroponics, gas exchange, chlorophyll fluorescence, quality |
| Abstract:
Effects of different potassium supply (1, 4, 6 and 8 mmol/L) on the growth, photosynthetic characteristics and quality of lettuce (‘Honglong’ and ‘Lvling’) were investigated by using hydroponics. The resulted showed that the highest shoot dry weight was obtained by 4 mmol/L K treatment in both cultivars. As K concentration in the nutrient solution was below 6 mmol/L, net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (E) increased significantly with increasing of K concentration in the nutrient solution, and then decreased as K concentration increased from 6 to 8 mmol/L. The decreases in maximal photochemical efficiency of PSII (Fv/Fm), efficiency of excitation energy capture by open PSII reaction centers (Fv’/Fm’), quantum yield of PSII electron transport in the light-adapted state (ФPSII) were significant as K concentration increased from 6 to 8 mmol/L in ‘Lvling’. Leaf nitrate content decreased significantly with increasing of K concentration in the nutrient solution, whereas soluble protein content and ascorbic acid contents increased with increasing of K concentration. | |
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