Effects of potassium level on photosynthetic characteristics and chloroplast submicroscopic structure of muskmelon leaves
Lin, D.; Huang, D-feng.; Yang, Y-jie.; Chen, N.
Ying Yong Sheng Tai Xue Bao 18(5): 1066-1070
2007
ISSN/ISBN: 1001-9332 PMID: 17650859 Document Number: 611805
With soilless culture in greenhouse, this paper studied the effects of three potassium (K) levels (120, 240, and 360 mg center dot L-1) on the photosynthetic characteristics and chloroplast submicroscopic structure of muskmelon cv. 'Tiantian No. 1' leaves. The results showed that at low (120 mg center dot L-1) and high (360 mg center dot L-1) K levels, the net photosynthetic rate (P-n) decreased, chloroplast lamellar structure disordered, and lamella number decreased. No significant effects were observed on CO2 compensation point (70 mu l center dot L-1), saturation CO2 for photosynthesis (600 mu L center dot (-1)) and light compensation point (50 mu mol center dot m-2 center dot s(-1)) at the three K levels. The saturation light for photosynthesis, carboxylation efficiency and apparent quantum yield at 240 mg center dot L-1 K level were significantly higher, being 1 200 mu mol center dot m(-2) center dot s(-1), 0. 1364 and 0. 0237, respectively. Under the conditions of this study, the optimal K level in the nutrient solution for muskmelon soilless culture was 240 mg center dot L-1.