Effect of Two Allelochemicals of Casuarina equisetifolia L. on Chlorophyll Fluorescence Parameters in Hydroponically Cultured Seedling: Effect of Two Allelochemicals of Casuarina equisetifolia L. on Chlorophyll Fluorescence Parameters in Hydroponically Cultured Seedling

In order to investigate the resistance of Casuarina equisetifolia L. to autotoxicity and to provide scientific basis for continuous planting of C. equisetifolia, clones of ‘Huian No.1’ C. equisetifolia were water cultivated to study the effects of chlorophyll fluorescence in branchlet under allelochemical stress (of seven concentrations: 0, 12.5, 25, 50, 100, 200 and 400 mg L) induced by quercetin-3-α-araboside (allelochemical A) and quercetin-3-β-glucoside (allelochemical B). The membership function of fuzzy mathematics was used to analyze the tolerance abilities of C. equisetifolia seedling under different allelochemicals stress. The results showed slight variations in F0, Fm, Fv/F0 and Fv/Fm of the branchlet under slight allelochemicals stress (12.5, 25, 50 mg L). The Fv/Fm was observed to maintain 78% of normal photosynthesis reaction. The F0, qN, Drate, LPAR of the branchlet significantly (P < 0.05) increased with the concentration of allelochemicals(100, 200, 400 mg L), while the values of Fm, Fv/Fm, Fv/F0, Prate, ΦPSII, qP decreased significantly (P < 0.05). Allelochemicals stress damaged the function of PSII reaction center and decreased the photochemical electron transfer rate, which led to the structural damage of photosynthetic organs and functional degradation in photosynthetic ability. The range of chlorophyll fluorescence parameters in branchlet of C. equisetifolia varied with different allelochemicals,the seedlings had better stress tolerance against allelochemical A than allelochemical B. Fig 3, Tab 1, Ref 28