Comparative analysis of leaf photosynthetic characteristics and fruit sugar content in trees of Citrus cultivar 'Huangguogan' of different age

Abstract

Citrus trees of cv. Huangguogan, 8-, 30-, and 280-year-old (8s, 30s, and 280s, respectively), were used to explore the photosynthesis and related enzyme activity. In spring shoot leaves, net photosynthetic rate (PN) of the 280s was significantly lower than that of the 30s and 8s, but it was opposite in summer shoot leaves. PN of the summer shoots was higher than that of the spring shoots. PN was significantly positively correlated with stomatal conductance, intercellular CO2 concentration, and transpiration rate, but was negatively correlated with maximum photochemical quantum yield of PSII photochemistry. The effect of age on variable fluorescence/minimal fluorescence was similar to that of minimal fluorescence, variable fluorescence, maximal fluorescence yield of the dark-adapted state. Fruits of the 280s had significantly lower sugar components than those of the 8s and 30s. Results showed that fruits of the 8s and 30s actively accumulated photosynthesis products, which was verified by the higher PN in the spring shoots, lower acidic invertase and neutral invertase activities, and higher sucrose phosphate synthase than that of the 280s.

Chemical Composition and Antioxidant Activity of Zanthoxylum armatum Leaves in Response to Plant Age, Shoot Type and Leaf Position

“…Moreover, the DPPH and ABTS radical scavenging activity of leaf ethanol and water extractions in four-year-old plants are higher than those of two-year-old plants, and the antioxidant capacity of leaf ethanol extractions was significantly higher than those of leaf water extractions (Figure 6). Plant age-related changes in the contents of C, N, P, AA, protein, TP and TF, etc., in Moringa oleifera, Olea Europaea and Manihot esculenta Crantz plants have been observed [16,32,35]. These variations of chemical compositions might be positively correlated with the photosynthetic capacity of leaves and the activity of enzymes related to carbon fixation and nitrogen fixation in different plant ages [32].…”

“…Plant age-related changes in the contents of C, N, P, AA, protein, TP and TF, etc., in Moringa oleifera, Olea Europaea and Manihot esculenta Crantz plants have been observed [16,32,35]. These variations of chemical compositions might be positively correlated with the photosynthetic capacity of leaves and the activity of enzymes related to carbon fixation and nitrogen fixation in different plant ages [32]. For example, the contents of AA, SS, TP and TF in Manihot esculenta Crantz leaves were influenced by plants' ages, showing an increase in older plants [16].…”

“…Plant age plays a major part in fruit yield and quality, especially in economic plants [31,32]. Earlier studies showed that the "mother" plant age has substantial influences on the tremendous intra-specific variation in many leaf traits [33,34].…”