Abstract:

The paper aims to compare leaf chlorophyll fluorescence characteristics of different aged Populus euphratica trees introduced in Yulin. The experiment was carried out with 11 introduced P. euphratica from the Hongshixia Sand Botanical Garden as the research materials. The chlorophyll fluorescence characteristics of leaves, including the chlorophyll content (SPAD), minmal fluorescence (F₀), maximal fluorescence (Fm), maximal photochemical efficiency (Fv/Fm), асtuаl photochemical efficiency (Φ_PSII), acyclic electron transfer rate (ETR), photochemical quenching coefficient (qP) and non-photochemical quenching coefficient (NPQ), were determined at the growing and yellowing stage, and different fertilizer treatments (organic fertilizer 0, 75, 150 kg/hm ²) were set up to measure the plant height, diameter at breast height and crown diameter of 6-year-old P. euphratica. The results showed that the difference of chlorophyll content, Fv/Fm, Φ_PSII, ETR, qP and NPQ of P. euphratica were significantly obvious under different tree ages (P<0.05). The chlorophyll content of 2-year-old P. talassica×P. euphratica was the highest, while the values of Fv/Fm, Φ_PSII, ETR, and qP of 4-year-old, 2-year-old and 5-year-old P. euphratica were relatively higher than those of other materials. Fertilization treatment significantly increased the plant height and crown width of P. , and 150 kg/hm ² organic fertilizer was the most effective fertilizer application amount. In summary, the 4-year-old, 2-year-old and 5-year-old P. euphratica are suitable for introduction in Yulin, and 150 kg/hm ² organic fertilizer is the optimum fertilization rate.

Key words: Populus euphratica, chlorophyll fluorescence, tree-age, growth index, plant height, crown diameter