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To screen soil nutrients and light conditions that effectively promote the growth of Picea koraiensis saplings and to provide a scientific basis for establishing growth promotion techniques for P. koraiensis saplings, a split-zone design experiment was conducted with P. koraiensis saplings plantations of 8-10 years old in Jiamusi City, Heilongjiang Province, using three light conditions (full light, 0. 5 depression, 0. 7 depression) with nitrogen addition (100 g / plant-yr) and control plots to analyze the effects of light and nitrogen addition on growth and leaf morphological function of P. koraiensis saplings. The results showed that: The annual growth of tree height was the highest under full light conditions, and the annual growth of ground diameter was the highest under full light fertilization conditions, followed by 0. 5 degree of depression; the effect of N addition on the annual growth of tree height and ground diameter was small. Between different light conditions, with the increase of canopy density, the specific leaf area and chlorophyll content increased, leaf dry matter content and chlorophyll a/b decreased, and leaf nutrient content did not change significantly; the effect of N addition on leaf morphology, chlorophyll content and leaf nutrient content was not significant. The effect of light on the growth, leaf morphology and photosynthetic capacity of P. koraiensis saplings was more significant than that of N addition, and saplings under full light and N addition had larger annual growth of tree height and ground diameter, and the lowest annual growth ratio of high diameter. Nitrogen addition can promote the photosynthetic efficiency of saplings. The full light condition or nearly full light condition should be selected for the forestation of P. koraiensis, and the photosynthetic capacity of saplings can be improved by nitrogen addition after forestation to promote growth. [ABSTRACT FROM AUTHOR]

In order to explore the effects of different irrigation amounts on the length and width of new citrus leaves under the pre¬cise root domain irrigation technology, citrus was taken as the research object and set different irrigation amount for irrigation. In the experimental group under the precise root field irrigation, 35, 30, 25L/ (plant • times) were respectively set and irrigated once in sev¬en days； in the control group under the micro - sprinkling irrigation method, 130L/(plant • times) irrigated once in 15 days. After ir¬rigating different amount of water, the growth of slightly new tip of the tree and the length and width of new leaves were recorded. Re¬sults showed that the root domain precision irrigation under different irrigation amount had a significantly influence on the new tip of the tree and the length and width of new leaves. In the 14 days observation period, test II had the best growth potential, the total growth of the new tip of the tree was 72. 1 mm, compared with the control group, the growth volume increased by 17. 7 mm and increased by 32.5% year - on - year. The total growth of new leaf length was 48. 9 mm, increased by 9. 6 mm compared with the control group, in¬creased by 24.4% year - on - year, and the total growth of leaf width was 23. 3 mm, which was higher than that of the control. The growth of the group increased by 5. 3 mm, a year - on - year increase of 29. 4% . Therefore, the irrigation amount of 30 L/( plant • times) under the precise root domain irrigation technology is more suitable for the growth of fresh citrus leaves. [ABSTRACT FROM AUTHOR]