[Effects of different integration of water and fertilizer modes on the absorption and utilization of nitrogen fertilizer and fruit yield and quality of apple trees].

We examined nitrogen use efficiency of N-urea of 15-year-old 'Gala' apple trees by broadcast fertilization (T), nitrogen fertilization with drip irrigation (T) and nitrogen fertilization with subsurface irrigation (T), to further improve the water and fertilizer integration technology for apple orchard and to improve nitrogen utilization efficiency. The results showed that leaf area, chlorophyll, and leaf nitrogen content of leaves were significantly higher in T treatment than those in T and T treatments. Soil mineral nitrogen content (20-40 cm) in each period followed the order of T>T>T, while that in 0-20 cm followed an order of T>T>T.

[Effects of potassium levels on translocation of C-photoassimilates to fruit in 'Fuji' apple during fruit expanding period].

A field experiment was carried out in a six-year old 'Fuji'3/M26/Malus hupehensis Rehd. apple with the C tracer method to examine the changes of chlorophyll fluorescence parameters, photosynthetic characteristics of leaf, sugar transporter gene expression, C assimilation capability and the characteristics of translocation and distribution of C-photoassimilates to fruit under different levels of potassium addition (KO 0, 0.5%, 1.

[Nitrogen application technology in dwarfed apple trees.].

N trace technique was used to explore the characteristics of N-urea absorption, utilization, loss and fruit quality of eight-year-old 'Yanfu3'/M26/Malus hupehensis Rehd. seedlings. There were three different nitrogen fertilization treatments: one-time nitrogen application in spring (1), two times nitrogen application (2), the intensive technique of nitrogen application with several times application and reduction in amount (3).

[Effects of nitrogen-supply levels on leaf senescence and characteristics of distribution and utilization of C and N in Fuji 3 apple grafted on different stocks].

Two-year-old potted Fuji 3 apple trees on different rootstocks [Fuji 3/M. micromalus Makin (joe), Fuji 3/M7 (semi-dwarf) and Fuji 3/M26/M. micromalus Makin (dwarf)] were used to study leaf morphology and photosynthesis and the characteristics of distribution and utilization of C and N at different nitrogen supply levels (0N, 25%N and 100%N, the N content in 100% N treatment was the same as that in Hoagland complete nutrient solution) under sand culture condition.