关键词: 苹果, 铵态氮, 硝态氮, 生物量, 氮素吸收

Abstract: One-year-old sand-potted seedlings of Tianhong 2/Jizhen 2/Baleng Crabapple were used to study the effects of different nitrogen forms(ammonium nitrogen and nitrate nitrogen) and nitrogen levels [5 mmol/L(control) and 0.625 mmol/L(low nitrogen concentration)] on the growth,nitrogen absorption and distribution in young apple seedlings,aiming to provide theoretical basis for reasonable application of nitrogen and improve nitrogen utilization.The results showed that the growth,chlorophyll content and net photosynthetic rate were higher under the treatment with nitrate nitrogen,and the concentration,absorption,transportation and distribution of nitrogen in young apple trees treated with nitrate nitrogen were better than those treated with ammonium nitrogen at the same nitrogen level.Under the control concentration,nitrate nitrogen treatment effectively promoted the growth of lateral shoot,central stem elonga ted shoot,stem diameter,biomass and nitrogen absorption and distribution,and improved chlorophyll content and net photosynthetic rate of leaves.Compared with ammonium nitrogen treatment,whole plant nitrogen absorption and nitrogen distribution increased by 63.70% and 43.95% respectively under nitrate nitrogen treatment.Except the growth of central stem elongated shoot,nitrate nitrogen treatment showed better performance at low nitrogen concentration. Compared with ammonium nitrogen,whole plant nitrogen absorption and nitrogen distribution increased by 34.35% and 21.69% respectively under nitrate nitrogen treatment.Different forms of nitrogen affected the growth through affecting the absorption,transportation and distribution of nitrogen,chlorophyll content and net photosynthetic rate,and in which the effect of nitrate control treatment was the most significant.The young red Fuji apple trees on Jizhen 2 interstock of nitrate control treatment could effectively improve the nitrogen absorption and distribution rate of central stem,which created favorable conditions for the construction of new organs.

Key words: Apple, Ammonium nitrogen, Nitrate nitrogen, Biomass, Nitrogen absorption