Effect of different nitrogen forms on distribution and utilization of ~(15)N and ~(13)C in young Fuji/Malus hupehensis apple trees

摘要

This study aimed at investigating the plant growth, distribution, and utilization of nitrogen (N) and carbon (C) in apple trees in response to different N forms (NH4-N, N03-N and urea-N). The track technology of C, N double mark was applied to study the effect of different N forms on the distribution and utilization of ~(15)N and ~(13)C in two-year-old young potted Fuji/Malus hupehensis apple trees. The results showed that both dry matter weight and root-cap ratio were obviously higher in the NO_3~-Ntreatment than in the urea-N and NH_4~-N treatments. In the three N treatments, the distribution pattern of ~(15)N was consistent in each organ : leaves > shoots > roots > stems. However, obvious differences were found in the same organ under the different N treatments, especially in the leaves and roots. The highest and lowest distribution ratios of ~(15)N in the leaves were found in the NO_3~-N and urea-N treatments, respectively. For the roots, the order was NH_4~-N treatment > urea-N treatment > NO_3~-N treatment. In addition, significant differences in ~(15)N utilizaton efficiency were found among the three treatments. The highest ~(15)N utilizaton efficiency was found in the N0_3~-N treatment, followed by the urea-N treatment and then the NH_4-Ntreatment. The different N treatments also caused different distributions in each organ of photosynthetic products. In the NH_4~-N and urea-N treatments, the order of ~(13)C distribution ratio in each organ was the same : leaves > shoots > roots > stems. In the NO_3~-N treatment, the order was shoots > roots > leaves > stems. Therefore, different N forms cause different physiological effects in apple trees.