State Key Laboratory of Crop Biology, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai'an, Shandong, 271018, China.
Sci Rep. 2017 Oct 26;7(1):14172. doi: 10.1038/s41598-017-14509-3.
In order to define the effects of fruit crop load on the distribution and utilization of carbon and nitrogen in dwarf apple trees, we conducted three crop load levels (High-crop load, 6 fruits per trunk cross-sectional area (cm, TCA)), Medium-crop load (4 fruits cm TCA), Low-crop load (2 fruits cm TCA)) in 2014 and 2015. The results indicated that the N derived from fertilizer (Ndff) values of fruits decreased with the reduction of crop load, but the Ndff values of annual branches, leaves and roots increased. The plant N-urea utilization rates on Medium and Low-crop load were 1.12-1.35 times higher than the High-crop load. With the reduction of crop load, the distribution rate of C and N in fruits was gradually reduced, but in contrast, the distribution of C and N gradually increased in annual branches, leaves and roots. Compared with High-crop load, the Medium and Low-crop load significantly improved fruit quality p < 0.05. Hence, controlling fruit load effectively regulated the distribution of carbon and nitrogen in plants, improved the nitrogen utilization rate and fruit quality. The appropriate crop load level for mature M.26 interstocks apple orchards was deemed to be 4.0 fruits cm TCA.
为了明确果实负载量对矮化苹果树碳氮分配和利用的影响，我们于 2014 年和 2015 年设置了 3 种果实负载水平（高负载量：每横断面积 6 个果实（cm TCA），中负载量：每横断面积 4 个果实（cm TCA），低负载量：每横断面积 2 个果实（cm TCA））。结果表明，随着负载量的降低，果实中来自肥料的氮（Ndff）值降低，但一年生枝、叶片和根系的 Ndff 值增加。中、低负载量的植株氮-尿素利用率比高负载量高 1.12-1.35 倍。随着负载量的降低，果实中 C 和 N 的分配率逐渐降低，而 C 和 N 在一年生枝、叶片和根系中的分配则逐渐增加。与高负载量相比，中、低负载量显著提高了果实品质（p<0.05）。因此，有效控制果实负载量可调节植物中碳氮的分配，提高氮利用率和果实品质。对于成熟的 M.26 中间砧苹果园，适宜的负载量水平被认为是每横断面积 4.0 个果实。
