ABSTRACT

This study quantified the effects of different establishment practices on survival, dieback and early growth of Juglans × intermedia NG23 and NG38 planted in a statistically designed field experiment on glacial till in southern Sweden. Establishment practices included the use or absence of nurse trees (Populus maximowiczii × trichocarpa var. OP42 planted one year before J. × intermedia), weed control (2 m²·tree⁻¹) and fertilization (+25 g N·tree⁻¹·year⁻¹). NG23 transplants were smaller than NG38 at the time of planting. The overall survival rate was 97%. NG23 suffered marginally more mortality than NG38. Leader shoot dieback occurred in all treatment combinations but was most severe in the presence of nurse trees. NG23 suffered less dieback than NG38. Annual height growth of trees unaffected by dieback increased with increasing levels of precipitation during the growing season (194–407 mm) and with increasing soil quality in terms of nitrogen (94·10⁻³–607·10⁻³ g·g⁻¹), base saturation (14–99%) or available soil water capacity (8.6–30.6 l·m⁻³). It was negatively influenced by poplar nurse trees and positively by fertilization. Weed control had no impact on height growth, possibly due to inefficient implementation. With nurse trees, NG23 had stronger growth than NG38. The opposite was true without nurse trees. It was hypothesized that less growth and more dieback resulted from competition for water.

摘要

本研究量化了不同种植方式对核桃 ×  intermedia NG23 和 NG38存活、枯死和早期生长的影响，该实验是在瑞典南部冰耕地进行的一项统计设计的田间试验中种植的。建立实践包括使用或不使用护理树（J . ×  intermedia前一年种植的Populus maximowiczii  ×  trichocarpa var. OP42 ）、杂草控制（2 m ² ·tree ^-1）和施肥（+25 g N·tree ^-1 ·年⁻¹）。NG23 移植物在种植时比 NG38 小。总生存率为97%。NG23 的死亡率略高于 NG38。所有处理组合中都发生了主枝顶枯，但在有护士树的情况下最严重。NG23 的顶枯病比 NG38 少。不受顶枯病影响的树木的年高度增长随着生长季节降水量的增加（194-407毫米）和土壤氮质量的增加而增加（94·10 -3 –607 ^· 10 ^-3 g·g ^-1）、基础饱和度（14–99%）或土壤有效持水量（8.6–30.6 l·m ⁻³）。它受到杨树护理树的负面影响，并受到施肥的正面影响。杂草控制对身高生长没有影响，可能是由于实施效率低下。对于护士树，NG23 的生长比 NG38 更强。如果没有护士树，情况恰恰相反。据推测，由于对水的竞争，生长减少和枯死增加。