渭北高原苹果根区土壤养分变化及对再植苹果植株生长的影响

Changes of Soil Nutrition in Root Zone and Their Effects onGrowth of the Replanted Apple

对渭北高原地区苹果园距树干基部水平方向0～200cm,垂直方向0～80cm土层深度范围内的果树根区空间土壤养分的盈亏变化进行了研究,并结合盆栽试验,分析了不同根区土壤对苹果再植植株的影响。结果表明:在水平方向上,随距树干距离的增加,土壤养分含量呈增高趋势;垂直方向上,除水溶性Ca、Mg外,其他养分随土层加深呈下降趋势。果园根区土壤速效P、水溶性Ca、水溶性Mg、有效Zn、有效Mn有亏缺现象,N/P、K/P、Ca/P、Ca/Mg、Ca/Mn、Ca/Zn存在养分比例失调。果园土壤的盆栽幼树株高、新梢长度、粗度、叶面积和根活力较生茬土壤的分别减少44.93%、34.46%、23.88%、49.48%和11.40%,表现明显的重茬障碍症状,土层愈深的土壤,症状愈重,距树干愈远的土壤,症状愈轻。果园土壤中Zn元素亏缺和Ca/Zn比例失调可能是造成渭北高原苹果再植病害发生的重要原因之一。距树干水平方向100～200cm、垂直方向0～40cm土层土壤养分含量较高,盆栽幼树再植病害较轻,是老果园更新再植应选择的栽植区域。

Soil nutrient distribution and imbalance were studied in the root zone of 0 -80 cm layer and far from the trunk 0 - 200 cm in Weibei highland orchard, while the replant diseases of potted apple plants were analyzed. Results indicated that soil nutrients advanced along with increasing of the tree root base distance in level distribution; In vertical direction, other soil nutrients dropped along with deepening of the soil layer except for available Ca and Mg. Available P, Ca, Mg, Zn, Mn were deficit in orchard soils and N/P, K/P, Ca/P, Ca/Mg, Ca/Mn, Ca/Zn were imbalance in the root zone. The average of replant plant height, shoot length and rough, leaf area and root-activity were reduced 44. 93%, 34.46%, 23.88%, 49.48% and 11.40% separately, which represented replant disease evidently, and which aggravated follow comply with deepening of the layer and lighten as far from the tree trunk in orchard. To sum up, deficiency of Zn and imbalance of Ca/Zn were one of main factors to cause replant diseases; The replant diseases were lighter relatively in the zone of 0 -40 cm layer and far from the trunk 100 -200 cm, where soil nutrients were concentrated, which will provide some reference to solve replant diseases in old orchard.