Effect of Tree Regulation on the Growth and Development of Walnuts of Different Tree Shapes 树木调控对不同树形核桃生长发育的影响
LIU Jin－li，CUI Li－xian＊，LIU Jing，YU Qiu－xiang＊ 刘金丽，崔丽贤*，刘静，于秋香*Changli Institute of Pomology，Hebei Academy of Agricultural and Forestry Sciences，Changli 066600，PRC 河北省农林科学院 昌黎果树研究所，河北 昌黎 066600
Abstract 抽象
To identify the most appropriate tree regulation mode for walnuts of different tree shapes，the effect of different regulation modes on the growth and yield of walnuts was studied，including branch－bending，short cutting，bud－notching and other regulation methods．The results revealed that branch－bending could help to control the excessive vegetative growth of walnuts and change the composition of branch types；walnuts of natural open center shape had the highest number of short and medium fruiting branches，while those of delayed－open central leader system had the lowest number；walnuts of spindle shape presented the longest new shoots，while those of natural open center shape displayed the shortest new shoots．The difference in the diameter of new shoots between different tree shapes was not significant．For the short cutting method，heavier short cutting led to faster growth of new shoots and smaller crown，while lighter short cutting led to higher number of germinated shoots．In this experiment，walnuts of Y shape after light short cutting had the highest germination number．For 1－year－old branches after bud－notching，walnuts of natural open center shape had the highest germination rate while those of delayed－open central leader system had the lowest germination rate．For 2－year－old branches after bud－notching，walnuts of natural round head shape and natural open center shape had the highest germination rate while those of Y shape had the lowest germination rate． There was little difference in the germination rate of perennial branches after bud－ notching，and as the growing years of branches went by，the germination rate after bud－notching gradually decreased． 为确定最适合不同树形核桃的树木调控模式，研究了不同调控模式对核桃生长和产量的影响，包括弯枝、短切、芽槽等调控方法，结果表明，弯枝有助于控制核桃营养过度生长，改变枝型组成;天然开心形状的核桃中短结果数最多。枝条中，延迟开放中央导引系统枝条数最少，纺锤形核桃新梢最长，自然开心核桃新梢最短，不同树形新梢直径差异不显著，短切较重，新梢生长较快，冠部较小，较轻的短切导致发芽 shoots.In 数较高试验中，光短切后 Y 形核桃发芽数最高，开芽后 1 年生枝条中，自然开心型核桃发芽率最高，延迟开中心型核桃发芽率最低。发芽后 2 年生枝条中，自然圆头型和自然开心型核桃发芽率最高，Y 型核桃发芽率最低。有多年生植物枝条发芽率在芽槽后发芽率差异不大，随着枝条生长年限的推移，芽槽后发芽率逐渐降低。
Key words Walnut；Tree structure；Branch－bending；Bud－notching；Short cutting 关键词 胡桃木;树状结构;枝弯;芽槽;短切
DOI：10．16175／j．cnki．1009－4229．2023．01．002 DOI：10.16175/j.cnki.1009-4229.2023.01.002
1．Introduction 1.引言
Walnut（Juglans regia L．）is a perennial lofty deciduous leaf arbor in the genus Juglans of family Juglandaceae．Cultivated throughout North China，Northwest China，Southwest China，Central China，South China，East China and Southern Xinjiang ^([1]){ }^{[1]} ，walnut is one of the most widely distributed economic forest tree species in China and an important economic woody oil tree species．Walnut oil can be used as high－grade edible oil and industrial oil ^([2-4]){ }^{[2-4]} ，and walnut kernels are known as one of the Four Great Nuts in the world，along with almonds，cashews and hazelnuts ^([5]){ }^{[5]} ．In foreign countries，walnuts are called＂food for unusual 核桃（Juglans regia L.）是胡桃科胡桃属的多年生高大落叶乔木，分布于华北、西北、西南、华中、华南、华东和南疆 ^([1]){ }^{[1]} ，是中国分布最广的经济林木树种之一，也是重要的经济木本油树种，核桃油可用作高档食用油和工业用油 ^([2-4]){ }^{[2-4]} ，核桃仁被称为世界四大坚果之一，与杏仁、腰果和榛子齐名 ^([5]){ }^{[5]} ，在国外，核桃被称为“不寻常的食物”
strength", “nutritious nuts”, and “clever nuts”; in China, they enjoy the laudatory name of “long live seed”, “longevity fruit”, “treasure of health”, etc… Now, walnuts are highly recommended by more and more people for their distinguished brain-invigorating effect and rich nutritional profile ^([6]){ }^{[6]}. strength“、”nutritious nuts“和”clever nuts“;在中国，他们享有“种子万岁”、“长寿果”、“健康之宝”等美誉。现在，越来越多的人强烈推荐核桃，因为它们具有卓越的健脑作用和丰富的营养成分 ^([6]){ }^{[6]} 。
As the planting scale of walnuts increases, it is important to maintain a high yield of walnuts to ensure the healthy development of walnuts industry. The key to a high and stable yield is to develop a reasonable tree structure that can carry a high amount of fruits and maintain a relatively balanced coordination between walnut growth and fruiting ^([7]){ }^{[7]}. Current studies on the application technology of walnuts mainly focus on processing, quality, photosynthetic characteristics, diseases, and benefits of walnuts. The relationship between tree structure and growth parameters of walnuts after tree regulation was rarely reported. Therefore, the identification of the most appropriate tree regulation mode for walnuts of different tree shapes was of great significance for walnut production and also provided a theoretic basis and technical support for the shaping and pruning of walnuts. 随着核桃种植规模的扩大，保持核桃的高产对保证核桃产业的健康发展具有重要意义。高产稳定的关键是开发合理的树木结构，能够承载大量的果实，并保持核桃生长和结果 ^([7]){ }^{[7]} 之间相对平衡的协调。目前对核桃应用技术的研究主要集中在核桃的加工、品质、光合特性、病害和益处等方面。树木结构与树木调控后核桃生长参数之间的关系很少报道。因此，确定最适合不同树形核桃的树木调控模式，对核桃生产具有重要意义，也为核桃的定型和修剪提供了理论依据和技术支持。
2. Materials and Methods 2. 材料和方法
2.1. Experimental materials and design 2.1. 实验材料和设计
The experiment was conducted at the walnut garden of Shigezhuang Base, Changli Institute of Pomology, Hebei Academy of Agriculture and Forestry Sciences. The trees for the experiment were 6-year-old “Qingxiang” late-maturing walnuts, which were strong and well-grown without pests and diseases. The planting space was 4mxx6m4 \mathrm{~m} \times 6 \mathrm{~m}. The management 该实验在河北省农林科学院昌黎果树研究所石各庄基地核桃园进行。实验的树木是 6 年生的“青香”晚熟核桃，这种核桃强壮且生长良好，没有病虫害。种植空间是 4mxx6m4 \mathrm{~m} \times 6 \mathrm{~m} 。管理层
techniques for the soil, fertilizer and water in the whole garden were basically the same, and the soil was sandy loam. 整个园内的土壤、肥料和水的施法基本相同，土壤为沙壤土。
The tree regulation was conducted in 2019, and five tree shapes were engaged, namely “Y shape”, “spindle shape”, “delayed-open central leader system”, “natural round head shape”, and “natural open center shape”. Twelve plants were randomly selected for each tree shape before the experiment, with three plants in a plot and four repetitions of experiments. Each plant was numbered and labeled after branch-bending, short cutting, bud-notching and other regulation measures. Branch-bending was carried out from late May to late June each year using pegging and twining method. Short cutting was conducted in late March, and all the medium and long branches with 100 cm or longer length were pruned according to different branch types. Four short cutting techniques were employed: light short cutting (cutting 1//41 / 4 of the branch), medium short cutting (cutting 1//21 / 2 of the branch), heavy short cutting (cutting 3//43 / 4 of the branch), and no short cutting. Bud-notching was conducted on 1-year-old, 2 -year-old and perennial branches 7∼10d7 \sim 10 \mathrm{~d} before budding. A small hacksaw blade was used to cut the bud at 0.5∼1cm0.5 \sim 1 \mathrm{~cm} above the selected bud, deep enough to reach the xylem, and the length was about 1//21 / 2 of the branch thickness. Different tree structure indicators were shown in Table 1. 2019 年进行了树木监管，采用了 5 种树形，即“Y 形”、“纺锤形”、“延迟开中央引线系统”、“自然圆头形”和“自然开心形”。在实验前，每种树形随机选择 12 株植物，每块地中 3 株植物，重复 4 次实验。对每株植株进行分枝弯曲、短剪、芽槽等调节措施后进行编号和标记。每年 5 月下旬至 6 月下旬使用钉子和缠绕方法进行树枝弯曲。3 月下旬进行短剪，所有长度为 100 cm 及以上的中长枝条均根据枝条类型不同进行修剪。采用四种短剪技术：轻短切（剪 1//41 / 4 树枝）、中短剪（剪 1//21 / 2 树枝）、重短剪（剪 3//43 / 4 树枝）和无短剪。在出芽前对 1 年生、2 年生和多年生树 7∼10d7 \sim 10 \mathrm{~d} 枝进行芽开槽。使用小钢锯片在所选芽 0.5∼1cm0.5 \sim 1 \mathrm{~cm} 上方切割芽，深度足以到达木质部，长度大约 1//21 / 2 与树枝的粗细差不多。表 1 显示了不同的树结构指标。
2.2. Experimental methods 2.2. 实验方法
The crown width, tree height, trunk height, ground diameter, yield per plant and shoot growth were measured for two consecutive years from September 2020 to mid-October 2021, and the composition of branches was obtained accordingly. 从 2020 年 9 月至 2021 年 10 月中旬连续两年测量冠宽、树高、树干高度、地径、单株产量和芽生长情况，并据此获得枝条组成。
Table 1 Different tree structure indicators 表 1 不同的树形结构指标
Tree shapes 树的形状
Tree indicators 树指示器
Tree height//m 树高//m
Trunk height//cm 躯干高度//cm
Number of main branches 主分支数量
Base angle of main branches// 主支管的底角 //
Number of lateral branches 侧支数量
Y shape 和形状
2.0∼2.52.0 \sim 2.5
100∼120100 \sim 120
2
50~60
8∼108 \sim 10
Spindle shape 主轴形状
3.5~4.0
80∼10080 \sim 100
8∼128 \sim 12
70∼8070 \sim 80
24~36
Delayed-open central leader system 延开中央领导系统
3.5~4.0
80∼10080 \sim 100
5~7
80~90
15∼2115 \sim 21
Natural round head shape 自然圆头形状
3.5~4.0
80∼10080 \sim 100
4~5
60∼7060 \sim 70
12∼1512 \sim 15
Natural open center shape 自然的开心形状
3.5~4.0
60~80
3
50∼7050 \sim 70
9~12
Main technical measures 主要技术措施
Short cutting, branch-bending, bud-notching 短切、弯枝、芽槽
Tree shapes Tree indicators
Tree height//m Trunk height//cm Number of main branches Base angle of main branches// Number of lateral branches
Y shape 2.0∼2.5 100∼120 2 50~60 8∼10
Spindle shape 3.5~4.0 80∼100 8∼12 70∼80 24~36
Delayed-open central leader system 3.5~4.0 80∼100 5~7 80~90 15∼21
Natural round head shape 3.5~4.0 80∼100 4~5 60∼70 12∼15
Natural open center shape 3.5~4.0 60~80 3 50∼70 9~12
Main technical measures Short cutting, branch-bending, bud-notching | Tree shapes | Tree indicators | | | | |
| :--- | :--- | :--- | :--- | :--- | :--- |
| | Tree height//m | Trunk height//cm | Number of main branches | Base angle of main branches// | Number of lateral branches |
| Y shape | $2.0 \sim 2.5$ | $100 \sim 120$ | 2 | 50~60 | $8 \sim 10$ |
| Spindle shape | 3.5~4.0 | $80 \sim 100$ | $8 \sim 12$ | $70 \sim 80$ | 24~36 |
| Delayed-open central leader system | 3.5~4.0 | $80 \sim 100$ | 5~7 | 80~90 | $15 \sim 21$ |
| Natural round head shape | 3.5~4.0 | $80 \sim 100$ | 4~5 | $60 \sim 70$ | $12 \sim 15$ |
| Natural open center shape | 3.5~4.0 | 60~80 | 3 | $50 \sim 70$ | 9~12 |
| Main technical measures | Short cutting, branch-bending, bud-notching | | | | |
Branches with length <= 10cm\leq 10 \mathrm{~cm} was set as the short branch, 10cm <10 \mathrm{~cm}< length <= 30cm\leq 30 \mathrm{~cm} as medium branch, and length > 30cm>30 \mathrm{~cm} as long branch according to the growing characteristics of walnuts. The plant height and new shoot length were measured by steel rule. The base thickness of the trunk, and the longitudinal diameter, transverse diameter, and edge diameter of walnuts were measured with digital caliper, and the weight per fruit and yield of walnuts were weighed by electronic balance. 根据核桃的生长特性，将长度 <= 10cm\leq 10 \mathrm{~cm} 为短枝， 10cm <10 \mathrm{~cm}< 长度 <= 30cm\leq 30 \mathrm{~cm} 为中枝，长度 > 30cm>30 \mathrm{~cm} 为长枝。用钢尺测量株高和新梢长。用数字卡尺测量树干的基部厚度和核桃的纵径、横径和边径，用电子天平称量核桃的单果重量和产量。
The number, length, thickness, germination number and germination rate of shoots after branchbending and short cutting were investigated. The germination number was obtained after bud-notching, and the germination rate was calculated according to the germination rate=the germination number/total number of shoots. 对弯枝和短剪后枝条的数量、长度、厚度、发芽数和发芽率进行了调查。开芽后得到发芽数，根据发芽率=发芽数/总芽数计算发芽率。
2.3. Data processing 2.3. 数据处理
All the data statistics and graphs were made by Excel. The statistical analysis was conducted using DPS7.05, and the significance of difference was analyzed by Duncan’s new multiple range test (DMRT). 所有数据、统计数据和图表均由 Excel 制作。使用 DPS7.05 进行统计分析，并通过 Duncan 新多范围检验 （DMRT） 分析差异的显着性。
3. Results and Analysis 3. 结果和分析
3.1. Effect of branch-bending on the growth of new shoots of different tree shapes 3.1. 树枝弯曲对不同树形新芽生长的影响
3.1.1. Effect of branch-bending on the number of new shoots of different tree shapes 3.1.1. 树枝弯曲对不同树形新芽数量的影响
As shown in Fig. 1, the numbers of new shoots of the five tree shapes were obviously different after branch-bending, and the numbers of long, medium and short shoots also varied but the difference was not significant. The number of short branches was ordered as natural open center shape > Y>Y shape >> natural round head shape >> delayed-open central leader system >> spindle shape. The number of 10∼30cm10 \sim 30 \mathrm{~cm} medium branches was sequenced as natural round head shape >> natural open center shape > Y>Y shape >> spindle shape >> delayed-open central leader system. The number of long branches was in the order 如图 1 所示，5 种树形的新梢数在枝条弯曲后存在明显差异，长、中、短梢数也存在差异，但差异不显著。短分支的数量排序为自然开中心形状 > Y>Y 、 >> 自然圆头形状 >> 、延迟开放中心导引系统 >> 、纺锤形状。中等分支的数量 10∼30cm10 \sim 30 \mathrm{~cm} 排序为自然圆头形状 >> 、自然开中心形状 > Y>Y>> 、纺锤形 >> 延迟开中心导引系统。长分支的数量是按顺序排列的
of spindle shape and delayed-open central leader system >> natural open center shape > Y>Y shape >> natural round head shape. 的纺锤形和延迟打开的中央导引系统 >> ，自然的开放中心形状 > Y>Y ， >> 自然的圆头形状。
Fig. 1 Effect of branch-bending on the number of new shoots 图 1 弯曲分枝对新芽数量的影响
3.1.2. Effect of branch-bending on the length of new shoots of different tree shapes 3.1.2. 树枝弯曲对不同树形新芽长度的影响
As shown in Fig. 2 and 3, the length of new shoots germinated in the next year after branch-bending was ordered as spindle shape > Y>Y shape >> delayed-open central leader system >> natural round head shape >> natural open center shape, with spindle shape having significant difference with natural open center shape but insignificant difference with Y shape, delayed-open central leader system and natural round head shape. The thickness of new shoots was in the sequence of spindle shape >> delayed-open central leader system >> natural open center shape > Y>\mathrm{Y} shape >> natural round head shape, and the difference in the thickness of new shoots of different tree shapes was not distinct. 如图 2 和图 3 所示，分枝弯曲后第二年发芽的新梢长度为纺锤形 > Y>Y>> 延迟开中心导引系统 >> 自然圆头形状 >> 自然开中心形状，纺锤形与自然开心形状差异显著，与 Y 形差异不显著，延迟开中心引导系统，自然圆头形状。新梢粗细依次为纺锤形 >> 延迟开中央导引系统 >> 自然开心形 > Y>\mathrm{Y}>> 自然圆头形，不同树形新梢粗细差异不明显。
Fig. 2 Effect of branch-bending on the length of new shoots of different tree shapes 图2 树枝弯曲对不同树形新梢长度的影响
Supported by Innovation Project of Hebei Academy of Agriculture and Forestry Sciences（2022KJCXZX－CGS－9） 河北省农林科学院创新项目（2022KJCXZX-CGS-9）
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