上海地区甜樱桃改良型篱壁式栽培模式初步评估

A preliminary evaluation of tree growth of sweet cherries under modified upright fruiting offshoots(UFO) system in Shanghai

【目的】对上海暖地条件下的甜樱桃改良型篱壁式栽培模式进行初步评价与优化。【方法】结合避雨设施和矮化砧木Gisela 5的应用,对苗木不同栽植方式、定植时修剪策略与定植角度及苗木质量等条件下篱壁式甜樱桃的生长特性进行对比研究。【结果】上海立地条件下,根域限制能有效抑制营养生长、提高成枝率和优化枝类组成;定植角度>30°、短截苗木和采用组培的G5嫁接苗均有利于甜樱桃的营养生长,快速成形,不利于短果枝的形成,枝类组成较劣。【结论】上海地区甜樱桃宜采用改良型篱壁式栽培模式建园,结合根域限制栽植方式有利于提早花芽形成和提高花芽比率,定植时苗木不宜进行短截,苗木定植角度≤30°且选择长势中庸苗木为佳。

【Objective】Sweet cherries have been introduced to south China, including Shanghai since1980 s. However, their commercial production is limited by poor fruit set despite that production has been improved by the application of hydrogen cyanamide, low chilling varieties and rain- shelters in recent years. A long rainy season and high water table in Shanghai usually result in poor fruit set and fruit cracking during growing season. It has been reported that rain shelters effectively control spindling and fruit cracking and increase fruit quality. In addition, the traditional non-dwarfing rootstocks normally lead to vigorous vegetative growth, poor fruit set, labor intensive tree management and difficulty in growing the crop under rain shelters. In recent years, the upright fruiting offshoots（UFO） system was developed by Washington State University, and shown to have many advantages, such as fast canopy establishment, simple pruning, and saving labor. To produce commercial sweet cherries under rain shelters in Shanghai, China, the varieties of sweet cherries, rootstocks and supporting systems need to be evaluated for fruit production. In the current study, a modified UFO system with rain-shelters and dwarfing rootstock‘Gisela 5’under rooting- zone restriction was evaluated for optimizing the planting angle, seedling quality, pruning strategy and rootstock-scion combination.【Methods】The dwarfing rootstock‘Giesla 5’and seven scion varieties, including‘Tieton’‘Sunburst’‘Zaoganyang’‘Zaodaguo’‘Hongdeng’‘Brooks’ and‘Summit’were selected for the experiment. Branching rate and shoot types were used as vegetative growth parameters for evaluating the modified UFO systems. The cherry trees for each treatment were divided into 2groups： the root restriction group and the conventional planting group with planting angle 〉30° or ≤30°.The seedlings were divided into pruned（cutting back） and non-pruned groups. Trunk diameter, branch diameter, branch length and the diameters and lengths of vertical shoots were measured. Branching rate was calculated as the percentage of vertical shoots developed in 2014 against the number of leave buds formed on the trunk in 2013. Shoot types were classified according to shoot length： water shoot（〉60 cm）, wood shoot（30-60 cm）, long shoot（15-30 cm）, medium shoot（5-15 cm）, short shoot（〈5 cm）, and fruiting spur（〈3 cm）. Five trees were selected for each treatment.【Results】Previous studies revealed that root restriction inhibited new shoot growth in young trees, improved the formation of flower buds and raised the quality of fruit. Pruning the seedlings advanced the growth of branches. Planting angle also influenced vegetative growth and reproductive growth. Stock pruning resulted in medium vigorous growth, and grafted plantlets with tissue-cultured stocks had a strong vigorous growth. The results of this study showed that root restriction significantly reduced vegetative growth as reflected by smaller vertical shoot diameter in all varieties accept for‘Sunburst’, shorter vertical shoot length except for‘Zaoganyang’,and higher branching rate except for‘Zaodaguo’and‘Hongdeng’, and increased the percentages of short shoots and fruiting spurs. The vegetative growth of vertical shoots in pruned seedlings were more vigorous than that in nonpruned seedlings. In‘Hongdeng’and‘Tieton’, the non-pruned seedlings had a higher percentage of fruiting spurs than the pruned seedlings. The branching rate varied according to varieties and was higher when seedling planting angle was above 30°. The seedlings with planting angle higher than 30° had greater trunk and shoot diameters and shoot length in‘Sunburst’, but not in‘Brooks’ and‘Hongdeng’. In other words, seedlings planted with an angle 〉30° had a greater vegetative growth and faster canopy establishment. In contrast, shoot composition in‘Brooks’ ‘Hongdeng’and‘Sunburst’trees with a planting angle ≤30° was superior to that in trees with a planting angle 〉30°. The tissue-cultured stock showed a more vigorous growth with greater trunk and branch diameters than the pruned stock. The‘Summit’trees grafted on pruned stock showed medium vigorous growth and a higher percentage of fruit spurs.【Conclusion】Root restriction is effective in reducing vegetative growth and improving precocity. The non-pruned seedlings, small planting angle（≤30°） and medium growth vigor were recommended for the cultivation of sweet cherries under the modified UFO system in Shanghai region. The reproductive growth will be studied so as to further evaluate the modified UFO system.