Detailed Guide to Potted Blueberry Cultivation Techniques: Planting Methods and Management Essentials

Research on Potted Blueberry Cultivation Techniques

Fund project: Key R&D Program of the Sichuan Provincial Department of Science and TechnologyR&D Program (2017NZ0026); Sichuan Provincial Financial Innovation Capacity Enhancement Project (2016ZYPZ-010).

Blueberry, scientific name Vaccinium, is a perennial deciduous or evergreen shrub of the genus Vaccinium in the family Ericaceae. The blueberry is a small berry; the fruit is blue and covered with a white bloom on its surface. The flesh of the blueberry is fine and delicate, the seeds extremely small, with a sweet-and-sour taste, a unique flavor, a refreshing juicy texture, and a crisp, pleasant aroma, making it an excellent fruit for fresh eating. Blueberries are rich in anthocyanins, polyphenols, flavonoids, VC and various other natural antioxidants, and have health benefits such as improving memory and eyesight, anti-aging, antioxidant effects, strengthening the human immune system, anti-cancer and antibacterial properties. The nutritional value of blueberries is far higher than that of apples, grapes, citrus and other fruits, and they can be called "the king of the world's third-generation fruits."

Blueberry is a new type of fruit with relatively high nutritional and health value, great development potential and broad market prospects. Blueberry is a shallow-rooted plant without root hairs; its root system is poorly developed, with many fine roots and very few thick, sturdy roots, appearing fibrous. At the same time, blueberry has relatively strict requirements for soil conditions; the most ideal soil type is loose, well-aerated, moist, acidic sandy loam or peat soil with high organic matter content [Jishan Huayao]. A pot experiment is one in which the medium is placed in a specially made container and the crop cultivation experiment is carried out under artificially controlled conditions. Because moisture, nutrients, and even temperature and light conditions can be strictly controlled, it is conducive to precise determination of the effects of various factors, and thus facilitates single-factor experimental research; it is an exploratory experiment that is difficult to carry out under field conditions. At present, there are many reviews on potted blueberry techniques, mainly summarizing and discussing variety selection and key technical points for potted blueberries, but there has been no specific study on their nutrient soil formulas and fertilizer ratios. Through studying the effects of different nutrient soil formulas and fertilizer ratios on the growth of potted blueberries, this paper aims to provide guidance for efficient field cultivation techniques for large-scale blueberry planting, and at the same time can meet people's need to cultivate potted blueberry plants on balconies and in courtyards for foliage, flower and fruit appreciation while beautifying the home environment.

1 Materials and Methods

1.1 Experimental Materials

Two-year-old robust cutting seedlings of the southern highbush blueberry varieties 'Shengshi' and 'Coast', from the seedling greenhouse of the scientific research base of the Institute of Cash Crops Breeding and Cultivation, Sichuan Academy of Agricultural Sciences, with seedling height above 25 cm. The pots used were plastic flower pots with an outer diameter of 30 cm, a height of 20 cm, and a bottom diameter of 18 cm. The fertilizers used were commercial organic fertilizer, monopotassium phosphate and ammonium sulfate, and potassium sulfate compound fertilizer; the biochemical agents were sulfur powder and phoxim.

1.2 Experimental Design

1.2.1 Nutrient soil formula experiment. A completely randomized single-factor experimental design was adopted, with 3 nutrient soil formula treatments, namely peat soil : sawdust : original soil mixed uniformly in ratios of 4:4:2 (A), 3:3:4 (B), and 4:3:3 (C) as the nutrient soil for potted blueberries. Each experimental treatment planted 10 pots, with 1 plant per pot, and 2 replicates. Before potting, an appropriate amount of sulfur powder needed to be added to the nutrient soil to adjust the acidity so that its pH value was between 4.5 and 4.8, which is the optimal soil pH value for blueberry growth [15]. Before the blueberry seedlings were planted and potted, 12.5 g of organic fertilizer and 7.5 g of phoxim were added to each pot and mixed evenly, after which potting and planting were carried out. This experiment was planted on October 9, 2015, and placed in an open-air experimental field.

1.2.2 Topdressing ratio experiment for potted blueberries. A completely randomized single-factor experimental design was adopted, with 4 fertilizer ratio treatments, namely Treatment 1: monopotassium phosphate and ammonium sulfate mixed at a 1:1 ratio; Treatment 2: monopotassium phosphate and ammonium sulfate mixed at a 2:1 ratio; Treatment 3: potassium sulfate compound fertilizer; CK: no chemical fertilizer topdressing as the control. One month after the potted blueberries were planted, 10 g/plant was applied according to the above fertilizer ratios every 15 d, dissolved in water first and then poured on as irrigation; each experimental treatment planted 10 pots, with 1 plant per pot, and 2 replicates. This experiment was planted on October 9, 2015, and placed in an open-air experimental field.

1.3 Survey Content and Methods

After the potted blueberries were planted, their plant height, stem diameter and number of basal shoots were measured as initial values; after 1 year of growth, their plant height, stem diameter and number of basal shoots were measured again, thereby calculating the growth increments of each potted blueberry under the different experimental treatments.

2 Results and Analysis

2.1 Effects of different nutrient soil formulas on the growth of potted blueberries. Compared with other fruit trees, blueberry has relatively strict requirements for soil conditions, requiring a soil pH value of 4.0-5.5, organic matter content of 8%-12%, and at least not lower than 5%, with a loose and breathable texture, good water-holding performance, and moist soil but no water accumulation. As shown in Table 1, the optimal nutrient soil formula for potted 'Shengshi' was a mixture of peat soil : sawdust : original soil = 4:3:3 (Treatment C), and the increases in plant height, stem diameter and shoot number were 26.33 cm, 2.06 mm, and 5, respectively; as shown in Table 2, the optimal nutrient soil formula for potted 'Coast' was a mixture of peat soil : sawdust : original soil = 3:3:4 (Treatment B), and the increases in plant height, stem diameter and shoot number were 37.00 cm, 3.12 mm, and 5, respectively. Analysis of variance showed that the different nutrient soil formulas for potted plants of the two blueberry varieties 'Shengshi' and 'Coast' had extremely significant differences in their effects on growth, among which plant height reached an extremely significant difference at the 0.01 level, with F values of 18.90 and 20.99, respectively. Therefore, the optimal potted nutrient soil formula differs among blueberry varieties, and potted blueberries need to have their nutrient soil formula adjusted according to the blueberry variety.

Table 1 Effects of different nutrient soil formulas on the growth of potted blueberries ('Shengshi')

Note: Capital letters in the same column in the table indicate significant differences at the 0.01 level. The same below.

Table 2 Effects of different nutrient soil formulas on the growth of potted blueberries ('Coast')

2.2 Effects of different topdressing ratios on the growth of potted blueberries

Blueberry is an oligotrophic plant, and its root system is relatively shallow, fine and without root hairs, so improper fertilization can very easily cause damage to the root system and the tree body. As shown in Table 3, for potted 'Shengshi' blueberries, topdressing with monopotassium phosphate and ammonium sulfate (2:1) mixed at 10 g/plant every 15 d (Treatment 2) had the best effect, and the increases in plant height, stem diameter and shoot number were 34.34 cm, 3.76 mm, and 5, respectively, among which the increase in plant height was 2.78 times that of CK; as shown in Table 4, for potted 'Coast' blueberries, topdressing with monopotassium phosphate and ammonium sulfate (2:1) mixed at 10 g/plant every 15 d (Treatment 2) had the best effect, and the increases in plant height, stem diameter and shoot number were 36.33 cm, 3.46 mm, and 2, respectively, among which the increase in plant height was 1.65 times that of CK. Analysis of variance showed that the different topdressing ratios for potted plants of the two blueberry varieties 'Shengshi' and 'Coast' had extremely significant differences in their effects on growth, among which plant height reached an extremely significant difference at the 0.01 level, with F values of 26.79 and 10.92, respectively. This indicates that the optimal topdressing ratio for potted blueberries is a 2:1 mixture of monopotassium phosphate and ammonium sulfate, and topdressing 10 g/plant every 15 d has the best effect, with blueberries growing well.

Table 3 Effects of different topdressing ratios on the growth of potted blueberries ('Shengshi')

Table 4 Effects of different topdressing ratios on the growth of potted blueberries ('Coast')

3 Conclusion and Discussion

There are many factors affecting the growth of potted blueberries, such as nutrient soil formula, fertilization ratio, water management, plant pruning, and pest and disease control. This study investigated the nutrient soil formula and fertilization ratio for potted blueberries. The results showed that the optimal potted nutrient soil formula differs among blueberry varieties, and the optimal fertilization ratio is a 2:1 mixture of monopotassium phosphate and ammonium sulfate, with topdressing of 10 g/plant every 15 d having the best effect, with blueberries growing well.

In terms of water management for potted blueberries, keeping the soil moist is sufficient; there must be no water accumulation at the bottom of the pot, otherwise it will lead to poor soil permeability and cause root rot. During the growth of potted blueberries, appropriate shaping and pruning should be carried out to balance the contradiction between vegetative growth and reproductive growth, thereby achieving the goals of ventilation, light penetration and air permeability, and realizing high yield and high quality. The cultivation technique for potted blueberries is relatively simple and makes it easier to grow them in home courtyards, balconies and on rooftops, which can both beautify the environment and allow a harvest of blueberries. Potted blueberries can be enjoyed for their foliage, flowers and fruit, enabling blueberry enthusiasts to create an ornamental art garden centered on blueberries in a short time, which helps the development and utilization of blueberry-related products and is conducive to promoting the development of blueberry-related industries.