The Latest High-Yield Cultivation Techniques and Methods Tutorial for Kyoho Grapes
The Kyoho grape variety is a European-American hybrid. In the autumn of 1954, a delegation from Okayama University of Japan visiting China presented 4 cuttings, which were propagated by Beijing Agricultural University and began to spread nationwide in the 1960s. At present, among the table grape varieties sold on the market, Kyoho grapes have large clusters, large berries, bright color, thick flesh, and a balanced sweet-tart taste, and are highly favored by consumers. In cultivation and management, several key technical points should be handled well:
Main characteristics of Kyoho grapes
1. Buds break in early to mid-March, blooms in early May, about 138 days from bud break to maturity, active accumulated temperature 3132°C——3412°C.
2. Good flower bud differentiation, stable yield.
3. Leaves: medium-sized leaves, generally leaf area 138.9 square cm, maximum leaf area at the pinch point 230 square cm.
4. Stress resistance: susceptible to black pox, gray mold, rachis brown blight, and downy mildew.
Symptoms and causes of poor fruit set
Poor fruit set has two situations: one is low fruit set rate with severe flower and fruit drop; the other is relatively good fruit set, but the cluster has severe large and small berry unevenness, with normal seeded large berries accounting for a small proportion, while abnormal seedless small berries are numerous.
The main causes of poor fruit set in Kyoho grapes are:
1. Abnormal floral organs. The ovule abnormality rate of female organs is high, reaching 76.8%, and only 23.5% can carry out normal ovule flowering and pollination.
2. Long fertilization time. Completing the entire pollination requires about 120 hours. If affected by poor nutrition or adverse environmental conditions, fertilization aborts midway, causing fruit drop.
3. Hormone imbalance in the plant. In flower buds with poor fruit set, the content of gibberellin A3 and cytokinins is relatively high, which can accelerate ovule development and maturation, while pollen tube germination remains relatively slow. As a result, the maturation processes of male and female organs do not coincide, and most ovules miss the opportunity for fertilization, leading to flower and fruit drop.
4. Overly vigorous and unbalanced tree vigor. Overly vigorous new shoots not only promote increased content of hormones such as gibberellin A3 in floral organs, but also compete with flowers for nutrients, weakening reproductive growth, causing fertilized young embryos to abort midway, and increasing ovary abscission and seedless small berries.
5. Environmental factors. When daytime temperature during flowering is below 20°C, the proportion of seedless berries increases, and rainfall washes away the secretion on the stigma, causing pollen to fall off.
Key cultivation techniques
Goal: increase fruit set rate, reduce fruit drop, stabilize yield
1. Control nitrogen fertilizer before flowering and control tree vigor. Before flowering, new shoots should be controlled below 70 cm, which is favorable for fruit set; if new shoot length reaches above 80 cm before flowering, fruit set is low. The main measures to control new shoot growth are controlling nitrogen fertilizer and water before flowering. For vineyards with medium fertility, apply less base fertilizer; per mu, 0.5 tons of chicken manure and 100 jin of phosphate fertilizer can be applied, with no pre-bud fertilizer. After fruit set, per mu, 100 jin of compound fertilizer + 40 jin of potassium sulfate can be applied, divided into 2 applications with a 10-day interval. During the hard-core stage, apply 40 jin of potassium sulfate per mu; for vineyards with many fruits, apply 20 jin of compound fertilizer per mu. Apply appropriate potassium fertilizer again as coloring fertilizer.
2. Pinch shoots before flowering. Pinch 3—5 days before flowering up to the visible flowering stage. Weak shoots can be pinched leaving 5—6 leaves above the cluster; vigorous shoots can be pinched leaving 3—5 leaves above the cluster. After pinching (5 days), the plant enters the flowering and fruit-setting stage, and a large amount of nutrients is concentrated in the cluster, which is favorable for fruit set.
⟦NL>3. Spray mepiquat chloride on leaves before flowering
The mepiquat chloride aqueous solution (mepiquat chloride) produced by Jiangsu Nantong Shizhuang Chemical Co., Ltd. has an effective ingredient content of 25%. Each bottle of 15 mg is diluted with 15 jin of water; for vigorous growth, the concentration can be increased to one bottle diluted with 12 jin of water, sprayed 5—7 days before flowering.
4. Yield-controlled cultivation
High-quality fruit enters supermarkets; yield per mu is controlled at 2500 jin, with 3400 clusters per mu. Generally, yield per mu should be controlled at about 3500 jin, with a vine-to-fruit ratio of 1:0.8—1:1. Each cluster should retain 20—25 effective leaves. For the 3—5 leaves above the cluster, do not retain secondary shoot leaves; starting from the 5th leaf above the cluster, retain secondary shoot leaves. Each cluster should retain 40 berries. At present, many vineyards in production exceed 4000 jin in yield, and the concept of high yield with low-price sales should gradually change.