How to Grow Daya Mandarin? Detailed Cultivation Techniques for the Improved Harumi Variety

Daya mandarin was bred by the Chinese Citrus Research Institute by crossing Kiyomi orange × new line No. 3 ponkan. Its fruit appearance and tree body closely resemble Harumi, but its quality surpasses Harumi, so some people call it “improved Harumi.” So, what cultivation techniques does Daya mandarin require?

1. Basic Introduction to Daya Mandarin

1. Variety Characteristics

Tree characteristics: The tree is relatively vigorous, with strong shoot-sprouting ability and rapid canopy formation; before fruiting, the tree shape is relatively upright, gradually opening up after fruiting, with a round-headed canopy. Leaves are light green, acuminate, with shallow serrations on the margins and mostly notched tips, and nearly linear wing leaves; some spring shoot leaves are twisted and curl inward; flowers are relatively large with high pollen viability.

Phenological period: Budding from late February to early March, spring shoot growth and leaf expansion from late March to early April; flowering in mid-to-late April; summer shoot sprouting in mid-May and June; fruit enlargement begins in late June; autumn shoot sprouting in mid-to-late July; fruit begins to color in mid-to-late October; fully ripe from late January to mid-February of the following year, and can be left on the tree until April at the latest.

Fruiting habit: Spring shoots and early autumn shoots serve as fruiting mother branches, and fruiting branches are mostly leafy flower branches, with a high fruit-setting rate.

Fruit traits: Ripe fruit has an orange-yellow surface, fine and dense oil cells, smooth and glossy, with relatively thin peel that is very easy to peel. The fruit is relatively large, generally seedless, occasionally with a small number of seeds under mixed planting conditions, polyembryonic, with excellent overall quality.

2. Main Advantages

High fruit-setting rate, strong early fruiting and high yield, marketed during Spring Festival, high yield, high sugar, delicate flesh, and excellent quality.

3. Some Shortcomings

The peel is thin, and fruit left on the tree over winter is susceptible to low-temperature freezing damage, requiring bagging and delayed harvest, which raises production costs; it is not tolerant of storage and transport, with high losses.

2. Cultivation Techniques for Daya Mandarin

1. Rootstock Selection

For planting in acidic soil, rootstocks such as trifoliate orange and red tangerine can be used, but for planting in weakly alkaline soil, it is recommended to use vigorous rootstocks such as fragrant orange.

For top-grafting to change varieties, consider grafting onto trees such as mandarin, ponkan, Jincheng orange, and navel orange, which come into production more quickly.

2. Fertilizer and Water Management

Daya mandarin has strong shoot-sprouting ability, a high fruit-setting rate, good yield, a long fruit-bearing period, and high nutrient demand, so water and fertilizer supply must be ensured to keep the tree vigorous and achieve high, stable yields.

Young trees: Follow the principle of frequent light applications, mainly soil application supplemented by foliar fertilizer. After planting, water to settle the roots; after 1 month, topdressing can begin, applying Sea Elf biostimulant (soil application type) + quick-acting nitrogen fertilizer 1-2 times per month; in late October, combine with hole expansion and soil improvement to heavily apply organic fertilizer.

Fruiting trees: Apply pre-flowering fertilizer before spring shoots sprout, mainly nitrogen fertilizer combined with drenching Sea Elf biostimulant (soil application type); because Daya mandarin has a high fruit-setting rate, fruit-stabilizing fertilizer can be applied sparingly or not at all; heavily apply fruit-swelling fertilizer by trenching in organic fertilizer + balanced or high-potassium compound fertilizer + medium and trace element fertilizer; after October, depending on tree vigor, an additional pre-harvest fertilizer can be applied, mainly phosphorus and potassium fertilizers and organic fertilizer, supplemented with a small amount of nitrogen fertilizer, to facilitate on-tree preservation.

3. Pruning and Shaping

Basic principles: Create a compact, full, and sturdy canopy framework; facilitate full utilization of light and achieve a balance between vegetative growth and reproductive growth; facilitate three-dimensional fruiting; facilitate early production and high, stable yields.

Daya mandarin branches and shoots are relatively upright, with very strong branching and shoot-forming ability. When shaping and pruning young trees, attention should be paid to opening up the tree shape, combining thinning and heading back, improving branch quality, and increasing ventilation and light penetration.

For fruiting trees, spring shoots and autumn shoots should mainly be thinned, removing crowded branches that affect light, cutting out strongly upright and water sprout branches, avoiding excessive shoot vigor that affects fruit set the following year, and retaining more moderate branches. Summer shoots and late autumn shoots should mainly be controlled.

4. Flower and Fruit Management

Because Daya mandarin has a relatively high fruit-setting rate, it will set fruit in clusters and strings even without any flower- or fruit-preserving agents. When fruit-preserving agents such as gibberellin and cytokinin are used, they can easily cause puffiness and quality decline, so spraying Sea Elf biostimulant (foliar type) during the young fruit stage is sufficient.

Excessively high yields of Daya mandarin not only affect quality but also lead to weakened tree vigor, yellowing trees, and even dead trees. Attention should be paid to flower and fruit thinning and moderate fruiting to reduce alternate bearing and ensure fruit quality.

Because the peel is thin, fruit left on the tree over winter is susceptible to low-temperature freezing damage. In production, bagging should be carried out in mid-October, and film should be applied in time during low-temperature periods in winter to protect against cold and freezing.

The suitable harvest period is from late January to mid-to-late March of the following year. Avoid leaving fruit on the tree too long, which affects quality and tree vigor.

5. Pest and Disease Control

Its main diseases include anthracnose, scab, greasy spot, and huanglongbing, and its main pests include red spider mite, rust mite, citrus leafminer, citrus leaf beetle, and aphids. Comprehensive control should be achieved by strengthening cultivation management, enhancing tree vigor, using pesticides scientifically, and protecting natural enemies.