Key Cultivation Techniques for Early Fruiting and High Yield of the Large Mayaw Date Jujube

Cultivation Techniques for Early Fruiting and High Yield of the Large Mayaw Date Jujube

1 Planting

The quality of planting stock is the foundation for early fruiting and high yield of the Large Mayaw Date Jujube, directly affecting the survival rate, growth speed, time to fruiting, and uniformity of the orchard.

1.1 Rational Planning with Suitable Density

Before planting, level the land first. To facilitate mechanized operations, leave access paths. The planting density should preferably be 55 trees per 666.7 sq m.

1.2 Timely and Prompt Planting

The best planting time for the Large Mayaw Date Jujube is spring, and the later before bud break, the better. Plant promptly in the suitable season. The planting sequence is: first mechanically dig the holes, then lift the seedlings, and plant them as they are lifted, transported, and planted, minimizing the time from lifting to planting. For long-distance transport of seedlings, proper packaging and transport must be ensured to minimize water loss. If the time from lifting exceeds 2 days and water loss is severe, soak the seedlings in water until they have absorbed enough water before planting.

1.3 Dig Large Holes, Press in Straw, Apply Base Fertilizer

Dig planting holes of 80 cm x 80 cm x 80 cm, and place the excavated subsoil and topsoil separately. Before planting, mix 5 kg of straw into the subsoil and backfill 20 cm to increase aeration and raise organic matter content; apply 30 kg of farmyard manure to the middle and lower layers, do not mix fertilizer within 40 cm of the ground surface, and bury the topsoil around the root zone to prevent fertilizer burn to the roots. After planting, water thoroughly immediately, leaving a tree basin of 1-1.5 m. Then cover the tree basin with 15 cm of straw, or cover the straw with plastic film, which serves to increase soil temperature, conserve moisture, loosen the soil, prevent weeds, increase fertilizer efficiency, and improve the soil, benefiting the growth of newly planted jujube seedlings. [Jishan Huayao]

2 Fertilizer and Water Management

2.1 Management Before Fruiting

Apply quick-acting chemical fertilizer once before bud break and once in mid-July. In the first year, apply 100 g per tree each time, increasing by 100 g per year thereafter. Water immediately after topdressing. In the autumn of the third year, carry out expanded-hole fertilization: dig a trench 0.5 m wide and 0.6 m deep outward from the original planting hole, fill the lower layer with topsoil mixed with 5 kg of crop straw per tree, mix the surface soil with 20-30 kg of farmyard manure plus 1 kg of NPK compound fertilizer and apply it to the middle layer where the main roots are distributed, then backfill and water. During the growing season, carry out foliar topdressing together with pest and disease control.

2.2 Management After Fruiting

The Large Mayaw Date Jujube enters the fruiting stage 3 years after planting. Management after fruiting is basically the same as before fruiting, but as the tree continues to grow and yield continues to increase, the amount of fertilizer applied must increase year by year. According to experiments: producing 100 kg of fresh jujubes requires 1.5 kg of nitrogen, 1 kg of phosphorus, 1.3 kg of potassium, and 300 kg of farmyard manure. Based on this index and the annual yield, the annual fertilizer application per tree can be calculated. Expanded-hole deep-digging fertilization is best done once every year. If it cannot be done once a year, then at least once every 2-3 years. As the canopy expands, the tree hole should also expand accordingly. Once the canopy stops expanding, when the tree hole area equals the canopy projection area, stop expanding the hole, and change the base fertilizer application to radial trench application at a depth of 40 cm.

3 Pruning

The Large Mayaw Date Jujube has two types of buds, primary and secondary. The secondary buds are sensitive and readily sprout to produce secondary branches and fruiting spurs, which are the fruiting branch system. Secondary branches have small growth, and the fruiting spurs drop off in autumn of the same year; neither contributes much to tree growth and canopy expansion. The primary buds sprout jujube heads, which are the basis for canopy expansion and tree growth, but primary buds are sluggish and not easy to sprout. Terminal primary buds sprout more easily than lateral primary buds, but can only extend upward in a single axis and cannot expand laterally. Only jujube head branches sprouted from lateral primary buds can grow laterally to expand the canopy, but lateral primary buds are especially sluggish and will not sprout without strong stimulation. This is the main reason for the slow growth of jujube trees. To promote the sprouting of lateral primary buds, shorten and pinch the trunk and scaffold extension branches, placing the lateral primary buds that need to sprout jujube head branches in the apical dominance position, promoting plumpness and differentiation, improving sprouting ability, and forcing jujube head branches to sprout, thereby achieving rapid canopy expansion.

3.1 Trunk Heading and Scaffold Branch Training

The open-center tree shape is suitable for the Large Mayaw Date Jujube. For trunk heading, cut off the terminal primary bud so that the lateral primary buds intended to produce branches are in the apical dominance position, sprout jujube head branches, and promote lateral canopy expansion. The trunk heading height is generally 1-1.2 m. In the second year, select and retain 4-5 vigorous jujube heads evenly distributed in planar angle across the whole tree and train them as scaffold branches. When the jujube heads grow to 70-80 cm (late June), pinch the tips to control growth, plumping the lateral primary buds below the pinching point to facilitate branching the following year. In the third year, before the jujube heads sprout, in conjunction with spring pruning, remove the 3 secondary branches below the pinching point of the scaffold branches to promote the sprouting of lateral primary buds. Of the sprouted jujube head branches, the first serves as the extension branch of the scaffold branch, and the second and third are trained as side branches, and in mid-to-late June, pinch the tips of branches that have grown to 80-100 cm. Thereafter, continue the above operations each year according to available space. The tree shape can be formed in 4-5 years and enter the high-yield period.

3.2 Pinching of Jujube Heads

According to the growth position and available space of non-scaffold jujube head branches, pinch them at different times in May. Scaffold jujube heads are pinched when they grow to about 80 cm in early-to-mid June. Pinching of jujube heads includes pinching the terminal bud and pinching the side buds. Although pinching the terminal bud inhibits vertical growth at the tip, it promotes lateral growth of secondary branches, dispersing one terminal center into several lateral growth centers. Therefore, only by pinching both the terminal bud and the side buds can the vertical and lateral growth of jujube heads be fully controlled and the load-bearing capacity of jujube heads increased. The suitable time for pinching secondary branches depends on their growth length, generally when they have grown to 15 nodes.

3.3 Trunk Girdling

Pinching of jujube heads in the Large Mayaw Date Jujube has a certain effect on inhibiting aboveground growth and improving fruit set rate, but it also has limitations: the farther from the pinching point, the smaller the effect. In addition, after aboveground jujube heads are pinched and stop growing, underground root growth is further strengthened. The massive root growth draws nutrients from the upper part of the tree downward, and the closer to the roots, the more is drawn away, resulting in poor fruit set in the lower parts of the canopy and main branches. To solve the problem of poor fruit set in the lower part of main branches, after 5 years when the canopy is formed, girdle the trunk in late May. The girdling cut should be 0.5-1.0 cm wide, flat on top and slanted at the bottom, wider outside and narrower inside, deep to the xylem but without damaging the xylem. Then peel off the bark so that aboveground nutrients temporarily cannot be transported downward and concentrate in the aboveground part for flowering and fruiting, improving the fruit set rate.

3.4 Reasonable Arrangement and Layout of Jujube Heads

Jujube heads include scaffold branch jujube heads and fruiting branch system jujube heads. Scaffold branch jujube heads are scientifically arranged through rational shaping. Fruiting branch system jujube heads are arranged on scaffold branches at all levels according to available space, staggered in position above and below, left and right, alternating in size, and rationally laid out. The general principle is: maintain a certain distance between branches so they do not affect each other and favor ventilation and light penetration. Without affecting light, arrange as many jujube heads as possible to expand fruiting positions and increase yield.

3.5 Carry Out Pest and Disease Control Well

The main diseases harming the Large Mayaw Date Jujube are ring rot and jujube rust. The main pests are green plant bugs, red spider mites, jujube gall midges, jujube leaf roller moths, etc. Timely pest and disease control is an important part of early fruiting and high yield cultivation management of the Large Mayaw Date Jujube. The policy of prevention first and integrated control should be implemented, adopting manual control, physical control, and biological control, combined with chemical control, minimizing the use of pesticides to protect natural enemies, prevent environmental pollution, and save costs. In chemical control, seize the key period, select the right pesticide, master the correct concentration, and spray evenly and thoroughly to achieve early and effective control.