A Detailed Guide to Selecting and Propagating Tree of Heaven Seeds

The tree of heaven can be said to be a fairly common tree in rural areas. Its flowers are white-green in color, and its fruit is a samara. Generally speaking, it rarely lives beyond fifty years. Some people also deliberately plant tree of heaven. So how should its seeds be selected? What are the propagation methods? If you want to know, read on!

1. How to select tree of heaven seeds

When buying tree of heaven seeds, growers should learn to judge seed quality themselves and select high-quality seeds. Generally, this is done by appearance: choose seeds that are plump and undamaged, and the seeds must not have a musty smell or be too damp. Such seeds will not have a high germination rate, and the plants grown from them will not perform well.

2. Propagation methods for tree of heaven seeds

1. Seed collection and treatment

Select vigorous mother trees 15-30 years old for seed collection. In September-October, when the samaras mature, cut them off together with the small twigs, turn and sun-dry them for 4-5d, and after drying and cleaning the seeds, store them by the dry storage method. It is required to use winged seeds with a purity of 85%-88%, a germination rate of about 70%, and a 1000-seed weight of more than 28 grams. Before sowing, first remove the seed wings (removing the wings is also optional), soak in 40°C warm water for 24 hours, then soak in clean water for 12 hours, skim off the floating empty seeds and debris, take out the sunken plump seeds (germination rate 88%-94%) and spread them flat in a wind-sheltered, sunny place to let the surface moisture evaporate, then soak them for 2 hours with gibberellin, 50×10-6 rooting powder, or 2 grams of yield-increasing hormone, then mix them with fine river sand at a 1:1 ratio, pile them in a warm, sunny place, cover with a straw curtain or wet burlap to promote germination, spray with clean water once a day to maintain humidity, and after about 7-8 days, when 40% of the seeds have split open, they can be sown.

2. Sowing time

The suitable temperature for tree of heaven seed germination is 9-15°C, and spring sowing is generally the main method. Tree of heaven seedlings are sensitive to damage from late frost, so spring sowing should not be too early. In Sichuan, late March to early-to-mid April is suitable, and the sowing rate should be 15-22 kg/hectare. If too late, the temperature is higher, which is not conducive to seedling growth.

3. Raising seedlings

The nursery site should be flat, with fertile soil, facing the sun and sheltered from the wind, and preferably with irrigation conditions. Before sowing, irrigate the nursery land thoroughly, then deep-plow and prepare the land. While preparing the land, apply an appropriate amount of organic fertilizer, rake and level it, build up the bed ridges, and make the seedbed. Generally, the bed width is 1.0-1.2 m, and the length depends on the site, with the bed surface kept level. The sowing rate is 3-5 kg per mu. For drilling, the row spacing is 0-40 cm, the sowing furrow depth is 3-4 cm, the sowing rate is 60-70 seeds/m, the covering soil thickness is 1.0-1.5 cm, and lightly press down. After sowing, cover the rows with grass to keep the surface moist, which helps the seeds emerge. If two-stage seedling raising is used, first in the mother bed and then transplanted at a sparse spacing, the sowing rate can be doubled.

4. Watering and weeding

After spring sowing, the young shoots begin to emerge in 4-6 days (emergence stage). At this time, watering is strictly prohibited; otherwise, soil crusting will affect seedling emergence. The focus should be on raising temperature and preserving soil moisture to promote early and complete emergence. In 10-15 days after sowing, the seedlings emerge completely. When the seedlings grow to 3-4 cm tall, carry out the first watering (thorough watering), but strictly avoid watering before emergence. During the entire growth process of the seedlings, water appropriately according to their physiological characteristics and the degree of soil dryness and wetness, but never allow water to accumulate in the nursery land (especially in the rainy season, drain if necessary); otherwise, the seedlings will rot at the roots, causing unnecessary losses. Weeds must be removed early, when small, and completely, and the number of cultivations must not be fewer than 6-8 times.

5. Thinning, planting out, or sparse transplanting

Thin the seedlings when they reach 3-14 cm tall, and finalize the stand when they reach 8-10 cm tall. Sparse transplanting should be carried out with a plant spacing of 20 cm; if growing large seedlings, the plant spacing is 40 cm. From late June to early July, when the seedlings reach 20-30 cm tall, they are in a slow-growth stage. At this time, dig down to a depth of 15-18 cm on the shady side of the seedlings and cut off the main root, then backfill and firm the soil, and at the same time water thoroughly once. If two-stage seedling raising is used, when the seedlings reach 8-10 cm tall, sparse transplanting should be carried out with a plant spacing of 20 cm. Root cutting is no longer carried out.

6. Fertilization

In the field used for raising seedlings, phosphate fertilizer should be applied as a base fertilizer. After finalizing the stand or sparse transplanting, topdress (urea) 2 times successively from May to July, applying about 150 kg per hectare each time.

7. Leaving the nursery

For spring seedling raising, in the autumn of the same year, each hectare can produce about 120,000 seedlings with a ground diameter of more than 1.0 cm and a height of more than 100 cm. If growing large seedlings, in the second year they can be planted out at a row spacing of 40×80 cm. In addition to routine loosening of the soil and weeding, focus on supplying water and fertilizer to promote rapid seedling growth. From May to July, apply fertilizer 2-3 times, generally urea at about 150 kg per hectare each time.

The above is all the content the editor wants to share with you today. If you are thinking of planting tree of heaven, you still need to pay extra attention when selecting seeds, and then learn some related propagation methods. I hope this article can help everyone!

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