What are the ways that poplar trees spread their seeds?

Poplar is a plant of the genus Populus, also known as hemp willow and centipede willow. It is distributed across most of China and is mostly used as a street, landscape and shelterbelt tree species. So what are its ways of spreading seeds?

1. What are the ways that poplar trees spread their seeds?

Naturally growing poplar trees rely on wind to spread their seeds. Once its fruit matures, it opens on its own, and at that time the poplar catkins fly everywhere, scattering seeds everywhere. Modern poplar seeds, however, are all sown by hand.

2. How are poplar trees planted?

1. Propagation

Poplar trees can be propagated by sowing or by cuttings. Among these:

Sowing: Collect seeds by cutting off the fruit clusters or gathering them from the ground, and it is best to sow them as soon as they are collected. Sow and raise seedlings on sandy loam soil rich in humus.

Cuttings: One-year-old cutting seedlings can be used, and the lower-middle portions of first-grade and second-grade seedlings are preferable as propagation material. Third-grade seedlings are not well developed and cannot be used as propagation material; the tips of second-grade seedlings, parts with poor lignification, and seedlings affected by pests or diseases cannot be used as propagation material. Cutting is best done in early February to early March, inserted upright, with the cutting inserted 2/3-3/4 into the soil. Be careful not to insert it upside down, and after insertion firm the soil and water once.

2. Management

From the time of cutting until the cuttings begin to root and unfold leaves generally takes 2-4 weeks. During this period the cuttings are most likely to lose water balance, their stress resistance is very weak, and cuttings that cannot root in time will wither and die. For example, in April 2007, during the critical period when the cuttings were rooting, there was no rain for nearly a month, causing the survival rate of many newly cultivated poplar nurseries to be only about 70%. Therefore, maintaining suitable soil moisture during this period is the key point of management. If there is severe drought, irrigate thoroughly once, and after irrigation promptly hoe shallowly to loosen the soil to prevent surface crusting, otherwise the survival rate will also decrease.

3. Topdressing

After poplar trees are planted and survive, topdressing can be done that same year, and applying it twice, in early May and late July, gives better results. In the year of planting, it can be applied less and later; after the young forest closes, it can be applied appropriately more. The type of topdressing is generally mainly quick-acting nitrogen fertilizer. Each year per 667 sq m (1 mu), 15 kg of urea and 30 kg of ammonium bicarbonate can be applied, with half of the annual fertilizer amount applied each time. Spring topdressing is mainly ammonium bicarbonate and binary compound fertilizer; at this time the ground temperature is low, and urea has slow fertilizer efficiency and poor results.

4. Pruning

For trees 1 to 3 years old, prune as little as possible or do not prune, and keep more branches and leaves; for trees 4 years old and above, pruning should be done after leaf fall in autumn and winter until before budding the following spring. During the tree's dormant period, pruning should focus mainly on thinning; when thinning branches, the cut or saw cut should be smooth, leaving no stubs. During the tree's dormant period, pruning should focus mainly on thinning; when thinning branches, the cut or saw cut should be smooth, leaving no stubs.