Artificial promotion of seed setting of Pinus koraiensis

Pinus koraiensis as a tree species with long rotation period, in addition to considering wood income, it is a very important problem to tap the seed economic potential, shorten the capital return period and solve the short-term economic income. There are 800 hectares of Korean pine plantation in Fengcheng area, of which 3600 hectares enter the fruiting stage, with an average seed yield of 350kg per hectare in the bumper year, with a total output value of 13 million yuan. Further increasing the seed setting capacity of these stands can effectively promote the development of forestry economy in mountainous areas.

Before the sap flow in February 1998, we carried out the technique of cutting off the existing Korean pine plantation which had entered the fruiting stage, and the seed setting amount was greatly increased. In the course of operation, the trees that have been bifurcated and the lower trees in the forest shall not be cut off. Use artificial climbing trees, fasten seat belts, and use high branch shears to cut off treetops with different treatments within a few meters around. Each worker can complete 2 mu of woodland every day, and the labor cost is 300.50 yuan. One-time investment, no need to cut off again in the future. The stands with a density of about 1000 trees per hectare were cut off between the 3rd and 4th layers of trees, and the stands with a density of about 6 trees per hectare were cut off between the 1st and 2nd layers of trees.

Practice has proved that for about 30-year-old Pinus koraiensis plantation, the cutting-off technique can effectively increase the seed-setting amount of trees, with an average yield increase of 75.47%. The technology of promoting fruiting is an important means to effectively increase the economic potential of Pinus koraiensis plantation. The output value can be increased by more than 1100 yuan per hectare. One-time low-cost investment can benefit for a long time.

Do not cut off the stand that has not entered the fruiting stage for the time being. The purpose of truncation is to increase seed yield, but wood yield and lumber production should also be taken into account. It is best to choose a stand of more than 30 years old, with a trunk at least 10 meters high below the truncation, which can meet the timber needs of 8 meters, 6 meters and 4 meters.

For the stand with excessive density to promote fruiting, thinning should be done first. The thinning intensity was carried out according to the "Technical regulations for the Construction of dual-purpose Forest of Pinus koraiensis in Liaoning Province", and then cut off.

Control the period of seed collection. The initial period of seed collection should be controlled after September 15. At this time, the nutrient index of kernel reaches the maximum, the cone turns yellow, it is easy to fall off when collecting seeds, and it is not easy to damage the trees when collecting seeds. If the seeds are picked prematurely, the cones are greener and the stalks grow firmly at the top of the treetops, which will easily break the tree head and cause artificial second amputation, resulting in low yield for many years. In addition, early seed collection, poor seed quality, low 1000-grain weight and kernel yield, and low nutrient content can not meet the requirements of export commodities, so it is easy for purchasers to identify, resulting in a decline in price, high yield but not bumper harvest. and will seriously affect the seed brand image of the region.