V. Seed Garden Management
(1) Tree Management
The ultimate goal of seed orchard management is to mass produce seeds with improved genetic foundations. Tree management is particularly important. The ideal tree shape is best dwarfed like a fruit tree. Larix principis-rupprechtii is the main tree species for afforestation in the mountainous areas of northern Fujian. It grows rapidly and has a tall tree. It should pay more attention to tree management. The related tree management was carried out according to the different ages and growth status of the mother trees in the garden.
1. After many years of growth, the truncated parent tree has a stronger apical dominance, and the faster it pushes forward, the more difficult it is for the seeds and other operations. Based on this, the field began to truncate the primary garden in 1996, once every two years, and controlled the high growth and promoted the horizontal development of the crown. Larch has a strong apical apex. After the top of the cut, it will have a new main shoot. Even a few shoots will be born at the same time. Therefore, the top cut cannot be achieved overnight. It must be processed until the growth of the mother tree is stable, and the height of the mother tree after truncating is maintained. At 8 to 10m, due to breaking the apical dominance, it promotes the vigorous growth of the mid-lower lateral branches, facilitating seed collection operations.
2. After many years of growth, the mother trees in the pruning and trimming garden naturally produce inner litchi, dead branches, weak branchlets, and dense stem branches in the lower part of the canopy, which seriously affects the light environment of the entire tree. The base performs stronger pruning of mature trees prior to the sap flow from March to April, maintaining 5 to 6 main lateral branches per round, with a track length of 60 to 100 cm. As a result, the conditions for ventilation and light transmission within the canopy are greatly improved, and new branchlets are created at the main lateral branch, which increases the area for seedlings in the following year.
Saplings and juvenile mother trees are lightly trimmed or anviled and trimmed.
3. After the progeny test, the mother trees of the thinning orchard seedlings will be cut off from those clones with poor genetic quality, which will increase the light in the garden and promote flowering and fruiting. Practice has shown that thinning is more productive and quality is better than non-leaving in the prosperous year. For example, in the Longtou Mountain seedlings planting base, the primary gardens have been thinned one or two times since 1995, and the results are good.
(b) Soil Management
The distance between the mother trees in the seed orchard is large. Especially in the young stage, bare forest land creates conditions for the growth of weeds. Therefore, we must conduct comprehensive cultivator and weed control, and implement horizontal leveling and soil preparation in the mountains. The soil within the 1m range of the mother tree is kept loose and no weeds grow. In order to grow and develop root system. Every year, we must do 1-2 times of loose soil weeding. Conditional green manure crops can be grown. It is conducive to growth and flower bud differentiation of the mother tree.
(III) Water and Fertilizer Management
Appropriate water and fertilizer management is conducive to promoting the growth and development of mother trees, early formation of flower buds, increase seed yield and quality, reduce the size of the phenomenon of seedling size. Reasonable fertilization should be based on the growth stage of the mother tree. Different application amounts and methods from colonization to maturity application. Practice has proved that in the young stage should be dominated by nitrogen fertilizer to promote its growth and development. In the middle age stage, due to the large amount of solid harvest, phosphorus and potassium fertilizers should be used as the main supplement to supplement the nutrients consumed by flowering. Aging time should be combined with pruning and shaping nitrogen and phosphate fertilizers, so that the mother tree reduces the rate of decline. In short, in order to ensure stable and high yield of seed orchards under conditions permitting, regular water and fertilizer management should be maintained throughout the growing season.
(d) Pollen Management
In the management of seed orchards, in addition to the rational allocation of clones at the initial stage of colonization, consideration should also be given to the uniformity of flowering periods, isolation measures, weather conditions during pollination, etc. within a clone and other clones during the process of open pollination. In the case of self-inflorescence or cross-fertilization, it depends on where the pollen is first reached, where the pollen from the female flower is coming from, in order to reduce self-pollination and improve the conditions for cross-pollination, especially when it is possible to grant supplementary pollination to increase The pollen concentration, in turn, reduces the chance of self-pollination. Especially in young seed orchards, attention should be paid to supplementary pollination.
Auxiliary pollination will have certain benefits, because the pollen source is an excellent pollen collected by a good mother tree. Can improve seed quality; increase seed production; expand genetic basis.
For example, in the Longtoushan Seedlings and Breeding Base, in 2001, the auxiliary pollination operations were carried out for the 10 clones of the improved Daiyuan 1 plot in the early stage of fertility. Compared with the control, the seed filling rate was significantly improved, and the pollen source was 5 excellent. Family mixed pollen and 60% talcum powder (talc powder dilution effect).
Table 2-10 Effects of Auxiliary Pollination on Seed Orchard Solidification
The number of filled seeds per cone
As can be seen from Table 2-10, assisted pollination is 122% of the number of open pollinated spherules. For the entire cell, it can be seen as extraordinary.
The method of pollination is to select a certain number of good types and mix their pollen. When the female ball is to be taught, when a duster made of gauze and bamboo sticks stabilizes in the early morning air, the duster is slightly shaken at the strong part of the canopy about 1.5 meters from the mother tree, and the pollen floats to the crown. Then make a mark.
(v) Pest control
Litter seed pests will seriously affect the yield and quality of seeds. Among them, Larch cones are the most common. Due to its special larvae feeding on seeds, it is the main pest that causes significant reduction in seed production. To a certain extent, the prevention and control of larch cone flies in the operation and management of seed orchards is one of the most important issues (for specific prevention and control methods, see the section on control of larch cone flies in Chapter 7).
Six, genetic testing
(I) Creation of offspring determination forest
The main task of offspring determination is to assess the genetic quality of the parents through the performance of offspring forests. In the management of seed orchards, it is mainly the selection of clones with high general combining ability to establish high-generation seed orchards. The following issues should be noted in the process of determining the forest construction process for offspring:
(1) The nursery and afforestation sites must be suitable for the growth of their tree species, and the conditions must be consistent and consistent.
(2) Seedlings determined for offspring must be treated in the same manner for seedlings, packaging, transportation, and planting.
(3) The soil fertility, slope, and aspect of afforestation sites in the district should be relatively consistent.
(4) 5 to 10 plots of plots are used for field design, and the district team must have more than 3 repetitions.
(5) The entire process is strictly managed to prevent the test serial numbers from being mixed and lost.
(6) Using the general seedlings of the tree species or other seedlings with assessed significance as a control, no inferior seedlings or seedlings of unknown origin can be used as controls.
(II) Investigation and filing
Timely investigation and filing is the basic requirement for the management of high-quality base technology files. In the process of genetic determination, the management measures, observation data, suggestions for data analysis, parental sources, measurement methods, management methods, measurement time, etc. shall be recorded in detail in order to carry out the results analysis and prepare the report. .
(III) Determination of genetic gain
In the construction of seed orchards, objective evaluation of genetic gain is crucial. For a long time, with the support of the Provincial Academy of Forestry, the Longtoushan seedlings improved seed base has created 417 hybrid combinations and 318 elite trees in the vast areas of the paddock dam, the Weibei Mountains, and the Taihang Mountains. Multi-point genetic assay Lin. In the autumn of 1980, 138 families and 30 cross combinations in 185 North China larch families in the primary park were used to create 2 hectares of free-pollinated progeny forest of North China larch and 3 hectares of full-sib progeny forest. Five plots, 6 to 10 repetitions, spacing 1Ã—2 meters, four years after the afforestation survey, in 1988 by the provincial Academy of Forestry breeding expert calculation analysis, the genetic gains of the seed orchard descendants was 23%. After multi-index cluster analysis, 40 excellent families were selected and their genetic gain was 57%. At the same time, 17 excellent trees were selected as full-sib progeny. The genetic gain was 65%. These families were retested several times later. The traits are stable. Later, using these excellent resources to establish a new generation of orchards. In the fall of 2002, 40 hectoli families, 50 cross combinations, and 32 cross hybrids were used to create 6 hectares of testing forests. This batch of surrogate forests will provide scientific basis for the promotion of future generations of high-generation seed orchards and larch varieties.
VII. Analysis of the operating benefits of seed orchards
Taking Mengliang Forest Management Bureau's Longtoushan seedlings breeding base as an example, 343 clones of various types have been invested so far, from the primary park to the 35 production areas of the improved Daiyuan and the Hybrid Garden. The seed garden area is 63.5 hectares. By 2001, the orchards had yielded an excellent seed of 1471K with a genetic gain of 23%. After the seedlings are cultivated, a total of 7400 hectares can be planted (afforestation density of 4950 plants/ha). These improved stands can shorten the production cycle to 25 years. It will be used in the middle 10 years after afforestation, and it will be used three times in the middle. It will create net income of 63,500 yuan per hectare during the final harvest period. Compared with common seedling plantation forests, these fine-grained stand stands can have an income of 88.356 million yuan at 25 years of age. The larch seedlings breeding base of Longtoushan has played and is playing an irreplaceable role in accelerating the pace of eco-environmental construction and revitalizing the regional economy.
Calculation basis for input and output: 20% of management fee, three times of tending construction cost 45 yuan/m3, construction cost of main cutting 60 yuan/m3, 10% of agricultural special product tax, 70% of material yield, average price of wood 500 yuan/m3 ( Current market price). The amount of material produced for the main logging and the amount of intermediate utilization materials are calculated based on the experimental forest data created in 1980.
135m3 Ã— 500 yuan = 67500 yuan per hectare;
The middle use of production materials 90m3 Ã— 200 yuan = 18,000 yuan;
The net income per hectare is 85,500 yuan (the sum of the final and intermediate utilization value) - 5,000 yuan (forestry cost fee) - 8100 yuan (full cost of the final cutting) - 8550 yuan (agricultural special product tax) = 63,850 yuan
Genetic gain (increased yield of wood):
General forest harvesting: 63,850 yuan Ã· 123% = 51,910 yuan (net income per hectare); improved seedlings afforestation of forest growth after harvesting wood benefits: 63850 yuan -51910 yuan = 11940 yuan (per hectare).
Total benefit = 7400 Ã— 11940 yuan = yuan
Section III Collection and Treatment of Larch Seeds
I. The seed setting rules of Larix principis-rupprechtii
V-w seeding of Larix principis-rupprechtii
Larix principis-rupprechtii has to go through five age periods from seed germination, growth and fruiting to plant senescence and death, and it must go through five age periods: seed period, juvenile period, youth period, adult period, and old age period. Forests have matured from youth to maturity in the adult period, and the amount of fertility has dropped significantly during the old age. Under the influence of different external environmental conditions, the age conditions of Larix principis-rupprechtii vary with different site conditions. Warm climate and sufficient illumination will promote early flowering of trees. In general, the trees will bloom earlier than the shady slope, and the isolated wood will be strong. The forest is older than the stand, and the soil, moisture, and nutrient conditions are better than the poor ones. The age of L. principis-rupprechtii in the forest area of â€‹â€‹the Mengzi Forest Management Bureau is generally 8 to 10 years, and it will enter the peak stage of fruiting in 12 to 14 years, and the amount of grain in 20 to 25 years will begin to decline.
Larix principis-rupprechtii is a unisexual flower and hermaphrodite. The female and male bulbs were solitary on the top of the short shoots, irregularly on each side of the 2 to 5 year old branchlets, and the first leaves or synchronized with the needles. Male bulbs are yellow, spherical or long-shaped, pollen-free. Female flower bulbs are smaller, often with short stems, erect, red or purple. The flower buds differentiated from June to July in the previous year, and flowered from late April to mid-May. The seeds matured from late August to early September.
(II) Size and year of solidification of Larix principis-rupprechtii
After the trees have entered the solidification stage, the amount of fertility is often very different each year. There is a phenomenon of large and small years of seed production, and the interval of abundance of Larix principis-rupprechtii is within 3-5 years.
According to observations over the years, the time period during which the larch is strong is greatly affected by environmental conditions. The formation of flower buds of larch mainly depends on nutrient conditions. After nutrient consumption, the nutrient is greatly consumed and the tree vigor is weakened. Especially after the New Year, the tree vigor recovery is different, and the formation interval is also different. The external factors such as wind, frost, rain, hail and other factors. The impact of this will also make the trees appear large and small in size or interval. In particular, freezing damage and larch cone fly have a decisive influence on the amount of larch.
The technical personnel at the base of the improved seedlings at the Longtoushan seedlings plant found that the â€œyear and yearâ€ phenomenon of larch is an inherent biological characteristic of trees, but this can be changed through human intervention. For example, by strengthening soil management such as weeding, watering and fertilizing, pruning and truncating, timely and effective management of pests and diseases, overcoming natural disasters, etc., and harmonizing the nutritional conditions of trees and flowering and solid relationships, the annual cycle can be shortened. The purpose of stable production of high yield seeds.
(3) Main factors affecting seed solidification
1. Meteorological conditions are indispensable factors for plant life activities. Adequate light can increase the temperature of the soil, make the soil microbial activity strong, release mineral nutrients, and ensure the supply of nutrients. The forest stands with good light conditions and long light-receiving periods are well established and have high yields. Temperature is one of the main factors affecting the yield and quality of forest seed. The flowering of trees has certain requirements on the temperature. If the temperature does not meet the requirements, the trees will not bloom normally. In the flowering period and fruit development period, if the temperature is appropriate, it will be conducive to the fruiting of larch. If the temperature is too low, it will easily cause freezing damage and affect the yield of the seed. Under normal circumstances, seed yield and quality of mother trees in high altitude areas are not as high as those at low altitudes. Normal and suitable rainfall is conducive to good growth and normal fruiting of trees.
2. Soil conditions Soil fertility of forest land, and whether the soil moisture is suitable or not, can all affect the yield and quality of forest seed. Because of the growth of the mother tree, the formation of flower buds, flowering and fruiting need to have sufficient soil nutrients and moisture. The trees that grow on fertile, moist, well-drained soil are more robust and of good quality. In addition, the application of some fertilizers containing phosphorus, potassium and other elements to the solid mother tree is beneficial to the early solidification of the trees and increase the yield. The effect of soil moisture on the flowering and solidification of forest trees is significant. The appropriate amount of water can promote flower bud formation and normal fruit development. In the fruit development period, if the soil moisture is insufficient, it will also result in poor fruit development, insufficient grain filling, or early shedding.
3, pests and rodent pests have the greatest impact on the larch yield is the larch cone fruit fly. After investigation, if the ball apology or harm to them is more than 95%, the seed damage rate reaches 62%. (For prevention and control methods, see chapter VII, Control of Larch Flies.)