"Hubei Larch Pine Fast-growing and High-yielding Forest Cultivation Technique" Eight

II. Collection of Larix principis-rupprechtii

In order to obtain a large number of high-quality seed, it is necessary to grasp the timing of seed production. Premature collection, the seeds have not yet matured affect the quality of the seed, and the delayed seed collection results in the shedding and scattering of the seeds, resulting in losses.

(i) Seed maturity and external characteristics

Seed maturation matures in physiological and morphological maturity. When the embryo develops to have the ability to germinate, it is called physiological maturity; when the appearance of the external morphology is mature, it is called morphological maturity. Normal seed collection is done when the morphology is mature. When the morphological maturity is mature, the characteristics are as follows: the accumulation of internal nutrients in seeds, the decrease of moisture content, the weak respiration, the dense and solid seed coat, the strong resistance to damage, and the resistance to storage.

With mature external characteristics, the seeds of most tree species change from green to tan, yellow, purple and black. When the Larix principis-rupprechtii matures, the cones change from green to yellow-brown.

(II) Seed production period

The suitability of the seed collection period has a great influence on the quality of the seeds. When the larch cones are mature, the species scales are easy to crack, and the seeds are light and winged, and they are easily scattered in a short period of time. From the mature color of cones to the scattering of seeds, there are generally only 15 to 20 days, and the seeds should be collected immediately without losing the opportunity. In the forest area of ​​the Mengzi Forest Management Bureau, the maturity period of L. principis-rupprechtii is generally from late August to early September.

(3) Seed production methods

In combination with harvesting operations, harvesting from felled wood is simple, inexpensive, and easy to obtain a large number of high-quality seeds at the top of the canopy. However, this method can be applied only when the seed matures and the harvesting period is the same. For the tall mother trees, tools such as wooden frames, ropes, and seed-picking ladders can be used to assist tree seed collection, or to use tools such as seed collection hooks, seed collection tools, and high branch shears. In order to avoid damage to the mother tree during the transition period, the diameter of fruit twigs that are required to be cut during seed collection must not exceed 1.5 cm, and the total number of branches must not exceed 1/3 of the canopy. Too many broken branches will affect future production, and even prolong the interval between harvest years. The collection of seeds from seed orchards requires the use of seed-picking ladders to collect seeds manually, and it is strictly prohibited to harm the mother tree branches.

III. Preparation and Storage of Seeds of Larix principis-rupprechtii

This is a general term for seeds and fruits. The purpose of the real preparation is to make the seeds suitable for sowing or storage. The contents of the modulation include: drying, threshing, net seeding, wing removal, seed grading, and the like. Seeds should be planted as soon as possible after seed collection, so as to avoid real fever and mildew, reduce seed quality.

(a) Real threshing

The threshing of the Larix principis-rupprechtii must first be dried so that the seeds of the cones are removed. There are two major methods for drying cones, natural drying and artificial heating. Artificial heating and drying require a drying room. The investment is high and generally does not meet the conditions. Therefore, the natural drying method is mainly introduced here.

The natural drying method is to use sun exposure to dry the seed bulbs. After the majority of the cones lose moisture, the cones will crack and the seeds will come out. This method is widely used in production. The harvested cones are naturally dried in a sunny drying place. The cones should not be thicker than 7 to 10 cm. They should be turned 3 to 5 times a day. After 5 to 7 days, the scales will crack, and the fallen seeds will be promptly retrieved. Until the seeds are completely removed, the seeding rate is generally 3.0-5.0%. After the cones are cracked, the seeds are separated by screening, and the wings are wiped off with a wing remover or in a bag of seeds. Finally, the impurities are removed after the fan car or rake is removed, and then the bag is fully bagged and stored. The prepared seeds require a purity of 95% or more and a water content of less than 10%. Larix principis-rupprechtii has many hollow seed grains, and its fineness is generally only 60% to 70%.

(ii) Storage of seeds

The purpose of seed storage is to ensure that the seed is not degraded during storage, so that the seed can maintain its germination rate to the maximum extent. Larch belongs to tree species sown in spring, so the seeds harvested in autumn must be stored in the spring of the following year, and because the seed production has a phenomenon of “size and year”, some seeds must be stored to maintain the germination rate of seeds for the sake of lack of year or harvest. The year of nursery use.

The time the seeds maintain their vitality is called seed life. Although the dormant seeds perform a very slow respiration, the respiration consumes stored nutrients. So how to control the respiration of the seeds is the key to the longevity of the seeds. In the long-term storage of seeds, natural "ageing" phenomenon occurs, that is, the physiological activity of the seeds is reduced, so that the germination rate and germination potential of the seeds are reduced.

The length of seed life varies according to the seed's contents, water content, and environmental conditions of storage. Practice has proved that as long as the proper conditions for storage seeds are correctly grasped, the lifespan of seeds can be extended.

The main factors influencing larch seed life are seed moisture content and storage temperature. The data shows that if the moisture content of larch seed is controlled between 8% and 9%, it can be stored for 2 to 3 years in a ventilated and dry common seed bank, and can be stored for 3 to 4 years in a mechanical cold store.

Fourth, seed quality inspection

The quality of seeds includes genetic quality and sowing quality. The “quality inspection” is mainly to test the sowing quality (use quality) of seeds, and its purpose is to provide scientific basis for sowing and raising seedlings. By examining the indicators of the seeds, the use value of the seeds can be determined, the seeds can be reasonably used, and the loss in production can be reduced.

To test the seed quality, a representative sample of larch seeds should be selected first. The general sample size should not be less than 50g. The test includes: clarity, 1000-grain weight, moisture content, germination rate, germination potential, and goodness.

(i) Batches and samples

For seed quality testing, the first step is to take seed samples. This work is a very important part of seed testing. If the sample is not truly representative, no matter how accurate the inspection work is, the results do not represent the quality of the batch of seeds. The key to making the seed sample the most representative is to strictly adhere to the technical regulations for the extraction of seed samples.

1. Seed lot approval is short for seed lot. For the same tree species or species, the site conditions, mother tree age grade, seed collection time, seed preparation, and storage methods are the same in the production area. The seeds whose weight does not exceed a certain limit are called seed batches or batches of seeds. One test sample was taken for each batch of seeds.

2. Seed samples

Initial sample: When a sample is taken directly from different containers or different parts of the same seed, each time a certain sample is taken, it is called a preliminary sample.

Mixed Samples: All the initial samples taken from one seed lot are mixed together uniformly and called a mixed sample. It is a seed sample used for checking the seed quality indicators and measuring water content. The number of mixed samples is generally not less than 10 times the amount of sample submitted.

Inspection sample: It is the seed sample sent to the inspection agency for testing the indexes of seed quality. It is to separate some of the seeds for testing from the mixed sample. The quantity should be greater than the sum of the required quantity of the indicators for testing the seed quality, that is, it should be more than four times the amount of the sample for the clarity test, and a sample for inspection should be taken from one seed lot.

Assay sample: A sample of seed taken from the test sample. It is the seed used to test an index of seed quality (such as clarity or grain weight, etc.).

(b) Clarity

Seed clarity (also known as purity) refers to the percentage of pure seed weight to the weight of the test seed. Clarity is an important indicator of seed quality. It is one of the main indicators of seed grading and is an indispensable factor for calculating seeding rate. High clarity with good seed quality and high use value. A low degree of clarity indicates that the seeds contain more impurities and are not easily stored. The purity of the seeds produced by the Mengzi Forest Bureau Seed Orchard and its mother trees are generally above 95%. The clarity of the sample seeds is calculated using the following formula:

Clarity (%) = [pure seed weight / (pure seed + other plant seed weight + inclusion weight)] × 100%

(c) 1000 grain weight

The weight of tree seeds generally refers to the weight of one thousand pure seeds in the air-dried state, so it weighs a thousand grains. In grams. Due to the geographical location of the mother tree, site conditions, altitude, age, growth and development status, seed collection time, and genetic traits and other factors vary. The greater the 1000-grain weight of seeds of the same tree species, the better the seed quality, and it is a necessary factor for calculating the seeding rate. For large seeds, it can also be expressed as 100 grains. The 1000-grain weight of the seed of Larix principis-rupprechtii in Mengzi Forestry Bureau is generally between 5.3g and 6.9g. The 1000-seed weight of the seed orchard and the mother tree is significantly higher than that of the ordinary stand. The seed weight of the seed orchard is higher than that of the common stand. 20% to 30%. The bigger the grain weight, the more full the seeds are, and the stronger the germination ability is.

(4) Water content

Seed moisture content refers to the percentage of the seed's moisture content of the total seed weight. The water content of seeds during storage directly affects the respiration of seeds, and also affects the activity of microorganisms on the surface of seeds, thus affecting the vitality of seeds. High moisture content, high respiration, large consumption of storage materials, will quickly lose seed germination ability. The moisture content is too low, the seeds are too dry, causing dehydration of the seeds and reducing the germination rate of the seeds. Research shows that the optimum moisture content of seeds is 8% to 9%.

(E) Determination of seed germination ability

Seed germination ability is the most important indicator of sowing quality. It can be directly measured by germination test. Now only the commonly used indicators are introduced as follows.

1. Germination rate Seed germination rate refers to the percentage of normal germinating seeds and the total number of tested seeds. The germination rate is the reaction of the vitality of the seed, and its level indicates the quality of the seed, which is one of the main factors for calculating the seeding rate. After soaking in warm water at 45°C for 24 days, the germination test can be completed at a constant temperature of 25°C for about 3 weeks.

2 Germinating potential Germination potential is an index of the degree of seed germination. The percentage of seed germinated grains in the total number of tested seeds is the standard when seeds germinate at the highest peak, which generally accounts for 1/3 of the total germination time The number of days is usually 3 to 4 days. The higher the germination potential, the more seedlings emerge. Indoor sprouting test specific practices: Remove the sample from the pure seeds, divided into four groups using the + lettering, each group to take 100 seeds, after soaking evenly into germination containers. Containers should be marked with a grouping mark and placed in an incubator or room. The temperature should be controlled between 20°C and 25°C. The germination bed was kept moist during the test, and if it was found to be moldy, immediately wash it with water and change bed. After the seeds started to germinate, they were observed at regular intervals and the number of sprouts was counted. The criterion for the larch germination is that the length of the young root is greater than the length of the seed, and the germinated seeds that have been counted at any time are picked out. In the later stages of seed germination, germination can be stopped if the average number of germinations is less than 1% for 5 consecutive days. The ungerminated seeds should be dissected and counted as healthy, empty, and rotten grains. Finally, the seed germination rate and germination potential were calculated. Nursery germination potential, can extract a certain number of seeds, simulated seeding environment test species, count the number of seedlings to calculate. The seed germination rate is often used to replace the seeds in the production to determine the seeding rate.

Table 2-11 National Standards for Larix principis-rupprechtii Seed Quality Classification (GB7908-1999)

Clarity not less than %

Germination rate is not less than %

Water content not less than %

Class I

98

60

10

Level II

95

50

10

Level III

90

40

10

3 The test of vitality can be done with the indigo staining method or the tetrazolium staining method. The method of indigo dyeing is as follows: a 0.05-0.10% concentration solution is prepared with distilled water and used together with the use. The seeds are peeled and cut into half with a scalpel along the embryo. Half of the embryos are immersed in the dye and the cut surface is face down. The temperature is kept at 30°C and placed for 3-12 hours. The non-coloring is high vitality. Seeds and embryos are stained as spots with weak vitality. Fully colored embryos or most of the radicles and embryonic stems are colorless seeds. The number of seeds with a certain vitality in the total number of seeds detected can be approximated. Germination rate.

(VI) Inspection of pests and diseases

First, the presence of wormholes was observed with the naked eye, and then the condition of the insect pests was examined by anatomical method. Diseases were then detected by pathological washing and isolation culture methods.

(7) Good seed quality

The quality of seed quality is judged by direct human observation, which is called excellent quality. Goodness is also one of the indicators that indicate the quality of seeds. Because in general, the appearance of seed coats, embryos, and endosperms can reflect the quality of seeds to a certain extent, experienced technicians can use cutting, squeezing, or sensory discrimination methods to make a rough estimate of seed quality. Evaluation, accuracy varies from person to person. This method is suitable for on-site inspection of seed collection, threshing and acquisition. The excellent seed appearance is as follows: Seed coat ventral brown, yellow-white back, shiny; seed full, endosperm milky part, blunt part white, endosperm white, rosin flavor, smooth seed face; seed after seed soaking Expanded, hard and brittle, endosperm milky white, the embryo is pale yellow by the apical part, and the part of the cotyledon is bright white. The quality of seed produced by the Mengzi Forestry Bureau is generally above 70%.

Put the tested seeds into standard bags and attach them with the seeds, which are filled with the place of production, germination rate, moisture content, and national standard level. Put them in the seed bank for storage and distribution.

Chapter III Nursery

The first section nursery selection and zoning

First, operating conditions

Nurseries should be selected on the edge of the town near the afforestation area or near the suburbs to facilitate transportation, to ensure that the nursery material materials, energy, and electricity are supplied in a timely manner to facilitate the management and transfer of seedlings to ensure the supply of labor. At the same time, attention should be paid to factories and mines that are away from large amounts of toxic gases and sewage. Long-term plots of low-lying land, saline-alkali land, over-water land, tuyere and lack of light should not be selected as nurseries, so as not to affect seedling growth.

Second, natural conditions

1. The terrain nursery should be located in a place with good drainage and flat terrain. If the slope is selected, the gradient should be less than 3°.

2. Loam soil or sandy loam soil with good soil aggregate structure, strong permeability, and slightly acidic soil due to larch, the soil pH value is preferably between 6.5 and 7.0, soil salt content is controlled below 0.1%, and the soil before the nursery is selected. Cultivated crops should avoid cruciferous plants as far as possible to reduce the occurrence of pests and diseases.

3, water source is the lifeblood of seedlings. The nursery must have sufficient water for irrigation. Natural water sources such as rivers, ponds and reservoirs are good. The water temperature is close to the natural temperature, the water quality is soft, and the pollution is small. The use of deep groundwater is avoided as much as possible. First, the cost of irrigation can be reduced. Second, the composition and temperature of deep groundwater are not as good as natural water.

4. Diseases, pests and animal hazards When choosing a nursery, the degree of pest and animal damage in selected nurseries and surrounding areas should be investigated in detail. For areas that are seriously endangered, effective prevention and control must be carried out before they can be selected as nurseries. There should be no intermediate parasitic plants near the nursery where there are infectious diseases and pests and diseases. For example, to avoid the occurrence of larch and poplar rust, avoid poplar tree species.

Third, the division of nursery land

The reasonableness of the division of nursery land is a key condition for giving full play to land strength, manpower and material resources, and achieving the best economic benefits. The division of nursery land should follow the following principles:

First, try to reduce the distance within the garden and shorten the overall length of the irrigation system to increase land utilization and reduce water consumption.

Secondly, the road inside Puurong has access to all parts of the nursery, and the main route is rationally arranged so as to occupy non-farming land as much as possible.

Third, roads and irrigation facilities should be rationally arranged and coordinated to avoid mutual obstruction.

Fourth, do a good job in the planning of the production area and auxiliary land use.

(1) Zoning of production land

1. The core part of the nursery in the sowing area should be set in a place where soil fertility is good, soil is deep, irrigation is convenient, and management is convenient.

2. Transplantation area (container nursery) The transplantation area (container nursery) has a certain root system for transplanted seedlings. Container nursery needs to be used for the synthesis of further nutrient substrates. Therefore, nursery areas with medium or inferior land conditions should be arranged.

3, vegetative propagation area The vegetative propagation area requires a strong soil permeability, watering drainage convenient place.