Key Technologies for the Construction of Guangzhou Germplasm Bank
China is a country with rich vegetable germplasm resources and is recognized as one of the centers of vegetable origin in the world. In China, there are great differences in the types of vegetables in the north and the south. The variety of vegetables in the south is richer than in the north, especially the vegetable resources in Guangdong Province occupy an important position in China. According to the long-term vegetable germplasm statistics of countries that have entered the country, the cabbage, kale, cowpea, zucchini, bitter gourd, gourd, etc. in Guangdong Province have an absolute advantage in the country. During the period from 650 to 850, the Vegetable Research Institute of the Guangdong Academy of Agricultural Sciences collected and preserved more than 3,000 germplasm resources of vegetables and identified the traits of vegetable germplasm resources in Guangdong Province. Send it to the National Germplasm Bank for long-term preservation. During the 950/s period, the Vegetable Institute of the Guangdong Academy of Agricultural Sciences and the Institute of Crop Germplasm Resources of the Chinese Academy of Agricultural Sciences jointly rescued the vegetable resources in four counties of Pingyuan, Heping, Longchuan, and Sixing in the northern Guangdong section of the Beijing-Kowloon Railway. During the inspection, 502 kinds of vegetable germplasm resources were collected. However, due to the lagging of the germplasm resource bank construction, the storage facilities and facilities are not perfect. Some of the original germplasm resources collected and preserved, including some of the traditional famous vegetable varieties in our province, have been lost.
In 2002, the Guangdong Science and Technology Department and the Guangzhou Municipal Science and Technology Bureau co-sponsored and established the Guangdong Vegetable Germplasm Resources Library. By October 2003, the Vegetable Research Institute of the Guangdong Academy of Agricultural Sciences had established a medium-term vegetable bank with a volume of 55 m3 and a storage capacity of about 23,000 pieces, which is adjustable in temperature and humidity. The key technical reports on the construction of this germplasm resource bank are as follows.
1 Unit selection The refrigeration unit is the core part of the germplasm resource bank, and its refrigeration dehumidification performance is directly related to the lifespan of germplasm storage. The technical indicators required for the external bidding of Guangdong vegetable germplasm resource bank construction are cold storage temperature (-5)e and relative humidity [50%. The selection of refrigeration units is based on the amount of cold consumed by the genebank.
1.1 Calculation Method for Generating Cooling Capacity of Genebanks The total consumed cooling capacity (Q) of this genebank is composed of three parts: the cooling capacity of the envelope structure (Qa), the daily consumed cooling capacity (Qb), and the operating cooling capacity (Qc). . The specific calculation method is: Q = (Qa + Qb + Qc) R [3], where R is the coefficient of cooling of the pipeline, which is taken as 1.07, and the total amount of cold consumed in this database is 2329.7 W.
1.1.1 Cooling Capacity of Enclosure Structure (Qa) Qa=KFvt. Among them, K: heat transfer coefficient, 150 mm thick polyurethane K=0.17 W/m2#e; F: external surface area of ​​the envelope, 105.3 m2; vt: temperature of the indoor assembly library is 32e, minimum design temperature of the cold storage is -10e, The vt value is calculated as 42e. The cooling capacity of the enclosure of this genebank is 751.8W.
1.1.2 Daily Cooling Quantity (Qb) This gene bank is a mid-term library. The usage requirement is to purchase 1 time every 10 days, about 25 kg each time. According to the aluminum foil bag, it will be purchased once a day and the daily stock consumption will be calculated. The cooling capacity Qb=Qb1+Qb2. (1) Germplasm cooling capacity Qb1 = G1@C1@/24=13.4 W, where G1 = 25 kg, C1 = 1.09 kJ/kg#e, vt = 42e, 0.28 for unit conversion rate (below); ( 2) Package cooling consumption Qb2=G2@C2@/24=2.1 W, where G2 is about 10 kg for aluminum foil bag packaging, C2=0.42 kJ/kg#e, and vt=42e. The amount of cold consumed for this genebank was 15.5 W.
1.1.3 Operational Cooling Capacity (Qc) Including Lighting Cooling Capacity (Qc1), Motor Running Cooling Capacity (Qc2), Open Door Cooling Capacity (Qc3), and Workers Cooling Capacity (Qc4), Operating Cooling Capacity Qc =Qc1+Qc2+Qc3+Qc4. (1) Illumination cooling capacity Qc1 = 7.5 W/m2@0.6 = 97.8 W, where 7.5 W/m2 is the lamp power per unit area, 0.6 is the coefficient for the same period, 21.73 m2 is the area within the cold room, and (2) the motor is running out Cooling capacity Qc2 = 860 N = 137.6 W, where N is the power of the cooling fan motor, the selected equipment is 0.16 W, and 860 is the thermal work equivalent; (3) the opening consumption is 0.5 h per day, the room temperature is 32e, and the storage temperature is - Calculated by 10e, Qc3 = 465.2 W; (4) The staff's consumption of cooling capacity is calculated on the basis of 4 persons per day entering the cold room and 0.5 hours per person per time, Qc4 = 709.4 W. The amount of cold consumed by this genebank operation is 1410.1 W.
1.2 Equipment selection Based on the above-calculated total cooling capacity, combined with the technical parameters provided by the equipment tendering, the Guangdong Vegetable Germplasm Resources Library has selected a low-temperature air-cooled, temperature-adjustable, adjustable agricultural seed storage special unit. The unit's cooling and dehumidification day operation time was designed to be 18 h in total, and the load on the sorting machine was 3106.3 W. In the summer outdoor environment temperature is 40e, and the storage temperature is -10e, the host (5HP) cooling capacity is 6047.6 W, and the standby machine (3HP) cooling capacity is 3605.3 W, which can fully meet the requirement of the cooling capacity of 3106.3 W when the storage temperature is -10e. .
2 Library Construction The library of genebank includes walls, roofs, underground insulation and floors. In order to reduce the external heat transfer into the library, affect the relative stability of the storage temperature, save energy, the insulation layer used in the genebank must have good thermal insulation properties. According to the technical indicators to be achieved by the Guangdong Vegetable Germplasm Bank and the commonly used insulation materials and thicknesses of the medium-term libraries, the high-quality 150 mm-thick polyurethane double-sided spray steel plate cold storage plates were selected for the wall and ceiling of the database. On-site assembly construction has the advantages of light weight, low thermal conductivity, low water absorption, and self-extinguishing properties. Cumen is a 150 mm thick polyurethane refrigerated door with imported door closers and hardware, and is pre-made according to the size of the original gateway to the genebank. The underground thermal insulation board uses imported Shutailong XPS thermal insulation material with a thermal conductivity of 0.027W/m#k and a thickness of 125mm. All store board joints and floor insulation boards are sealed against moisture. Taking into account the bearing load of the sliding seed rail, a 10 cm thick reinforced concrete was placed on the underground insulation to reduce the partial pressure of the rails on the insulation board. In order to prevent freezing, the cement used for concrete is high-grade portland cement, and when the concrete is laid, the floor drain for defrosting water is also reserved.
3 Selection of Seed Racks Seed Racks of Germplasm Resources are fixed and movable. Fixed seed stands cannot be moved and corridors are kept between seed stands to allow access to seeds and personnel. The corridors occupy more area, thus greatly reducing the effective storage capacity of the genebank. The Guangdong vegetable germplasm resource bank uses a mobile dense seed rack consisting of a frame, a seed basket and a transmission. The size of the mobile seed rack is 2.65 m wide, 4.16 m long, 2.00 m high, and 22.05 m3 in volume. The seeds are divided into 12 layers with a 15 cm spacing; 8 columns are 52 cm wide and 265 cm long; each column is 4 cm long and 60 cm long. The seed baskets are placed 15 cm above the floor and a total of 384 seed baskets with a size of 59.5 cm@49.0 cm@13.0 cm can be placed. The transmission consists of rails, rollers, chains, bearings, sprockets, shafts, and cranks. The seed rack can be moved back and forth by the handle.
The design and storage capacity of the Guangdong Vegetable Germplasm Bank is: 120-200 g of large-grain vegetable germplasm and 30-60 g of small-grain vegetable germplasm. Each seed basket can contain 40-60 large-grained seeds and 100 small-grained seeds. For ~150 copies, 2/3 of the seed baskets are used to store large seeds and 1/3 of the seed baskets are used to store small seeds. The library of Guangdong germplasm resources has a repository capacity of more than 23,000 copies.
4 Selection of packaging materials To prevent the seeds from losing their vitality due to moisture absorption during storage, the dried seeds must be packed in a sealed container. At present, more commonly used sealed packaging containers are glass containers, metal containers and aluminum foil bags, of which aluminum foil bags are the most widely used in the world. The seed packaging containers used in the National Germplasm Bank of China include spiral tinplate seed boxes, rust-proof aluminum disposable sealed seed boxes and aluminum foil bags. The use of aluminum foil bags as packaging containers in the Guangdong Vegetable Germplasm Resource Bank has the advantages of ease of use, low cost, small storage space, light weight, and ease of handling and management. Its raw materials are mainly aluminum foil and polyethylene, and the amount of water seepage per bag is less than 40 mg per year. There are three kinds of aluminum foil bag size, large bags of 26 cm @ 12 cm, used to package large seeds, such as kidney beans, kidney beans, bitter gourd, loofah, sweet corn, etc.; middle bag is 18 cm @ 10 cm, used to package medium grain seeds, Such as cucumber, white melon, watermelon, etc.; small bag is 12 cm @ 8cm, used to package small seeds, such as eggplant, leafy vegetables and so on. Due to the need for seed bag sealing, it is also equipped with an automatic heat sealer.
5 Construction of the pre-processing room for germplasm In order to ensure the initial germination power of the stored seeds and to maintain a longer storage time in the library, the germination rate must be measured and dried before the seeds are put into storage. The Institute of Vegetable Germplasm Resources pre-processing room was established in December 2003. The pre-processing room was equipped with drying ovens, electronic analytical balances, and rapid moisture analyzers. The techniques used to determine the seed germination rate are mainly based on the requirements of the germination test 6 (GB/T 3543.4-1995) of the 5 Crop Seed Inspection Regulations, and appropriate adjustments have been made in light of actual conditions. The conditions for seed drying are that the oven temperature is (30?2)e, the indoor temperature is <18e, and the relative humidity is <40%; the drying time varies depending on the seed size, seed shell thickness and density, and is usually 3 to 5 days. . The moisture content of the stored seeds was measured by the method of random sampling. The water content of the seed that was sampled was measured to meet the medium-term storage requirement (<9%). The sampling rate is 15% to 20% of the number of seeds sent to each bank for each crop.
6 Operation of Guangdong Vegetable Germplasm Bank After the establishment of the genebank, it will be commissioned and commissioned. The purpose is to check whether the refrigeration dehumidification effect of the unit has reached the design standard. Before the unit runs, it needs to be warmed up. The warm-up time depends on the temperature, generally 2 to 8 hours. If the temperature is low, the warm-up time is long. After the warm-up is completed, the temperature and humidity of the warehouse can be set as required. The unit used in this database is first dehumidified after cooling, that is, when the temperature drops to the set value and the humidity in the storage tank rises to a certain value, it is dehumidified. See Table 1 for monitoring results after the Guangdong Vegetable Germplasm Bank has been operating for a period of time. From Table 1, it can be seen that in the middle of June in Guangzhou, where the temperature is relatively high, even during daytime when the daily temperature is high, the temperature and humidity of the main engine and the standby machine can both fall to the set value (-5e, 45%). When the storage temperature starts at -2.9e, the relative humidity increases, and the relative humidity decreases after shutdown. When the relative humidity reaches 48.0%, the dehumidification starts. At this time, the temperature in the storage tank increases. During operation, the unit will automatically defrost based on the frosting condition of the evaporator. The temperature in the storeroom will increase slightly, and the relative humidity will increase greatly. However, in the subsequent cooling process, the relative humidity will decrease to a certain value. . According to the cold storage design specification [5], the temperature increase in the defrost process should be [7e. Under nominal conditions, when the storage capacity is 100 m3, the working time coefficient of refrigeration equipment should be [0.7. The test results show that both the working time coefficient of the two units and the temperature rise of the defrosting process meet the specification requirements, indicating that the various indicators of operation of the germplasm resource bank meet the design requirements. Due to the low power of this kind of database, according to the original design requirements, it will only be used in the 12~2 months when the host computer fails and the annual temperature is lower.
Note: (1) The host inspection date is June 12, the ambient temperature is 29.6~33.6e, and the relative humidity is 57%~65%; the backup machine detection date is June 13 and the external ambient temperature is 31.8~33.1e. Relative humidity is 41%~46%. (2) The temperature and humidity in the table are the values ​​in the environment of the warehouse, and the average value is taken; in the table, /-0 indicates that the corresponding data cannot be obtained. (3) Working time coefficient = working hours per day / 24.
7 Conclusion After 9 months of operation of the Guangdong Vegetable Germplasm Bank, the temperature and humidity technical indicators of the library have met the requirements for the medium-term bank design of crop germplasm resources, ie, the storage temperature is (-5?5)e, relative humidity [50%, The operation is normal and the germplasm can be accepted for storage. The genebank adopts a mobile dense seed rack, so that only two channels perpendicular to each other are needed in the library, which greatly improves the effective storage capacity of the genebank, and the storage capacity reaches more than 23,000 copies. After being dried and sealed, the vegetable germplasm whose original vitality meets the standard of the initial germination rate of the national germplasm bank will be preserved in this genebank. The vitality of the vegetable germplasm is expected to be maintained for 10 to 15 years, and this will be the vegetable germplasm resources of our province. Proper preservation creates extremely favorable conditions.
At present, there are two types of refrigeration units: air-cooled and water-cooled. The water-cooled units need to be equipped with pumps, water tanks, cooling towers, etc. The investment will be relatively high. When the water supply system is stopped for a long time, it will not work properly. The air-cooled unit needs no auxiliary equipment. It has less investment and is easy to use. It is easy to implement automatic control, but at higher temperatures, the condensing temperature is also higher. Therefore, when constructing a germplasm resource bank, comprehensive consideration should be given based on the actual situation, balance the advantages and disadvantages, avoid weaknesses, and select suitable refrigeration units. The Guangdong Vegetable Germplasm Bank is an independent warehouse, so it is necessary to equip two units: one for the host and one for the standby. If multiple germplasm repositories are built at the same location, from the perspective of cost savings, two or three cold storage units with the same temperature and humidity technical requirements can share one standby unit through the joint control system, and can also use a variety of databases. The control system is centrally installed in a room, and the networked computer is used to centrally monitor the operating conditions (temperature and humidity conditions) in the library. The closed-circuit television monitoring system is used to monitor the entire scene in real time to realize multiple germplasm resource banks. Modern management.
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