Breeding and pollination Variety allocation techniques of Changshan Carya cathayensis

Breeding and pollination Variety allocation techniques of Changshan Carya cathayensis

1 seed temperature increasing and germination technology

As a result of fruit ripening, the skin of Carya cathayensis will split and the seeds will fall off naturally. When the exocarp is slightly cracked from green to yellowish brown, it should be harvested in time, usually from mid-October to early November. The fruits should be accumulated indoors in time after harvesting, and the seeds should be taken out after most of the fruits are cracked, spread out and hung for 3-5 days, and then stored indoors with wet sand or in cold storage. The seeds were germinated before spring sowing.

Method 1: after the seeds were harvested, soak them in clean water for 12 hours, drain them, then soak them in clear water for 12 hours, spread them out and store them in sand, then mix them with grain sand with a certain humidity (hand-pinched into a ball, not loose) and seeds layer by layer. The thickness of the bottom sand is about 15 cm, the thickness of the sand between the two layers is about 5 cm, and the thickness of the top sand is about 15 cm. The suitable height of the whole germination bed is 50 cm. If the area of the budding bed is too large, grass handles can be inserted into the sand to ventilate. It is stacked outside under natural conditions and goes through the process of low temperature dormancy under natural conditions. In early February, it was covered with black plastic film and covered with 10 cm thick straw. After about 20 days of warming and budding, most of the seeds have broken or grown radicles, which can be sown in the field.

Method 2: after the seeds were harvested, the seeds were spread indoors for about one month, and then direct seeded in the field at the end of December or early January of the following year, with a row spacing of 20 cm and a plant spacing of 4: 5 cm, poured through water and covered with plastic film for heat preservation, and straw could be covered with plastic film if possible. When the weather warms up and the highest temperature reaches 25-28 °C, remove the plastic film. Pay attention to observation, if the day is dry and there is no rain, it can be watered once and seedlings can emerge in the middle and last ten days of March. In this method, the seeds are easily damaged by animals, diseases and insects, and the emergence of seedlings may be irregular.

2 Container seedling raising technique

The container seedling of Carya cathayensis has the advantages of short seedling time, neat seedlings, no root injury, no slow seedling stage after afforestation, transplanting is not limited by season and so on. Choose a container made of white non-woven fabric, commonly known as a nutrition bowl, with a caliber of 28 cm and a caliber of 25 cm. The white non-woven fabric has the property of light transmittance, and the root system stops growing when it touches the membrane wall of the container, and there is no cochlear root phenomenon. The container substrate is loam, peat, organic fertilizer (rotten chicken manure, slow-release compound fertilizer, etc.), rice husk according to 50 ∶ 25 ∶ 15 ∶ 10, mixed with phoxim granules, and then sprayed with ferrous sulfate and carbendazim for disinfection. Install the substrate and place it neatly on the seedbed. Place the germinated Carya cathayensis seeds in a nutrition bowl, cover with the same substrate of 3-5 cm, and water until wet. Changshan Carya cathayensis like water and fertilizer, diligent fertilizer and water management, about 1 month seedling.

(3) grafting seedling technique

3.1 Spring grafting

Generally, from the middle of March to the first ten days of April, the temperature is stable above 15 °C. the main methods of grafting are split grafting and cutting, and the nursery can not be irrigated before grafting. 3-5 days before grafting, the nursery can not be irrigated, cut 2-3 times at 8: 10 cm above the ground 3 days before grafting (to prevent bleeding at the marriage interface), and then grafting at 30 cm from the ground.

3.2 Big square budding in summer and autumn

The budding time is generally from mid-late May to early September. The bud pieces with a length of 3 cm and a width of 0.8 cm are taken from the scion with a blade, and the bud should be located in the middle of the bud piece. On the rootstock, the same length and width of the same bud piece was cut to increase the cortex of 1~2mm. At the same time, the bark of 2 cm long and wide 1~2mm was torn off on the lower side of the incision as the wound orifice to "drain". Stick the bud piece on the mouth of the rootstock, close on the left side, leave the wound orifice on the right side, and seal it with plastic film, loose and tight moderately, do not wrap the wound orifice strictly and expose the bud body. When the new shoot of bud grafting grows to 20 cm, cut the anvil from 2 cm above the bud.

4 high grafting technology with large anvil

The fruiting period of Carya cathayensis seedlings usually begins in 10-12 years, and the grafted seedlings begin to bear fruit 4-5 years later. By using the technology of high grafting of large rootstock, the fruit began in 2 to 3 years, and the tree crown and yield were formed rapidly. The method is to choose suitable thickness (diameter 2 ~ 10 cm) and sawing off the smooth bark. From the end of March to the beginning of April, when the air temperature is stable at 20 ~ 25 °C, pry bark grafting is used. Rootstocks with a thickness of more than 4 cm can be grafted.

(5) Rapid seedling raising technique

Changshan walnut dual-use, good economic benefits, straight trunk, good wood type and material, deeply welcomed by the market, especially in the Yangtze-Huaihe River Basin. In order to provide seedlings quickly and efficiently, we tried to explore the annual grafting technology, so that the seedlings were raised in the same year and came out of the nursery in the same year.

The harvested seeds of Carya cathayensis were stored in sand in the middle of October, and the seeds with broken or radicle were selected in the middle of January of the following year, and the seedlings were raised in containers, and the arch shed was built on the seedling bed. Pay attention to observation, timely watering, control the greenhouse temperature 35 °C, humidity 70%. In order to maintain the temperature and humidity, most of the nutrition bowl was buried in the seedbed soil, and the sunshade net with a shading rate of 70% was covered in the greenhouse to prevent the damage of high temperature and strong light to the seedlings. The leaves of the seedlings spread normally, and when the stem turns green, the two ends of the arch membrane can be opened around noon in a sunny day to ventilate and cool down, so as to enhance the adaptability of the seedlings to the external environment. When the seedlings grow close to the arch shed film, remove the arch shed in time so as not to burn the seedlings. In August, 80% of the seedlings have reached the grafting standard (10 cm from the ground, the ground diameter is more than 7 cm, and the height is more than 80 cm). Large square bud grafting can be carried out one after another. as it is in the peak growth period at this time, drainage "water release" during bud grafting is an important link. The way to do this is to tear a 2 cm long and wide 1~2mm hole at the bottom of the interface. The survival rate of bud grafting can reach 85%. The seedlings grafted in the middle and late August generally do not need to be cut, and all the seedlings are cut off above the interface when they come out of the nursery for afforestation. When tending and management, pay attention to timely erase the buds under the buds.

(6) moisturizing cultivation techniques of trunk mulch

The main root of Carya cathayensis seedlings is well developed, the whisker root is less, the bark of the branch is thin, and the survival rate is not high under the conventional cultivation of bare root seedlings. The use of trunk plastic film moisturizing cultivation technology can greatly improve the survival rate of afforestation. The method is that after the seedlings are planted, a strip cylinder is made of plastic film, and the long cylinder plastic film bag is soaked out in water, leaving some water droplets in the film, and then the strip cylinder plastic film bag with water droplets is placed on the planted trunk of Carya cathayensis, and the lower part is buried in the soil, so that the branches of the seedlings will get a good moisturizing effect until the branches sprout and the new shoots grow to 5 cm. Remove the moisturizing plastic cartridge.

7 collocation techniques of pollination varieties

Changshan Carya cathayensis series monoecious flowers, wind-pollinated flowers, male and female flowers mature successively, through different variety configuration, reasonable shaping and pruning to achieve high and stable yield. For example, the common varieties are male flower prematurity, Maoshan 1 and Weston are female flower prematurity, and the combined cultivation of Maoshan 1, Boni and Weston is the better pollination configuration, and the performance is better in the Yangtze River basin.

(8) the technique of pulling branches and taking branches

Drawing branches: the internodes of Carya cathayensis are longer. in order to increase the amount of branches per unit area, plastic ropes are used to lengthen the branches before sprouting in winter and spring, so that the internodes are fully exposed to light and promote short branches (fruiting branches).

Take the branch: when the front end of the long branch is semi-lignified, hold the branch by hand and gradually move from the base to the tip and slightly break the xylem, prompting the branch to open at an angle. Pay attention to the strength of the hand when holding the branch to avoid breaking the branch or seriously injuring the cortex of the branch. The main objects are upright branches, competitive branches, auxiliary branches and so on. Taking branches can open the angle of branches, improve the germination rate of branches, promote the formation of flower buds and medium and short branches, and cultivate fruiting branches.