Introduction to the suitable pollination period and methods of walnut trees

   1. Collect pollen from adult trees that grow strongly locally or elsewhere, collect male inflorescences whose base is going to be pollinated (inflorescences change from green to yellow) or which are just beginning to disperse, and dry them on clean sulfuric acid paper or newspaper in a dry, ventilated and non-direct sunlight room. At the temperature of 20-25 ℃, most of the male flowers were pollinated after 1-2 days, and the pollen was screened out. The pollen was then collected in a finger tube or penicillin bottle and set aside at a low temperature of 2 to 5 ℃. The pollen viability can be maintained for about 3-5 days at room temperature and more than 20-30 days in a refrigerator of 3 ℃. Note that the bottled pollen should be properly aerated (the bottle mouth should be stuffed with cotton) to prevent mildew and reduce the pollination effect. In order to meet the needs of large-scale pollination, the pollen can be diluted, generally adding starch or talc powder at the ratio of 1: 10, and the diluted pollen can also achieve a good pollination effect.

   2. According to the opening characteristics of female flowers, when the stigma of female flowers is cracked and open in inverted eight shape, and the stigma is feathered and secretes a large amount of mucus with a certain luster, it is the best time for female flowers to pollinate. At this time, the female flower is in full bloom and lasts for 2-3 days, while the male-type plants have only 1-2 days. When the stigma is reversed or the stigma discoloration secretion becomes less, the pollination effect decreases significantly. Therefore, it is necessary to seize the time to pollinate so as not to miss the most suitable pollination period. Sometimes due to bad weather conditions, the early flowering period of the female on the same tree may differ by 7 to 15 days. In order to improve the fruit setting rate, pollination can be carried out twice when possible.

   3. Pollination method

   (1) pollinator pollination method can be used to pollinate early-bearing walnut young trees with short body, or "medical throat sprayer" can be used instead. Put the pollen into the glass bottle of the powder sprayer and spray it in the middle and upper part of the crown (note that the sprinkler should be more than 30 cm away from the stigma). The pollination speed of this method is fast, but the amount of pollen is large.

   (2) artificial point teaching method dips a small amount of pollen with a new brush, gently click on the stigma, the brush head can not touch the stigma, is above the stigma, a little 1-2 cm distance, hit the pen with your fingers, shock the pollen on the stigma. Be careful not to rub directly on the stigma, lest excessive pollination or damage to the stigma, resulting in falling flowers and fruits.

   (3) Pollen bag feeding method can be used for adult trees or tall late-bearing walnut trees. The specific methods are as follows: mix the male and female inflorescences of loose powder or pollen with starch at 1:10, put them in a 2-to-4-layer gauze bag, fasten the mouth of the bag and tie it to the bamboo pole, and then gently shake above the crown to release pollen.

The    (4) crown hanging inflorescence method is to collect the male inflorescences that begin to disperse powder, tie them in a bunch every 4 to 5, hang them on the top of the crown, and let them disperse powder freely. This method is also very effective, and it can avoid the trouble of collecting pollen.

   (5) liquid pollination method is used to spray pollen into aqueous suspension (the ratio of pollen to water is 1: 5000). When conditions permit, 10% sucrose and 0.2% borax (acid) can be added to the water to promote pollen germination and fertilization. Spray at 9~l0 in the morning or at 3: 4 p.m. This method can not only save pollen, but also be combined with foliar fertilizer spraying at the same time, so it is suitable for mountainous areas or areas with lack of water. The pollen liquid should be used at any time, not for a long time and overnight.