Determination of harvest time and harvest method of walnut

  Timely harvesting of walnuts is very important. Early harvest, green peel is not easy to peel, kernel is not full, yield is reduced, kernel yield is low, oil yield is also reduced during processing, and it is not resistant to storage. According to the measurement, the average early harvest of 1 day, the weight of dried fruit decreased by 0.49%, kernel weight decreased by 1.17%, half a month early harvest, yield decreased by 10.6%. After harvest, the fruit is easy to fall off, and at the same time, the green peel stays on the tree for too long after cracking, which will increase the chance of being infected by mold, resulting in the decline of nut quality, especially some paper-skin varieties, which will be affected, resulting in reduced edible value. Therefore, timely harvest is an important link to obtain a high yield and ensure the quality of kernels.

  The maturity of walnut fruit varies according to varieties and climatic conditions. The mature period of early-maturing varieties and late-maturing varieties may differ by 10~25 days. Generally speaking, the maturity period in the north is mostly from early to mid September, while in the south it is relatively early. The mature period of the same variety was different in different areas, and also different in the same area. The mature period of plain area was earlier than that of mountain area, the mature period of low altitude area was earlier than that of high altitude area, the mature period of sunny slope was earlier than that of shady slope, and the mature period of dry year was earlier than that of rainy year.

  When walnut green peel turns yellow or light yellow, hair becomes less, cracks appear on the top of some fruits, green peel is easy to peel, a few mature seeds have naturally fallen off, endocarp has been completely ossified, this is the most live harvest period of walnut fruit. At present, most of the early recovery in production should be corrected.

  recovery method

  There are two main walnut harvesting methods, one is manual harvesting method, the other is mechanical vibration harvesting method. China's labor resources are relatively cheap, mainly manual harvesting, while European and American developed countries have replaced manual labor in walnut harvesting with mechanization, greatly improving harvesting efficiency and saving harvesting time.

  Artificial harvesting is more common in China. Before harvest, the walnut tree should be located according to the terrain and crown size to decide how to pick. If the maturity period is inconsistent, it should be harvested in batches, strictly according to the varieties, and processed separately.

  ① In flat land or when the crown is small, it can be picked directly by hand, and the fruits are picked and put into baskets, bags or bamboo baskets. After the picking process is over, the fruits are concentrated on the transport vehicle and transported to the processing site for peeling.

  ② When the hillside or crown is large, it is inconvenient to pick by hand. Generally, plastic cloth is laid in the walnut tree tray in advance, and then bamboo pole or long wooden pole with elasticity is used to knock down the branches where the fruits are located or directly shoot down the fruits. The beating should be carried out from top to bottom and from inside to outside to prevent the branches from splitting, but it should be noted that excessive force should not be used to avoid damaging the branches and buds and affecting the yield of the next year.

  2, mechanical vibration harvesting mechanical vibration harvesting is to use mechanical vibration trunk, the fruit will fall to the ground after collection. has the characteristics of time and labor saving, high efficiency and low cost.

  The machinery for mechanical harvesting includes a vibration fruit dropping machine, a cleaning strip collecting machine and a picking and sorting machine. The operation procedure is that the walnuts are vibrated to the ground by the vibration fruit dropping machine, then the walnuts on the ground are collected into strips by the cleaning strip collecting machine, and finally the walnuts are picked up and simply cleaned by the picking and sorting machine before packing. Because the fruit ripening period of the same walnut tree is not completely consistent, when mechanical harvesting is adopted, 500~2 000 mg/kg ethephon must be sprayed on the tree body 10~20 days before harvesting to accelerate ripening and make it mature uniformly. The advantage of this method is that the green peel is easy to peel off and the fruit surface is lightly polluted, but the disadvantage is that the ripening with ethephon often causes a large number of leaves to fall off and affect the tree vigor.