Detailed Explanation of the Key Technical Points for Jujube-Grain Intercropping
The key technique of jujube-grain intercropping is to properly regulate the conflicts between jujube trees and intercrops over fertilizer, water, and light, so as to achieve mutual benefit and reciprocity between jujube and grain and realize a double bumper harvest of both.
1. Master an appropriate planting density. Row spacing has a marked effect on air temperature, humidity, light, and wind speed, and is also an important factor affecting jujube and grain yields. Therefore, overall arrangements should be made according to cultivation purposes and local conditions. For jujube-oriented planting, a row spacing of 6 m is best; for grain-oriented planting, a row spacing of 15 m is best; for giving consideration to both jujube and grain, a row spacing of 8 m is best.
2. Choose a suitable planting row direction. Row direction has a certain effect on jujube tree yield. Practice has proved that when jujube trees are planted in a north-south row direction, the light received under the canopy is more uniform, and the daily light interception is also greater than that of an east-west row direction. Therefore, it is generally best to plant jujube trees in a north-south row direction, while also adapting to local conditions and applying this flexibly.
3. Properly control the height of jujube trees. Tree height has a certain relationship with the amount of direct light received. In order to improve light energy utilization efficiency and economic benefits, tree height should be controlled below 6 m, so the trunk-training height should be 1 m to 1.5 m.
4. Prune reasonably and control tree shape. According to investigations, canopy shape has varying degrees of influence on the growth and yield of jujube trees and intercrops. When the canopy is dense and branches are crowded, ventilation and light penetration are poor, the fruiting zone moves outward, the fruit-setting rate declines, and the impact on intercrops is aggravated. Therefore, the canopy shape should preferably be an open-center shape with scattered main branches.
5. Selection and arrangement of intercrops. Selecting suitable intercrops and arranging them reasonably is one of the key techniques for regulating the "three competitions" conflict between jujube trees and intercrops. The selected intercrops should have the characteristics of having phenological periods that are staggered with those of jujube trees, short plants, strong shade tolerance, a short growth period, and an early maturity period. Based on practical experience, the following crops are relatively suitable for intercropping
(1) Wheat crops. These include winter @#@245@#@, spring wheat, barley, etc. These grain crops have small plants and shallow root distribution, and their phenological periods are staggered with those of jujube trees, making them ideal crops for jujube-grain intercropping.
(2) Legumes. These include soybean, pea, mung bean, adzuki bean, etc. These crops have short plants, strong shade tolerance, a short growth period, and early maturity. They also have the ability to fix nitrogen on their own, making them relatively good crops for intercropping with jujube trees.
(3) Miscellaneous grain crops. These include corn, foxtail millet, sesame, peanut, and cotton, etc., all of which can be intercropped with jujube trees. However, rational layout and arrangement must be done well, because these crops are all light-loving crops, but their light saturation points and compensation points differ greatly. When intercropping with jujube trees, on the side close to the jujube trees, first sow several rows of legume crops, and then sow foxtail millet, corn, sesame, cotton, etc. Adopting a "short-tall-short or short-medium-tall-medium-short" arrangement combination is beneficial for ventilation and light penetration, meets the intercrops' requirements for light intensity and light interception, helps alleviate the conflicts between jujube trees and intercrops over fertilizer and water, and is also beneficial for pest and disease control and convenient management under the trees.