Cultivation and management techniques of walnut trees during growing period

   according to the significant changes of tree growth and development characteristics in walnut life, the growth period of fruit trees can be divided into: young stage, early fruit stage, full fruit stage and aging stage. In production, according to the characteristics of each growth and development period, corresponding cultivation and management technical measures can be taken to adjust its growth and development so as to meet the requirements of production.

   I. infancy

   is called juvenile stage from seedling colonization to before the first flowering and fruiting. The length of this period varies greatly according to different walnut varieties or types. Generally, the early bearing walnut is only 1 ~ 3 years, the fruiting walnut is about 7 ~ 10 years, the iron walnut is about 10 ~ 15 years, and the grafted seedlings of the latter two are also 5 ~ 8 years.

The basic characteristics of    are as follows: the tree grows vigorously in eccentric direction, with erect branches, growing 2-3 times a year, and sometimes it is easy to strip when overwintering because it stops growing later. The young tree height of early bearing walnut is 0. 5%. At 5cm and 1.0m, there were only 1 and 2 branches with vigorous growth, but the medium and short branches formed earlier. The young tree height of late-bearing walnut is about 3.0 meters, and the number of new shoots can reach more than 100, among which the proportion of short branches is less. The grafted walnut seedlings have smaller crown and more branches than the seedlings.

Key points of    management: in cultivation and management, we should not only strengthen its vegetative growth as a whole, pay attention to shaping to form a solid and balanced skeleton as soon as possible, and expand the crown, but also control or slow release non-backbone branches to promote early flowering and fruiting.

   II. Early fruiting stage

   walnut is called the early fruit stage from the first flowering and fruiting to a large number of fruit.

The basic characteristics of   : the tree grows vigorously and the branches increase massively. With the increase of seed set, the branching angle opens gradually, until the centrifugal growth slows down, and the tree is basically stable. Early fruiting walnut is about 2 ~ 4 years old, walnut is about 7 ~ 20 years old, iron walnut is about 12 ~ 24 years old, or more. The average number of mother branches of fruit bearing walnut was 2, and that of early fruit walnut was 1 ~ 3. The amount of fruit increases by 0. 5% every year. 5 / 2. 0 times. At this time, the crown diameter of Juglans regia can reach 50.6 meters, while that of early walnuts is only 30.4 meters. The plant yield of early bearing walnut variety is 58kg, and that of early bearing walnut variety is 510kg. Early fruiting walnut has a strong ability to produce secondary branches at this stage, especially in the first 2-3 years. Wang Hantao et al showed that the crown width of late-bearing walnut trees increased rapidly in 15 years, which belonged to the peak period of vegetative growth, while the investigation of Fang Wenliang showed that while the fruit amount of iron walnut increased year by year, the vegetative growth was still exuberant and the centrifugal growth was enhanced. Liu Wansheng and other observations showed that the number of branches of early fruiting walnut increased in multiples before 6 years old, and then decreased gradually, but the absolute number of fruiting branches increased significantly.

Key points of    management: the main task of this period of cultivation is to strengthen comprehensive management, promote tree formation and increase fruit yield.

   III. Full fruiting period

The full fruit period of    refers to the period from the peak fruit period of walnut to the beginning of senescence. The duration of this period is closely related to the site conditions and the level of cultivation and management. Usually, it is 50 ~ 100 years old, the late bearing walnut is longer and the early bearing walnut is shorter. The investigation of 630 walnut trees in Anyang, Luoyang, Zhengzhou, Xinxiang, Sanmenxia and other places by Wang Hantao and Luo Xiujun of Henan Forestry Research Institute showed that the yield of walnut trees began to increase rapidly at 16 years old, reached the peak period of fruit in 40 ~ 90 years, and entered the period of high yield and stable yield after 60 years old.

The basic characteristics of   : the main characteristics of the tree in this period were that the crown and root system extended to the maximum, and began to show the phenomenon of internal chamber branch drying, fruit site outward movement and obvious local alternating results. The early bearing walnut was 8 ~ 12 years old, the early bearing walnut was 15 ~ 20 years old, and the iron walnut (cultivated type) began to enter the full fruit stage at about 25 years old. The vegetative growth and reproductive growth were stable in this period. The number of female flowers and the yield of walnut vary from variety to variety. As a result, the fruit range of the peak walnut is mostly concentrated in the periphery of the crown. According to the adjustment of 60-year-old trees, the outer fruit of the crown accounts for about 70%, the middle accounts for about 26%, and the inner chamber accounts for about 4%.

Key points of    management: this period is the period when walnut trees produce the greatest economic benefits in their lifetime. Walnut operators should pay attention to the scientific management of this period and prolong the peak period of fruit in order to obtain higher economic benefits. The main task of cultivation is to strengthen the comprehensive management, keep the tree strong, prevent the fruit-bearing part from moving out too much, cultivate and renew the fruiting branch group in time, and even renew some weak secondary backbone branches, so as to maintain high and stable yield and prolong the full fruit period.

   IV. Aging period

The stage of    is from plant senescence to death. The beginning of this period is related to the site and cutting conditions. The late bearing walnut and iron walnut began about 80 years old, and the early bearing walnut entered the senescence and renewal stage earlier.

The basic characteristics of   : the fruit yield decreased obviously, the backbone branches began to die, and the regeneration branches occurred at the back, indicating that it entered the period of human aging and renewal. At the initial stage, the end of the main technique and side branches began to die, the crown volume shrunk, more empty branches occurred in the inner chamber, the centripetal growth appeared, and the yield decreased, while in the later stage, a large number of regenerated branches occurred in the backbone branches. after many times of renewal, the tree potential was significantly weakened. the yield also decreased sharply, and even lost the significance of economic cultivation.

Key points of    management: the main task of cultivation management in this age period is to renew backbone branches in a planned way, form new crowns and restore tree potential on the basis of strengthening soil, fertilizer and water management and tree protection, so as to maintain a certain yield and prolong its economic life. The length of early harvest and duration at the beginning of the senescence renewal period of walnut trees varies greatly due to different varieties, site conditions and management levels.

   described the growth and development characteristics of walnut in four stages, which are organically linked and changed. In order to obtain high and stable yield, reasonable cultivation techniques must be adopted according to the ontogenetic characteristics of walnut to promote the early arrival and postponement of the peak fruiting period.