| Quercus robur is an important landscaping tree species in Europe.Introduced and cultivated in Tacheng,Xinjiang,my country,it performed well.In recent years,the introduction and trial planting in Shenyang and Fushun areas have encountered problems such as inadequate sowing technology,difficulty in cultivating high-quality and strong seedlings,and difficulty in preventing sunburn in summer,sunscald in winter and spring.In this paper,the seeds of Quercus robur were used as the test materials,and the stratified germination and seedling raising and fertilization experiments were carried out.The suitable stratified germination and seedling-raising techniques for the seeds of Quercus robur were studied,and the effects of different contents of N,P and K fertilizers on the stress resistance of the seedlings were studied;using the transplanted seedlings of Quercus robur as the test material,the characteristics and prevention methods of sunburn in summer and sunscald in winter and spring were studied,and the key technical support for the cultivation and maintenance of Quercus robur in Shenyang was provided.This paper draws the following conclusions:(1)After adopting the low temperature stratified sand storage method and the stratified snow storage method,the seeds of Quercus robur are mixed with sand to promote germination,which is beneficial to the germination of seeds.The germination rate of seeds in the layered sand storage was 83.4%,and that in the layered snow storage was 75.4%,and the former was better.The seeds of Quercus robur after germination were raised in containers and seedbeds in the field.The average ground diameter and plant height were0.85 cm,44.6cm,0.55 cm and 31.7cm,respectively,indicating that container seedlings were more conducive to cultivating high-quality and strong seedlings.(2)The container seedlings of Quercus robur grow rapidly from June to July,and fertilizers with a ratio of N:P:K of 6:2:3 can accumulate more chlorophyll,thereby,the growth of the plant height and ground diameter of the seedlings is accelerated,which is beneficial to the cultivation of strong seedlings.During the period of slow growth of seedlings in August,the application of fertilizers with a ratio of N:P:K of 5:5:6 is conducive to the accumulation of soluble sugar,soluble protein and peroxidase(POD),and can effectively improve the ability of Quercus robur to solidify organic matter,make the seedlings fully lignified,strengthen the cells to resist the harm of bad environmental climate,and protect them from low temperature and drought.(3)In Shenyang area,the cut and dried seedlings of Quercus robur are prone to sunburn in summer in the southeast and southwest(magnetic azimuth angle 97°-265°)due to lack of canopy,the magnetic azimuth of summer sunburn is 117°-237°,and the average magnetic azimuth is 179°;the closer it is to the notch,the heavier the water loss of the trunk,and the most water loss is in the range of 0-30cm;the sunny side of the trunk(magnetic azimuth 117°-237°)loses more water than the shaded side,and the most loss is 10 cm away from the notch.In the range of 90°-225° of magnetic azimuth after summer sunburn,the water content of xylem was 2.67% lower than that of phloem,indicating that the xylem was the first place to lose water.The wound healing effect of the trunk and side branches of Quercus robur has obvious directionality,and the positive side(magnetic azimuth angle of 117°-233°)has the worst healing effect.The reason why Quercus robur is prone to sunscald in winter and spring during the dormant period is that the water loss on the sunny side is faster than that on the shady side,30-50 cm from the ground is the origin of the sunscald of Quercus robur in winter and spring,and it extends up and down in the axial direction year by year,and extends from the outside to the inside in the radial direction;compared with Quercus mongolica and Quercus aliena,the diameter of the xylem vessels,the specific hydraulic conductivity of the stem and the xylem embolism vulnerability index were larger in Quercus robur,it can lead to severe freeze-thaw embolism,which is the physiological basis for the easy occurrence of sunburn in winter and spring in Quercus robur.The way to prevent sunscald in winter and spring is to increase the accumulation of nutrients in the Quercus robur during the growing period,and use effective materials to protect the trunk during the dormant period.The test results show that,compared with plant bandages and whitening agents,the cross-linked polyethylene foam aluminum film has a good water retention effect,which is beneficial to prevent the occurrence of sunscald in Quercus robur in winter and spring. |
