Problems needing attention in the process of walnut tissue culture

   (1) pollutes the aseptic environment of tissue culture, which is often infected by fungi, bacteria and other microorganisms, which affects the normal growth and development of culture materials. In all aspects of culture, attention must be paid to full disinfection and sterilization, and inoculation utensils, inoculation materials and operators should be strictly sterilized before inoculation operation, including used inoculation bottles and corks should be carefully cleaned and sterilized before they can be used again. Inoculation room, culture room, super clean worktable should be fumigated with formalin regularly and often sterilized with ultraviolet lamp.

The picture shows walnut

   (2) vitrification is a physiological disorder of test-tube plantlets, which shows that the leaves and shoots of test-tube plantlets are water-immersed transparent or translucent, and the leaves become smaller and deformed. It is difficult for glass seedlings to take root and survive after cutting. With the appearance of it, the growth of test-tube plantlets was slow and the propagation coefficient decreased. The main factors causing vitrification of test-tube plantlets are Agar and sucrose concentration of culture medium, culture temperature, liquid degree of growth regulator, ethylene concentration in culture bottle, light and nitrogen content in culture medium, which should be paid attention to in the process of culture.

   (3) the content of phenols in various tissues of browning walnut is high. In the process of tissue culture, polyphenoloxidase in tissues is activated and phenolic compounds are oxidized to form brown west most class substances. The polymerization of Xikun substances and proteins leads to the inactivation of other correct systems, metabolic disorders and growth inhibition. The browning phenomenon is serious, which is a bottleneck problem in walnut tissue culture.

The commonly used measures to prevent browning in    are: selecting young explants with strong meristematic ability and low phenol content; selecting suitable medium; lowering temperature and light without affecting normal growth and differentiation; adding antioxidants or adsorbents in the medium, such as ascorbic acid, sodium thiosulfate, citric acid, polyvinylpyrrolidone, active me, etc.