Influence Of Arbuscular Mycorrhizal Fungi And Sugar-free Culture On Physiological Effects Of Malus Pruniolia Var Ringo Plantlets In Vitro

Plant tissue culture is a widely used biological technique method for production of large number of genetically identical plantlets. It has many advantages over conventional propagation techniques, and has been developed to an important means of plantlet propagation. In this paper, due to the problems of the conventional tissue culture, such as: the unhealthy growth environment, the vulnerable pollution, the vitrification, the long dormant period, and the technical difficulties of the plant sugar-free tissue culture, such as: low CO₂ control precision, the high humidity, the lack of means to improve the plantlet quality and so on. Researches were undertaken on the large-scale vessel design, the environment accuracy control, the sugar-free exposition culture pattern, relevance of PPFD and CO₂ concentration, as well as the mycorrhiza technology to improve the plantlet and so on. The sugar-free culture technology system for high-quality plantlet was founded. The main achievement of this research as follows:1. A novel 180 litres large-scale cultural vessel for sugar-free culture was designed. The vessel consisted of CO₂ release pipe (with holes in the pipe), environmental control device and gas exchange holes. This design made the operation to be easier; At the same time, a bigger vertical space enhanced the gas density cushion performance; the installment of CO₂ release pipe created the condition for high control precision; Through the small-flow control, the three-way-valve adjustment and the PWM, The control precision was up to±50μmol·mol^-1; the membrane tectoria and the gas-cycle adsorption to eliminate the humidity were used to automatically control the relative humidity; the control precision was±2%.2. The sugar-free culture box with environmental control system independently designed was adopted, the sugar-free exposed culture pattern in the membrana-tectoria plate were proposed for the first time, which improved the traditional method using the small container, and broke away from many of the traditional constraints of plant tissue culture. The open-vitro cultivation became true, which omitted from the acclimation phase, and established a new technical system. Using this pattern, the plantlets had higher photosynthesis, the developed root, the more dry matter, the growing unanimity, and the better quality.3. The relevance of PPFD and CO₂ concentration to the photosynthesis of plantlets was studied, it was showed that when the high CO₂ concentration was matched with high PPFD the photosynthetic rate of plantlets in vitro would be promoted effectively, and the plantlets was vigorous and healthy.4. An integrated inoculation technology to enhance of the growth of the plantlets had been established in rooting stage in sugar-free culture in vitro, which formed the balanced rhizosphere biology environment, and promoted the growth of the plantlets, such as: reduced leaf's stoma resistance, increased chlorophyll content and CO₂ fixation, enhanced the photosynthesis rate of the host plantlets, and improved physiological condition and the quality of the plantlets; Moreover, this kind of paragenesis relations still existed after transplanted, which reduced environment stress after transplanted, and shortened the dormant period of crabapple, the sprout time of new leaf was ahead of time 7 days than those of non-mycorrhizal explants.5. The key technology of mycorrhizal inoculation with AM fungus on the photosynthesis of plantlets in vitro was:(1) Reducing the nutrition ion concentration in the culture medium. 1/4 hormone-free and sugar-free MS medium was used to culture Malus pruniolia var ringo plantlets, which reduced mineral ion concentration, and provided a low-osmolality living environment for microbial growth.(2) Choosing species of highly colonization. The better selection of mycorrhizal inoculation species of Malus pruniolia var ringo plantlet in vitro was Gv.(3) Using suitable amount of inoculums. The better selection of mycorrhizal inoculation amount in vitro of Malus pruniolia var ringo plantlet was 5 g pot^-1.(4) Increasing the light intensity and CO₂ concentration in plant tissue culture can improve the plantlets' photosynthesis, accelerate accumulation of photosynthetic products, and reduce the side effects of AM initial infection to the host plantlets...