Effects Of Silicon On Growth And Physiological Metabolism Of Blueberry Plantlets In Vitro

Tissue culture technology is the main method of rapid propagation of blueberry plantlets,but there are some problems in commercial production,such as weak growth of plantlets,low survival rate of transplanting,serious glass and browning,and low reproduction coefficient of some varieties.A large number of studies have shown that silicon can promote the growth and development of plants,improve the quality and comprehensive resistance of plants,but there are few studies on the role of silicon in plant tissue culture.In this article,plantlets in vitro of blueberry?Vaccinium spp.?were used as materials to explore the effects of the addition of different concentrations of K₂SiO₃ and Nano-silica in 1/2Ms medium on the growth,physiological metabolism and microstructure of blueberry plantlets under different conditions,so as to clarify the role of silicon in blueberry tissue culture and alleviating stress.The main results are as follows:1.The addition of low concentration(0.3 g·L^-1)K₂SiO₃ in the medium could improve the proliferation coefficient,plant height and dry mass of blueberry plantlets of varieties such as?O?Neal??Elliott??Springhigh??Patriot?and?Bluegold?.At the same time,the content of water,chlorophyll and potassium were significantly increased while sodium,calcium and iron,malondialdehyde and relative electrical conductivity of?O?Neal?were significantly decreased.2.0.3 g·L^-1 K₂SiO₃ could reduce the browning rate and increase the height of blueberry plantlets under high pH?7.0?and Polyethylene glycol?PEG?simulated drought stress while the content of malondialdehyde?MDA?and Reactive oxygen species?ROS?were decreased.At the same time,the contents of chlorophyll,soluble sugar,soluble protein and potassium,calcium and phosphorus in the test tube seedlings under high pH stress were significantly increased,while the contents of sodium and magnesium were decreased.The damage of PEG simulated drought stress on the microstructure and epidermal scanning structure of blueberry plantlets were alleviated,and the water content of blueberry plantlets was significantly increased.3.Different concentrations of Nano-silica had different effects on the growth and physiological metabolism of blueberry plantlets.Low concentration(0.05,0.1 g·L^-1)increased the free water content,promotes the metabolism,and they were conducive to the growth of weak plantlets and transplanting plantlets.High concentration(0.2 g·L^-1)could promote chlorophyll synthesis and increase proliferation rate,which was suitable for varieties with low reproduction coefficient and difficult to propagate.At the same time,under high pH?7.0?stress,low concentration of Nano silica is more conducive to the proliferation of test-tube seedlings.The addition of appropriate amount of silicon source(0.3 g·L^-1 K₂SiO₃/0.05 g·L^-1Nano-silica)in the culture medium could promote the growth and differentiation of blueberry plantlets under conventional culture conditions through enhancing the photosynthesis of blueberry plantlets.Apart from this,silicon could alleviate high pH and damage to blueberry plantlets under drought stress and promote the growth of tube seedlings and differentiation by improving nutrition absorption,the activity of antioxidant enzymes,the assimilation organization and conducting tissue structure,meanwhile,reducing Na/K ratio and transpiration.This study provided theoretical support and technical guarantee for improving the reproduction efficiency,quality and comprehensive resistance of blueberry seedlings,and also provided guidance for the rational development and utilization of silicon.