Hongyan MA

Technology Industry Group of Beijing University of Agriculture, Beijing 102206, China

Flammulina velutipes, widely used as food or a medicine, is of Flammulina species, in the family Physalacriaceae, order Agaricales, class Agaricomycetes, and division Basidiomycota[3].It is extensively distributed in Japan, China, Europe and the US[4]. With crisp and delicate stipe, and sticky and smooth cap[5], it tastes delicious[6], containing rich protein, vitamin and crude fibre[7]. What’s more, it performs excellent in improving intelligence[8]and anti-cancer[9-10],so that innovations are made in terms of production technologies and techniques. For example, the cultivation mode with plastic bags is the simplest,with high biotransformation efficiency and good benefits[11], which is widely applied among factories[12].In contrast,regeneration method mainly adjusts environment factors to induce withering of Flammulina velutipes and makes full use of stipe and base to promote secondary differentiation of base, which produces Flammulina velutipes with better quality and yield compared with traditional methods.Currently,edible mushroom-based enterprises face fierce competition, and the core is related to technology to a great extent.The research made conclusion on different chains of regeneration of Flammulina velutipes in order to resolve the restrictive problems in cultivation and to provide new thoughts of highly-yielding cultivation for practitioners.

In general, the technological process of Flammulina velutipes cultivation consists of opening bags, inducement to primordium, inhibition, regeneration, bagging and management in growth stage.

Opening Bags and Inducement to Primordium

Mushroom hypha would ripe from the 23rdto the 40thd after inoculation,and the ripening stage including formation period, development period and fully-grown period of buds. When culture compost swells, Flammulina velutipes can be shelved from bags.Specifically, plugs and lantern rings can be unplugged and the cultivation bags are bagged with low-pressure polyethylene plastic bags. It is notable that the external bags should be lower than cultivation bags, and the rest can be folded into turnover baskets. Subsequently, inner bag entry is lifted by left hand and plastic films about 3-5 cm away from bag entry is cut by right hand to rip off the thin films at entry.Meanwhile,the temperature of cultiva-tion room can be adjusted to 5-7 ℃,humidity to 85%-92%,and illumination intensity to 50-200 lux for co-stimulatory. After 10 d, then, primordium would form on surface of medium and the primordium would develop to tiny buds after days of cultivation.

Inhibition and Regeneration

When buds grow to 2-4 cm in length, the temperature of the cultivation room can be adjusted to 6-9 ℃,and humidity to 60%-70%. With an evaporator and an inner-circulating fan intermittently operated in refrigerating unit, the frontier of buds would lose water fast and fall down. If sporocarps grow sparsely in a small number, the growth period can be extended in case of effects on yield. In general, these aim at inhibiting big fruits, promoting small ones and guaranteeing full growth of the buds,which is an important chain for enhancing yield and quality of sporocarp,under influence of light,humidity and temperature.

After the inhibition treatment, the temperature of the cultivation room can be adjusted to 9-12 ℃and humidity to 80%-90%. After 2-4 d, new buds would grow from bases of the fallen stipes and by low-temperature cultivation, the buds would grow denser and denser. As time goes on,stipes would extend and sporocarps would grow in a semi-hydrangea shape. It is notable that withering of buds is key for the success of regeneration method. For example, if the withering degree is not high enough,sporocarp would grow again, so that the regeneration process would be affected, and the yield can not be improved,either.

Lifting Bags

If sporocarp continues growing,stipe would extend out of the bags,and external films should be pulled up every day. However, the supply of oxygen should be guaranteed, or the grown plants might be tall or short,with uneven flatness.

Growth Management of Sporocarp

The suitable temperature for sporocarp growth should be kept in 5-8 ℃and the concentrations of CO2of 8 000-12 000 cm3/m3. It is notable that CO2at a high concentration is conductive to extending of stipe and producing of highly-qualified Flammulina velutipes (Fig.1). Natural ventilation quantity meets the cultivation demands already and therefore,the door of cultivation room can not be kept open for a long term.Furthermore,relative humidity should be 85%-90% in the process of sporocarp growth.If the humidity is too high, for example, the moisture content of grown Flammulina velutipes would be higher also, resulting in poor quality of fruits and short storage term.In contrast,if the humidity is lower, the content of moisture would be lower, so that the quality would be guaranteed and storage term would be longer.

Besides, if the concentration of CO2is higher and humidity of cultivation room is higher, new buds would grow from cultivation composts, resulting in lodging of plant tips, low yield of regenerated Flammulina velutipes.

Harvesting

Flammulina velutipes can be harvested when cap tips curl, shaping bamboo-hat or spherical surface, with diameter of 0.5-1.2 cm and sporocarp length of 16-18 cm (Fig.2). Specifically,the staffs could hold the bases of Flammulina velutipes and sway a little bit to pull the plants out.After harvesting, Flammulina velutipes can be weighed per bag, followed by packaging for marketing(Fig.3-Fig.4).

However, Flammulina velutipes should be harvested in advance if the following phenomena occur. Firstly, if the cap is too large and sporocarp declines earlier, continuing cultivation would result in aging of Flammulina velutipes and decreasing of the commercial value.Secondly,if Flammulina velutipes is damaged by diseases or insects, continuing cultivation would lead to decomposition of the plant and even destruction of the whole growth environment.

Conclusions

Compared with traditional bagging cultivation, regeneration method takes advantages.For instance,the nitrogen source in soyabean cake and wheat bran cane be transformed into amino acid necessary for humans,which indicated that Flammulina velutipes is abundant with nutritional and medical components. Hence, for enterprises with advanced technology in China should conduct large-scale production in refrigerators, with saw dusts as major materials. In conclusion, the yield of Flammulina velutipes reaches 450-460 g and biological transformation rate is in the range of 125% -128% . What’s more, the cultivatedFlammulina velutipes proves better in quality and longer in shelf-life,and the source of raw materials is not confined in a specific region,showing a promising prospect. For governments,therefore, more supports should be given to enterprises engaging in planting Flammulina velutipes in order to stimulate development of leading enterprises with high intensive management and advanced cultivation technology and facilities.

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