| Torreya grandis is a dioecious species of Torreya,Taxaceae.T.grandis ‘Merrillii' is a clone of an elite,natural variant(individual)vegetatively propagated and only cultured on a large scale so far in production.Plantlets of T.grandis ‘Merrillii' mainly used in production are grafted ones with 2-year-old seedlings of T.grandis as a stock and shoots of T.grandis ‘Merrillii' as a scion,which are cultured for two more years.Nowadays there is tendency to plant with large-size,grafted seedlings.Therefore,cultivation of stock-oriented seedlings is of significance to the industrial development in T.grandis ‘Merrillii'.With seedlings propagated by Zhuji Liqin Eco-agricultural Development Co.,Ltd.of Zhejiang from seeds of T.grandis(including those of T.grandis ‘Merrillii'),studies were conducted inside a shed supported by steel frame and a shading net in terms of growth traits(height,ground diameter,number of branchlets,and ratio of height to ground diameter of the seedling)and biomass(both fresh and dry weights of all the shoots and leaves,those of roots,and ratio of roots to the sum of shoots and leaves)based on measurement and calculation,chlorophyll content using an ethanol extraction method,TCC-based root activity,nutritional elements of both seedlings and media measured with a H2SO4-H2O2 diffusion method,Mo-Sb colorimetric method,Kjeldahl method,heat of hydration-based method and atomic absorption-based spectrophotometry,volume weight and porosity based on a weighing method,and p H of media measured with a p H meter to have an understanding of effects of different seeding time on growth of 0.5-year-old potted seedlings,effects of pot sizes and transplanting dates on growth of 1.5-and 2.5-year-old potted seedlings,and effects of different media on growth of 1.5-year-old potted seedlings as well as to make a comparison in seedling growth between T.grandis and T.grandis ‘Merrillii' and between potted seedlings and those directly cultured in the land.All the data were analyzed with SPSS17.0.The results are as follows:(1)It was suitable to have germinating seeds of T.grandis in place in pots from January to March.In the mass production of seedlings,seeding in pots could be done during this period based on the realistic germinating radical of seeds,which would favor even distribution and arrangement of labor force.(2)It would be good to transplant 0.5-year-old seedlings of T.grandis once 150 days after seeding since the initial container(4.5cm(diameter)×8cm(height))was limited in size,which was unfavorable to seedling growth.Therefore transplanting should be done with such a big size of pots as 18 cm × 22 cm,which would be good for root extension.It would not be suitable to transplant seedlings one year after seeding when seedlings started to grow.(3)The medium used when seeding in the pot was done was composed of 50% of peat and 50% of a mixture of perlite,vermiculite and chaff.Other three media tested for transplanted seedlings had a proper p H and an abundance of instant N,instant P and instant K and therefore were suited to culture seedlings of T.grandis.But Medium A(20% earth,20% chaff,20% diatomite,20% peat and 20% fermented organic matter)was best for its proper air permeability and water-holding capacity,quality seedlings cultured,a high root vigor,and a high quality index for seedlings.(4)As compared with seedlings cultures with seeds of T.grandis,seedlings cultured with seeds of T.grandis ‘Merrillii' performed well in several parameters including those of growth traits,but seedlings of T.grandis were significantly better than those of T.grandis ‘Merrillii' in the root vigor.In consideration of the survival rate of seedlings planted and cost of seeds in T.grandis ‘Merrillii',it is suggested to use seeds of T.grandis to culture seedlings.(5)There was no significant difference between 1.5-year-old potted seedlings and those cultured in the land in terms of several parameters,but the seedlings cultured in the land were superior to potted seedlings in the root vigor,which was especially true with 2.5-year-old seedlings cultured in the land that were significantly better than potted seedlings.But the seedlings cultured in the land were significantly lower than those potted seedlings in growth-related parameters and biomass.In addition,roots of the seedlings cultured in the land are easily hurt during transplanting and transportation,and the period of time suitable for planting of these seedlings is relatively short.But it is possible to culture potted seedlings all the year round.And since potted seedlings are planted with no pot(made of non-woven fabric)removed and the time needed for recovery of growth is relatively short after the seedlings are planted,culture of potted seedlings is a tendency for further development.(6)Growth in seedling height increasingly continued in the growing season for seedlings of various ages,but growth in ground diameter mainly started after July,which implied that measures could be taken according to the rhythm of seedling growth.In summary,a flat site rich in water sources and convenient in transportation could be used to culture containerized seedlings of T.grandis,which are to be used as a stock for T.grandis ‘Merrillii'.After collected in October,seeds of T.grandis were stored with moist sand and covered with an arched plastic shed to accelerate the germination of seeds.When the seed had a 0.5 to 1 cm long radical in about 1.5 month,the seed could be placed in a 4.5 cm(diameter)× 8 cm(height)container made of non-woven fabric from early December to January 10 of the Chinese Lunar Calendar,the medium of which contained 50% of peat and 50% of a mixture of perlite,vermiculite and chaff with no fertilization but with a proper moisture rate kept.The potted seedlings were then transplanted to a large-size container(e.g.18 cm × 22 cm)with no pot removed 150 days after seeding in the same year when germinating seeds were placed into the container.The medium at this time was composed of 20% earth,20% chaff,20% diatomite,20% peat and 20% fermented organic matter,to which an approprate amount of organic matter fermented(about 75 – 100 g per seedling)from a mixture of chaff,chicken shit and stalk for seedlings could be added in the intersection of winter and spring.Two-or three-year-old seedlings could be used for planting,followed by grafting,or for grafting with a scion from T.grandis ‘Merrillii'. |
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