| This study investigated the effect of the growth characteristics under different exogenous light of seedlings,in order to provide a theoretical basis for quickly raising seedlings,shortening the period of seedling cultivation and the technology of seedling cultivation.In this paper,the seedlings of Quercus mongolica,Acer truncatum and Pinus tabulaeformis were taken as experimental materials,supplemented with nutrients by exponential fertilization and placed in three kinds of external light treatments: LED red-blue light,LED white light and full spectrum light to determine the seedling height,ground diameter,biomass,the content of N and P,and the content of soluble sugar and starch of seedlings under different exogenous light.The results are as follows.1.Effects of the growth characteristics under different exogenous light of seedlings.(1)Compared with other exogenous lights,LED red-blue light promoted the growth of ground diameter,biomass and seedling index of three seedlings.Otherwise,LED red-blue light promoted the underground fresh weight and dry weight,increased the root to shoot ratio and root allocation ratio of Quercus mongolica,LED white light promoted the growth of height,the aboveground fresh weight and dry weight,that shows LED red-blue light can promote seedlings on root growth of Quercus mongolica,with a maximum stem diameter of 5.04 mm and the average underground dry weight of 2.91 g,LED white light can promote seedlings on aboveground growth of Quercus mongolica,with a maximum height of 13.8cm,and the average aboveground dry weight is 1.98 g;LED red-blue light promoted the growth of height,reduced the root to shoot ratio and root allocation ratio,that shows LED red-blue light greatly promotes the stem and leaves growth of Acer truncatum,with a maximum height and stem diameter of 56.9 cm and 7.17 mm;LED red-blue light promoted the growth of height of Pinus tabulaeformis,with the stem diameter was 4.5 times higher than full spectrum light,increased the root to shoot ratio and root allocation ratio,that shows LED red-blue light can promote root growth of Pinus tabulaeformis and is more conducive to its growth.(2)Compared with full spectrum light,LED red-blue light can increase the starch content of three seedlings,but the effects on soluble sugar is diversity among different tree species.Then,LED red-blue light increased the underground soluble sugar content of Quercus mongolica,LED white light increased the aboveground soluble sugar content of Quercus mongolica and reduced the underground starch content;LED red-blue light and LED white light increased the soluble sugar and the starch content of Acer truncatum;LED red-blue light and LED white light reduced the soluble sugar content and increased the starch content of Pinus tabulaeformis.(3)Compared with full spectrum light,LED red-blue light and LED white light reduced the total nitrogen and total phosphorus content of three seedlings.LED red blue-light and LED white light significantly reduced the total nitrogen and total phosphorus content of Quercus mongolica and Acer truncatum seedlings,and it was the lowest content under LED white light on the total nitrogen and total phosphorus of Quercus mongolica seedlings,it was the lowest content under LED red-blue light on the total nitrogen and total phosphorus of Acer truncatum;LED red-blue light and LED white light significantly reduced the total phosphorus content of Pinus tabulaeformis seedlings,and its total nitrogen content was slightly lower,it shows that LED red-blue light and LED white light promote the growth of seedlings,resulting in dilut io n of nutrient content.2.Changes in field planting of the growth characteristics after different exogenous lightCompared with the light experiment period,the fresh and dry weight,and the growth of Pinus tabulaeformis seedlings was increased in field planting,and the previous differences in the light experiment period were maintained,it was increased of dry to fresh weight ratio,root to shoot ratio,root al ocation ratio and seedling index,and the seedling index of seedlings cultivated by LED red-blue light was better than that of seedlings cultivated by LED white light.However,the soluble sugar content was slightly reduced and the previous differences were not retained,the starch content was slightly increased and it was significantly of seedlings cultivated by the LED red-blue light higher than other seedlings.The contents of total nitrogen and total phosphorus of the seedlings cultivated by LED red-blue light and LED white light did not retain the previous differences,and it had positive correlation with the growth index of seedlings,which were higher than seedlings those cultivated by full spectrum.It shows that the physiological characteristics of seedlings growing under different light sources are likely to not be reflected in field planting cultivation,but the impact of seedling growth indicators on different light sources is likely to determine the growth of seedlings and the accumulation of biomass in field planting cultivation and the adaptability of environmental impact. |
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