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| On effect of soil hardness on development of seeded and planted seedling root system |
| Yang Xitian1, Dong Huiying3, Yoshinari Yamadera2 |
| 1.Henan Agricultural University, Zhengzhou, 450002;2.Shinshu University, Nagano 399-4501 Japan |
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Abstract Effects of soil hardness on the growth of seeded and planted Pinus densiflora Sieb. et Zucc. seedlings were investigated. Soil hardness was managed for 5 levels (10, 15, 20, 25 and 30 mm of soil hardness index for Yamanaka Type) , and P. densiflora was planted and seeded in each treatment. The root length, the state of root system, stem height, stem basal diameter, biomass of above- and below-ground were investigated . The planted seedling had thinner and shorter roots and the number of roots was more than that of the seeded plant. The main root of the planted plant disappeared in each soil hardness treatment, but the seeded plant remained the main root in every treatment. The ratio of root length to stem height in the seeded plant increased with the soil hardness increasing (2.1, 3.3 and 5.8 when soil hardness was 10 mm, 25 mm and 30 mm, respectively). On the other hand, the ratio of root length to stem height in the planted plant decreased when soil hardness became harder (4.0, 2.5 and 2.4 when soil hardness was 10 mm, 25 mm and 30 mm, respectively) . This means that the root of the seeded plant grow more preferentially than the growth of stem under hard soil conditions. When the plant was planted in the soil harder than 25mm, seedlings could not extend their roots beyond the planting holes and the root system became twisted. These differences between seeded and planted seedlings will effect plant growth, stability of trees, soil conservation ability and the tolerance to the consequence of variation of climate such as dryness. Thus, when we restore forest in degraded lands, soil modifying and the choice of restoring strategy of seeding will be important and necessary to facilitate forest succession and develop balanced forest population.
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Received: 05 May 2005
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