| About a dozen years ago, Root Biology is an abroad raised cutting-edge science fromplant biology. Moso bamboo (Phyllostachys edulis) is a bamboo species with the largest area,the highest economic value and the best industry in China, which occupies an importantposition in forestry economy and industrial structure. The research about Moso bamboo rootwas mainly centered in overground parts, and the underground parts was very few for a longtime. This paper studied the root biology of Moso bamboo in terms of root architectural,morphological characteristics, anatomical structure, root biomass dynamics and in situmonitoring of growth.The main results are as follows:(1) The root growth of Moso bamboo seminal roots were studied by paper pouch methodaccording to the statistics20seeds into seedlings. The growth rate of root had two peaks, thesixth day-14.72mm/d and the fourteenth day-13.33mm/d, and the new leaves and the newroots grew by turns.(2) The architectural of Moso bamboo seedling roots were studied by root-boxmethod.Moso bamboo was fibrous root plant. The root indexes of length, number, surface area,volume and average diameter in different soils had extremely remarkable hierarchy. Rootlength, number, surface area and volume concentrated in0-20cm soil, occupied64.2%,69.98%,66.74%and71.66%of the total, respectively, those root indexes were decreased asdepth increased. The maximum and minimum of average diameter of root appeared in0-10cmand20-30cm soils respectively. The ratio of width to depth of Moso bamboo seeding rootswas0.682, the width was less than depth, the ratio was decreased as depth increased. The dryweight of Moso bamboo seeding roots were concentrated in the soil of0-5cm in the horizontaldirection and0-20cm in the vertical direction, showed the characteristics of bell-shapeddistribution.(3) The root order of rhizome root of Moso bamboo can be divided into four levels. Theroot diameter, root length, specific root length, root tissue density of Moso bamboo among the first to fourth root orders were systematic studied. Root diameter, root length and root tissuedensity were significantly positively related to root orders. The minimum was the first-order,the maximum was the fourth-order. Root diameter would increase three-to-fourfold and rootlength would increase fourfold for each level of root order increased. The specific root lengthwas decreased as root order increased, the maximum was the first-order, the number was36.28g·m-1, which was150times larger than the fourth-order.(4) The anatomical structure of different root orders were studied by paraffin and scanningelectron microscopy method. The anatomical structure of Moso bamboo root were mostlymade up of epidermis, cortex and stem. The epidermis of Moso bamboo consists of2-3layersof cells, and have many root hairs.The cortex were made up of exodermis, parenchyma cells,and endodermis. significantly increased as root order increased. The exodermis cells weresmall and arranged closely. The parenchyma cells occupied the largest proportion of the wholecortex, the cells closed to the exodermis and endodermis were small, the cells in the middlewere big. The air chamber structure was observed in cortical parenchyma among third tofourth-order. The shape of the cell of endodermis was square or approximately circular, andranged around the column. The Pith was clearly observed among the first to third-order, andhollow among some third to fourth-orders.The minimum of the the thickness of cortex and thediameter were the first-order, the number was0.237mm and0.212mm, respectively, themaximum was the fourth-order, the number were0.736mm and1.446mm, respectively. Theratio of vascular bundle diameter to root diameter increased as root order increased, it representthe conduction features of different orders.(5) The distribution and seasonal dynamic of rhizome root biomass was studied. Theaverage biomass of roots was12.891t·hm-2,88.8%of the roots concentrated in the soil layerof0-40cm, the root biomass decreased as depth increased, the biomass in0-20cm layeroccupied62.3%, which was2.35and5.56times more than20-40cm layer and40-60cm layer,respectively. The root biomass had obviously seasonal variation and their variation ranges were7.686t·hm-2～17.386t·hm-2, the highest was in July and the lowest was in February. The root biomass was significantly associated with temperature and had no significant correlation withrainfall.(6) The in situ growth dynamics of root was studied by minirhizotron. The root numberdensity and root length density had the same varying tendency that increased from March toAugust, and presented a tendency of straight upward after June. Reached the maximum inAugust, the number were0.037a·cm-2and0.155cm·cm-2, then decreased. The root diameterof bamboo was1.22mm in early March, and increased slightly in April and May, reached themaximum in May (1.28mm). The diameter started to drop in early May, and had a significantdecline from June to August. The diameter reached the minimum in August (0.29mm), andthen increased.These research results of bamboo root biology could provide scientific basis and industrial guidance for Moso bamboo resources protection and utilization and enhancing bamboo forest productivity. |
