Studies On Relationships Between Morphological Characteristics Of Root In Different Classes And Root Respiration Of Pinus Tabulaeformis, Platycladus Orientalis, And Pinus Bungeana

To explore the differences of root absorption function, root architecture, total and maintenance root respiration, short-term responses of root respirationrate to temperature, water potential and nutrient availability were studied on basis of Pinus bungeana, Pinus tabulaeformis and Platycladus orientalis trees in the paper. Results were as following:Root in diameter of <2mm was the main part for nutrient absorption, and root in diameter of 1~2mm was the stable part. Root length in diameter of <2mm took 86.1~93.7% of total root length, and root surface area which was in the same diameter took 42.9~75.4% of total root surface area. The link number and surface area of root in order 0~3 was took 78.6~82.0% of total link number and over 70% of total root surface area respectively. The link number, root numer, accumulative root length and root surface area of root in diameter of <1mm took over 90%, 78.6~82.0%, 69.2~76.7% and 25.4~40.6% respectively.Based on dry root biomass, the affirnity (1/Km) of root to ion was increase with diameter, and the maximum absorption rate of ion (Vmax) changed in opposite way. The Vmax was the highest and the ion affirnity was the lowest for root in diameter of .5mm to Pinus bungeana rather than other species. The result was closely relative to higher specific absorption area for root in diameter of .5mm.Total root respiration rate, maintenance respiration rate and growth respiration rate was obviously different to three species. The highest total root respiration rate per root volume and dry biaomass of Pinus bungeana was occured in root of in diameter of <5mm. and total root respiration rate, maintenance respiration rate and growth respiration rate was decrease with increase of root diameter. Root maintenance respiration rate took 61.0~99.7% of total root respiration rate. Q10 of root respiration ranged from 1.09 to 3.66, and species order in Q10 value was Platycladus orientalis > Pinus tabulaeformis> Pinus bungeana. Pinus tabulaeformis allocated more carbon to root growth than Pinus bungeana and Platycladus orientalis which allocated more carbon to root maintenance.Root respiration rate was obviously affected by tenperature, water stress and nutrient availability in short-term treatment. The sensitivity of root respiration response to temperature was higher for Platycladus orientalis root than for Pinus tabulaeformis, and Pinus bungeana was the most unsensitive pspecies. Change of root respiration rate for Pinus tabulaeformis and Platycladus orientalis in nutrient absorprion was sharper than for Pinus bungeana, and was Pinus tabulaeformis the most sensitive species. It indicated that Pinus tabulaeformis allocated more carbon to ion uptake. Respiration rate...