指数施肥对楸树无性系生物量分配和根系形态的影响

Abstract

In order to study the differences of Catalpa bungei clones′ biomass allocation and root morphology,an exponential fertilization trial was conducted with three nitrogen dose levels of 6 10,14 g urea per plant and CK.The experimental materials were two-year Catalpa bungei clones 1-4,7080 and 015-1 tissue culture-seedlings.We conducted the experiment in Xiaolongshan forestry science and technology research institute,Tianshui city,Gansu province from March to August 2011.The results showed that:(1) After the end of the fertilization,the root biomass,stem biomass,leaf biomass,total biomass,root length,root surface area,volume of root and root average diameter with 10 g urea per plant treatment were higher than other treatments in the same clone.The clone 015-1 showed higher values of biomass parameters and root morphological parameters than the clone 1-4 and clone 7080.The root biomass,stem biomass,leaf biomass and total biomass of clone 015-1 with 10 g urea per plant treatment were 89.44 g,61.30 g,79.97 g,230.71 g,which were 1.48,1.52,2.09,1.66 times that with CK.The root length,root surface area and volume of root of the same treatment were 22667 cm,6260 cm2,578.14 cm3,and 1.94,1.54,2.43 times that with CK respectively.(2) Exponential fertilization and genetic differences of the clones significantly affected three Catalpa bungei clones′ biomass allocation pattern.The application of nitrogen exponential fertilization significantly promoted the root biomass,stem biomass,leaf biomass and total biomass accumulation of three Catalpa bungei clones,while nitrogen deficiency or excess showed negative effects to the accumulation of biomass.In August the root to shoot ratio of the same clone decreased with the increase of the amount of nitrogen.For the same treatment,the clone7080 showed higher ratio than the clone 1-4 and clone 015-1.The biomass of the clone 1-4 and clone 7080 were mainly allocated to leaves and stems,while the clone 015-1 to leaves.(3) Exponential fertilization in June and July increased three Catalpa bungei clones′ fine root lengths and surface areas,accounting for the proportion of the whole plant′root length and root surface area up to 96.99%,86.82%,93.10%,72.52%.Exponential fertilization mainly increased three Catalpa bungei clones′ volumes of roots.The fine roots,roots,and coarse roots in August increased by 36.88%,124.96%,and 154.79% compared with those in July.This helped the roots intake more nutrients in the late of exponential fertilization,thus would affected the changes in the pattern of biomass allocation of three Catalpa bungei clones.(4) The biomass parameters and root morphological parameters of three Catalpa bungei clones were closely related.After the end of the fertilization,the root biomass,aboveground biomass and total biomass were extremely positively related to root length,root surface area,root volume and root average diameter.The root-shoot ratio was significantly negatively correlated with root length,root surface area,root volume,root average diameter.The specific root length was significantly positively correlated with aboveground biomass,total biomass and significantly negatively correlated with root-shoot ratio.