Phosphorus (P) is necessary for growth and nitrogen fixation, and thus its deficiency is a major factor limiting legume production in most agricultural soils. The effect of phosphorus supply on nodule development and ...Phosphorus (P) is necessary for growth and nitrogen fixation, and thus its deficiency is a major factor limiting legume production in most agricultural soils. The effect of phosphorus supply on nodule development and its role in soybeans (Glycine max L.) was studied in a nutrient solution. Plants were inoculated with Bradyrhizobium japonicum and grown for 35 days in a glasshouse at a day and night temperature of 25℃and 15℃, respectively. Although increasing P supply increased the concentrations of P and N in the shoots and roots, the external P supply did not significantly affect the P concentration in the nodules, and the N fixed per unit nodule biomass decreased with increasing P supply. The nitrogen content in the shoots correlated well with the P content (r = 0.92**). At an inoculation level of 102 cells mL-1, the P supply did not affect the number of nodules; however, at inoculation levels of 103.5 and 105 cells mL-1, increasing P supply increased both the number and size of nodules. Irrespective of the inoculation level, increasing P supply increased the nodule biomass relative to the biomass of the host plant. It is suggested that the P deficiency specifically inhibited the nodule development and thereby the total N2 fixation.展开更多
Due to various geological processes such as tectonic activities fractures might be created in rock mass body which causes creation of blocks with different shapes and sizes in the rock body. Exact understand- ing of t...Due to various geological processes such as tectonic activities fractures might be created in rock mass body which causes creation of blocks with different shapes and sizes in the rock body. Exact understand- ing of these blocks geometry is an essential issue concerned in different domains of rock engineering such as support system of underground spaces built in jointed rock masses, design of blasting pattern, optimi- zation of fragmentation, determination of cube blocks in quarry mines, blocks stability, etc. The aim of this paper is to develop a computer program to determine geometry of rock mass blocks in two dimen- sional spaces. In this article, the eometrv of iointed rock mass is programmed in MATLABTM.展开更多
基金Project supported by the National Basic Research Program of China (Nos. 2005CB121101 and 2003CCB001)the Basic Research Program of Heilongjiang Province (Nos. GB05C201-01 and CC055303)the Field Station Foundation of the Chinese Academy of Sciences.
文摘Phosphorus (P) is necessary for growth and nitrogen fixation, and thus its deficiency is a major factor limiting legume production in most agricultural soils. The effect of phosphorus supply on nodule development and its role in soybeans (Glycine max L.) was studied in a nutrient solution. Plants were inoculated with Bradyrhizobium japonicum and grown for 35 days in a glasshouse at a day and night temperature of 25℃and 15℃, respectively. Although increasing P supply increased the concentrations of P and N in the shoots and roots, the external P supply did not significantly affect the P concentration in the nodules, and the N fixed per unit nodule biomass decreased with increasing P supply. The nitrogen content in the shoots correlated well with the P content (r = 0.92**). At an inoculation level of 102 cells mL-1, the P supply did not affect the number of nodules; however, at inoculation levels of 103.5 and 105 cells mL-1, increasing P supply increased both the number and size of nodules. Irrespective of the inoculation level, increasing P supply increased the nodule biomass relative to the biomass of the host plant. It is suggested that the P deficiency specifically inhibited the nodule development and thereby the total N2 fixation.
文摘Due to various geological processes such as tectonic activities fractures might be created in rock mass body which causes creation of blocks with different shapes and sizes in the rock body. Exact understand- ing of these blocks geometry is an essential issue concerned in different domains of rock engineering such as support system of underground spaces built in jointed rock masses, design of blasting pattern, optimi- zation of fragmentation, determination of cube blocks in quarry mines, blocks stability, etc. The aim of this paper is to develop a computer program to determine geometry of rock mass blocks in two dimen- sional spaces. In this article, the eometrv of iointed rock mass is programmed in MATLABTM.
