Gao Z.,China Agricultural University |
Gao Z.,Beijing Agricultural Vocation College |
Li T.,China Agricultural University |
Zhyang X.,Richuanhe Pomological Research and Development Center
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2010
The diurnal responses of photosynthetic rates (P n), stomatal conductance (G s), transpiration rates (T r) and water use efficiency (WUE) to the daily march of microclimatic conditions were simulated by the coupled model of apple leaves gas exchange. Values of P n and G s increased in the morning, reached a maximum about 8:00 AM, decreased to lower values in the midday, recovered to the second maximum about 4:00 PM, and decreased in late afternoon, creating an asymmetrical double-peak curve on sunny days. The diurnal change of T r was similar to that of P n and G s, following n shape curves on clear days, reached the maximum after midday. But the midday depressions of P n and G s were more strongly expressed than T r. On clear days, the peak of WUE was reached early after sunrise; it then decreased to a stable level maintained through most of the day until falling to zero at sunset. The mathematical simulation showed the diurnal course of gas exchange was driven mainly by radiation and midday depressions mostly caused by the reduction of leaf water potential and relative humidity. These established models were tested by the observation data in an apple (Malus pumila Mill. 'Fuji') orchard (latitude 40°13' north, longitude 116°13' east, altitude 79 m). There was a satisfactory correspondence between measured and simulated values of P n in different photosynthetically active radiation (PAR), air relative humidity (RH), air temperature (T a), air CO 2 concentration. The diurnal variations of P n and G s in upper layers of canopy, compared with the model predictions, showed a good general agreement. Only a slight overestimation of T r was in our study, which might be caused by leaves shading and non-linear relationship between P n and PAR.
Zhao H.-Y.,Beijing Agricultural Vocation College |
Jiao Y.-Q.,Beijing Agricultural Vocation College |
Jiao Y.-Q.,Beijing Forestry University |
Zhang Y.,Beijing Shougang International Engineering Technology Co. |
Nan G.-R.,Beijing Urban Construction Group Co.
Applied Mechanics and Materials | Year: 2014
Aimed at engineering problems lied in inshore saline soil in the northern part of China, the store environment is analysed, and the relation between the salinity and the engineering property index is studied. The result shows that the plasticity index and the compression coefficient of the northern inshore saline soil reduce with the increase of the salt content, and the shear strength attains a limit value with the increase of the salt content. © (2014) Trans Tech Publications, Switzerland.
Zhao H.,Beijing Agricultural Vocation College |
Zhang Y.,Beijing Shougang International Engineering Technology Co.
Civil Engineering and Urban Planning 2012 - Proceedings of the 2012 International Conference on Civil Engineering and Urban Planning | Year: 2012
According to investigation data, we analysis the existing condition of earthquake-resistance performance of Beijing rural masonry structure and present the existing questions about site foundation material structural component and aseismatic measure of this type structure. Through analyzing the reasons, the author gives the measures on how to improve the aseismatic performance of masonry structure in rural area. © 2012 ASCE.
Ma X.,University of Western Australia |
Considine J.,University of Western Australia |
Yan G.,University of Western Australia |
Feng S.,Beijing Agricultural Vocation College
Acta Horticulturae | Year: 2011
Nuclear ribosomal DNA ITS region and chloroplast DNA non-coding region trnF-trnVr were studied using PCR-RFLP method to review the phylogenetic relationship of selected species in Verticordia. Eighteen species from three subgenera were clustered into two main groups with one representing subgenus Eperephes and another representing two subgenera, Chrysoma and Verticordia. This suggested that two subgenera rather than three are supported in Verticordia by this approach. Restriction site variation was found in both nuclear and chloroplast genomes but no amplified fragment length variation was found in trnF-trnVr. Intra-individual variation was detected in ITS region possibly due to restriction site variation among loci, alleles or repeat units. Chromosomal evolution was studied by correlating chromosome numbers with restriction site variations. A negative correlation was detected which suggests that the chromosome number was evolved from 11 downwards.
Guo Q.,Beijing Academy of Agriculture and Forestry Sciences |
Meng L.,Beijing Academy of Agriculture and Forestry Sciences |
Mao P.-C.,Beijing Academy of Agriculture and Forestry Sciences |
Jia Y.-Q.,Beijing Agricultural Vocation College |
Shi Y.-J.,Chinese Academy of Agricultural Sciences
Biochemical Systematics and Ecology | Year: 2013
To understand the role of salicylic acid (SA) in alleviating cadmium (Cd) toxicity in Kentucky bluegrass (Poa pratensis L.), we investigated the changes of biochemical and physiological indexes in five-week-old Kentucky bluegrass seedlings exposed to 0, 5, 10 or 50μM Cd with or without 500μM SA for 7d. Results showed that, compared to the Cd treatment applied alone, 500μM SA pretreatment significantly decreased Cd accumulations and increased the chlorophyll level, growth and nutrient elements content (K, Ca, Mg and Fe) in plants, accompanying with the reduction in malondialdehyde and hydrogen peroxide contents. Furthermore, SA pretreatment enhanced remarkably the superoxide dismutase, ascorbate peroxidase and peroxidase activity in the Cd-stressed plants, but decreased catalase activity. Overall, SA might regulate the antioxidant defense activities, reduce Cd uptake and stimulate nutrient elements absorption in Cd-treated with Kentucky bluegrass, thereby improving its resistance to Cd stress. © 2013 Elsevier Ltd.