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To investigate soil NO3--N dynamics and yield increasing effect of mulching planting for Linum usitatissimum (oil flax) in semi-arid Loess Plateau, we examined the effects of three mulching modes (whole field plastic mulching and micro ridges with soil cover and bunch-seeding; whole field plastic mulching with soil cover and bunch-seeding; and straw mulching with strips) on seed yield and distribution of soil NO3--N during the main growth periods of oil flax, with the conventional planting model as control (CK) in 2015 and 2016. Results showed that the average yield under mulching modes was increased by 56.1% (2015) and 22.7% (2016). The treatment of whole field plastic mulching with soil cover and bunch-seeding had the highest grain yield. Mulching treatments significantly increased soil water content. Soil water content was increased first and then reduced in the whole growth stage of oil flax. The soil N03--N content was gradually decreased during the oil flax growth process. In both years, N03--N content in 0-40 cm soil depth under mulching treatments were increased by 3.1%-18.6% (2015) and 5.1%-16.4% (2016) at budding stage of oil flax, respectively. The whole field plastic mulching with soil cover and bunch-seeding treatment showed the larges increases across all treatments. In 2015, NO3--N accumulation in 0100 cm soil depth between the flowering and maturity stages of oil flax were increased by 10.2%- 22.2% and 8.6%-21.4%, respectively. Especially during the more rainfall period of maturity stage, NO3--N accumulation in 0-40 cm soil depth was significantly enhanced by 3.3%-4.9% than that in 40-100 cm soil depth. It indicated that more rainfall could slow down the migration of NO3--N to the lower layer under the mulching modes in the maturity stage. In 2016, high temperature and drought at late growth stages had a great influence on oil flax growth. The N03 -N accumulation in 0 100 cm soil depth at the maturity stage was increased by 6.6% 18.0%. There was significant correlation between NO3--N content and grain yield during the main growth stages of oil flax. In conclusion, the whole field plastic mulching with soil cover and bunch-seeding treatment was the most appropriate way of oil flax production in arid and semi-arid area. [ABSTRACT FROM AUTHOR]

In order to predict effects of climate changing on growth, quality and grain yields of spring wheat, a field experiment was conducted to investigate the effects of air temperature increases (0 °C 1.0 °C 2.0 °Cand 3.0 °C and precipitation variations (decrease 20%, unchanging and increase 20%) on grain yields, quality, diseases and insect pests of spring wheat at the Dingxi Arid Meteorology and Ecological Environment Experimental Station of the Institute of Arid Meteorology of China Meteorological Administration(35°35' N,104°37' E). The results showed that effects of precipitation variations on kernel numbers of spring wheat were not significant when temperature increased by less than 2.0 °C but was significant when temperature increased by 3.0 °C Temperature increase enhanced kernel numbers, while temperature decrease reduced kernel numbers. The negative effect of temperature on thousand?kernel mass of spring wheat increased with increasing air temperature. The sterile spikelet of spring wheat response to air temperature was quadratic under all precipitation regimes. Compared with control (no temperature increase), the decreases of grain yield of spring wheat when air temperature increased by 1.0 °C 2.0 °C and 3.0 °C under each of the three precipitation conditions (decrease 20%, no changing and increase 20%) were 12.1%, 24.7% and 42.7%, 8.4%, 15.1% and 21.8%, and 9.0%, 15.5% and 22.2%, respectively. The starch content of spring wheat decreased and the protein content increased with increasing air temperature. The number of aphids increased when air temperature increased by 2.0 °C, but decreased when air temperature increased by 3.0 °C. The infection rates of rust disease increased with increasing air temperature. [ABSTRACT FROM AUTHOR]

Field experiments were carried out to determine the effect of different nitrogen application rates on nitrogen nutrient uptake, transfer and nitrogen utilization efficiency of dry land oil fax. The results indicated that diferent nitrogen application rates affected nitrogen nutrient uptake, accumulation and transfer at diferent growth stages, and changes tendencies were consistant. The amount of niirogen translocation from leaf, translocation efficiency and contribution to grain were 89.18%, 83.36% and 86.36% higher than from stem. The nitrogen in grain, among which 47.10% - 57.66% was transferred from leaf, 22.46% - 30.94% was transferred from stem and 21.00% - 30.48% was absorbed from soil. The result indicated that compared to no nitrogen application, the yield of nitrogen treatments ( as 27.6, 55.2 and 82.8 kg.hm-2) increased 10.21%, 16.92% and 15.55%, respectively. The nitrogen transfer amounts, transfer efficiency and contribution efficiency of leaf and stem to grain were maximum when the nitrogen application rate was 55.2kg.hm-2. With increased nitrogen application rate, apparent nitrogen recovery efficiency of oil flax first increased then decreased. The partial nitrogen factor productivity of oil flax decreased significantly. After taking into account of grain yield, nitrogen utilization efficiency and ecological environment, the recommended nitrogen fertilizer rate for dry land oil flax was 27.6 - 5 5.2kg.hm-2 at the soil fertility level in our experiment. [ABSTRACT FROM AUTHOR]

Making a quantitative prediction on the combined risk of the water body is helpful for the objective evaluation of the water environment system's state of health, and also has important results for the water environment system's safety management. In this paper, the Markov status switching theory (Markov Switching, MS), Monte Carlo method (Monte Carlo, MC) and Copula theory were used together, to establish a method for the water environment system's combined risk assessment. This method firstly using MS theory established the water quality time series' autoregression model (MS-AR); then the MS-AR model and MC method were used to carry out random simulation on the water quality time series; finally, multi-dimensional joint distribution among random simulation results were established by Copula function, and this distribution utilized to make a quantitative analysis of the water environment system's combined risk. By means of the above combined risk analysis model, the combined risk prediction and correlation analysis of the water quality of the Guohe River bridge section were carried out. The results showed that the total phosphorus (TP) and 5-day biochemical oxygen demand (BOD5) had an important effect on the Guohe River water environment's state of health, and there was a strong positive correlation between TP and BOD5. [ABSTRACT FROM AUTHOR]

Accurately assessment of the water environment system combined risk may contribute to the evaluation of the water environment system health status, which has great significance to the safety management of water environment. Markov switching theory (MS), Monte Carlo method (MC) and Copula function were comprehensively applied to the establishment of the method system of water environment system combined risk analysis. Firstly, the water quality series auto-regression model (Al%) was constructed by using the MS. Secondly, the MS-AR and MC were applied to the simulation of water quality series. Thirdly, the Copula function was applied to the construction of multivariate joint distribution of water quality simulation series to calculate the combine risk of the water environment system. Finally, the method system was applied to the Guohe section's water quality combined risk evaluation. The result shows that TP and BOD5 have important effects to the water environment health status of the Guohe, and that there is a positive correlation between TP and BOD5. [ABSTRACT FROM AUTHOR]

A completely random split zone experiment with irrigation as main plots and nitrogen application rate as sub-plots was carried out to examine the optimal water-nitrogen coupling mode for oil flax planting in dryland. There were three irrigation levels, no irrigation (0 m 3 ·hm -2 , I 0 ), irrigation at 1200 m 3 ·hm -2 (I 1200 ) and at 1800 m 3 ·hm -2 (I 1800 ); and three nitrogen application rates, no nitrogen (0 kg N·hm -2 , N 0 ), 60 kg·N hm -2 (N 60 ) and 120 kg·N hm -2 (N 120 ). We investigated nitrogen accumulation content at different growth stages, nitrogen transport characteristics after anthesis, grain yield and nitrogen utilization efficiency of oil flax. Results showed that the coupling effects of water and nitrogen application on nitrogen uptake in different organs, nitrogen accumulation during different growth stages and grain yield of dry land oil flax varied greatly. Under no irrigation, nitrogen application was beneficial to stem nitrogen absorption at anthesis and maturity stages, but 120 kg N·hm -2 inhibited it at different irrigation levels. At the 1200 m 3 ·hm -2 (I 1200 ) irrigation level, foliar nitrogen content at anthesis stage increased first and then decreased with increasing nitrogen rates, and N 60 increased foliar nitrogen content by 11.0% and 28.9% respectively compared with N 0 and N 120 . At the 1800 m 3 ·hm -2 (I 1800 ) irrigation level, nitrogen application increased foliar nitrogen content at maturity stage, with that in N 60 and N 120 treatments being 39.7% and 26.9% higher than N 0 , respectively. The effects of water-nitrogen coupling on nitrogen accumulation in different growth stages of oil flax was mainly shown after budding stage. Under the same irrigation level, N 60 promoted and N 120 inhibited nitrogen accumulation in each stage after budding. Nitrogen application increased nitrogen transport rate and contribution rate of leaves and stems under I 1200 and I 1800 . The coupling of I 1800 and N 60 significantly increased the number of effective capsules per plant and grain yield of oil flax (6.6%-22.8%), which was a suitable water-nitrogen coupling management mode in this area.

To optimize the effects of nitrate (NO 3 - -N) to ammonium (NH 4 + -N) ratios on water consumption characteristics, grain yield and water use efficiency (WUE) of maize under full film mulching on double ridges, a field experiment was conducted at semi-arid Loess Plateau of Gansu Province, China during 2015 to 2017 cropping seasons. The treatments with different ratios of NO 3 - -N to NH 4 + -N included: N 1 (1:0), N 2 (1:1), N 3 (1:3) and N 4 (3:1). The results showed that different NO 3 - -N/NH 4 + -N ratios had significant impacts on soil water storage in 0-200 cm soil layer. Treatment N 3 had the lowest soil water storage. Treatment N 4 significantly increased total water consumption by 2.9%, 1.9% and 0.9% in 2015, and 2.3%, 1.4%, and 2.2% in 2017, compared with N 1 , N 2 and N 3 treatments, respectively. Compared with the other treatments, treatment N 4 increased grain yield by 3.3%-9.9%, 3.5%-24.2% and 8.3%-36.1% and improved WUE by 1.6%-6.8%, 4.9%-21.8%, and 6.6%-32.9% in 2015, 2016 and 2017, respectively. Treatment N 4 had the highest partial productivity of nitrogen fertilizer, followed by N 2 , N 3 and N 1 , respectively. We recommended treatment N 4 as the best nitrate and ammonium ratio to improve water use efficiency, N partial productivity, and grain yield of maize in arid and semi-arid Loess Plateau.

To investigate soil NO 3 - -N dynamics and yield increasing effect of mulching planting for Linum usitatissimum (oil flax) in semi-arid Loess Plateau, we examined the effects of three mul-ching modes (whole field plastic mulching and micro ridges with soil cover and bunch-seeding; whole field plastic mulching with soil cover and bunch-seeding; and straw mulching with strips) on seed yield and distribution of soil NO 3 - -N during the main growth periods of oil flax, with the conventional planting model as control (CK) in 2015 and 2016. Results showed that the average yield under mulching modes was increased by 56.1% (2015) and 22.7% (2016). The treatment of whole field plastic mulching with soil cover and bunch-seeding had the highest grain yield. Mulching treatments significantly increased soil water content. Soil water content was increased first and then reduced in the whole growth stage of oil flax. The soil NO 3 - -N content was gradually decreased during the oil flax growth process. In both years, NO 3 - -N content in 0-40 cm soil depth under mul-ching treatments were increased by 3.1%-18.6% (2015) and 5.1%-16.4% (2016) at budding stage of oil flax, respectively. The whole field plastic mulching with soil cover and bunch-seeding treatment showed the larges increases across all treatments. In 2015, NO 3 - -N accumulation in 0-100 cm soil depth between the flowering and maturity stages of oil flax were increased by 10.2%-22.2% and 8.6%-21.4%, respectively. Especially during the more rainfall period of maturity stage, NO 3 - -N accumulation in 0-40 cm soil depth was significantly enhanced by 3.3%-4.9% than that in 40-100 cm soil depth. It indicated that more rainfall could slow down the migration of NO 3 - -N to the lower layer under the mulching modes in the maturity stage. In 2016, high temperature and drought at late growth stages had a great influence on oil flax growth. The NO 3 - -N accumulation in 0-100 cm soil depth at the maturity stage was increased by 6.6%-18.0%. There was significant correlation between NO 3 - -N content and grain yield during the main growth stages of oil flax. In conclusion, the whole field plastic mulching with soil cover and bunch-seeding treatment was the most appropriate way of oil flax production in arid and semi-arid area.

In order to predict effects of climate changing on growth, quality and grain yields of spring wheat, a field experiment was conducted to investigate the effects of air temperature increases (0 °C, 1.0 °C, 2.0° C and 3.0°) and precipitation variations (decrease 20%, unchanging and increase 20%) on grain yields, quality, diseases and insect pests of spring wheat at the Dingxi Arid Meteorology and Ecological Environment Experimental Station of the Institute of Arid Meteorology of China Meteorological Administration (35°35' N ,104°37' E). The results showed that effects of precipitation variations on kernel numbers of spring wheat were not significant when temperature increased by less than 2.0° C , but was significant when temperature increased by 3.0° C. Temperature increase enhanced kernel numbers, while temperature decrease reduced kernel numbers. The negative effect of temperature on thousand-kernel mass of spring wheat increased with increasing air temperature. The sterile spikelet of spring wheat response to air temperature was quadratic under all precipitation regimes. Compared with control ( no temperature increase), the decreases of grain yield of spring wheat when air temperature increased by 1.0°C, 2.0°C and 3.0°C under each of the three precipitation conditions (decrease 20%, no changing and increase 20%) were 12.1%, 24.7% and 42.7%, 8.4%, 15.1% and 21.8%, and 9.0%, 15.5% and 22.2%, respectively. The starch content of spring wheat decreased and the protein content increased with increasing air temperature. The number of aphids increased when air temperature increased by 2.0°C , but decreased when air temperature increased by 3.0°CT. The infection rates of rust disease increased with increasing air temperature.

Objective: Characters of stem epidermis, leaf epidermis and stoma could be used as important microcosmic morphological characteristic when inheritance trend is studied in Ephedra breeding and identification., Method: The stomatic density, stoma major axis and mimor axis, stomatic morphylogy, characters of leaf and stem epidermis of 6 Ephedra plants' stems were examined by SEM., Result: The stomatic density and characteristic of leaf epidermis and stem epidermis in six Ephedra species was differenc, there were no obvious morphological differences in stoma shape and size. The guard cells were covered with heavy cuticle and sunken stomata, which were the typical characteristics of xerophytes. The stomas of leaf lower epidermis were oblong or hexagon, but the stomas of steam epidermis were narrowed-oblong or dumbbell-shape, they all belonged to anomalous type., Conclusion: The stoma type and characters of Ephedra plants is stable and conservative, there was no obvious morphological differences in stoma shape and size between species, so it is difficult to distinguish different species by the variance of stomas, but that can be applyed to distinguish Ephedra from others at plant taxonomy.

A field experiment was conducted to study the effects of planting density and nitrogen application rate on the topsoil (0-15 cm) microbial activity under wheat/forage rape multiple cropping. The results showed that multiple-cropping forage rape with wheat could significantly increase soil microbial biomass C (Cmic), soil microbial biomass N (Nmic), soil bacteria number (SBN), soil fungi number (SFN) and soil actinomyces number (SAN), but decrease soil microbial biomass C/N (Cmic/Nmic). The Cmic/Nmic and SBN increased with increasing planting density of forage rape, while Nmic and SAN were in adverse. SFN increased significantly with increasing nitrogen application rate, but Cmic and Nmic decreased first, increased then, and decreased again, with the highest in treatment 1000 kg x hm(-2) N. Also with increasing nitrogen application rate, the SFN and SAN during harvest stage of forage rape decreased first and increased then, while the SAN during seedling stage increased first and decreased then. Soil microbial activities at rape harvest stage were all higher than those at seedling stage, except for SAN in treatment 600 kg x hm(-2) N. SBN and SAN were positively correlated with Cmic and Nmic, but negatively correlated with/Nmic. No significant correlation was observed between SFN and Cmic, and SMBN and Cmic/Nmic.