济源市农业水价分析及其调整策略

科学合理的农业水价能起到价格杠杆作用,促使农业节约用水。以济源市为例,分析区域农业用水概况、农业水价现状及其存在问题,以全成本水价理论和能值价值理论为基础估算得到区域内主要灌区的农业成本水价;以亩均产值和亩均净效益为基础测算得到农民水价承受能力为0.11元/m3;参考计算结果,明确了农业水价的调整范围,针对济源实际,提出了农业水价调整策略。为济源市农业水价调整提供了参考依据,也可供其他地区农业水价调整借鉴。     

球形接头调角度应用于坡地喷灌

坡地喷灌中,由于喷洒图形的改变影响了喷洒均匀性,改变立管倾角和改变喷头仰角成为必要,利用球形接头可方便地实现角度调节.通过对10PXH喷头转动均匀性分析,坡地上射程分析以及坡地上径向水量分布试验,给出球形接头的调节范围,以及在不同地形坡度情况下,球形接头合适的调节角度,用于改善坡地喷灌的质量.     

近50年中国东部林区最高气温序列

运用线性回归插补途径和RHtest方法分别对1961-2010年我国东部林区853个站点的日最高气温资料进行插补和均一化检验订正,建立完整且均一的日最高气温数据集.在此基础上,对比分析我国东部林区近50年来最高气温订正前后的变化特征.结果表明:订正后东部林区年及四季(春、夏、秋、冬)平均最高气温每10年分别增加0.171,0.233,-0.002,0.201和0.263℃,订正后整个区域年平均最高气温均呈上升趋势,而订正前有部分站点呈降温趋势;春、秋、冬3季平均最高气温在整个林区几乎全部呈现上升趋势,夏季东部林区多数站点呈降温趋势,尤其是长江和黄河流域之间的区域.     

Water relations of Eucalyptus nitens × Eucalyptus grandis: is there interclonal variation in response to experimentally imposed water stress?

This study tested the hypothesis that water stress increases the hydraulic efficiency of Eucalyptus nitens × E. grandis saplings as a result of osmotic and elastic adjustments. Eucalyptus nitens × E. grandis clones (NH00, NH58, NH69 and NH70) were potted in coarse river sand supplemented with a slow-release fertiliser, drip-irrigated four times daily and exposed to full sunlight for eight months. Thereafter, irrigation was withheld twice for seven consecutive days from half of the saplings of each clone, with a seven-day recovery period (regular irrigation) in-between. Relative soil moisture content did not correlate with stomatal conductance (g_s) at pre-dawn and at midday. Leaves of plants subjected to the water-stress treatment wilted in 7 d, and the reduction in g_s was significant at midday with no significant differences between clones. Stomatal conductance and all traits derived from pressure-volume graphs (e.g. osmotic potential at full turgor) were constant in the control treatment. There were no clear patterns in osmotic and elastic adjustments in both treatments. Root hydraulic conductance was constant between treatments and clones. However, water stress reduced shoot hydraulic conductance and stem hydraulic conductivity with significant interclonal effects. Plant biomass, leaf area and leaf weight ratio were significantly lower in the water-stressed plants, but there were no differences between the clones. In conclusion, the water-stress treatment did not introduce significant differences in stomatal conductance and tissue-water relations of Eucalyptus nitens × E. grandis clones. Interclonal variation in water-stress response was found in shoot hydraulic traits, and clone NH58 may be more suitable for planting across sites prone to moderate water stress.     

J-80A型轮式集材拖拉机底盘的保养和调整方法

介绍了J-80A型轮式集材拖拉机底盘的保养和调整方法.     

Effects of the interaction between drought and shade on water relations, gas exchange and morphological traits in cork oak (Quercus suber L.) seedlings

The combined effect of drought and light on different physiological and biochemical traits was assessed in cork oak (Quercus suber L.) seedlings grown under two levels of light availability and submitted to a long-standing drought. Watering was withdrawn after germination and seedlings were allowed to dry to a water content of ca. 50% of field capacity. At this point, water-stressed seedlings were grown under moderate drought and two light regimes: high light (HL—50%) and low light (LL—2%). Soil water in control plants was kept close to field capacity (90–100%) for both light environments. Water-relations parameters derived from P–V curves, gas exchange and water status at predawn (Ψ_pd) were evaluated at twice during the experiment. Nitrogen and chlorophyll contents were determined in the same leaves used for the gas exchange measurements. In addition, maximum rate of carboxylation (V_cmax) and electronic transport (J_max) were derived from A–C_i curves in well-watered seedlings.

The variation on moisture availability during the experiment was the same under both light environments. In control plants, Ψ_pd was over −0.3 MPa at the two harvests, while stressed seedlings decreased to −0.9 MPa, with no differences between light treatments. Water stress decreased osmotic potentials at full (Ψπ₁₀₀) and zero turgor (Ψπ₀). The regressions between both potentials and Ψ_pd showed a higher intercept in shade grown seedlings. This fact will point out the higher osmoregulation capacity in sun seedlings whatever water availability.

Nitrogen investment on a per leaf mass (N_mass), chlorophyll content (Chl_mass) and SLA tended to show a typical pattern of sun-shade acclimation. Thus, the three parameters increased with shade. Only for N_mass there was a significant effect of watering, since water stress increased N_mass.

LL plants showed a lower photosynthetic capacity in terms of maximum net photosynthesis at saturating light (A_max), which was related to a decrease in V_cmax and J_max. Both parameters varied with specific leaf area (SLA) in a similar way. The low-light environment brought about a higher nitrogen investment in chlorophyll, while under high-light environment the investment was higher in carboxylation (V_cmax) and electronic transport (F_max).

Stomatal conductance to water vapour (g_wv) and A_max were lower in low-light seedlings independently of watering. In addition, there was a trend to keep higher intrinsic water use efficiency (IWUE) under high light environment. The increase of IWUE under water stress was higher in HL seedlings. This was as consequence of the steeper decline in g_wv as Ψ_pd decreased. The decrease of A_max with Ψ_pd occurred in a similar way in LL and HL seedlings. Thus, the HL seedlings tended to sustain a higher ability to increase IWUE than LL seedlings when they were submitted to the same water stress.     

浅谈如何调节燃烧才能提高锅炉的经济效益

针对链条炉在实际运行中,几个调节燃烧的因素不能达到最佳匹配的现象,进行分析,并提出建议,以提高锅炉的经济效益。     

The effect of Tuber melanosporum Vitt. mycorrhization on growth, nutrition, and water relations of Quercus petraea Liebl., Quercus faginea Lamk., and Pinus halepensis Mill. seedlings

Mycorrhizal and nonmycorrhizal Quercus faginea Lamk., Quercus petraea Liebl., and Pinus halepensis Mill. one-year-old seedlings inoculated with Tuber melanosporum Vitt. have been analyzed with the purpose of studying the influence of mycorrhization on their growth, water relations, and mineral nutrition. The mycorrhization improved Q. petraea and P. halepensis seedling growth. In addition, the mycorrhization created an elastic adjustment in P. halepensis, although it did not cause any osmotic adjustment. Additionally, the mycorrhization increased phosphorus uptake in Q. faginea and P. halepensis, content of all nutrients in P. halepensis, and N content in Q. petraea.     

《京津风沙源治理工程二期规划》战略调整

在回顾京津风沙源治理工程一期建设的基础上,根据京津地区生态环境现状和国际、国内对生态建设的要求,运用科学发展、综合治理和系统工程学理论,对京津风沙源治理工程二期规划建设范围西扩、布局优化、建设内容增加和农业、林业、水利、异地搬迁等工程措施的协同与系统治理战略调整进行了阐述。     

平面测量导线闭合差调整一步法

在平面测量中,导线平差,先平内角闭合差,后平座标增量闭合差,分为两个步骤进行。在座标增量闭合差调整中,又分为按边长比例分配、按座标增量值大小比例分配及按累积边长比例分配。这些方法都是简易计算近似平差法,由于内角闭合差调整,会过多干扰导线边的方向角。因而笔者提出:省略内角闭合差调整这一步,将二步简化为一步,简称一步法,使计算更为简化与完善。