钙对低磷胁迫杉木叶绿素及其荧光特性的影响

通过设计7个钙磷浓度室内水培模拟试验,进行不同钙磷胁迫杉木叶绿素及其荧光参数的比较,探讨钙对低磷环境杉木抗逆性的影响。结果表明：随着低磷胁迫时间的推移,不同钙浓度处理杉木叶绿素含量变化明显,与正常供养CK处理相比,钙对缓解低磷逆境杉木叶绿体受伤程度、保持较高光合效率有显著作用,其中钙浓度Ⅳ（2.0 mmol/L）和Ⅴ（1.0 mmol/L）的这种作用尤为明显。无磷无钙Ⅵ处理条件下杉木叶片PSⅡ反应中心破坏最为严重,且受光抑制程度最大,处理Ⅲ和Ⅳ则较小。施钙可有效缓解低磷胁迫对Fm值的抑制作用。     

直剪法用于糙米内摩擦角的测定与研究

利用土工合成材料综合测定仪（直剪仪）,以水分含量14.57%的糙米为样品,测定了在不同的法向压应力、不同的剪切速率下糙米的剪切应力并计算出内摩擦角。实验结果表明：糙米的剪切应力随着法向压应力（25kPa～100kPa）的增大而增大;剪切速率（1.33mm/min～2.67mm/min）较低时糙米的内摩擦角随着法向压应力的增大而减小;随着剪切速率（1.33mm/min～5.20mm/min）的增大,糙米的内摩擦角减小。     

不同生育时期干旱胁迫对马铃薯生理生化指标的影响

研究不同生育时期干旱胁迫下马铃薯相关生理生化指标的变化,以期探讨干旱胁迫下马铃薯抗旱的生理机制。选取生产上推广的‘冀张薯8号’和‘夏波蒂’两个马铃薯品种,在旱棚内分区栽培。不同生育时期进行干旱处理,测定马铃薯超氧化物歧化酶（SOD）、丙二醛（MDA）、脯氨酸（Pro）的含量变化。结果表明,各生育时期干旱胁迫下,马铃薯MDA、Pro含量均增加,而SOD活性下降。花期干旱胁迫对马铃薯的生理生化指标影响最大;抗性强的品种MDA、脯氨酸含量增加的幅度较小,SOD的活力较高,而抗旱性弱的品种则相反。抗旱性强的品种在生理生化指标上具有抗旱的调节机制。     

Intensity Comparative Analysis Based on Ideas Between Involute Gear and Double Involute Gear

Modeler and simulation modules in Ideas software are used to build the finite element models on involute gear and double involute gear with accurate tooth shape, and with the same design parameters and under the same loads, finite element contact analysis has been done. At last, the contact stress and bending stress on the two types gear transmission at the different meshing positions are solved out, and comparative analysis and study have been done. At the same time, that the ladder-shape tooth on the double involute gear how to influence contact stress and bending stress is emphatically analysed. All above offer the theoretical foundation that bring the double involute gear with ladder-shape tooth into the industry.     

木本植物逆境胁迫研究进展

木本植物(Woody plant)具有多年生、木质部发达和茎坚硬等特点,能抵御复杂多变的外界环境。本综述归纳了木本植物逆境胁迫的几个重要方面,例如盐胁迫、干旱胁迫和低温胁迫。归纳并总结了与应激有关的基因、蛋白质、转录因子和应激反应机制,并简要概述了木本植物在植被保护、园林绿化和土壤改良等方面的应用价值,最后对木本植物研究的局限性和存在的不足进行了讨论。蒙古柳(Salix linearistipularis)作为松嫩平原盐碱地区唯一具有群落分布的木本植物,是研究逆境胁迫的重要树种材料。因此,本综述着重介绍了耐盐碱木本植物蒙古柳对盐等逆境胁迫的研究进展,以期为木本植物逆境胁迫研究提供一定的理论基础;并针对目前研究存在的不足,为进一步研究提供了参考方向。     

根系对土壤环境胁迫响应的研究进展

根系是土壤和植物的动态界面,植物根系具有锚定植株、吸收和运输土壤中的水分及养分、合成和贮藏营养物质等重要功能。近年来,随着研究方法的改进和现代根系定量分析技术的发展,对根系的研究日益受到重视和关注。因而,根系的研究在多个新的研究方向上展开。本文简要介绍了国内外近年来在根系对土壤环境胁迫响应的研究进展,以供根系研究参考。     

Barley mutants with increased tolerance to aluminium toxicity

Acid soil and associated aluminium toxicity are considered as the number one abiotic factor limiting crop production. Over 2 billion hectares of acid soils exist world-wide, both in tropical and moderate climatic zones. In Poland acid soils represent up to60% of arable land. At soil pH < 5.0 Al ions become soluble in water and toxic to plants. Genetic improvement of Al tolerance in crops is the only alternative to soil liming, a traditional but short term and expensive agricultural cure to raise soil pH. Of the various cereals, barley is the most sensitive to Al toxicity. The known sources of Al tolerance in barley are limited to old cultivars and landraces. While they represent multiple alleles of a single locus, there is no potential to improve Al tolerance through recombination of non-allelic additive genes. In the Department of Genetics, Silesian University we have employed induced mutations for rapid creation of variability for Al tolerance in barley. Thirteen mutants with increased levels of tolerance to Al toxicity have been selected in M₃ generation after mutagenic treatment of four barley varieties with N-methyl-N-nitroso urea (MNH) and sodium azide. Six further Al tolerant mutants were identified in the collection of semi-dwarf mutants of the Department. All selected mutants confirmed Al tolerance with the use of three different methods of screening, i.e., root re-growth, root tolerance index and hematoxylin staining. Fourteen mutants exhibited significant root re-growth after 48 hour incubation with 3 ppm Al⁺³ and two of them, namely RL819/2 and RL820/6 were tolerant even to 6 ppm Al⁺³. Crosses of two selected mutants with their respective parent varieties indicated that Al tolerance in each mutant was controlled by a single recessive gene. Out of three methods tested, the root re-growth method facilitated by hematoxylin staining proved to be the most reliable technique for large scale testing. Double treatment with MNH or combined treatment with sodium azide and MNH and 6hinter-incubation germination between treatments were the most successful treatment combinations for induction of aluminium tolerance in barley. This revised version was published online in August 2006 with corrections to the Cover Date.     

Artificial Neural Networks Models for Flow Stress during High Temperature Plastic Deformation of Al-Li Alloy

Using gained experimental data to develop the models of stable flow stresses at high temperature plastic deformation by statistical methods for alloy materials, precision of the models is poor and at the same time the processes of modeling are complicated with great workload. On the basis of the data obtained on Gleeble-1500 Thermal Simulator,the predicting models for the relation between stable flow stress during high temperature plastic deformation and deformation strain, strain rate and temperature for 1420 Al-Li alloy have been developed with BP Artificial Neural Network method. The results show that the model on basis of BPNN is practical and it reflects the real feature of the deforming process. It states that the difference between the real value and the output of the model is in order of 5 percent.     

Determination of Moisture Deficit and Heat Stress Tolerance in Corn Using Physiological Measurements and a Low‐Cost Microcontroller‐Based Monitoring System

In the southern United States, corn production encounters moisture deficit coupled with high‐temperature stress, particularly during the reproductive stage of the plant. In evaluating plants for environmental stress tolerance, it is important to monitor changes in their physical environment under natural conditions, especially when there are multiple stress factors, and integrate this information with their physiological responses. A low‐cost microcontroller‐based monitoring system was developed to automate measurement of canopy, soil and air temperatures, and soil moisture status in field plots. The purpose of this study was to examine how this system, in combination with physiological measurements, could assist in detecting differences among corn genotypes in response to moisture deficit and heat stress. Three commercial hybrids and two inbred germplasm lines were grown in the field under irrigated and non‐irrigated conditions. Leaf water potential, photosynthetic pigments, cell membrane thermostability (CMT) and maximum quantum efficiency of photosystem II (Fv/Fm) were determined on these genotypes under field and greenhouse conditions. Variations observed in air and soil temperatures, and soil moisture in plots of the individual corn genotypes helped explain their differences in canopy temperature (CT), and these variations were reflected in the physiological responses. One of the commercial hybrids, having the lowest CT and the highest CMT, was the most tolerant among the genotypes under moisture deficit and heat stress conditions. These results demonstrated that the low‐cost microcontroller‐based monitoring system, in combination with physiological measurements, was effective in evaluating corn genotypes for drought and heat stress tolerance.     

水分胁迫对白羊草光合生理特性的影响

测定了白羊草(Bothriochloa ischaemum)在黄土高原丘陵沟壑区大田干旱条件下叶片光合速率、叶片水势、叶绿素含量、气孔阻力、蒸腾强度、细胞膜透性和脯氨酸积累指标。结果表明：土壤干旱条件下,降低了白羊草叶水势、气孔蒸腾强度、光合速率和叶绿素含量,增加了叶片气孔阻力、细胞膜透性和脯氨酸的积累。解除水分胁迫、恢复供水48h后,上述各项指标可以恢复到正常供水值的50%以上,说明了白羊草自身调节能力强,对干旱有良好的适应性和忍耐性。