Effects of smoke,ash and heat shock on seed germination of seven species from Central Zagros rangelands in the semi-arid region of Iran     

Ali Asghar Naghipour  Seyed Jamaleddin Khajeddin  Pejman Tahmasebi  Majid Iravani 《African Journal of Range and Forage Science》2016,33(1):67-71

Fire products have been widely identified as germination cues for a number of species from both fire-prone and fire-free ecosystems. However, there is uncertainty about the effects of fire products on seed germination of semi-arid rangeland species. We examined the germination of seven dominant species from Central Zagros rangelands in the semi-arid region of Iran under various heat shock (60, 80 and 120 °C), aerosol smoke, ash and control treatments. Our findings showed that fire products could enhance, inhibit or not affect the seed germination of rangeland species in this area. The germination percentage of Astragalus adscendens increased following 60 °C heat treatment in comparison with the control. The germination of Astragalus verus, Bromus tectorum, B. tomentellus and Phlomis olivieri were increased significantly using smoke treatment (P<0.0001). The seed germination of B. tomentellus and B. tectorum was promoted by ash treatment, whereas the other species exhibited no response or were inhibited by fire products. In addition, smoke treatment shortened the overall germination time of B. tectorum. These findings suggest that fire products affect the germination of several species and can serve as potential tools for understanding the vegetation dynamics and restoration of disturbed semi-arid rangelands.  相似文献   

CO₂浓度增加对半干旱区马铃薯生长动态及产量、品质的影响     

张凯  王润元  王鹤龄  赵鸿  赵福年  齐月  陈斐  杨阳  雷俊 《干旱地区农业研究》2023,(4):238-246

为了解CO₂浓度升高条件下马铃薯生长动态及其产量、品质的变化特征,在典型半干旱区（甘肃定西）利用开顶式气室(OTC)试验平台,以马铃薯‘新大坪’为供试品种,设对照(390 μmol·mol^-1)和590 μmol·mol^-1共2个CO₂浓度梯度,开展CO₂浓度增加模拟试验。结果表明：CO₂浓度增加至590 μmol·mol^-1时,马铃薯发育加快,生育期提前,全生育期天数缩短3 d;CO₂浓度升高对马铃薯株高、叶面积指数、叶绿素含量和叶片水势有明显促进作用。随着生育进程的推移,马铃薯地上部干物质生产对CO₂浓度的响应值呈现先变大再变小的趋势。CO₂浓度增加促进了马铃薯块茎产量的提高,单株结薯数和单株薯块质量也有所增加。与对照相比,590 μmol·mol^-1CO₂处理马铃薯块茎水分、蛋白质、维生素C含量以及铁、锌、铜元素含量分别下降3.43%、11.78%、13.09%、25.58%、31.94%和9.76%,而粗淀粉、粗脂肪、粗纤维和还原糖含量分别增加10.56%、240.00%、14.28%、106.38%。  相似文献   

Seasonal turnover and insights into the overwintering biology of wireworms (Coleoptera: Elateridae) in the Canadian Prairies     

Ivan Drahun  Elise A. Poole  Katherine A. Hunt  Willem G. van Herk  Christophe M. LeMoine  Bryan J. Cassone 《Pest management science》2023,79(2):526-536

  相似文献   

半干旱草甸草地不同处理下植被特征与土壤酶活性的变化     

王志婷  刘廷玺  童新  段利民  李东方  刘小勇 《草业学报》2023,32(3):41-55

不同草地处理措施对植被和土壤会产生重要的影响。为探究不同草地处理措施对草甸草地的影响,以科尔沁草甸草地不同点为研究对象,设置围封（UNM）、围封+刈割（M）、围封+火烧（F）、放牧（G）4种处理,针对生长季土壤脲酶（S-UE）、碱性磷酸酶（S-AKP）、蔗糖酶（S-SC）活性和植被特征等开展研究,以探究草甸草地的最佳处理方式。结果显示：1）土壤酶活性随着土层深度的增加而降低,不同处理间的差异随着土层深度增加逐渐降低。2）放牧较围封处理,不同点植被高度、盖度、地上生物量和酶活性均降低,而丰富度指数增加。3）刈割较围封处理,不同功能群物种的补偿能力不同,禾本科的补偿能力大于菊科。4）火烧较围封处理,不同点植被高度、盖度、地上生物量、丰富度指数和3种水解酶活性均增加。5）多年刈割较放牧处理,植被高度、盖度和地上生物量和蔗糖酶、碱性磷酸酶活性均增加,丰富度指数和土壤脲酶活性均降低。综上所述,控制性火烧是半干旱地区草甸草地的最佳处理方式。  相似文献   

考虑陀螺效应的动力总成悬置系统分析和优化     

刘献栋  周贤杰 《农业机械学报》2007,38(3):10-14

应用陀螺力学理论，对传统动力总成悬置系统的无阻尼动力学方程进行修正，引入陀螺矩阵，得到新的动力学方程。对新的动力总成悬置系统动力学模型进行计算分析，研究了陀螺矩阵对频域、时域响应的影响。使用遗传算法分别对修改前后的方程进行优化计算，并进行比较分析。结果表明，对于低转速发动机，曲轴转动的陀螺效应不明显，而对于高转速的发动机，陀螺效应不能忽略，应以考虑陀螺力矩的方程为基础进行设计分析。  相似文献   

FLUENT软件及其在植保机械方面的应用     

孙小华  祁力钧  王俊  宋吉林 《农机化研究》2006,(9):187-188,191

FLUENT软件是流体力学中通用性较强的商业软件之一，由于FLUENT软件的应用，节省了大量的人力和物力。对实际应用有重大的指导作用。为此，通过简述FLUENT在植保机械方面的应用实例，提出了FLUENT在植保机械方面的发展前景。  相似文献   

砌石拱坝加高倍厚的三维接触仿真     

张社荣  蔡胜利  陈敏岩  黄昌清 《中国农村水利水电》2005,(4):86-89

对砌石拱坝的加高倍厚中新、老坝体结构面，用有限元软件ANSYS结合接触理论进行计算，并分析结果得出：温升、水压力和淤沙压力使结合面上的接触压力增大，从而接触摩擦应力较大，有利于结合面的结合，而结合面在温降的作用下有脱离的趋势。  相似文献   

Simulation on the Characteristics of Flow Pattern in Sprial uP-flow Reactor     

LUO Gu-yuan  ZHANG Ming-xuan  JI Tie-jun 《保鲜与加工》2007,(5):11-14

In order to analyze the reason why the Spiral Up-flow Reactor system has excellent removal effect of COD, N and P, the authors use PHOENICS, a computational fluid dynamics program, to investigate the hydraulic characteristics and flow model of the anaerobic part of Spiral uP-flow reactor. The result shows that the fluid in the reactor unit flowed upward by the spiral way, and that flow pattern was combined by plug flow and complete-mix flow, and that the percentage of plug flow was about sixty-five percent. Spiral Up-flow Reactor units the Characteristics of PFR and CSTR, which makes it work well.  相似文献   

陆地棉品种间杂种苏杂16棉铃发育动态研究   总被引：5，自引：6，他引：5  

徐立华  钱大顺  陈祥龙  张香桂  杨德银 《棉花学报》1996,(2)

棉铃发育过程中，苏杂１６单铃子棉主的提高表现为二个方面：一是纤维干重的增加，１９９１～１９９２两年平均增加１０．０％；二是种子重量的提高，两年平均单铃种仁重增加９．４％。单铃纤维干重的增长与棉铃对位叶大小呈正相关关系，与棉铃对位叶中全Ｎ含量呈负相关关系．该杂文组合在棉铃发育过程中表现了较强的“源”“库”生理优势，光合产物积累多，营养物质运转快是该组合获得高产的重要生理基础。  相似文献   

Analysis and FEM Simulation of the Forming Process of Front Bumper Bracket     

ZHOU Jie  ZHANG Yu-ping  WEI Guang-zhen  YANG De-sen 《保鲜与加工》2007,(7):14-17

The processing characteristics of the front bumper bracket are analyzed,and a reasonable process scheme is worked out.The three-dimensional sheet metal forming analysis software PAM-STAMP are adopted to simulate the bracket's drawing process.Then the surface of die is proved fine through analyzing the FLD diagrams and the forming results.An economical and optimized die structure is decided,and a complete set of dies of the bracket is designed.The spacing block is added in the sizing mold,which control the size precision of end products and assembling columns actively,and finally the certified products.The material utility and the labor productivity are raised,the production cost is saved,and the mold design quality and the efficiency are improved effectively.  相似文献