良种良法是获取高产的保证   总被引：1，自引：0，他引：1  

班秀文 《广西蔗糖》2001,(3):5-6,31

1　前言　　我省蔗区主要分布于南、北盘江 ,红水河流域的低热河谷地区 ,95%以上的甘蔗分布在旱坡地 ,缺乏灌溉条件 ,不能做到旱期引灌 ,雨季排水 ,人为抗拒自然灾害的能力弱 ;雨水对蔗地冲刷 ,水土流失严重 ,土壤保水保肥力差 ,既破坏了生态平衡又影响了甘蔗生长。因此老式栽培方式 ,是造成我省甘蔗产量低的重要因素之一。2　贵州蔗区的现状　　我省蔗区以春植蔗为主 ,播种期一般在3月中旬～ 4月上旬 ,此时蔗区月平均温度在1 2 .5～ 2 2 .9℃之间 ,月降雨量为 31 .7～88.1 mm。甘蔗种芽的萌发温度基本满足 ,然而蔗种的萌发却受到土壤含水量…  相似文献   

Responses of surface SOC to long‐term experimental warming vary between different heath types in the high Arctic tundra     

Ji Young Jung  Anders Michelsen  Mincheol Kim  Sungjin Nam  Niels M. Schmidt  Sujeong Jeong  Yong‐Hoe Choe  Bang Yong Lee  Ho Il Yoon  Yoo Kyung Lee 《European Journal of Soil Science》2020,71(4):752-767

  相似文献   

凯特芒果不同叶果比对果实品质和营养元素含量的影响   总被引：1，自引：0，他引：1  

杜邦  李贵利  周文静  刘斌  黄云 《广东农业科学》2011,38(24)

通过调整叶果比例,研究凯特芒果不同叶果比处理对果实品质和营养元素含量的影响.结果表明:不同叶果比处理对果实品质影响较小,其中糖酸比处理间差异显著,叶果比为30/1的处理与其他处理相比,总酸含量最小、为0.27％,糖酸比和固酸比均达最大值、分别为54.837和68.859;不同叶果比处理对果实中的营养元素N、P、Ca、Mn、B含量有不同程度的影响.总体来说,从不同叶果比对果实品质和营养元素含量的影响来看,凯特芒果的叶果比为30/1时较理想.  相似文献   

Chitosan nanoparticles enhance developmental competence of in vitro-matured porcine oocytes     

Pantu Kumar Roy  Ahmad Yar Qamar  Xun Fang  Ghangyong Kim  Seonggyu Bang  Mahanama De Zoysa  Sang Tae Shin  Jongki Cho 《Reproduction in domestic animals》2021,56(2):342-350

Oxidative stress is inevitable as it is derived from the handling, culturing, inherent metabolic activities and medium supplementation of embryos. This study was performed to investigate the protective effect of chitosan nanoparticles (CNPs) on oxidative damage in porcine oocytes. For this purpose, cumulus–oocyte complexes (COCs) derived from porcine slaughterhouse ovaries were exposed to different concentrations of CNPs (0, 10, 25 and 50 µg/ml) during in vitro maturation (IVM). Oocytes treated with 25 µg/ml CNPs showed significantly higher levels of GSH, along with a significant reduction in ROS levels compared to control, CNPs10 and CNPs50 groups. In parthenogenetic embryo production, the maturation rate was significantly higher in the CNPs25 group than that in the control and all other treated groups. In addition, when compared to the CNPs50 and control groups, CNPs25-treated oocytes showed significantly higher cleavage and blastocyst development rates. The highest concentration of CNPs reduced the total cell number and ratio of ICM: TE cells in parthenogenetic embryos, suggesting that there is a threshold where benefits are lost if exceeded. In cloned embryos, the CNPs25 group, as compared to all other treated groups, showed significantly higher maturation and cleavage rates. Furthermore, the blastocyst development rate in the CNPs25-treated group was significantly higher than that in the CNPs50-treated group, as was the total cell number. Moreover, we found that cloned embryos derived from the CNPs25-treated group showed significantly higher expression levels of Pou5f1, Dppa2, and Ndp52il genes, compared with those of the control and other treated groups. Our results demonstrated that 25 µg/ml CNPs treatment during IVM improves the developmental competence of porcine oocytes by reducing oxidative stress.  相似文献   

Fault Section Diagnosis Algorithm of Distribution Networks Based On Topology Identification     

LIN Jing dong  CAO Chang xiu  ZHANG Bang li  WU Jian lin 《保鲜与加工》2001,(5):51-54

An algorithm of fault section diagnosis based on topology identification for distribution networks is presented. By decomposing the topologic matrix which describing the distribution network into two parts,one part only contain the complex coupling factor ,and the other ignore the complex coupling factor. Using this method, the fault zones in distribution network can be identified and isolated efficiently, and the vertexes of the zones can also be identified automatically. This approach adapts to the changefully network structures.  相似文献   

Loads Equalization Based on Optimization Principle and the Hierarchical Model for Distribution Networks     

LIN Jing dong  CAO Chang xiu  ZHANG Bang li 《保鲜与加工》2002,(5):29-32

Loss reduction is important for distribution networks and it is available to reduce loss by loads equalization. With increasing numbers of vertexes in distribution networks, compounding of loads are rapid increasing. It is hard to achieve the global optimization for load balancing by traditional model of distribution networks. Base on analyzing character of loads equalization for distribution networks, this paper provides a new method which conjugate the optimization principle and the hierarchical model of the distribution networks, can transfer the optimization issues into multi stage decision making problems,and can also achieve the optimization equalization of the distribution networks loads.  相似文献   

泵房异常振动的原因及处理措施     

许帮田 《排灌机械》2001,19(3):33-34

通过对泵房振动实际情况进行分析，探讨了振动发生的原因及治理措施，可为同类型泵站的设计、安装提供参考。  相似文献   

北京市典型沙地景观动态变化分析——以康庄为例   总被引：1，自引：0，他引：1  

贺然 徐伟王棒  孙保平 《水土保持研究》2007,14(5):145-148

本研究通过选取北京典型沙地-康庄为研究对象,借助遥感技术、地理信息系统技术、全球定位技术、景观生态学理论和相关数学研究方法,对康庄80年代、90年代和2000年以后3三时期的景观动态进行分析和比较。从80年代至今,康庄沙化土地景观类型发生巨大变化。露沙地面积大幅度减少,由2117.03 hm^2减少到1 249.65hm^2减少了59.03%。通过选取相关景观指数对研究区景观类型进行分析可知,康庄风沙危害区先增加后减缓;对研究区景观类型的变化的分析表明,变化的原因与研究区所处地理位置,社会经济发展背景和人为干扰、政策导向密切相关。对影响研究区景观动态变化的主要因素分析可知,研究区主要受自然和人为两种条件影响最大。自然因素中,沙化土地变化主要与地形地貌、地表物质、降雨、温度、大风、水文条件等因素关系较密切;人为因素中,主要受人口增长、农业结构调整、林业工程实施和社会经济发展背景等因素的影响。  相似文献   

当代大学生择业观存在的问题及其引导     

杨邦勇 《安徽农业大学学报》2007,(5):119-122

本文分析了大学生择业观取向发展轨迹, 剖析了大学生择业观取向的内在冲突, 阐明了通过择业观念、就业指导、职业生涯规划、社会实践、创业教育等途径来帮助大学生确立正确的择业观。  相似文献   

厦门市行道绿化树种凤凰木的调查研究   总被引：7，自引：0，他引：7       下载免费PDF全文

叶功富  廖福霖  倪志荣  肖胜  蔡邦平  陈登雄 《林业科学研究》2002,15(3):332-337

本文研究了厦门市行道绿化树凤凰木的生长状况，并拟合了树高（H）与年龄（Y）的最优模型，H＝（－35．652＋9．003Y）／Y，胸径D1，3）与年龄（Y）的最优模型：D1，3＝（－316．647＋48．462Y）／Y。结果表明，凤凰木行道绿化树在夏季具有降温增湿的小气候效应，凤凰木对台风的抗逆性强而且抗病虫害。  相似文献