城市功能区视角下的都市农区研究

为了科学规划城市农用地,有必要确立都市农区概念,研究都市农区的基本内涵、空间特征和地域类型。都市农区是指由城市空间内农用地构成的城市功能区,一般仅限于市辖区。相对理想化的都市农区的空间尺度大体上为200 hm²,宜以呈小集中大分散的空间形态融入城市功能组团。都市农区有城市化地区、准城市化地区、半城市化地区、浅城市化地区和城市生态敏感区5种地域类型。依据都市农区区位特征、资源禀赋与功能需求的差异性,合理配置依托城市、服务城市的多功能农业,是形成城乡经济社会发展一体化新格局对城市规划提出的重要新课题。     

Combined effects of sodium chlorite dip treatment and chitosan coatings on the quality of fresh-cut d’Anjou pears

This study evaluated the effects of sodium chlorite (SC) alone and its sequential treatment with edible coatings on browning inhibition and quality maintenance of fresh-cut d’Anjou pears. Edible coatings were prepared from chitosan (CH) and its water-soluble derivative carboxymethyl chitosan (CMCH), separately. Pear wedges were immersed in SC solution, followed by coating with CH or CMCH solutions. The samples were packed in unsealed bags and stored at 4 °C for subsequent color, firmness, and weight loss measurement. The effects of the SC and coating treatments on polyphenol oxidase (PPO) inhibition and microbial inactivation were also evaluated. Results indicated that SC exhibited significant (P < 0.05) inhibition of browning and PPO activity. The SC treatment was also strongly effective in inactivating Escherichia coli O157:H7 on pear slices. Coating SC-treated pear slices with CH adversely affected the quality of pear slices by accelerating the discoloration of cut surfaces and increasing the PPO activity. On the contrary, coating SC-treated samples with CMCH significantly prevented the browning reaction and inhibited PPO activity. In addition, SC and CH/CMCH coatings maintained tissue firmness and did not affect weight loss. Our study may provide a scientific basis for the use of SC + CMCH treatment as an alternative preservation treatment for fresh-cut fruits and vegetables.     

Assessment of cytoplasmic effects of cytoplasmic male-sterile lines in upland cotton

Paired A- and B-lines, cytoplasmic male-sterile (CMS)-lines and main-tainer lines, respectively, were crossed with R-lines (restorer) to produce A × R, R × B and B × R hybrids, which were used in 1993 and 1996 to predict the performance of three lypes of CMS cotton lines available in China. A significant difference in yield and yield components was revealed between paired A × R and B × R hybrids. This difference was greatly influenced by both CMS cytoplasm and the interaction between cytoplasm and nuclear genotypes. It is suggested that there are detrimental effects of CMS cytoplasm on yield and yield components. General combining ability of near-isogenic CMS lines was also affected by this negative effect. The detrimental effect was closely related to an increased number of immature seeds per boll, which might be caused by partial female sterility associated with CMS cytoplasm. The possibility of developing specific combinations of CMS Upland × Upland restorer hybrids that express enough heterosis for yield to overcome the detrimental effect of the CMS cytoplasm is discussed.     

中国大陆新纪录种:石蒜绵粉蚧(Phenacoccus solani Ferris)

石蒜绵粉蚧(Phenacoccus solani)Ferris为中国大陆新纪录种,本文介绍了其形态特征、地理分布、寄主和为害等.     

不同密度和肥料对杂交棉主要农艺性状的影响研究

本文通过不同肥料和密度对杂交棉主要农艺性状的影响研究，结果表明，在22500株/ha—31500株/ha的密度水平和600kg/ha---1050kg/ha的施肥（折尿素，下同）水平范围内，各处理对杂交棉的生育期影响不大；而随着密度增加，杂交棉每株果档数减少、单铃重下降、衣分降低，有效铃增加，产量总体上呈增加趋向势；随着肥料水平增加，不同密度水平的产量性状因子表现不一致,，而较低密度时，除每株果档数外其余产量性状及产量均增加，而较高密度时，各产量性状及产量则表现先增后降，但二者均在移栽地区杂交棉适宜密度范围内。综合来看，生产上应以27000株/ha密度 和900kg/施肥水平为基础上，视田间具体条件，选择适宜的肥料和移栽密度水平。     

强酸性电解水浸种对黄瓜种子发芽与幼苗生长影响的研究

研究了不同浓度（有效氯浓度）强酸性电解水浸种对黄瓜种子发芽与幼苗生长的影响, 结果表明：低、中浓度电解水对黄瓜种子发芽率没有影响,高浓度电解水会抑制种子发芽;适宜浓度电解水浸种可提高种子胚芽生长速率,促进黄瓜幼苗生长与干物质积累,提高黄瓜幼苗素质,而高浓度电解水则产生抑制作用;黄瓜浸种适宜的电解水指标为：pH 2.35左右、ORP 1135mV左右、有效氯浓度 30 mg·L-1左右。     

转Bt基因玉米对亚洲玉米螟的抗性评价

转Bt基因抗虫玉米为诺华公司含Bt11转化系的杂交种NX4777,能全株表达Cry1Ab杀虫蛋白,以其非转基因受体玉米品种NX4906为对照。在玉米生长至心叶中期(50~60cm高)、抽雄前期和抽丝散粉期分别进行人工接亚洲玉米螟[Ostrinia furnacalis (Guenée)]初孵幼虫40~60头。以食叶级别、存活幼虫数、蛀孔数、隧道长度和雌穗被害级别等,分别作为评价玉米心叶期和穗期的抗性标准。结果表明,Bt玉米食叶级别仅为1级,显著低于对照的7级。Bt玉米平均每株存活幼虫0.04~0.20头、蛀孔0.11~0.15个、隧道长度0.13~0.41cm,雌穗被害级别为0,植株折茎率为0,而对照玉米平均每株存活幼虫6.19~12.41头、蛀孔4.48~7.05个、隧道长度12.41~24.09cm,雌穗被害级别为5.9,植株折茎率高达73.6%~95.5%。室内生测结果亦表明,取食Bt玉米心叶、雄穗的初孵幼虫3d全部死亡,取食花丝7d死亡率达到99%,相比之下取食常规玉米的存活率在88.7%以上。表明表达Cry1Ab杀虫蛋白的Bt对亚洲玉米螟具有很高的抗虫性,能够保护玉米全生育期免受玉米螟的危害。     

劳动力输入地农民工对待培训态度的调查

【研究目的】为了了解农民工培训工作中存在的问题,挖掘农民工现实或潜在培训需求。【方法】通过向农民工发放问卷调查并通过统计分析对农民工的学习意愿、学习效果、所能接受的学习条件进行分析。【结果】大多数的进城农民工接受过一定的学习或培训,其内容包括法律知识、文明习惯、专业技能、职业道德、企业规章制度等,培训效果因培训主体而有所不同,其中以不以盈利为目的政府、企业为培训主体的效果较好。农民工对参加培训的愿望不尽相同,但如果能给他们提供较好的学习机会、较低的学习费用、较充分的学习时间他们中的大多人是愿意接受培训的。【结论】为解决农民进城就业问题,要从培训的主体、内容、费用、生活、收入、劳动时间等各方面关怀他们并提供更好的学习环境。     

新疆内陆干旱区不同灌水量对长绒棉光合特性的影响

为探索新疆内陆干旱区不同灌水量对长绒棉新海14号光合特性的影响,利用小区试验,在5种灌水量（W）条件下,对其光合特性进行研究。结果表明：灌水量为7650m3/hm2时,叶片净光合速率日变化呈单峰曲线;随着灌水量的降低,其净光合速率日变化呈双峰曲线。新海14号的光补偿点为50μmol/m2·s;灌水量为2850m3/hm2时,其光饱和点为310μmol/m2·s,灌水量为5475m3/hm2以上时,其光饱和点为1280μmol/m2·s。叶片的净光合速率及蒸腾速率随灌水量的升高而增加,气孔阻力随灌水量的升高而降低。水分利用效率随着灌水量的降低而提高,呈极显著负相关;棉花产量对灌水量极为敏感。净光合速率与蒸腾速率呈显著正相关,与气孔阻力呈极显著负相关;蒸腾速率与气孔阻力呈显著负相关。新海14号的光合作用最适宜灌水量为6945m3/hm2;灌溉的临界值为5250m3/hm2     

硒对小麦生理功能的影响之研究进展

硒是小麦生长所必需的微量元素。硒在小麦体内通过吸收转化,能够促进小麦新陈代谢,增强小麦生物抗氧化作用和对环境胁迫的抗性,从而刺激生长发育、提高产量、改善品质。通过施入外源硒肥的方式增加小麦中的硒含量,使硒进入食物链,是为人体安全补硒的有效途经。从上述几方面综述了硒在小麦中的生理功能及富硒小麦的研究进展。