Field‐grown Cotton Exhibits Seasonal Variation in Photosynthetic Heat Tolerance without Exposure to Heat‐stress or Water‐deficit Conditions

Thermotolerance acclimation of photosystem II to heat and drought is well documented, but studies demonstrating developmental impacts on heat tolerance in field‐grown plants are limited. Consequently, climatic variables, estimated canopy temperature, predawn leaf water potential (Ψ_PD), and the temperature responses of maximum quantum yield of photosystem II (F_v/F_m), variable fluorescence (F_v/F₀), quantum yield of electron transport (φ_Eο) and efficiency of PSI electron acceptor reduction (REο/ABS) were characterized for Gossypium hirsutum at three sample times during the growing season (21 June, 2 July and 18 July 2013) under well‐watered conditions. The temperature decreasing a given photosynthetic parameter 15% from the optimum is referred to as T₁₅ and served as a standardized measure of heat tolerance. Ambient and estimated canopy temperatures were well within the optimal range for cotton throughout the sample period, and leaves were verified well watered using Ψ_PD measurements. However, T₁₅ varied with sample date (highest on July 2 for all parameters), being 2 °C (F_v/F₀) to 5.5 °C (φ_Eο) higher on July 2 relative to June 21, despite optimal temperature conditions and predawn leaf water potential on all sample dates. These findings suggest that even under optimum temperature conditions and water availability, heat tolerance could be influenced by plant developmental stage.     

家庭绿化植物种类选择

通过对家庭居室不同空间特点的分析,根据家庭绿化的趋势,从绿化植物材料的适应性、观赏性、生态性和经济性方面探讨了家庭绿化材料的选择,以期为居室绿化提供参考依据。     

常绿植物在杨凌居住区绿地中的应用调查研究

采用样地调查的方法对杨凌居住区绿地中常绿植物的种类组成、栽植类型、生长状况等进行研究,结果显示:杨凌居住区绿地常绿植物共计15科24属32种,其中,常绿乔木11种,多为松柏科,数量占17%,常绿灌木17种,多为阔叶植物,数量占55%;78%的常绿植物生长良好;常绿植物在居住区绿地中多采用孤植、对植、列植、丛植、片植、绿篱的栽植类型。调查中发现,在居住区绿地中存在着常绿植物的应用未做到适地适树、种植密度不够合理、养护管理不到位等问题,为此提出增加常绿植物种类、保持常绿落叶植物适宜比、注重植物生态性、营造有特色的常绿植物景观和重视日常养护管理等建议。     

乡镇污水处理厂运行管理相关问题探讨

乡镇污水处理厂作为环保基础设施建设的重点,普遍存在重建设轻运营的问题。笔者结合重庆市实际情况,重点分析了乡镇污水处理厂运行管理中存在的问题,并有针对性地提出了建议,包括提高收集率、完善末端工艺、专业化运营、改变考核体系、优化污泥处置、加强再生利用和远程在线监控等。     

南粤居住区园林植物应用现状调查

通过对南粤地区6个居住区园林工程项目的绿化设计进行调查,收集南粤居住区常用的植物种类以及使用量,此总结了居住区绿地规划设计中园林植物品种选择的规律,为华南地区园林苗圃的生产提供参考。     

油菜新品种宁杂1818氮肥运筹试验

以油菜(Brassica campestris L.)新品种宁杂1818为试验材料,以秦优7号为对照,研究不同氮肥运筹条件下,宁杂1818的植株长势和产量变化,旨在为深入了解宁杂1818的生长特性,建立宁杂1818高产、高效栽培技术体系提供理论依据。     

Single and Interactive Effects of Temperature and Light Quality on Four Canola Cultivars

Combined effects of temperature and light quality on plants have received little attention. We investigated the single and interactive effects of temperature and light quality on growth and physiological characteristics of four canola (Brassica napus) cultivars – Clearfield 46A76 (cv₁), Clearfield 45H72 (cv₂), Roundup Ready 45H24 (cv₃) and Roundup Ready 45H21 (cv₄). Plants were grown under lower (24°/20 °C) and higher (30°/26 °C) temperature regimes at low red/far‐red (R/FR), normal R/FR and high R/FR light ratios in environment‐controlled growth chambers (16 h light/8 h dark). Higher temperature reduced stem height and diameter; leaf number and area; dry matter of all plant parts; and specific leaf weight, but increased leaf area ratio; and chlorophyll (Chl) fluorescence (Y). Low R/FR increased stem height; Y; and ethylene, but decreased stem diameter; F_v/F_m; Chl a; Chl b; and carotenoids. Among cultivars, plants from cv₄ were tallest with thickest stems and greatest dry matter. None of the main factors affected gas exchange. Higher temperature at high R/FR caused cv₃ to be shortest, whereas lower temperature at low R/FR caused cv₄ to be tallest. We conclude that heat and other stress factors will adversely affect sensitive crops, but tolerant genotypes should perform well under future climate.     

浅谈高速公路的生态绿化

随着社会经济的高速发展,人民生活水平的不断提高,人们对精神文化生活及生活环境有了更高层次的要求,人们的出行不再是满足于位置转移的心态,而是要求在出行办事的同时,能尝试到轻松的感觉,也就是要求高速公路的运行空间环境应该是高质量的,在满足安全、快速、便利的同时,又要做到美观漂亮。文章在分析了创建高速公路的必要性和实施高速公路生态绿化的重要性的基础上,提出了高速公路生态绿化的思路、实施原则及具体措施。     

投加硅藻土对城镇污水处理厂出水水质影响研究

对好氧池出水混合液进行了加药絮凝试验，探讨了加药量、污泥浓度对絮凝沉淀效果的影响，并通过生产性试验，验证了试验结果的正确性，从而解决了某污水处理厂因进水水质波动影响，出水SS不能稳定达标的问题。     

优良经济植物结香栽培技术

结香是一种中药材兼优质纤维用材树种,有很高的经济价值,开发利用前景广阔。结香投产后通过科学管理、合理利用、及时复壮,可连续获得收益,年产值可达5.0万～7.5万元/hm2,经济寿命达10～15 a。通过多年实践,总结出结香苗木繁殖、造林方法、林分管理、采收利用和复壮技术等主要栽培技术,可在生产中推广应用。