甘薯联合收获机高度自适应集薯装置设计与优化

甘薯收获是甘薯生产中用工量最多、劳动强度最大的环节。为了解决甘薯联合收获机集薯环节存在伤薯率高、自动化程度低等问题,该研究开展了高度自适应集薯装置的机械结构设计与控制系统搭建。系统及结构设计充分考虑物料物理性状及作业过程中的运动学与力学特性,通过新的集薯方式以满足落薯高度自适应、集薯装筐和自动卸料换筐等作业要求。通过落薯高度自适应功能减小并控制薯块下落的高度达到有效减少甘薯伤薯率与破皮率的目的。在单因素试验分析结论的基础上,以清选平台转速、落薯机构转速和落薯设定高度为试验因素,开展三因素三水平Box-Benhnken试验,以伤薯率、破皮率、微破率和损伤率为试验指标建立多元回归方程并进行响应面分析。回归模型进行多目标优化后获得装置最优工作参数组合为：清选平台转速108.07 r/min、落薯机构转速74.75 r/min、落薯设定高度18.15 cm。对优化结果进行验证试验,试验结果为：伤薯率0.39%、破皮率0.54%、微破率22.93%和漏薯率0.54%,各评价指标与模型预测值相近。研究结果可为甘薯联合收获机高度自适应集薯装置进一步设计与优化提供参考。     

Cotton Chemical Topping by Applying DPC in Different Cotton-Growing Regions

[Objective] The objective of this study was to investigate the stability and universality of cotton chemical topping by applying mepiquat chloride (1,1-dimethyl-piperidinium chloride, DPC) in different cotton-growing regions. [Method] Field experiments were conducted in 2018 at 10 locations in the Yellow River basin (Hejian and Handan, Hebei province; Dezhou and Wudi, Shandong province), the Yangtze River basin (Dafeng, Jiangsu province; Huanggang, Hubei province), and Xinjiang area (Shihezi location I and loacation II, northern Xinjiang and Luntai and Shaya, southern Xinjiang). Local cultivars/lines were used, and the experiments were performed using a randomized complete block design with three or four replicates. Accompanied with typical DPC multi-application in each location, chemical topping was conducted at 10 days before manual topping (T1) or at the same time with manual topping (T2) by applying four dosages of DPC (0, 90, 180, 270 g·hm^－2), manual topping was used as the first control and non-topping as the second control. [Result] The time of chemical topping significantly affected cotton plant height (except for the results in Handan, Dezhou and Wudi) and the number of fruit branches (except for the results in Dafeng and Huanggang). It was observed that earlier chemical topping would result in lower cotton plant height and a fewer fruit branches. In Hejian and Shihezi location I, the average plant height across DPC chemical topping at T1 stage was not only lower than that of T2 stage but also 3.3 cm and 4.6 cm lower than that of manual topping, respectively. In most locations, chemical topping at T1 stage increased around two fruit branches per plant compared with manual topping, while in T2 stage the increased fruit branches per plant ranged from 2.3 to 7.7. Also, we found that a higher dosage of DPC resulted in shorter plant height (except for that in Huanggang). In some locations, plant heights of chemical topping with 180 g·hm^－2 or 270 g·hm^－2 DPC were even shorter than that of manual topping. The number of fruit branches per plant of 0 g·hm^－2 DPC increased by 2.4-8.3 compared with manual topping. However, chemical topping with 90-270 g·hm^－2 DPC significantly reduced the number of fruit branches compared with 0 g·hm^－2 DPC. There were no significant differences in the number of fruit branches among three DPC dosages (90, 180, and 270 g·hm^－2). In Handan, seed cotton yield of chemical topping at T2 stage was significantly lower than that of manual topping due to the decreased boll number, which is possibly associated with the high temperature and drought weather after chemical topping. While at other locations, most treatments of chemical topping by using DPC did not produce significant effects on yield. In addition, chemical topping by using DPC did not delay cotton maturity, characterized by their similar boll-opening rate and the first harvest rate to those of manual topping before spraying harvest aids. [Conclusion] Cotton chemical topping with DPC is more stable and universal across different cotton-growing regions. We suggest that 90-180 g·hm^－2 DPC could be used at the same time with manual topping for cotton chemical topping.     

矮秆基因Rht_NM9在小麦株高建成中对内源激素含量的影响

普通小麦品种"南农9918"经甲基磺酸乙酯(ethyl methanesulfonate,EMS)诱变获得一个矮秆、多蘖、长穗突变体"NM9",在该突变体中定位到一个新的矮秆突变基因Rht_NM9。内源激素在普通小麦株高建成的过程中发挥重要的调节作用,为了解析Rht_NM9致矮的生理机制,本研究以南农9918及其矮秆突变体NM9为材料,利用酶联免疫吸附分析法(enzyme-linked immunosorbent assays,ELISA)测定了不同生育期各节间内源赤霉素(GA)、生长素(IAA)、脱落酸(ABA)和玉米素核苷(ZR)的含量,分析小麦发育关键时期的内源激素含量变化与株高的关系。结果表明,在孕穗期和抽穗期,矮秆突变体NM9中GA、ABA含量均显著高于南农9918,而ZR含量则显著低于南农9918,IAA含量在南农9918和突变体NM9之间无明显差异。此外,突变体NM9各节间中GA/ABA比值显著高于南农9918,而IAA/ABA、(IAA+GA)/ABA、ZR/ABA比值显著低于南农9918。以上结果表明小麦株高受多种激素调控,突变体中内源ABA含量升高,IAA/ABA和ZR/ABA比值降低会抑制植物株高伸长。     

Comparison of three types of adhesives in attaching coral transplants to clam shell substrates

• 1. Nubbins from 12 coral species were transplanted onto dead giant clam shells at three sites in a lagoon near Bolinao, north‐western Philippines. Transplants were attached using three types of adhesives: cyanoacrylate glue (SG), epoxy putty (EP) and marine epoxy (ME) and were monitored over five months for detachment, in situ mortality and natural self‐attachment by tissue growth.
• 2. Corals attached with SG showed a significantly higher rate of detachment (logrank test) than those attached with either EP or ME (P<0.001 in each case). Also, those attached with EP showed a higher rate of detachment than corals attached with ME (logrank=6.46, P<0.05).
• 3. ANOVA (P>0.05) and survival analysis (logrank=2.85, P>0.05) showed no among‐adhesives differences in in situ mortality. Among the species used, Porites cylindrica, Pavona frondifera, Heliopora coerulea and Porites rus had the highest survivorship with 82%, 80%, 76% and 73%, respectively, of nubbins alive at the end of the experiment and also displayed the highest cumulative rates of self‐attachment. Species with the lowest survival rates included Acropora muricata and four pocilloporids.
• 4. Although there was no significant difference in the number of self‐attaching transplants among the adhesives, corals transplanted using ME and EP self‐attached earlier than those transplanted using SG (logrank=11.19, P<0.01).
• 5. Results from this study highlight the importance of selecting the appropriate means of attaching corals to substrates and carefully considering species‐specific traits of candidate corals for transplantation.

Copyright © 2008 John Wiley & Sons, Ltd.     

基于CRISPR/Cas9技术的水稻miR1866突变体构建

microRNA (miRNA)是长度为18～25个碱基的非编码单链RNA,在植物生长发育过程中起着重要的调节作用.水稻是世界上重要的粮食作物之一,近年来调控水稻生长发育的miRNA不断被发掘,但目前关于miR 1866的研究还比较少.本研究通过构建miR1866的CRISPR/Cas9表达载体,创制miR1866的突...     

不同浓度硝基苯对水稻发芽和秧苗生长发育的影响

试验结果表明,硝基苯浓度达到27倍(0.34 mg/L)以上对水稻发芽产生明显影响,致使芽率下降.不同浓度的硝基苯对不同品种的发芽率影响不显著.随着浓度的增加,同一品种株高基本呈降低趋势,根数、叶片与对照差异显著.     

杨树1年生整株苗造林树体控制技术研究

为了论证杨树1年生整株苗造林树体控制技术中最适宜的截干高度以及后期采用何种主干控制技术能使苗木获得较好的生长,本研究采取双因素完全随机试验设计,设置不同截干高度和不同主干控制方式两个因素进行试验.结果表明:1年生整株苗造林树体控制技术的苗木造林平均成活率达97.4％以上,显著高于常规整株苗造林的平均成活率;合理截干高度...     

短轮伐期桉树人工林个体林木特征研究

利用广东高要和广西扶绥两地14个2~10年生桉树林分样地共287株样木,研究短轮伐期桉树人工林个体林木特征指标,并比较现有广西良种桉二元带皮和去皮材积公式估算个体林木材积的准确性,分析不同年龄、林分和径阶林木的出材率。结果表明:带皮和去皮林木的胸高形数为0.504±0.004 2和0.529±0.004 4、实验形数为0.410±0.002 4和0.427±0.002 7、形率为0.657±0.003 4和0.690±0.003 6、高径比为1.22±0.017和1.43±0.019。用广西良种桉二元带皮和去皮材积公式估算单株林木带皮和去皮材积与实际材积高度相关(r>0.99),但估算值普遍偏低,平均分别小3.7%和21.0%;尤以用带皮材积公式估算去皮材积比用去皮材积公式估计要准确,平均只小2.3%。如以6年生以上样地和尾径4 cm以上的去皮林木为实际出材,5个相关样地林分平均出材率为(73.3±4.31)%,最小为54.6%,最大为81.5%。     

地方依恋中植物景观因素对人类情感的作用

指出了地方依恋是描述人与地方之间的积极情感,它包括地方依赖和地方认同.回顾国内外的地方依恋的研究,人们在与某个地方的长期互动过程中,发展出对该地的依恋.由于目前地方依恋影响因素中的植物景观因素研究较少,因而提出了可通过对植物景观色彩、气味、植物形态、季相变化以及植物不同的观赏部位等的讨论来阐述植物景观与地方依恋关系;在...