Plant growth inhibitory activity and active substances with allelopathic potential of cogongrass (Imperata cylindrica) rhizome

Cogongrass (Imperata cylindrica [L.] Raeusch.) is a perennial rhizomatous grass that belongs to the Poaceae and is widely distributed in tropical, subtropical and temperate regions over the world. The grass is strongly invasive and is suggested to have allelopathic potential. However, limited information is available on allelopathic substances in cogongrass rhizomes. Therefore, the allelopathic potential and substances in cogongrass rhizomes were investigated. The extracts of cogongrass rhizomes inhibited the root and shoot growth of barnyard grass, ryegrass, timothy, cress, lettuce and alfalfa. After bioassay‐guided separations of the extracts, four growth inhibitory substances, 5‐methoxyflavone, 5,2′‐dimethoxyflavone, methyl caffeate and abscisic acid, were isolated. 5‐Methoxyflavone, 5,2′‐dimethoxyflavone and methyl caffeate significantly inhibited the root and shoot growth of cress at concentrations of ≥0.03–0.3 m mol L^?1 and their concentrations required for 50% growth inhibition were 0.079–0.24, 0.23–1.1 and 0.59–0.88 m mol L^?1, respectively. The other isolated substance, abscisic acid, has been reported to have strong growth inhibitory activity. Its concentrations required for 50% growth inhibition on cress were 0.31–0.61 μ mol L^?1. The present study suggests that cogongrass rhizomes might have allelopathic potential and that those four substances might contribute to that potential.     

薏米山药曲奇饼干的研制

以低筋面粉,糖和黄油为主要原料,以感官评定分数为指标,通过单因素实验及正交实 验对薏米山药曲奇饼干进行了研制。结果表明,影响产品感官品质的主要因素由大到小依次为: 糖含量＞薏米粉和山药粉占总粉量的百分比＞黄油含量。确定了薏米山药曲奇饼干的最佳配方 为黄油含量100 g,糖含量40 g,薏米粉和山药粉占总粉量（130 g）的百分比为35%。制得的产品 不仅具有曲奇饼干的酥脆,还具有良好的营养功能和保健功能。     

基于砂质轻质土壤的根茎收获机研究设计

针对我国根茎作物种植和收获机械现状,设计出一种基于砂质轻质土壤根茎收获机.生产试验和性能测试表明:装置作业质量和性能指标参数符合设计要求,具有田间作业中成型切削、抬升土壤、快速摔落和疏松土壤、自然覆土和人工采取根茎等农艺功能.试验结果表明:该设计解决了同类机具结构庞大、传动和震动机构复杂、适应区域性差、对土壤扰动较大等...     

Optimization of slow-release fertilizer application improves lotus rhizome quality by affecting the physicochemical properties of starch

To achieve the dual goals of high yield and good quality with low environmental costs, slow-release fertilizer (SRF) has been widely used in lotus cultivation as new type of fertilizer instead of traditional nitrogen fertilizer.  However, the optimal amount of SRF and how it would promote lotus rhizome quality remain unclear.  This study was designed to investigate the photosynthetic characteristics and the synthesis, accumulation, and physicochemical properties of lotus rhizome starches under six SRF levels (CK, S1, S2, S3, S4, and S5).  Compared with CK (0 kg ha^–1), the net photosynthetic rate (P_n) and SPAD values of leaves remained at higher levels under SRF treatment.  Further research showed that SRF increased the lotus rhizome yield, the contents of amylose, amylopectin, and total starch, and the number of starch granules.  Among the six SRF levels, S3 (1 035 kg ha^–1) showed the greatest difference from CK and produced the highest levels.  With the increasing SRF levels, the peak, hot and final viscosities decreased at first and then increased, but the setback viscosity and pasting temperature increased.  In order to interpret these changes at the molecular level, the activities of key enzymes and relative expression levels of starch accumulation related genes were analyzed.  Each of these parameters also increased under SRF treatment, especially under the S3 treatment.  The results of this study show that SRF, especially S3 (1 035 kg ha^–1), is a suitable fertilizer option for lotus planting which can improve lotus rhizome quality by affecting starch accumulations related enzymes and genes.  These results will be useful for SRF application to high-quality lotus rhizome production with low environmental costs.     

宁前胡仿生挖掘铲设计与试验

针对宁前胡采挖过程中挖掘阻力大的问题，以鲨鱼背鳍为研究对象，并结合农艺要求，设计了一款宁前胡仿生挖掘铲；根据摩尔-库仑理论中土体应力分析，当选用鲨鱼背鳍结构作为仿生铲的凸起结构时，土壤更易达到破裂状态；通过三维扫描仪扫描鲨鱼标本，获取鲨鱼背鳍三维模型，根据背鳍三维模型确定仿生铲的凸起结构，并通过NX12.0创建仿生挖掘铲三维模型；利用三维扫描仪获得宁前胡根茎外形轮廓特征，创建宁前胡根茎的离散元模型，并选用Hertz-Mindlin with JKR建立宁前胡根茎-土壤离散元复合模型；通过离散元仿真对比试验，得出X、Y、Z方向颗粒位移和挖掘阻力的平均值，分析挖掘铲的减阻机理，仿生铲比平面铲在采挖过程中阻力减小14.37%;通过开展土槽试验，对比根茎挖掘效果，与仿真试验中得出的宁前胡根茎在仿生挖掘铲挖掘后，根茎在X、Y、Z方向上有更好的位移表现，仿生铲和平面铲的挖掘阻力平均值分别为1 342.28、1 622.73 N,仿生铲比平面铲在采挖过程中阻力减小17.28%,与仿真试验得出的减阻率十分接近，满足宁前胡采挖过程中的减阻要求。     

平贝母收获挖掘设备研究现状与发展趋势

平贝母采收作业是林区贝母种植的关键一环，对平贝母的成色与药用价值产生重要影响。现有的采收设备存在作业效率低、环境适应性差等问题。挖掘铲作为平贝母收获机的核心部件，尚存在结构设计单一化，研究思路半经验化等问题直接影响采收作业的质量。为研发能够满足行业需求的平贝母采收设备，结合现有种植条件及技术发展，对国内外根茎类作物收获机进行整体分析，提出研发可兼收其他作物的小型自走式联合收获机这一思路；对平贝母收获机及挖掘铲的发展情况进行深入剖析，提出平贝母收获机的发展方向为高效化、采收过程专业化、采收作物兼容化，平贝母挖掘铲的发展方向为研究思路科学化、研发手段专业化、运行性能稳定化，以期推动贝母产业全程机械化进程。     

热风干燥法生产山药粉工艺优化研究

山药具有良好的保健功效,营养价值丰富,山药粉食用方便,易储存,具有广阔的应用前景。以柠檬酸、抗坏血酸、乙二胺四乙酸二钠(EDTA-Na2)为护色剂,筛选了最优护色剂组合;以水分和营养成分为测定指标,探讨了不同干燥温度和时间对山药粉品质的影响;以山药粉的流动性为指标,探讨了粉碎工艺参数。结果表明,最佳护色剂组合为:0.8%柠檬酸+0.25%抗坏血酸+0.4%EDTA-Na2;山药粉制备最佳工艺为:切成4 mm薄片,在复合护色剂柠檬酸(0.8%)、抗坏血酸(0.25%)、EDTA-Na2(0.4%)中浸泡15 min,用清水冲洗干净后于60℃干燥箱中干燥8 h,取出放凉,粉碎后过120目筛。在此条件下制得的山药粉品质最佳,颜色为正常白色,香气浓郁,流动性好。     

基于梯度下降和角点检测的玉米根茎定位导航线提取方法

针对玉米根茎图像信息，提出一种在拔节期后玉米大田环境下快速、精准提取导航基准线的新方法。首先利用2G-B-R和最大类间方差法分割图像，并利用形态学处理提高图像质量，对去噪图像像素按列累加获取垂直投影。传统峰值点法在寻找特征点时需要设定阈值，耗时长且伪特征点多，因此提出一种基于梯度下降的特征点寻找方法，利用某点沿梯度下降的方向求解极小值从而求得特征点。根据角点检测原理，利用特征点像素各个方向梯度变化不同剔除伪特征点，解决了传统算法异常点过多、错误剔除玉米根茎定位点等问题，最终采用随机采样一致算法拟合导航线。试验结果表明，与传统算法相比该算法能够很好的适应复杂环境，实时性强，即使在缺苗、杂草等情况下仍具有很强的鲁棒性，平均处理准确率为92.2%，处理一帧分辨率为1 280像素×720像素的图像平均耗时为215.7 ms，该算法为智能农业化机械在玉米田间行走提供了可靠的、实时的导航路径。     

墨兰根状茎绿芽分化的研究

对影响墨兰根状茎绿芽分化的几个因素进行研究的结果表明:在基本培养基中添加5.00 mg·L-1 6-BA+0.50 mg·L-1 NAA的激素配比,绿芽产率高达180%,且绿芽生长势旺盛.低剂量(1和2 Gy )60Coγ-射线辐射可促进根状茎绿芽分化,提高绿芽产率和生长势;高剂量(5～10 Gy )辐射则显著降低绿芽产率,使其生长势减弱.活性炭完全抑制绿芽分化,促进了脱分化状态下的根状茎增殖生长.