海南6种切叶花卉植物橡胶林下套种的适应性研究

通过对散尾葵、金心巴西铁、金边富贵竹、莲花竹、龟背竹、朱蕉等6种耐荫型切叶花卉植物在橡胶林下进行套种(扦插)试验,观测这些植物的叶片生长物候期、植株整体感、株高、叶片色泽和病虫害危害程度,分析这6种切叶花卉植物在橡胶林下的生长适应性。结果表明,适应性强弱排序为金心巴西铁朱蕉散尾葵龟背竹莲花竹金边富贵竹,其中金心巴西铁在橡胶林下生长综合表现最好,评价得分最高,为17.22,适合在海南橡胶林下推广种植。     

油莎豆排种离散元仿真参数标定与试验

油莎豆种球形状不规则,表面凹凸不平,国内油莎豆播种装置多数是基于大粒种球排种器进行改进,由于离散元模拟试验过程中缺乏准确的仿真参数,导致对排种器进行仿真优化分析时产生误差。针对此问题,本文测量油莎豆种子的本征参数和与排种装置间的接触参数,利用逆向工程技术构建油莎豆种子颗粒填充模型。依据方形壳体和圆筒的仿真堆积试验结果,采用Plackett-Burman试验筛选出对种群堆积角有显著影响的种间静摩擦因数和种间滚动摩擦因数,建立以这两种显著影响因子为自变量、种群堆积角为响应值的二元回归方程。用Matlab对方程组求解后得到标定后的种间静摩擦因数和种间滚动摩擦因数分别为0.246、0.083。为检验标定后参数的可靠性,在EDEM中进行仿真验证试验,结果显示方形壳体装置仿真和物理堆积角的误差为0.43%,圆筒装置仿真和物理堆积角的误差为0.55%。为进一步验证标定后参数的准确性,采用气力式精量排种器,并选取3个关键特征尺寸和堆积截面积占比率,待种群稳定后将仿真和物理试验做对比,最后得到进种口种群上边界最大凸点处与排种盘水平中心线距离H1、种群轮廓边界与透明观察窗左侧竖线的交点到排种盘水平中心线距离H2和堆积截面积占比率r等参数的相对误差均在8.33%以内。     

百色杧果栽培种质果实品质多样性分析

广西的杧果(Mangifea indica L.)以百色右江干热河谷为重要栽培地区,百色地区的杧果栽培品种仍然以传统品种为主,伴随着新兴杧果产区的崛起,急需选育适宜百色的杧果新品种,以提升百色杧果的竞争力.目前,在广西以外的其他地区已经开展了不同杧果品种性状评价的研究,而针对广西百色地区杧果栽培种质的多样性分析评价鲜有...     

病害胁迫下玉米LAI遥感反演研究

为了在病害发生条件下进行玉米LAI的遥感估算,针对41个不同抗性的玉米自交系品种,通过人工接种方法,获得了不同病害严重程度(1～9级)的LAI数据,同时采集了地面高光谱和无人机多光谱数据,构建了K近邻算法、支持向量机、梯度提升分类树和决策分类树分类模型对病害进行分类,对玉米种质资源抗病性进行了划分。基于不同玉米病害胁迫程度分类结果,采用随机森林回归、梯度提升回归树、极端梯度增强算法、轻量梯度提升机4种机器学习模型对玉米LAI进行反演,讨论了不同模型在病害胁迫下的鲁棒性。研究结果表明,对不同生育期玉米病害程度进行划分,基于地面高光谱识别精度分别为84.72%(梯度提升分类树)、47.67%(支持向量机)、55.05%(K近邻算法)、83.02%(决策分类树)。基于病害分类结果,本文利用无人机多光谱数据估算了不同病情等级胁迫下的玉米LAI。构建了4种集成学习模型对不同病情等级的LAI进行估算,4个LAI反演模型的总体反演精度(rRMSE)分别为：19.11%(梯度提升回归树)、15.94%(轻量梯度提升机)、14.51%(随机森林回归)和15.45%(极端梯度增强算法)。其中极端梯度增强算...     

油菜宽幅折叠式浅旋精量联合直播机设计与试验

针对长江中下游稻油轮作区油菜播种作业工序复杂、效率低的问题,设计了一种油菜宽幅折叠式浅旋精量联合直播机,可实现开畦沟、浅旋灭茬、油菜精量播种、种床覆土等功能。分析确定了整机基本结构和工作过程,对液压折叠机构进行了运动学和动力学分析,利用Matlab软件确定了液压缸结构参数以及承受的最大负载,基于拖拉机液压油路设计了液压折叠控制系统;根据开畦沟深度、宽度、耕深、覆土均匀性等作业要求,确定了刀轴转速为360～480 r/min,开沟刀、浅旋刀辊旋转半径分别为320、175 mm,开沟刀盘开沟刀数量为8;分析了分土导流板结构参数的取值范围,应用EDEM软件开展了分土导流板不同结构参数组合下的覆土均匀性正交试验,建立了覆土均匀性与分土导流板安装距离、导流板长度和分土板角度的回归数学模型,试验结果表明,当分土导流板安装距离为200 mm、导向板长度为600 mm、分土板角度为60°时,覆土均匀性可达93.33%。田间试验结果表明,当机组前进速度为3.6 km/h、畦沟深度为150 mm、刀轴转速为480 r/min时,油菜宽幅折叠式浅旋精量联合直播机作业后种床碎土率为91.62%,秸秆埋覆率为9...     

基于脸部RGB-D图像的牛只个体识别方法

为实现非接触、高精度个体识别,本文提出了一种基于牛只脸部RGB-D信息融合的个体身份识别方法。以108头28~30月龄荷斯坦奶牛作为研究对象,利用Intel RealSense D455深度相机采集2334幅牛脸彩色/深度图像作为原始数据集。首先,采用冗余图像剔除方法和自适应阈值背景分离算法进行图像预处理,经增强共得到8344幅牛脸图像作为数据集;然后,分别选取Inception ResNet v1、Inception ResNet v2和SqueezeNet共3种特征提取网络进行奶牛脸部特征提取研究,通过对比分析,确定FaceNet模型的最优主干特征提取网络;最后,将提取的牛脸图像特征L2正则化,并映射至同一特征空间,训练分类器实现奶牛个体分类。测试结果表明,采用Inception ResNet v2作为FaceNet模型的主干网络特征提取效果最优,在经过背景分离数据预处理的数据集上测试牛脸识别准确率为98.6%,验证率为81.9%,误识率为0.10%。与Inception ResNet v1、SqueezeNet网络相比,准确率分别提高1、2.9个百分点;与未进行背景分离的数据集相比,准确率提高2.3个百分点。     

金属元素对Xhhh菌株表达MnP酶及降解污染物的影响

测定分析了制药废水中Mn2 、Cu2 、Zn2 和Se4 4种金属元素离子水平对跨界原生质体融合(IKPF)特效菌株Xhhh表达锰过氧化物酶(MnP)水平及降解有机污染物效率的影响。结果表明,影响MnP表达水平的金属元素离子顺序为Mn2 >Se4 >Zn2 >Cu2 。在MnP水平与生物比降解率(SDR)之间,存在极显著的正相关性(P<0.01)。研究结果为应用IKPF-Xhhh特效菌株处理制药废水的工艺设计提供了重要的分子生物学参数。本文还对Xhhh在土壤修复中的应用前景进行了分析讨论。     

基于DPSIR概念框架的区域水土保持效益评价新思路

 定量评价区域水土保持效益并得到综合质量指数,便于区域水土保持效益的纵向或横向比较,进而为水土保持技术的提升和区域生态环境建设的科学决策服务。DPSIR(driving force-pressure-state-impact-response)概念框架有助于全面分析水土保持的"驱动力"、"压力"、"状态"、"影响"和"响应",有助于理解水土保持社会、经济和环境各因素的作用过程以及彼此之间的因果关系。在介绍DPSIR概念框架的基础上,根据区域水土保持效益评价指标体系构建的主导原则,初步提出水土保持效益评价的DPSIR框架,进而提出水土保持效益评价从基础数据到综合指数集成的新思路。     

Cross-resistance profile of mesosulfuron-methyl-resistant Italian ryegrass in the southern United States

Diclofop-resistant Lolium species (ryegrass) is a major weed problem in wheat production worldwide. This study was conducted to determine the resistance pattern of diclofop-resistant ryegrass accessions from the southern United States to mesosulfuron-methyl, a recently commercialized herbicide for ryegrass control in wheat; to determine the cross-resistance pattern of a Lolium multiflorum Lam. (Italian ryegrass) accession, 03-1, to acetolactate synthase (ALS) and acetyl-CoA carboxylase (ACCase) inhibitors; and to determine the resistance mechanism of Italian ryegrass to mesosulfuron-methyl. Seventeen ryegrass accessions from Arkansas and Louisiana, including standard resistant and susceptible accessions, were used in this experiment. Fourteen of the 17 accessions were more resistant (four- to > 308-fold) to diclofop than the standard susceptible biotype. One accession, 03-1, was resistant to mesosulfuron-methyl as well as to other ALS inhibitor herbicides such as chlorsulfuron, imazamox and sulfometuron. Accession 03-1, however, did not show multiple resistance to the ACCase inhibitor herbicides diclofop, fluazifop, clethodim, sethoxydim and pinoxaden, nor to glyphosate. The in vivo ALS activity of the 03-1 biotype was less affected by mesosulfuron-methyl than the susceptible biotype. This indicates that the resistance mechanism of Italian ryegrass to mesosulfuron-methyl is partly due to an alteration in the target enzyme, ALS. It is concluded that diclofop-resistant ryegrass in the southern United States can be generally controlled by mesosulfuron-methyl. However, mesosulfuron-methyl must be used with caution because not all ryegrass populations are susceptible to it. There is a need for more thorough profiling of ryegrass resistance to herbicides.     

Quantification of allele E198A in beta-tubulin conferring benzimidazole resistance in Monilinia fructicola using real-time PCR

BACKGROUND: Thiophanate-methyl, a member of the benzimidazole class of fungicides, is used in California to control brown rot of stone fruit caused by Monilinia fructicola (G. Wint.) Honey. The goal of this study was to develop a real-time polymerase chain reaction (PCR) assay as an efficient method to quantify the E198A allele of beta-tubulin that confers benzimidazole resistance. RESULTS: Using the real-time PCR assay, the frequency of allele E198A (FEA) in a population was determined from the quantities of DNA amplified with the E198A allele-specific primer pair HRF/HRR and the M. fructicola-specific primer pair MfF6/MfR6. The average proportions of highly resistant isolates determined with the conventional fungicide sensitivity method were within the range of average FEA values determined with the real-time PCR assay. We also determined the FEAs of M. fructicola populations sampled from 21 stone fruit orchards in California. Only one orchard showed a high FEA over 0.20, seven orchards had values between 0.01 and 0.1, and 13 orchards had values less than 0.01. CONCLUSION: The real-time PCR assay developed in this study provides a potentially useful tool to efficiently quantify benzimidazole resistance for large M. fructicola populations.