The performance of the leaf mulches ofLeucaena leucocephala,Flemingia macrophylla andGliricidia sepium in weed control

The performance of the leaf mulches ofLeucaena leucocephala, Gliricidia sepium andFlemingia macrophylla in weed control has been tested in two trials. The length of the period during which a mulch layer yields significantly less weedbiomass compared to the control plots is called the ‘effective life-span’ of the mulch. Of the three mulch materials only that ofF. macrophylla shows promise in retarding weed development. In the second trialF. macrophylla leaf mulch was applied at rates of 3, 6 and 9 tons dry matter per ha. The effective lifespan of a mulch layer of 3 tons is between 12 and 13 weeks. The treatments 6 and 9 tons have effective life-spans of over 14 weeks. For moderate quantities (up to 5 tons of dry leaf mulch per ha) the effective life-span is estimated at about a 100 days. The value of mulching in weed control is limited to the control of weed species that multiply by seed. Regrowth originating from roots or stumps from former vegetation is unlikely to be checked by a mulch layer. The subject of this paper is part of a broader study, presently conducted in Southern Ivory Coast, on the production, agronomical value and use in alley-cropping systems of the species mentioned in the title of the paper. A final report is scheduled for publication in 1988.     

24%氨氯吡啶酸水剂防治林地阔叶杂草试验

选用24％氨氯吡啶酸水利，对林地一年生及多年生阔叶杂草、灌木进行防除试验。结果表明，试验剂量在1200～3600g ai／hm^2范围内时，对杂草的防效可达90％以上，对灌木防效达70％以上。该药剂对针叶用材林幼林慎用。     

森泰除草剂防除香椿幼林地杂草的试验研究

使用25%森泰水剂和5%森泰颗粒剂防除香椿幼林地的杂草研究试验结果表明:25%森泰水剂和5%森泰颗粒剂均能够有效防除香椿幼林地的五节芒、苦竹、刚竹、芒萁骨等多年生恶性杂草,防除效果均可达93%以上。使用25%森泰水剂除草比人工除草可减少用工56 1%～92 2%,降低除草成本36 1%～61%。同时,可根据幼林地杂草的种类、高度、盖度和水源等因素选择合适的森泰除草剂的剂型和剂量组合,以达到理想的防除杂草效果。     

Woody and herbaceous competition effects on the growth of naturally regenerated loblolly and shortleaf pines through 11 years

Four levels of vegetative competition were used to quantify the growth of loblolly and shortleaf pines (Pinus taeda L. and P. echinata Mill.) in naturally regenerated, even-aged stands on the Upper Coastal Plain of southeastern Arkansas, USA. Treatments included: (1) no competition control, (2) woody competition control, (3) herbaceous competition control, and (4) total control of nonpine vegetation. After pines became established from natural seeding, herbicides were used to control herbaceous plants for 4 consecutive years and woody plants for 5 consecutive years. Even though 89% of crop pines on untreated check plots were free-to-grow 11 years after establishment, crop pines on vegetation control plots were larger (P<0.001) in mean dbh, total height, and volume per tree. From age 5 through 11 years, crop pine diameter growth increased on woody control plots and decreased on herbaceous control plots because of hardwood competition in the latter treatment. At age 11, crop pine volume production averaged 207 m³/ha on total control plots, 158 m³/ha on herbaceous control plots, 130 m³/ha on woody control plots, and 102 m³/ha on untreated check plots.     

Effects of Gliricidia sepium (Jacq.) Steud and Leucaena leucocephala (Lam.) de Wit on growth and development of Imperata cylindrica (L.) Raeuschel.

Field studies carried out in a forest transition site on a tropical Alfisol in southwestern Nigeria, show that shading by gliricidia (Gliricidia sepium (Jacq.) Steud) and leucaena (Leucaena leucocephala (Lam.) de Wit) hedgerow species reduced density of speargrass (Imperata cylindrica (L.) Raeuschel) by 67% and 51%, respectively. Shoot biomass of speargrass decreased by 81% and 78% in gliricidia and leucaena hedgerows, respectively. Reduction in speargrass rhizome biomass in gliricidia plots was 96% while rhizome reduction in the leucaena plots was nearly 90%. Rhizome mortality was significantly higher in gliricidia plots than in leucaena and control plots. The bulk of rhizomes was found between 10 cm and 20 cm of soil depth but rhizome did not penetrate further than 30 cm depth in the Alfisol in which this study was carried out. Gliricidia was better than leucaena hedgerow species in suppressing speargrass.     

基于改进DeepLabv3+的水稻田间杂草识别方法

针对实际稻田环境中水稻与杂草相互遮挡、难以准确区分的问题,提出一种基于改进DeepLabv3+的水稻杂草识别方法。以无人机航拍的复杂背景下稻田杂草图像为研究对象,在DeepLabv3+模型的基础上,选择轻量级网络MobileNetv2作为主干特征提取网络,以减少模型参数量和降低计算复杂度;融合通道和空间双域注意力机制模块,加强模型对重要特征的关注;提出一种基于密集采样的多分支感受野级联融合结构对空洞空间金字塔池化模块(ASPP)进行改进,扩大对全局和局部元素特征的采样范围;对模型解码器部分进行改进。设置消融试验验证改进方法的有效性,并与改进前DeepLabv3+、UNet、PSPNet、HrNet模型进行对比试验。试验结果表明,改进后模型对水稻田间杂草的识别效果最佳,其平均交并比(MIoU)、平均像素准确率(mPA)、F1值分别为90.72%、95.67%、94.29%,较改进前模型分别提高3.22、1.25、2.65个百分点;改进后模型内存占用量为11.15 MB,约为原模型的1/19,网络推算速度为103.91 f/s。结果表明改进后模型能够实现复杂背景下水稻与杂草分割,研究结果可...     

基于改进YOLOv3网络模型的茶草位置检测算法

精准高效的茶草识别是智能茶园植保机械进行除草工作的关键。针对目前茶园除草智能化程度较低等问题,提出改进YOLOv3网络模型的茶草检测算法。首先,分季节和时间段,在多个茶叶品种的种植园中以自适应的距离和角度采集茶草混合图像并建立试验数据集。接着,使用K均值聚类算法重新设计先验锚框尺度。然后,以YOLOv3网络模型为基础,选取17×17的网格划分图像区域;采用残差网络（ResNet）作为主干网;加入过程提取层,增强草株检测性能。最后在原损失函数中引入广义交并比损失。通过消融试验和不同目标检测算法对比试验验证此改进算法对茶树与杂草的检测效果。试验结果表明,改进 YOLOv3网络模型对杂草的检测精确率和召回率分别为85.34%和91.38%,对茶树的检测精确率和召回率最高达到82.56%和90.12%;与原YOLOv3网络模型相比,检测精确率提高8.05%,并且每秒传输帧数达到52.83 Hz,是Faster R-CNN网络模型的16倍。这些数据说明所提算法在茶园复杂环境下,不仅对于茶树和杂草具有更好的识别效果,而且满足实时检测的要求,可以为智能茶园植保机械提供技术支持。     

40%砜吡草唑悬浮剂的除草活性及对花生的安全性评价

为明确砜吡草唑在花生田应用的可行性, 采用整株生物测定法测定40%砜吡草唑悬浮剂对马唐Digitaria sanguinalis、狼尾草Pennisetum alopecuroides、稗Echinochloa crus-galli、藜Chenopodium album、反枝苋Amaranthus retroflexus及马齿苋Portulaca oleracea的除草活性, 评价药剂对花生的安全性, 并利用田间小区药效试验进行验证。结果表明:40%砜吡草唑悬浮剂对6种供试杂草均表现出极高活性, GR 50为0.76~2.90 g/hm 2, 在13.32 g/hm 2剂量下, 对供试杂草防效均达100%。40%砜吡草唑悬浮剂对3种禾本科杂草、3种阔叶杂草的毒力分别是960 g/L精异丙甲草胺乳油的5.60~9.30倍和22.16~25.24倍。在盆钵底部渗灌、喷淋浇水2种灌溉条件下, 40%砜吡草唑悬浮剂对花生的GR 10分别为212.03、87.68 g/hm 2, 剂量越高, 对花生生长的抑制愈明显, 对花生安全性欠佳。在盆钵底部渗灌条件下, 砜吡草唑在花生和供试杂草间的选择性指数为29.45~142.30, 具有较高选择性。田间试验表明, 40%砜吡草唑悬浮剂施用剂量120~240 g/hm 2时, 对杂草的总体防效在92.6%以上, 花生增产率21.09%~22.71%, 杂草防效及花生产量均显著高于960 g/L精异丙甲草胺乳油720 g/hm 2处理, 所有药剂处理未见药害症状。综上, 40%砜吡草唑悬浮剂可作为花生田低量、高效化学除草的备选药剂, 但需关注砜吡草唑过量施用及降雨积水等因素导致的花生安全性问题。     

无人机播前喷施除草剂防除棉田杂草效果评价

【目的】 分析不同喷药处理喷施33%二甲戊灵乳油对棉田杂草防效及棉花生长发育的影响,为棉田无人机播前喷施除草剂提供理论依据。【方法】 在新疆机采棉种植模式下,选择土壤封闭剂二甲戊灵为供试除草剂,设计播前无人机3个不同浓度喷药,车载喷药机喷药和不喷药5个处理,分析不同处理对棉田杂草防效及棉花生长发育的影响。【结果】 无人机喷施二甲戊灵进行棉田播前土壤处理,处理2(3 450 mL/hm²时)控草效果与车载喷药机处理相当,防治效果均达到94.00%,且显著好于不施药效果,出苗率均达59.71%,与不施药处理差异不显著。增加药剂浓度1 200 mL/hm²对棉花出苗有影响,出苗率降低7.54%,但差异不显著。无人机喷药处理株高、叶龄、地上部干物质重、叶面积指数与车载喷药机喷药处理间差异不显著,显著高于不喷药处理。【结论】 无人机喷施播前二甲戊灵浓度3 450 mL/hm²时与车载喷药机喷施浓度3 450 mL/hm²防草效果和棉花生长发育相当,可在大田推广使用。     

21%氟磺·烯草酮油悬浮剂对绿豆田一年生杂草防效研究

为寻找绿豆田适宜除草剂,于绿豆1~2片复叶期,一年生禾本科杂草3~5叶期进行21%氟磺·烯草酮油悬浮剂药效评价试验。结果表明:21%氟磺·烯草酮油悬浮剂对绿豆田稗草、狗尾草、藜和反枝苋等一年生杂草具有较高防除效果,对绿豆生长安全。在生产中推荐应用剂量为1 800g·hm-2,喷药量为450L·hm-2。