基于虚拟仪器技术的自动立木整枝机离合弹簧性能测试系统的设计

离合弹簧在自动立木整枝机变速换向过程中起着重要的作用.本文分别从硬件设计和软件设计两方面介绍了基于虚拟仪器技术开发的自动立木整枝机离合弹簧性能测试系统,该测试系统支持不同类型信号的多通道数据采集和处理,能够实现信号的产生、数据实时采集、数据处理、分析、显示及存储等功能,并通过多次测试离合弹簧的实验,验证了该测试系统的实用性和可靠性.     

退化人工梭梭林的恢复技术研究

对退化人工梭梭林进行恢复试验研究发现:滴灌可使梭梭林地土壤含水率显著提高;梭梭光合作用增强;群落物种数增多,盖度增大;防风固沙作用增强.布设机械沙障可使退化梭梭林地表粗糙度增大,林内近地面层风速、输沙量显著下降.春灌3 a后,不仅退化梭梭个体恢复正常生长,同时梭梭林群落物种组成数明显增加,盖度显著增大,生态功能也逐渐恢复.雨水集流和雨水下渗改造两种模式应用1～2 a后,退化梭梭林地土壤含水率均有明显提高.滴灌、布设机械沙障、春灌和改造结皮4种技术措施对退化梭梭林生长及其环境均有明显的恢复作用,其中滴灌、机械沙障恢复技术是当前和今后推广的主要措施;春灌和改造结皮可作为前两种技术的补充措施.     

Differential overstory leaf flushing contributes to the formation of a patchy understory

Understory individuals were found to form patches in a 100-year-old deciduous broad-leaved forest. The closed forest canopy was uniform, and so the light conditions at various locations across the forest floor differed little after the leaf flush of the overstory. To explain the distribution pattern in the understory, a hypothesis was proposed: in spring, the forest floor is divided into patches according to the timing of leaf flush of the overstory individuals, and the light conditions are more favorable for understory plants under the crowns of trees with later-flushing leaves. In the plot, three groups of early, intermediate, and late, were recognized in the overstory concerning the timing of leaf flush. As for the start of leaf flush, a difference of 31.6 days was recognized among tree species, and for the end of leaf flush, a difference of 40.3 days. In the spring of 1998, the relative photosynthetic-photon-flux density under an intensively studiedCastanea crenata tree (late-flushing species) usually showed higher values than that under a similarly studiedAcer mono tree (early-flushing species). Analysis of the spatial-distribution pattern using Morisita’s1δ index revealed that the understory community had an aggregated distribution. In the overstory, the late- and the intermediate-flushing-species groups showed aggregated distributions, while the early-flushing-species group showed random distribution. Spatial correlation between the understory and the overstory was analyzed by using Morisita’sRδ index. The distribution of whole understory community spatially co-occurred with that of the late-flushing-species group of the overstory. In contrast, the understory community was less developed below the members of the early-flushing-species group of the overstory. We consider that the data presented here support our hypothesis, and we suggest that the growth and survival of understory individuals were promoted in the places receiving light for long periods in spring.     

松树截根菌根化育苗和造林的研究*

根据苗木根系分泌物能促进菌根真菌萌发和生长的原理，结合我国林业育苗的特点，提出了松树幼苗截根与人工接种菌根真菌结合的育苗方式。结果表明，截根菌根化育苗在促进根系发育和菌根形成，加速苗木生长，提高苗木生物量、苗木质量和产苗量等方面都有显著优势，苗木的侧根数、侧根总长、苗木菌根化率、吸收根菌根化率、苗高、地径、鲜重、干重分别提高２０．０％～９６０．０％、５６．２％～３８９．５％、０．０％～４００．０％、５６．２％～１７９２．０％、２２．３％～１７９．３％、３１．２％～２５３．８％、３３．３％～９１８．２％和２１．８％～７４０．０％，苗木成活率和Ⅰ级苗分别提高９．０％～２２．１％和４９．３％～１５０．０％，Ⅱ、Ⅲ级苗和等外苗分别降低４０．６％～７７．３％、６１．６％～８８．５％和８２．５％～１００．０％。利用截根菌根化苗木造林，提高成活保存率５．５％～４６．０％，并促进幼树生长，树高、地径和材积指数分别增加１３．０％～５６．４％、２５．５％～６１．７％和８７．８％～４５０．０％。效益分析证明，截根菌根化育苗具有明显的经济效益和社会效益，仅苗期可定量计算的增收（节支）总额可达４４６６２元／ｈｍ２。     

民勤荒漠区无霜期及春季低温变化特征分析

以甘肃民勤治沙综合试验站数十年气象定点观测资料为基础,统计、分析了民勤荒漠区无霜期、春季低温、冻土层的变化特征。结果显示:该地区平均终霜期为5月10日,初霜期为9月28日,50 a来终霜期有逐渐提前、初霜期有逐渐推后的趋势,但不同年份变异幅度增大;3-5月份地表平均最低温度、气温逐渐上升,≤0℃出现比率下降,但4月下旬至5月上旬大强度的降温天气时有发生;3月份冻土层的变化与气温变化趋势相近。30 a以来地表平均日最低温度和气温亦有所提高。     

Walnut demonstrates strong genetic variability for adaptive and wood quality traits in a network of juvenile field tests across Europe

Adaptive and wood quality trait data were collected and analyzed on commercially available Juglans regia and J. regia×J. nigra provenances and progenies planted across Europe in a multi-site network. A total of 19 seed sources, replicated 35 times per site, were planted at 13 sites from 5 European countries, encompassing the potential distribution area of timber production plantation sites. The following traits were evaluated: survival, height, diameter at breast height, stem form, apical dominance, vegetative budbreak, along with biotic and abiotic damage. Mean values were significantly different both among provenances/progenies and sites. Most common damage was late spring and early autumn frost. Bud break ranking was significantly correlated with provenance and progeny origin. Although J. regia is fast growing, southern European early budbreak plant material should not be planted under most middle European conditions where late spring frost can be expected, as it has a significant negative impact on architectural (and thus wood quality) traits. Hybrid J. regia×J. nigra progeny performed better than J. regia provenances/progenies for most traits measured. Differences were significantly in favor of hybrids at sites with medium to low fertility, although some locally selected seed sources tended to perform as well as hybrids on high fertility sites.     

水肥调控模式对滨海盐碱地水肥盐迁移及春玉米水肥利用率的影响

为了探明滨海盐碱地不同灌溉方式及氮肥施用量对水肥盐迁移过程及作物生长的影响,基于大田试验,研究不同灌溉方式及灌水量(F:漫灌,360 mm;D1:滴灌,360 mm;D2:滴灌,288 mm;D3:滴灌,216 mm)、氮肥处理(N1:280 kg/hm²;N2:196 kg/hm²;N3:112 kg/hm²)对盐碱地土壤水肥盐分布含量及对春玉米各生长指标的影响.结果表明,在滴灌模式下,同一灌水量,N1的剖面平均含水量最低,D1,D2出现洗盐点,存在适合作物生长的浅盐区;灌水后D1N1的硝态氮含量增加最显著且含量最高,滴灌处理对应的低氮处理无明显硝态氮积累点,相同灌水量下,漫灌的有效氮含量均高于滴灌,但其有效氮利用率低于滴灌处理;不同施氮对春玉米干物质的差异随灌水量增加而增加.各处理水分利用效率与肥料偏生产力之间产生明显差异,高水低氮肥料偏生产力明显提高,但其水分利用效率低下,D1N1产量最高;在考虑作物产量及水肥利用效率时,采用滴灌方式,则灌水量288~360 mm、施氮量196 kg/hm²为推荐水肥措施.     

外包滤料对暗管排水与土壤脱盐效果的影响

为了探究不同外包滤料条件下的暗管排水性能和土壤脱盐效果,基于室内试验研究成果,在田间设置4种暗管排水系统(各系统中暗管埋深均为80 cm,间距均为20 m),所用外包滤料分别为68 g/m²土工布(L)、砂滤料(S)、68 g/m²土工布+砂滤料(LS)和无外包滤料(W),以当地常规明沟排水(CK)作为对照,通过田间试验分析了春灌过程中各暗管系统的排水性能指标及土壤脱盐效率.结果表明:相比处理W,处理L,S和LS平均排水速率提升了7.44%,12.55%和15.75%,平均流量衰减度降低4.07%;处理S和LS累积排水量提高了5.11%和8.31%(P<0.05).各暗管处理春灌后平均土壤脱盐率均达47%以上,较CK提升显著,其中处理LS效果最优,为50.94%.综上,应优先选择处理LS作为河套灌区暗管排水系统外包滤料布设方案.该研究结果可为河套灌区暗管排盐技术的推广应用提供理论支撑和科学指导.     

玉黄金对春玉米茎秆显微结构及抗折强度的影响

【目的】研究化控剂(30%胺鲜酯·乙烯利水剂以下称玉黄金)对春玉米茎秆显微结构及抗折强度的影响。【方法】选取京农科728和金农738为材料,测定不同种植密度下喷施玉黄金后春玉米茎秆抗折强度,利用光学显微镜观察其茎节的显微结构,对维管束各项显微结构与茎秆抗折强度进行相关分析及通径分析。【结果】维管束数目对茎秆抗折强度的直接影响最大,且呈极显著负相关为-0.760;与木质部面积呈极显著正相关为0.970;与单个维管束平均面积、维管束最大直径和表皮细胞厚呈显著正相关分别为0.661、0.659和0.632。【结论】京农科728和金农738在不同种植密度下,喷施浓度为200 mg/L的玉黄金后茎秆单位面积内维管束数目减少、表皮厚度增厚、维管束最大直径最大、抗折强度提高,抗倒性增强。     

西北旱区不同覆膜和灌溉水平下的玉米冠层氮含量垂直分布及高光谱反演

为探究不同覆膜和灌溉水平下玉米叶片氮含量垂直分布特征及其遥感反演规律,2020年在甘肃省武威绿洲农业高效用水国家野外科学观测研究站进行大田试验,设置3种灌水量水平(春玉米灌溉需水量的100%(W₁₀₀)、70%(W₇₀)和40%(W₄₀))和3种覆膜处理(不覆膜(M₀)、普通塑料膜(M₁)和生物可降解膜(M₂)),测定春玉米在不同灌水量和覆膜条件下叶片氮含量垂直分布、冠层反射特征和反射率与叶片氮含量等指标,并采用随机森林法构建氮含量估测模型分析垂直分布的叶片氮含量。结果表明,相同灌水处理的玉米冠层叶片中氮含量由高到低为M₀>M₂>M₁,M₀比M₂的上、中、下部位叶片氮含量分别增加6.78%、5.11%、2.55%,M₂比M₁的上、中、下部位叶片氮含量分别增加7.14%、5.24%、5.39%。相同覆膜条件下玉米冠层叶片氮含量由高到低为W₁₀₀>W₇₀>W₄₀,W₁₀₀比W₇₀的上、中、下部位叶片氮含量分别增加6.84%、6.23%、7.74%,W₇₀比W₄₀的上、中、下部位叶片氮含量分别增加4.41%、3.32%、9.49%。在M₀W₁₀₀处理中,玉米冠层叶片氮含量从上到下依次减小,上部比中部叶片氮含量增加7.44%,中部比下部叶片氮含量增加7.60%。在相同覆膜条件下,在可见光波段范围内,冠层反射率随着灌水量的增加而降低;在近红外波段范围内,冠层反射率随着灌水量的增加而增加。综上,基于随机森林的春玉米不同垂直部位叶片中氮含量估算模型均与实测结果相吻合(验证的R²>0.5),上部叶片中氮含量估算精度最高(R²为0.63,RMSE为1.66 g/kg,RPD为1.57),其次为中部叶片(R²为0.73,RMSE为1.66 g/kg,RPD为1.30),精度最低的下部叶片(R²为0.00)。