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1.
一万多年来乌伦古湖地区花粉组合及其古环境   总被引:13,自引:2,他引:13  
本文通过对新疆乌伦古湖钻孔剖面进行孢粉分析研究,划分出5个花粉组合带及3个组合亚带。结合岩性特征,介形虫资料及^14C测年数据,详细讨论了一万多年来该区古气倏变迁及湖泊环境演变历史,其古气候经历了由冷湿(12-10kgB.P.)→温湿→温干→温湿(3-1kaB.P.)的变化过程。于晚冰期后期(12-10kgB.P.),乌伦古湖开始成湖,此后,随着气候的变化,湖泊曾出现两次较大规模的退缩,约7-5k  相似文献   

2.
旱地小麦抗旱播种方式研究   总被引:2,自引:0,他引:2  
在播种期严重干时的1989,1991,1993和1994年,对3种播种方式的效应进行了系统研究。结果表明,0cm-20cm土壤不量在11%-15.4%的范围内,抢墒播种,小麦出苗早,出苗率可达90%以上,苗情发育较好,产量最高可达1909.5kg/hm^2-4650kg/hm^2;0cm-20cm土壤不量在8%以下时,干旱寄种,比雨后播种出苗早,出苗率可达705以上,苗情稻优,产量可达543kg/  相似文献   

3.
短小芽孢杆菌D82对小麦根腐病原菌拮抗的研究   总被引:11,自引:0,他引:11  
平板培养结果表明,短小芽孢杆菌D82对小麦根腐病有强抗生作用,共同培养至第4天,抑菌圈直径为4-5.5cm;发酵液稀释平板培养结果表明,稀释浓度100倍以下的抑菌效果为100%。1000倍、2000倍、4000倍稀释液的抑菌效果分别为64%、54%和34%。  相似文献   

4.
本文报道甲霜铜、粉锈宁和多菌灵对辣椒白绢病原整齐小菌核和拮抗木霉菌株T150的毒性研究结果。上述3种杀菌剂对木霉T150菌株的最低抑制浓度分别为4×10^-3、3×10^-4和4×10^-5。粉锈宁浓度为3×10^-4时,整齐小菌核的菌丝生长、产菌核量和菌核萌发率分别为对照的41.58%、3.60%和3.58%。用3种杀菌剂1000倍液分别施于土壤和叶面,药后12天除甲霜铜灌根外,各处理的土壤木霉  相似文献   

5.
东亚小花蝽人工饲养方法的研究   总被引:3,自引:1,他引:3  
用5种食料饲养东亚小花蝽的结果,成虫获得率以用高梁蚜的最高,达90%;嫩玉米粒、脱脂奶粉、花粉酥分别为45%、20%、10%;生鸡蛋作食料,羽化前全部死亡。用直径22cm的花盆,覆以尼龙纱罩,以蚜虫为食料,从卵开始饲养小花蝽,每盆放卵200-400粒,成虫获得率均在25%左右,400粒卵的处理可羽化成虫90.2头。  相似文献   

6.
溴甲烷熏蒸检疫处理豇豆上的巴西豆象   总被引:1,自引:0,他引:1  
何光超 《植物检疫》1995,9(2):77-78
溴甲烷熏蒸检疫处理白豇豆上的巴西豆象。10-12℃,溴甲烷35g/m^3,熏荪24时;16-18℃,溴甲烷25g/m^3,熏蒸24小时,21-23℃,溴甲烷20g/m^3,熏蒸24小时;可以100%杀死巴西豆象卵,幼虫,蛹和成虫。  相似文献   

7.
箭杆杨和梭梭柴水量平衡的研究   总被引:8,自引:3,他引:8  
采用非称重蒸渗仪对箭杆杨、梭梭柴的水量平衡各分量变比规律进行了探讨.箭杆杨和梭梭柴水量平衡各分量的分配比例为:灌溉+降水均为100%,蒸散量51.1%、77.7%,渗漏量48.9%、14.2%,土壤水变化量不足0.1%、8.1%.分别就两个树种灌溉对蒸散和渗漏水分循环的影响进行了分析。初步确定二年生箭杆杨合理灌溉指标为:5、9两月每月灌溉1次,灌溉量900m3/ha(90mm),6、7、8三个月每月灌溉两次,每次的灌溉量也为90Om3/ha,每月为1800m3/ha。每公顷每年由造林规程的9900—13200m3/ha减少到7200m3/ha。梭梭柴保证每年11月初灌溉1次.灌溉量1500m3/ha(150mm)。  相似文献   

8.
经3a试验示范及观测调查,水稻半旱式栽培即垄作与节水灌溉相结合,其纹枯病比平作的轻。病丛率,病株率和病指,早造分别少23.0%-41.7%,21.7%-37.0%和5.6-12.3;晚造分别少13.4%-40.3%,9.3%-19.2%和3.0-10.5。两种栽培方式的统一枯病消长曲线是相似的,惟半旱式栽培的水长曲线自水稻分蘖盛期至黄熟期一直在平作之下。  相似文献   

9.
施保克浸种防治大麦散黑穗病目前大面积推广的种子处理剂对大麦条纹病、坚黑穗病的防治效果较好,但对散黑穗病的防治效果不够理想。1995年全县调查六棱大麦146.7hm2,散黑穗病自然病穗率5.5%~12.0%,平均6.7%,损失大麦27.5kg/667m...  相似文献   

10.
光调期对荔蝽卵平腹水蜂日产卵量及后代性比的影响   总被引:2,自引:0,他引:2  
在室内用作蚕剖腹卵为寄主在温度25±1℃,相对温度70-85%,光照工500lx条件睛研究不同光周期,(0L:24D,6L:18D,12L:12D,18L:6D和24L:0D)对荔蝽卵平腹小蜂日产卵量及后代性比的影响。结果表明,在5个不同光周期处理之间,平腹小蜂日产卵量没有显差异,在无光照条件下也可以正常产卵,除24L:0D外其它4个处理,在一天中不同时间的产卵数量有显差异,而且在5L:18D  相似文献   

11.
利用2014年7月至8月塔中地区沙尘与扬沙天气下风沙流运动的实测数据,对0~85 mm高度内风沙流运动进行了研究。结果表明:(1)0~85 mm高度层,输沙率(Q)随风速(v)增大呈幂函数规律增加,R2≥0.975 7,且输沙率主要集中在0~35 mm高度内。(2)总输沙率和撞击颗粒数的最佳拟合函数为线性函数,R2≥0.878 2,相关性较好;塔中地区1 min最小临界起沙风速为4.0 m·s-1。(3)跃移运动集中在10:00—20:00,总输沙率最大值出现在12:00—16:00,17:00以后输沙率明显下降。  相似文献   

12.
毫米波扫描昆虫雷达空中昆虫监测的初步应用   总被引:4,自引:1,他引:3  
2007年6~10月,利用毫米波扫描昆虫雷达在广西兴安县植保站进行了空中昆虫的初步监测,结合地面灯和高空灯诱集,分析了地面和高空昆虫种群动态变化。结果表明:空中昆虫种群数量、种类季节性变化明显,6~9月夜间昆虫虫口密度相对较高,进入10月份夜间昆虫相对减少,雷达回波点密度和灯下诱集虫量有很高的一致性。夏季,19:00~22:00与05:30~07:00雷达回波密度各有一明显高峰期;秋季,只在20:00~21:00有一明显回波密度高峰期。昆虫飞行高度主要集中在2 000 m以下,大部分集中在500~1 000 m。姊妹灯诱捕表明,稻飞虱和稻纵卷叶螟为优势迁飞种类。昆虫飞行受气象条件影响较大。  相似文献   

13.
为研究沙地植物幼苗生长对降水和风速变化的响应过程,于2016年4月中旬利用40个2m×2m×2m的混凝土样方池,通过人工增雨及遮风网降低风速的方法开展模拟控制实验。结果表明:①风速、降水以及两者的协同作用对萌发物种数无显著影响(P> 0. 05)。风速降低20%和降水增加60%使种子萌发物种数与对照相比分别增加4.9%和1.3%;风速降低20%条件下,自然降水和降水增加60%均可使种子萌发物种数增加7. 2%。②不同降水处理会使植物幼苗密度大幅度降低、高度波动变化;风速降低可以较显著地促进沙地植物幼苗生长高度,特别是优势植物猪毛菜(Salsola collina)、大果虫实(Corispermum macrocarpum)的生长高度(P <0.01)。在自然风速条件下,降水增加30%明显促进猪毛菜幼苗高度生长,降水增加60%则相反;风速降低20%条件下,降水增加60%可以大幅度的促进雾冰黎(Bassia dasyphylla)幼苗的生长高度;风速降低40%与降水增加30%和60%的协同作用使雾冰黎、猪毛菜和大果虫实幼苗的生长高度均明显降低。③不同风速和降水处理对植被的Simpson优势度指数(D)、香浓–威纳多样性指数(H)、Pielou均匀度指数(J)无显著影响(P>0.05)。以上研究结果表明:降水增加30%对种子萌发阶段物种丰富度的抑制作用较大;与降水相比,风速是沙地植物幼苗生长高度的主要影响因素,并且自然降水条件下,风速降低40%可以使沙地植物幼苗生长高度最大限度地增加;沙地植被物种多样性指数对降水及风速的变化不敏感,这说明科尔沁沙地生态系统群落结构相对较为稳定。  相似文献   

14.
Fipronil is an insecticide developed for use on rice seed and other crops. In a series of cage and pen trials, we evaluated the responses to dyed, fipronil-treated rice seed of three bird species likely to encounter it in the field. Individually caged red-winged blackbirds (Agelaius phoeniceus), brown-headed cowbirds (Molothrus ater), and boat-tailed grackles (Quiscalus major) displayed no evidence of adverse reaction to treated seed. Chemical analyses of hulls from treated seeds eaten by captive birds revealed that 10–20% of the fipronil originally present was removed during feeding. In group enclosures, male red-winged blackbirds ate as much fipronil-treated rice as they did dyed, untreated seed. In four-day tests within a 0·2-ha flight pen, 10-bird blackbird flocks removed 11·4% of fipronil-treated seed from a test plot compared to 12·5% of dyed, untreated seed removed from the alternate plot. When the alternate plot contained undyed rice, however, seed removal from the treated plot averaged 2·4% compared to 28·9% from the alternative plot, suggesting that the groups of test birds avoided treated seed based on its appearance. We conclude that 325 and 500 mg kg-1 fipronil applications alone do not affect avian feeding activity. © 1998 SCI.  相似文献   

15.
Jasmine moth (JM), Palpita unionalis (Hübner) (Lepidoptera: Pyralidae) is a very important pest in the commercial, densely planted olive orchards in Egypt. In years of its highest population density, it can destroy a significant part of the crop. The objectives of this study were to determine the male flight trend and egg laying trend of the JM in three large plots of different olive varieties (two varieties/plot) in two successive fruiting seasons. Differences in male flight trend and egg laying trend of JM were observed among the different varieties (??Sennara??, ??Toffahi??, ??Shamy??). In 2003, more males were captured in traps placed in the Sennara/Toffahi plot than in the two Shamy/Toffahi plots. Egg densities were higher on Toffahi trees grown between Sennara trees than on Toffahi trees grown between Shamy ones. In 2004, in the plot where Toffahi and Sennara were grown together, JM females laid more eggs than in the olive plot where Toffahi rows alternated with Shamy rows. The results suggest that the Shamy variety discouraged gravid females from ovipositing, compared with Toffahi or Sennara varieties. In conclusion, olive variety, cropping system (mixed culture) and trapping season are among those characteristics that affect this pest.  相似文献   

16.
塔克拉玛干沙漠腹地沙尘天气特征   总被引:4,自引:1,他引:3  
利用塔克拉玛干沙漠腹地塔中气象站2007—2011年的地面(10 m)风速、风向和沙尘天气等气象要素,分析沙漠腹地的沙尘天气特征。结果表明:1塔克拉玛干沙漠腹地沙尘频率和强风频率年、月分布具有较好的一致性,沙尘天气具有明显的季节性,春、夏季占全部沙尘频次的88.3%,冬季仅占总数的2.3%。2春、夏季沙尘天气的高发时段为12:00—00:00;20:00发生频次最多,分别占春、夏季沙尘频次的12.7%和10.8%,秋季和冬季沙尘天气高发时段为14:00—21:00。3出现沙尘天气时,风向主要集中在E、ENE、N和NNE 4个方向。4沙漠腹地临界起沙风速ut5%为4~5 m·s-1,一般地表的临界起沙风速ut50%为5~6 m·s-1;5从NfDO分布来看,春、夏两季要明显高于秋冬季节,其中4月最大,为0.284。因此,沙漠腹地春、夏季易发生沙尘天气。  相似文献   

17.
苹果果实日灼预测预报计算机模型   总被引:1,自引:0,他引:1  
为了及时准确地预测预报苹果果实日灼发生的时间,提高预防措施的效果,特研制了本计算机模型.通过对树上活体果实表面温度进行生长季全程连续监测,同步对比相应的气象资料,研究了主要气象因子(包括气温、日照、风速和相对湿度)与果实表面温度的相关性,确定了上述气象要素与果实表面温度变化的多元回归方程.此外,通过比较研究不同品种、果实发育期以及树势对果实日灼敏感性的差异,确定了不同品种果实日灼阈值温度以及这些因子在影响果实日灼中的效应参数.将模型预测值与田间果实温度实测值进行对比,验证该模型预报结果符合率达85.22%.近两年该模型已开始在美国华盛顿州果园试用.通过在本模型的用户界面下拉菜单中选择品种、月份和树势,并在相应位置输入当日11∶00~14∶00平均日照、气温、风速和相对湿度数值,即可得到当日是否发生果实日灼的预测预报结果.  相似文献   

18.
研究了栗山天牛Massicus raddei(Blessig)成虫的日活动节律,结果表明,栗山天牛成虫的取食、交配、产卵、爬行和飞翔等行为的昼夜节律均表现为单峰型。其取食的高峰期是在晚上18时至20时;交配高峰期为17时至22时;产卵和爬行的高峰期均为19时至22时;飞翔的高峰期为19时至21时。提出了昆虫活跃值的概念及其计算方法,并应用该方法评价了栗山天牛成虫的群体活跃值,结果表明,栗山天牛成虫的群体活跃值日变化规律亦为单峰型,而且不同时间的活跃值差异极显著,成虫主要在下午16时至晚上24时活动,高峰期是天黑以后的19时至21时。在高峰时段,栗山天牛雌雄成虫的活跃值差异不显著,但部分行为存在较大差异。不同天气条件下栗山天牛成虫的活跃值差异显著,晴天成虫的活力最强,阴天次之,雨天成虫的活动能力最弱,而且全天没有明显的活动高峰期。温度在22℃~26℃、相对湿度在50%~80%时利于天牛成虫的活动。  相似文献   

19.
In semi-arid lands, vegetation is distributed in shrub patches immersed in a less vegetated interpatch matrix. Grazing affects perennial grass seed bank through a decrease in seed rain and an increase in seed predation and soil compaction. Nevertheless, some species with anchorage mechanisms in their seeds might overcome this, such as Nassella tenuis (Phil.) Barkworth. This is an important species in grazing paddocks because it has an intermediate palatability and its relatively tolerant to grazing. These characteristics allow N. tenuis to increase its abundance in grazed sites. Our objective was to assess how grazing affects the key palatable species from seeds to seedlings: i.e., seed rain, soil seed bank, and seedling recruitment in different microsites along a windward-leeward transect across shrub canopy. We hypothesized that: (1) the negative effects of grazing on N. tenuis fructification are reflected in its seed rain, soil seed bank, and seedling recruitment, especially in interpatches; (2) Nassella tenuis seed rain reduction, soil compaction by cattle in grazed sites, and removal of seeds by wind decrease its soil seed bank, especially in microsites exposed to the predominant wind; and (3) the decrease in N. tenuis soil seed bank and cover increase in annual species in grazed sites have negative effects on its seedling recruitment, especially in microsites exposed to predominant wind. We placed seed traps, collected soil samples, and monitored seedling recruitment in different locations around shrub canopy to address our hypotheses. Also, we established a manipulative experiment in which we sow N. tenuis seeds and followed its recruitment in different microsites. We compared the seed rain, soil seed bank, natural seedling recruitment, and sown seeds recruitment of N. tenuis between grazed and ungrazed sites. We analyzed differences between microsites along a windward-leeward transect across shrubs patches. Seed rain and soil seed bank had the same density in patches and interpatches both in ungrazed and grazed sites. But seed rain was higher, and soil seed bank was lower in ungrazed sites than in grazed sites. Almost all under-canopy microsites showed greater soil seed bank abundance and natural seedling recruitment in ungrazed sites. Sown seeds recruitment was the same between grazed and ungrazed sites, but it showed protective effects of shrubs in leeward microsites under grazed sites. As a conclusion, seed rain and soil seed bank are complementary under grazed sites.  相似文献   

20.
本文对古尔班通古特沙漠及其南部不同距离绿洲的温度、气压、风向风速及净辐射进行了比较分析。结果表明,沙漠地表面温度和气温升降速度比绿洲观测点要快、变化幅度大;由于各观测点空气相对湿度和温度升降度不同,使得各观测点的气压升降幅度也不同,白天气压的变化曲线呈单蜂型;各观测点在12:00到18:00期间主导风向主要是南风,还有东南或西南风,在20:00时风速几乎为0;早上和晚上沙漠的净辐射高于绿洲,白天近地面净辐射绿洲大于沙漠;对绿洲气象要素时空效应特征分析,为棉花等绿洲优势作物的播种期、物候期、作物生育及生理生态特性具有一定的指导意义。  相似文献   

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