杨十斑吉丁虫空间分布型及其应用的研究   总被引：1，自引：1，他引：1  

屈邦选  邵崇斌陈辉 李宗明 《西北林学院学报》1989,4(2):55-61

杨十斑吉丁虫空间分布型可用频次分布拟合或用一些聚集度指标来度量。它的幼虫频次分布符合负二项分布,用聚集度指标度量适合聚集型分布。Iwao回归与Taylor幂法则也是确定聚集型分布的好方法,结果都说明是聚集型的。以此可以确定抽样调查的最适抽样数,编制序贵抽样分析表,用于防治效果的检验与危害程度的分级。  相似文献   

球孢白僵菌生物学性状与对玉米螟毒力相关性分析     

李乐  路杨  赵宇  李启云  徐文静  张正坤  毛刚 《玉米科学》2021,29(1):162-169

球孢白僵菌的生物学性状与对靶标害虫的毒力具有显著相关性,对球孢白僵菌高毒力菌株的初步筛选具有重要意义。鉴定随机分离自亚洲玉米螟幼虫僵虫的10个球孢白僵菌菌株,对其进行产孢量、孢子萌发率、菌落生长速度以及对亚洲玉米螟幼虫的毒力测定。结果表明,不同菌株的生物学特性和毒力均呈现显著差异。在此基础上,分别进行不同菌株生物学性状与毒力的相关性分析。结果表明,球孢白僵菌菌落生长速度与其毒力呈正相关,孢子萌发率与其毒力无相关性。因此,可以将白僵菌菌落生长速度作为白僵菌高毒力菌株筛选的初步评价指标。  相似文献   

Sustainable green tea production through agroecological management and land conversion practices for restoring soil health,crop productivity and economic efficiency: Evidence from Northern Vietnam     

Viet San Le  Laetitia Herrmann  Lambert Bräu  Didier Lesueur 《Soil Use and Management》2023,39(3):1185-1204

Tea is a very important cash crop in Vietnam as it provides crucial income and employment for farmers in poor rural areas. Unfortunately, the dominance of long-term, conventional tea cultivation has caused severe soil health degradation and environmental pollution. At the same time, as tea production may provide a better net income compared with other annual crops such as rice and vegetables, farmers have been converting parts of their allocated land to cultivate tea plants. Little is known about the benefit of agroecological management as an alternative to conventional tea management practices, and thus, there is a need to understand how it can improve tea yields, quality and the livelihoods of the farmers. Conducted in Northern Vietnam from 2019 to 2022, this study examined the impacts of agroecological tea management practices on soil health indicators, tea yield and quality, and net income of tea farmers. We showed that agroecological management practices significantly enhanced soil organic matter by 0.8% and soil pH by 0.5 units on average. Conversely, conventional management based on chemical fertilizer applications, significantly increased soil total nitrogen by 0.15%–0.2%. No significant differences were observed between soil texture and other soil chemical characteristics. Soil biological parameters were also significantly higher in agroecological tea soil and root samples than in conventional tea plots. Average AMF frequency and intensity of the agroecological tea roots were 98% and 37%, respectively, compared with 73% and 15% of the conventional tea roots. Likewise, soil macrofauna and mesofauna abundance in the agroecological tea plantations was 76 individuals/m² and 101 individuals/100 g fresh soil on average, respectively, while that of conventional tea farms were 34 and 63 individuals/100 g fresh soil, respectively. Interestingly, a comparison between the converted and nonconverted lands did not show any significant effect of the conversion on soil physicochemical and biological characteristics, apart from tea root AMF colonization. Conventional tea management consistently resulted in higher tea yield and yield components, even though the differences were not always statistically significant. Despite lower tea yields, agroecological tea adopters earned around USD 8400 ha/year more than the farmers still practicing conventional management. This study shows that it is economically and environmentally more sustainable to produce organic tea than conventional tea, and our results should encourage more farmers to adopt such agroecological practices in Northern Vietnam.  相似文献   

The effect of ornithine and citrulline on tile utilization of arginine in rice callus tissue     

Katsuhisa Furuhashi  Kuk Ki Le  Michihiko Yatazawa 《Soil Science and Plant Nutrition》2013,59(5):185-189

There are many reports on the effect of arginine on the growth of cultivated tissues or organs. Arginine usually enhances the growth of tissues and organs (1-9).  相似文献   

基于冲刷试验的贵州耕地土壤抗冲性研究   总被引：4，自引：1，他引：3  

任乐  张科利  郭继成 《水土保持学报》2013,(1):56-59

对5种不同坡度(5°～25°)的翻耕地以及有苔藓覆盖的荒坡地(20°)进行不同流量下(0.042～0.250L/s)的放水冲刷试验,以探讨贵州耕地坡面水动力性质、土壤抗冲性及地表生物(苔藓)对坡面侵蚀产沙的影响。结果表明,贵州地区坡耕地坡面流速与冲刷流量呈较好的幂函数关系,而与坡面坡度无关。坡面土壤分离速率与坡度及冲刷流量均呈显著正相关,并可用水动力学参数水流剪切力来估算贵州坡耕地土壤分离速率。与黄土高原相比,在同一坡度、同一冲刷流量下贵州坡耕地坡面产沙速率低于黄土高原坡耕地,表明贵州黄壤抗冲性高于黄土。苔藓覆盖可显著减小坡面侵蚀速率,在同一冲刷流量下,具有苔藓覆盖的荒坡地坡面产沙速率低于翻耕地达3个数量级。  相似文献   

重金属铜对玉米的影响   总被引：15，自引：1，他引：15  

金进  叶亚新  李丹  韩乐 《玉米科学》2006,14(3):083-086

采用溶液培养的方法,研究了铜对玉米生理特性的影响。结果表明:随着铜浓度的增加,其中叶绿素含量、光合强度、根系活力和CAT活性呈逐渐下降趋势;质膜透性、脯氨酸含量、MDA含量和SOD活性上升;POD活性表现为低浓度刺激效应和高浓度的抑制效应。  相似文献   

The host range ofSpongospora subterranea f. sp.subterranea in the United States     

Xinshun Qu  Barbara J. Christ 《American Journal of Potato Research》2006,83(4):343-347

This study was performed to determine the host range ofSpongospora subterranea f. sp.subterranea on common crops and weeds in the northeastern United States. Seedlings of the plants were grown in nutrient solutions and inoculated with spore balls ofS. subterranea. The roots were microscopically examined for the presence of plasmodia or zoosporangia 14 days after inoculation. The plants were then transferred to a greenhouse and grown in a soilless mix. The roots were examined for the presence of symptoms and spore balls after 4 months. Of 26 species within 10 families from monocotyledons and dicotyledons tested, 16 species were found to be susceptible toS. subterranea. Twelve species were newly recorded hosts forS. subterranea. Gall symptoms were observed on the roots of six species and spore balls were found on three species. Evidence is presented for the first time that galls and spore balls ofS. subterranea might form on non-Solanaceous species. This investigation is important for the cultural management of potato powdery scab disease because there currently are no effective controls.  相似文献   

Leaching of solutes and sloughing of potato tuber tissue     

W. C. Davis  D. J. Le Tourneau  Mary V. Zaehringer  Helen H. Cunningham 《American Journal of Potato Research》1973,50(2):35-41

Thin slices of tissue from low (1.075–1.078 and high (1.092–1.094) specific gravity tubers were soaked in distilled water (100g/250ml) for 0, 1, 2, 3, 4, and 6 hours. Following the soak periods, the soak water and remaining tissues were separated and analyzed. Analyses of the soak water included pH, electrical conductivity, total solids, K, P and citric acid. The tissue analyses included total ash, alkalinity of ash, Ca, Mg, total N and phytate P. Other tissue samples were soaked the same periods of time and used to evaluate the amount of sloughing that occurred during cooking. All constituents studied diffused into the water during the soak periods. The greatest loss from the slices occurred in the first 2 to 3 hours and were similar for both specific gravity groups. After 6 hours the average amounts of material in the soak water were: total solids — 23%, P — 68%, phytate P —55%, K — 71%, total ash — 62%, total nitrogen — 56%, Ca — 35% and Mg —50%. Citric acid diffused into the soak water during the first 3 hours and the amount in the water then decreased. This apparent change may be due to metabolism of the acid. The sloughing of tissue decreased with the length of the soak period. The decrease in sloughing was highly correlated (P<1 %) with the length of the soak period, increases in electrical conductivity of the soak water, and with the leaching of all constituents measured.  相似文献   

湖南省及自然保护区蝶类资源记述及保护利用研究   总被引：7，自引：0，他引：7  

刘桦  熊恩国  游兰韶  朱开林  王永江  黎家文  屈建中  傅鹏  顾仁  肖治术  喻传明 《作物研究》1999,(Z1)

对湖南省及自然保护区蝶类8 000 余号标本的鉴定,确定湖南省及各自然保护区蝶类284 种,隶属于11 科132 属,其中凤蝶科13 属32 种、粉蝶科9 属24 种、斑蝶科4 属7 种、环蝶科3属3 种、眼蝶科14 属51 种、蛱蝶科37 属82 种、珍蝶科1 属1 种、喙蝶科1 属2 种、蚬蝶科2 属4种、灰蝶科23 属35 种、弄蝶科25 属43 种。对已鉴定的标本抽取有详细分布资料的240 种进行区系分析,得出湖南省蝶类在世界动物地理区划中,以东洋区种为主,占38.33% ,中国特有种占26.67% ,古北区种占15.42% ,古北- 东洋共有种占13.32% ,其他组合比例较低;湖南蝶类在中国地理区划中,以华中- 华南共有种、华中-华南- 西南共有种为主,分别占17.50% 和16.25% ,其次华中- 华南- 青藏共有种占12.08% ,其他组合比例较低;对湖南省240 种蝶类在湖南4 个农业区的归属进行分析,得出其在湘西农业区所占比重为25.83% ,四区共有种20.83% ,其它农业区及组合所占比重较低。并提出了蝶类资源保护与利用措施。  相似文献   

湖泊水-沉积物界面SiO₃-Si交换通量研究     

颜道浩  吕昌伟  何江  王伟颖  左乐  李磊 《农业环境科学学报》2015,34(12):2349-2356

以乌梁素海(WLSH)和岱海(DH)为研究对象,采用柱状芯样模拟法,开展了湖泊水-沉积物界面溶解性硅酸盐(SiO₃-Si)扩散通量研究。结果表明,在夏季90 d的时间内,浅水草型湖泊乌梁素海明水区沉积物-水界面交换速率约为1.28 mmol·m^-2·d^-1,沉积物约向上覆水体释放了963.07 t SiO₃-Si;而深水藻型湖泊岱海深、浅湖区沉积物-水界面交换速率分别为1.10、1.95 mmol·m^-2·d^-1,沉积物约向上覆水体释放了893.41 t SiO₃-Si.SiO₃-Si在水-沉积物界面的交换速率与两湖沉积物中粘土矿物含量、生物硅(BSi)含量及沉积物的粒度有较好的相关性。沉积物释放的SiO₃-Si对维持湖泊初级生产力有重要作用,乌梁素海沉积物释放的硅可提供浮游植物所需硅的11.96%,岱海沉积物释放的硅可提供浮游植物所需硅的41.3%.从元素化学计量学角度考虑,结合两个湖泊上覆水营养盐浓度变化,随湖泊富营养化水平的逐渐提高,磷有可能成为乌梁素海初级生产力的潜在限制因子,而Si是岱海初级生产力可能的限制因子。  相似文献