Effect of various doses of 3,4-dimethylpyrazole phosphate on mineral nitrogen losses in two paddy soils

Journal of Soils and Sediments - Nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) has been widely proposed to reduce nitrogen (N) loss and improve N availability in paddy soil....     

杀菌剂和杀虫剂使用对玉米病虫害防治及效益分析

玉米病虫害是影响玉米产量和品质的重要因素。本研究选择2种杀虫剂(40%氯虫苯甲酰胺·噻虫嗪WG和100 g/L顺式氯氰菊酯EC)和4种杀菌剂(18.7%丙环唑·嘧菌酯SE、250 g/L吡唑醚菌酯EC、125 g/L氟环唑SE和17%吡唑醚菌酯·氟环唑SE),通过单独或组合在玉米心叶期(V12)一次性施药,并在药后7 d接种玉米弯孢菌,随后对各处理的防治效果和经济效益进行比较分析。基于施药成本、施药后的增产效益和玉米价格,采用贝叶斯推断统计方法计算净利润的概率。在盈利平衡点(纯利润为0),通过施药获得净利润的概率变幅在0.328～0.998之间;如果要获得1 500元/hm~2的净利润,各施药处理概率的变幅为0.024～0.993,其中40%氯虫苯甲酰胺·噻虫嗪WG+18.7%丙环唑·嘧菌酯SE处理的盈利概率最高(0.986～0.993),其次18.7%丙环唑·嘧菌酯SE和40%氯虫苯甲酰胺·噻虫嗪WG+17%吡唑醚菌酯·氟环唑SE处理的盈利概率也超过0.947。本研究表明40%氯虫苯甲酰胺·噻虫嗪WG+18.7%丙环唑·嘧菌酯SE是防治当地玉米病虫害理想的杀虫剂杀菌剂施药组合。     

紫化和黄化茶树品种叶色色差研究

对24个叶色紫化、黄化以及绿色叶片茶树品系(种)的叶片色泽进行感官分类赋值,并用色差计测定供试品系芽下第二叶的色差参数,分析叶片色差参数与色泽赋值之间的关系。结果显示,叶色赋值与Hunter E(r=0.96,P<0.01)、L(r=0.96,P<0.01)、a(r=-0.57,P<0.01)和b (r=0.87,P<0.01)存在极显著相关性。用E和L值可以作为紫化和黄化茶树品种选育的筛选指标,a和b值可以作为紫化茶树筛选的参考指标。     

1株新疆胡杨林昆虫病原线虫鉴定及生物学特性

【目的】对新疆天然胡杨林中昆虫病原线虫(EPNs)进行分离、鉴定并测试其杀虫活性,为胡杨林害虫生物防治提供新的选择。为新疆天然胡杨林中EPNs资源挖掘和基于EPNs的胡杨林害虫生物防治提供资源储备和奠定研究基础。【方法】利用经典方法,诱导及富集EPNs、分子生物学与形态学相结合鉴定,以及不同剂量杀虫测试分析其种属及生物学特性。【结果】在新疆天然胡杨林中存在EPNs,采集地检出率达25%。线虫18S rDNA系统发育树分析其在进化关系上与Steinernema litorale strain Pak.S.P.7 进化关系最近,获得基因登录号No: MK416208;形态学表明其与Steinernema litorale模式株大部分特征值基本吻合,主要区别在于第1代雄虫:体长略长(1 461.01 μm)、排泄孔至头部距离短(86.98 μm)、交合刺短(69.49 μm)、D%(60.45)与SW%158.21 值小于模式株;侵染期幼虫:体长(885.88 μm)和尾长(74.81 μm)短、E%(83.88)值大。共生细菌16S rDNA系统发育树分析与Xenorhabdus bovienii strain Zakharovo 的进化距离最近。杀虫分析表明,在160IJs/Gm (Galleria mellonella) 及其以上处理组36 h之内校正致死率达到100%;对黄粉虫60 h内40IJs/Tm (Tenebrio molitor) 及以上剂量校正致死率超过50%,160IJs/Tm及以上试验组校正致死率超过75%。【结论】在新疆天然胡杨林中发现有EPNs的分布,Steinernema litorale 在采集地是优势种,同时其具有较强的杀虫能力。     

红豆杉枝叶干燥及贮存工艺研究

研究了红豆杉（Taxus chinensis）鲜枝叶采收后的干燥、贮存方式及贮存期限对枝叶中有效 产物10-DAB Ⅲ和紫杉醇含量的影响，结果表明：（1）采用不同干燥方法处理时，红豆杉样品中10DAB Ⅲ、紫杉醇含量具有显著差异（P<0.05）。同一温度干燥时，干燥时间越长，样品中 10-DAB Ⅲ和紫 杉醇含量下降越快；在一定温度范围内（约25~100℃）干燥时，干燥温度越高，则干燥时间越短。产物 含量与枝叶干燥时间和温度呈负相关；（2）贮存期间发生霉变的红豆杉鲜枝叶和枝叶干粉其产物含量均 会逐渐降低，且新鲜枝叶中产物含量降低较快；（3）贮存期间红豆杉枝叶中10-DAB Ⅲ产物较紫杉醇不 稳定，更易受环境条件影响而降解。（4）长期贮存的红豆杉枝叶的含水量应控制在 10% 以内，贮存环境 应该阴凉、干燥，且贮存时间不宜超过 1 a。     

山西省历山自然保护区鸡桑品种的特征及分布

历山自然保护区发现有野生种质资源鸡桑品种。介绍了山西省鸡桑品种资源的地理分布、形态特征和主要用途。     

遮光对光照敏感型新梢白化茶春梢化学成分含量的影响

以光照敏感型新梢白化茶树‘黄-2’、‘黄-8’和‘黄-13’为供试材料,在春季一芽一叶期采用30%透光度的黑色遮阳网覆盖遮光处理7天,HLPC法检测一芽二叶新梢咖啡因、儿茶素类、氨基酸类和色素类化合物含量。结果显示,遮光处理对茶叶咖啡因含量无显著影响;遮光对儿茶素类总含量的影响因品种而异,在品系‘黄-2’显著提高,而品系‘黄-8’和‘黄-13’则显著降低;遮光显著提高品系‘黄-13’的氨基酸总含量,降低品系‘黄-8’氨基酸总含量,但对品系‘黄-2’无显著影响;遮光显著提高β-胡萝卜素、叶绿素a、叶绿素b和新黄质的含量,显著降低紫黄质含量。具有热耗散作用的黄体素在光照敏感新梢白化茶品种的含量很低,是其容易受到强光胁迫伤害的原因。在强光照条件下,光照敏感型新梢白化茶叶片呈现黄色,主要是叶绿素含量显著降低,而不是因为胡萝卜素和叶黄素含量提高所致。根据这些研究结果,作者认为:在高温强光季节采取适度遮光,将有助于光照敏感型新梢白化茶提高叶片叶绿素含量,增强光合作用,进而提高茶苗生长势和抗性,有助于提高茶苗移栽成活率。     

基于稀疏存储的有限元结构分析高效缩聚并行计算方法

基于稀疏存储技术和直接稀疏求解器提出了一种有限元结构分析高效缩聚并行计算方法。该方法将缩聚过程转换为一系列线性方程组的求解过程,并通过直接稀疏求解器进行求解。它能够避免传统变带宽格式缩聚并行计算方法对带宽内大量零元素的存储和运算,从而大幅度节省内存空间和有效减少计算量。最后通过发动机曲轴的有限元数值仿真实验对算法的有效性进行了验证。结果表明:相对传统变带宽格式缩聚并行计算方法,稀疏存储格式缩聚并行计算方法能够大幅度节省内存空间和有效提高计算效率;各子区域规模越大,该方法对内存空间的节省和计算效率的提高效果就越明显。     

Release and migration of colloidal phosphorus from a typical agricultural field under long-term phosphorus fertilization in southeastern China

Purpose

Colloid-facilitated migration of phosphorus (P) is a widely accepted phenomenon in surface and subsurface environment. Release and migration of colloidal P (P_coll) in agricultural fields are closely related to P fertilization regimes. In this study, a site-specific experiment with rice/oilseed rape rotation was conducted to determine the export potential of P_coll from the field and literatures reporting the impact of P fertilization regimes on release and migration of P_coll in other agricultural fields were compared.

Materials and methods

In this 2-year field experiment, four P fertilization regimes (no fertilizer control, inorganic P fertilizer of low and high rates, and swine manure treatment) with three replicates were conducted. Floodwater and runoff samples were collected in flooding season and the 100-cm-depth soil samples were collected after both crops’ harvest seasons. Colloidal particles were separated by microfiltration and ultracentrifugation processes and determined gravimetrically. The P_coll value was calculated as the difference between the concentration of total P in non-ultracentrifuged and ultracentrifuged samples. The same method was applied for the colloidal mineral elements (Fe and Al) and organic carbon.

Results and discussion

Total P concentration in paddy floodwater significantly increased after fertilization but decreased quickly in the following days, maintaining at 6.0 mg m^?2. In soil extracts, concentration of P_coll was low but stable, which ranged from 6 to 22 % of total P after oilseed rape season and from 7 to 18 % after rice season. In runoff samples, there were positive correlations between P_coll, colloidal Fe (Fe_coll), colloidal Al (Al_coll), and colloidal TOC (TOC_coll); the majority of P forms was molybdate reactive P. In both crops’ seasons, the amount of colloids increased with soil depth. Content of soil P_coll was low and occupied 0.1–2 % of total P. The literature review showed that P_coll in soil solution, runoff, and leachate ranged from 1.4 to 94 % of total P.

Conclusions

These results suggested that although the concentrations of P_coll were not high, they widely distributed in paddy floodwater, runoff, and soil profile. Fertilization regimes and planting systems had a significant influence on the contents of P_coll. Moreover, the P_coll binding with Fe/Al minerals and organic carbon might be an alternative route of P loss in paddy field.

     

棉花商业化育种实践

建立以企业为主导的棉花商业化育种体系,成为企业科技创新的主渠道。商业化育种要确立企业的主导地位,与科研院所和高等院校开展技术合作和交流,建立棉花新品种测试评价机制,广泛引进技术人才,争取国家项目的支持。