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1.
谷子氮（Ｎ），磷（Ｐ２Ｏ％）二因素，三水平正交回归设计试验得出，在豫西旱地谷子生产中，增施氮，磷可以增加谷子产量，不同产量水平条件下其增产模式分别为：高产田（亩产〉２００ｋｇ）ｙ＝２１９．０５＋１３．６９Ｎ＋１７．８９Ｐ－１．１２Ｎ＾２－２．０３Ｐ＾２－０．１７ＮＰ；低产田（亩产〈２００ｋｇ）ｙ＝１６６．６５＋１２．９０Ｎ＋１５．８２Ｐ－０．７２Ｎ＾２－１．３１Ｐ＾２－０．７７ＮＰ。氮，磷两种元素 相似文献
2.
茶赤叶斑病的发生规律 总被引：2，自引：0，他引：2
于１９８８－１９９４年对茶赤叶斑病的发生规律进行了研究。室内培养表明,２２,２４,２６,２８℃等４个处理均适宜病原菌的生长发育,离体插枝接种显示,品种间有抗性差异,且以晚间接种发病率高。该病流行程度与５－７月３个月的平均ＲＨ（Ｘ１）呈正相关,与８月份雨日数（Ｘ２）呈负相关,其综合影响的二元回归式为Ｙ＝－３７．３８４２＋０．６４７１Ｘ１－０．７０７９Ｘ２,ｒＹ１．２＝０．８２７４,ｒＹ２．１＝－０． 相似文献
3.
）为预报因子，提出桑瘿蚊发生预测指标（见表２）。根据当年的长期气象预测，在５月中旬即可获得６－８月的温度和雨量趋势，从而可提前２到３个月对桑瘿蚊发生趋势作出预测，为基层搞好宣传发动及防治准备工作提供科学依据。２．２．２气象因子的曲线回归式建立将原始资料进行逐步回归筛选，选相关性较好的７月下至８月中旬日照（ｒ＝－０．６８５０）和６－８月温水系数（ｒ＝０．８５０６）为预报因子，组建多元回归预测式：Ｙ＝３．７２８５－０．０１９７６Ｘ１＋０．１８１９Ｘ２±０．５９８０经计算Ｒ＝０．９３７９＞Ｒ０．０１＝０．８８６，说明回归关系可靠，预测式成立。拟合率测验：将历年资料代入预测式回测检验，结果８年资料的历史拟合率为１００％，可作为桑瘿蚊发生程度的中、长期预报。 相似文献
4.
水分对复苏后亚洲玉米螟越冬代幼虫化蛹的影响 总被引：4，自引：1，他引：3
作者对复苏后玉米螟的饮水作用研究表明,玉米螟幼虫摄取水分的过程是通过口器主动饮水,饮水后促进虫体重量增加、死亡率降低和提高化蛹率。在一定范围内,饮水量取决于饮水时间的长短。死亡率（Ｄ）和化蛹率（Ｐ）与饮水时间（ｔ）的关系为：Ｄ＝７０．５１８０ｔ＾－０．３５７６（ｒ＝０．９１８８＾＊＊）和Ｐ＝３．５８９９＋１．０５１０ｌｇｔ（ｒ＝０．９５３５＾＊＊）。饮水量（Ｘ）与化蛹率的关系：Ｐ＝０．８４０８Ｘ＾ 相似文献
5.
采用二次回归最优设计，研究苏云金素对东亚小花蝽捕食作用的影响，得出日均捕食量（ｙ）与猎物（ｘ１）和捕食者（ｘ２）之产作关系模型。处理捕食数量回归方程：ｙ＝－０＼００２１ｘ１＾２＋１．２１１ｘ２＾２＋０．８８２２ｘ１－１０，３４６５ｘ２－０．０６４９ｘ１ｘ２＋１．７１７４；对照捕食数量回归方程：ｙ＝－０．００１７ｘ１＾２＋０．７７３４ｘ２＾２＋０．６９４１ｘ１－６．４９１４ｘ２－０．０４７４ｘ１ｘ２ 相似文献
6.
张建宁 《干旱地区农业研究》1995,13(2):73-77
按不同肥力讨论了寒旱山区马铃薯施用氮磷肥的增产效果，提出了氮磷肥经济最佳施用量，低肥力Ｎ５．２９７ｋｇ．亩＾－１，Ｐ２Ｏ５３．２５３ｋｇ．亩＾－１，Ｎ２Ｐ２Ｏ５＝１：０．６１，亩施肥利润３８．５７元；中肥力Ｎ６．６８０ｋｇ．亩＾－１，Ｐ２Ｏ５３．９９７ｋｇ．亩＾－１，Ｎ１Ｐ２Ｏ５＝１：０．６０，亩施肥利润１４６．１３元，高肥力Ｎ８．４５１ｋｇ．亩＾－１，Ｐ２Ｏ５４．０９３ｋｇ．亩＾－１，Ｎ：Ｐ２Ｏ 相似文献
7.
渭北旱地冬小麦不同降水年型栽培技术模型研究 总被引：4，自引：0，他引：4
在旱控制条件下，用四因素五水平通用旋转设计，研究渭北旱塬氮、磷、水、密度因素对冬小麦产量的影响，结果表明：①氮、磷、水、密度对冬小麦的增产顺序是水〉氮〉磷〉密度；②氮、磷的增产作用随水量的增加而显著增加，在干旱年份，增施氮、磷肥无显著增产作用，正常年与丰水年，增施氮磷肥有显著的增产作用。密度对冬小麦产量无明显影响；③水分对施肥量的校正模型为Ｘ１（Ｎ）＝０．２３－０．２４８Ｘ４，Ｘ２（Ｐ２Ｏ５）＝０ 相似文献
8.
9.
内蒙古主要草原植物群落地上生物量和理论载畜量及其与气候的关系 总被引：15，自引：1，他引：15
本文应用除趋势对应分析方法（ＤＣＡ）对内蒙古草原中东部草原植被１２０个群落样地的分析表明：该区六种主要的草原群落类型在生境干燥度梯度上的顺序依次为：小针茅草原→短花针茅草原→克氏针茅草原→大针茅草原→贝加尔针茅草原和羊草草原。在上述分析基础上，研究了每种草原的群落组成、地上生物量及其种群结构，以及各类草原的理论载畜量。六种草原群落的地上生物量介于１１２Ｋｇ．ＤＭ．ｍ￣（－２）──１６２０Ｋｇ。ＤＭ．ｍ￣（－２）之间；相应地，理论载畜量变化于０．１０─１．５７羊单位／公顷。研究地区草原地上生物量（Ｂ）与年降水量（Ｐ）、年平均气温（Ｔ）和与≥１０℃的积温（Ｔａｃ）的关系分别为：Ｂ＝－１３４．９２＋０．８４Ｐ，Ｂ＝１３６．３７－２５．６８Ｔ，Ｂ＝３５１．６１－０．１２Ｔａｃ；与气候干燥度（依Ｐｅｎｍａｎ方法计算）的关系为Ｂ＝０．２６＋４．３３ｅ． 相似文献
10.
采用二次回归最优设计，研究苏云金素对东亚小花蝽捕食作用的影响，得出日均捕食量（ｙ）与猎物（ｘ１）和捕食者（ｘ２）之间互作关系模型。处理捕食数量回归方程：ｙ＝－０．００２１ｘ２１＋１．２１１２ｘ２２＋０．８８２２ｘ１－１０．３４６５ｘ２－０．０６４９ｘ１ｘ２＋１．７１７４；对照捕食数量回归方程：ｙ＝－０．００１７ｘ２１＋０．７７３４ｘ２２＋０．６９４１ｘ１－６．４９１４ｘ２－０．０４７４ｘ１ｘ２－０．４６３６。综合定性分析和定量分析结果，苏云金素处理东亚小花蝽若虫，减弱了其对二斑叶螨卵的捕食能力，但二者的差异不显著，对种群变化影响不明显 相似文献
11.
为了提高定量构效关系(QSAR)研究的预测精度,发展了一种基于支持向量机回归(SVR)与K-最近邻法(KNN)的组合预测方法:以均方误差(MSE)最小为原则,基于SVR实施核函数寻优;基于MSE最小原则与最优核函数以SVR进行描述符筛选并得到保留描述符;通过"多轮末尾强制淘汰法"揭示各保留描述符对预测精度的影响程度;从保留描述符出发,以不同KNN预测值反映样本集异质性并构建子模型,然后基于SVR以留一法实施组合预测。运用该组合预测方法研究苯乙酰胺类除草剂QSAR建模,结果表明:基于SVR与KNN的组合预测方法在参比模型中预测精度最高,具结构风险最小、非线性、能有效克服过拟合、泛化推广能力优异等优点,在QSAR研究中具有广泛的应用前景。 相似文献
12.
Jos J. T. I. Boesten 《Pest management science》1990,30(1):31-41
The influence of the solid/liquid ratio on the experimental error in the sorption coefficient in pesticide/soil systems was assessed by theoretical analysis. It was assumed that the sorption coefficient is derived from the measured decrease in concentration in the liquid phase of a soil suspension. A first analysis based on systematic errors in the concentration in the liquid phase showed that the relative error in the sorption coefficient is controlled by the product of the solid/liquid ratio and the sorption coefficient (a dimensionless quantity). If this quantity tends to zero, the relative error tends to infinity. A second analysis, based on random errors in the concentration in the liquid phase, gave a similar result. To minimize experimental errors the solid/liquid ratio should be taken as large as possible unless the equilibrium concentration becomes too low to be measured accurately. 相似文献
13.
为实现大田作物灌溉的精细化管理,研究了基于气象因素的生育期ET0预测模型。采用灰色理论对ET0与日均、日最高、最低温度,日均风速,相对湿度以及日照时数进行灰色关联度分析,结果表明ET0与温度（包括日均、最高、最低温度）及相对湿度的灰色关联度较高。在分析ET0与上述气象因素间的相关系数基础上,采用日均温度、日均风速以及日照时数作为模型的输入,ET0作为输出,建立了BP神经网络（BPNN）预测模型;采用日均温度、日均风速、日照时数及灰色关联度作为输入,建立了模糊最小二乘支持向量机（FLSSVM）预测模型。研究结果表明,BPNN模型的训练值决定系数为0.8643,平均相对误差6.29%,预测值决定系数为0.8099,平均相对误差7.83%;FLSSVM模型的训练值决定系数为0.9684,平均相对误差2.89%;预测值决定系数为0.9663,平均相对误差3.43%。BP神经网络与FLSSVM模型的精度均较高,可以用来预测ET0日值,这为大田作物的精细化灌溉管理提供理论与技术支持。 相似文献
14.
Tamara Lazarevi?-PaštiBranislav Nastasijevi? Vesna Vasi? 《Pesticide biochemistry and physiology》2011,101(3):220-226
The present paper deals with the investigations of optimal conditions for the myeloperoxidase (MPO) mediated oxidation of chlorpyrifos, azinphos-methyl and phorate, organophosphorous pesticides (OPs) containing phosphorothionate group, from thio- to oxo-forms, in the presence of hydrogen peroxide. The aim of the work was to apply this oxidation method in the AChE based bioanalytical tests for OPs determination. The maximum concentration of oxo-forms for all tested pesticides was achieved after 10 min incubation of OPs in 50 mM phosphate buffer (pH 6.0) with 100 nM MPO in the presence of 50 μM H2O2. Optimal temperature for obtaining maximal concentration of oxo-forms was 37 °C. Only the parent compounds and their oxo-forms were identified chromatographically in the OPs samples after their exposure to MPO. Moreover, no hydrolysis products were detected in the time interval of 1 h after the MPO catalyzed reaction was stopped by catalase. The efficiency of OPs transformation from thio- to oxo-forms was measured using acethylcholinesterase (AChE) test, by comparison of percent of AChE inhibition before and after exposure to the oxidized sample. 相似文献
15.
Three diagrammatic grading keys were designed for the assessment of the severity of late blight (caused by Phytophthora infestans ) in tomato leaves. Simplified and broad keys considered, respectively, six (3, 12, 22, 40, 60 and 77%) and eight (3, 6, 12, 22, 40, 60, 77 and 90%) levels of disease severity, whilst a modified key based on a previous proposal for potato late blight considered six levels (1, 5, 10, 16, 32 and 50%). The keys were validated by 24 evaluators who assessed digital images of tomato leaves exhibiting different areas with lesions. Evaluator errors were compared using a mixed model in which evaluators were considered as random effects and the keys and evaluations as fixed effects. The accuracy and precision of the evaluators were compared by simple linear regression between the estimated and actual values of disease severity. The repeatability of evaluators was assessed using Pearson's correlation coefficient. There was significant ( P ≤ 0·001) variability amongst the errors made by evaluators, although the precision of each of the three keys was high with a coefficient of determination (R2 ) of 0·96, 0·93 and 0·83 for the simplified, broad and modified key, respectively. Repeatability of estimations amongst the evaluators was adequate (correlation coefficients of 0·91, 0·91 and 0·90 for the three keys, respectively). The simplified and broad keys resulted in higher precision and accuracy for the estimation of severity than did the modified key. Since the simplified key considers a smaller number of disease severity levels, its use is recommended in the assessment of late blight in tomato leaves. 相似文献
16.
建立了QuEChERS-液相色谱-串联质谱(HPLC-MS/MS)测定果蔬及其制品中噻霉酮的分析方法。样品经含0.1%乙酸的乙腈提取,聚苯乙烯/二乙烯苯(PEP)和C18粉净化,以0.1%甲酸水溶液(含2 mmol/mL乙酸铵)和甲醇为流动相梯度洗脱,经C18色谱柱分离,正离子模式扫描,多重反应监测模式检测。以保留时间和特征离子对(母离子和两个碎片离子)信息比较进行定性,基质匹配外标法定量。结果表明:在10~500 ng/mL范围内,噻霉酮在黄瓜、葡萄、葡萄干、番茄酱、番茄和苹果6种基质中的决定系数(R2)均大于0.996;定量限(LOQ) (以S/N≥10计)为10.0 μg/kg,在10、20和100 μg/kg 3个添加水平下,平均回收率在80%~98%,相对标准偏差(RSD)在2.4%~13%。该方法高效快捷、准确度和精密度均符合农药残留检测要求。 相似文献
17.
The incidence of hop powdery mildew on leaves, caused by Podosphaera macularis, collected from 1,606 transects in 77 commercial hop yards in Oregon and Washington over 9 years was used to assess variability in heterogeneity of disease and the estimated binary power law parameters. Spatial analyses of data sets were conducted at the level of individual rows (row level) and multiple rows within a yard (yard level). The binary power law provided a good fit to all data sets, with R(2) values ranging from 0.933 to 0.993. At the row level, the intercept parameter ln(A(x)) was >0 for 8 years, but was not significantly greater than 0 in 2006. The parameter b was greater than 1 for all row-level data sets collected from 1999 to 2005, but was <1 in 2006 and not significantly different from 1 in 2007. Covariance analysis indicated the factor 'region' affected ln(A(x)) in 3 years, and b in 2 years. 'Cultivar' had an effect on ln(A(x)) in 3 years and b in year. At the yard level, ln(A(x)) was greater than 0 for 6 years, but in 2006 and 2007, ln(A(x)) was not significantly different from 0. The slope parameter b was greater than 1 in 6 years, but was not significantly different from 1 in 2006 and 2007. Differences in b among years were large enough to have practical implications for sample sizes and precision of fixed and sequential sampling. Although the binary power law parameter tended to be relatively stable, variability of the estimated parameters may have practical consequences for sampling precision and costs. 相似文献
18.
壳寡糖诱导对烟草体内TMV-CP基因表达的抑制作用 总被引：1，自引：0，他引：1
采用实时荧光定量PCR方法, 研究了壳寡糖诱导对烟草体内TMV-CP基因表达量的影响。结果表明, 壳寡糖诱导后烟草表达了对TMV侵染的系统获得抗病性, 植株显症推迟4~7 d, 症状减轻, 平均严重度比对照降低了82.9%。同时烟草叶片中CP基因的表达量显著降低。壳寡糖诱导处理的植株在接种病毒时(0 h), CP基因的表达量(拷贝数/2μL)为0.918, 接种后168 h增加到167.730。而在不诱导对照植株内, CP基因的表达量在0 h为1.218, 接种后168 h猛增到648.623。换言之, 不处理对照的表达量在此期间增长了532.53倍, 而壳寡糖诱导处理植株中仅增长了182.71倍。试验证明壳寡糖诱导的系统获得抗病性强烈抑制了烟草体内TMV-CP基因的表达。 相似文献
19.
It was found that, in order to estimate the number of weed seeds in soil with a desirable degree of accuracy and confidence level. the sample size depends to large extent on the spatial distribution pattern of the seeds in the soil. The seeds of most weeds found in cultivated soils are distributed according to one of two statistical distributions: Poisson or Negative Binomial. For an acceptable degree of accuracy in estimating the number of seeds in the soil, the sample size must be large, Taking this into account, in this study a practical solution based on a theoretical approach is proposed for the problem of establishing the sample size for a species distributed according to either statistical pattern. In addition, given the sample size, it was possible to determine the estimation error to be expected. This theoretical approach is compared with that proposed in previous studies. Two abaci, based on simple expressions, are provided to determine the sample size, according to the Poisson or the Negative Binormal distribution of the weed species. For Poisson distribution, the sample size is determined (given the desired maximum relative error estimation and the confidence level) as a function of only one parameter: the expected number of seeds per sampling unit m (estimaied by the sample mean). For Negative Binomial distribution, the sample size is determined as a function of two parameters: m and p (estimated according to the relationship between the sample mean and the sample variance). A sample size n nol very different from those given in previous studies is obtained, but the lower limit found for the n -values is lower than that found in these studies. 相似文献
20.
R. A. Daamen 《European journal of plant pathology / European Foundation for Plant Pathology》1986,92(5):197-206
Assessments of pustule number and severity of powdery mildew on winter wheat in the Netherlands were made in commercial fields and in experimental plots. The sample variance (s2) of the number of pustules per leaf (m) was fairly constant over years, varieties, growth stages and leaf postitions, but depended strongly on the average pustule number:
. The effect of sample size on the precision of the estimate is discussed and it is concluded that it is difficult to estimate low disease intensities accurately. Estimates are given for the detection level of pustule counts in relation to sample size.Mildew intensity on the lower surface of leaves can be estimated from the intensity on the upper surface. This method reduces the duration of the observation, but introduces an additional error. At low disease intensities and small sample sizes this method is more efficient than sampling mildew on both surfaces of leaves. The common practice of assessments of the upper surface of leaves only may not be the most efficient method.Samenvatting Aantallen puistjes meeldauw per blad werden geteld in praktijkpercelen en veldproeven met wintertarwe. De steekproefvariantie van het aantal puistjes was tamelijk constant in de jaren, rassen, gewasstadia en bladposities, maar was sterk afhankelijk van het gemiddeld aantal puistjes
. Het effect van de steekproefgrootte op de nauwkeurigheid van de schatting wordt besproken en het blijkt dat het moeilijk is om lichte aantastingen nauwkeurig te schatten. Er worden schattingen gegeven van de detectiegrens in afhankelijkheid van de steekproefgrootte.Meeldauwaantastingen aan de onderkant van het blad, kunnen worden geschat uit de aantasting op de bovenkant van het blad. Deze methode levert een tijdsbesparing op, maar ook een extra onnauwkeurigheid. Alleen bij lichte aantastingen en kleine steekproeven is deze methode efficiënter dan een directe tweezijdige bemonstering. Het schatten van meeldauw op de bovenkant van bladeren is, hoewel algemeen gebruikelijk, waarschijnlijk niet de meest efficiënte methode. 相似文献