共查询到19条相似文献,搜索用时 106 毫秒
1.
2.
第2代棉铃虫是危害番茄最严重的世代,95%左右的卵产在番茄植株顶尖至第4复叶层的嫩梢、嫩叶、果萼和茎基上,平均每株落卵32.8粒。在番茄上的卵量和幼虫量与第1代蛾量密切相关,卵量(Y1)与第1代蛾量(X)关系式为:Y1=一315.9+1.7783X,n=6,r=0.8562,幼虫量(Y2)与第1代蛾量(X)关系式为:Y2=31.3+0.134X,n=6,r=0.8652。在第2代棉铃虫产卵初盛期应用B.t菌剂含孢子100亿个/mL200倍液喷雾3次,或1.8%爱福丁乳油45mL/667m2对水75kg喷雾2次,防效显著。 相似文献
3.
青稞品种抗麦鞘毛眼水蝇的初步研究 总被引:4,自引:0,他引:4
不同青稞品种麦鞘毛眼水蝇着卵量与其倒三叶叶基部脉间距、平均严重度均呈正相关[Y=2.4769+0.0331X(r=0.5747*)、Y=42.6346+1.3424x(r=O.7625)]此外,旗叶和倒一叶叶鞘内叶绿素、蛋白质含量与平均严重度也呈正相关[Y=30.7957+8.3442X(r=0.6191*)、Y=23.67+3.9044x(r=0.5559*)];蛋白质含量与千粒重产量损失率之间有显著的负相关性[Y=55.1483-2.4633X(r=─0.5786)]。试验表明不同青稞品种对麦鞘毛眼水蝇存在着一定的理化抗性和耐害性。 相似文献
4.
采用Iwao的M*=α+βX回归式测定稻纵卷叶螟,虫苞种群的α=0.4334>0,β=1.3149>1,判定虫苞为聚集分布型;在t=1,D=0.2时其理论抽样数为n=35.8/X+7.87;利用有虫苞丛率(P)与百丛虫苞密度(Y)的关系,建立Gerrard模型为Y=157.976[-ln(1-P)]1.0616,其抽样精度可达90%以上 相似文献
5.
6.
7.
8.
采用饱和-D最优回归设计,建立以苹果蚜虫校正减退率为目标函数的氧乐果(X1)、久效磷(X2)两因子效应编码值回归模型Y^(%)=105.56+21.27X1+16.10X2-22.32X21-18.10X22,计算得出:5~6a生苹果树每棵用40%氧乐果乳油3.15ml和50%久效磷乳油2.88ml混配药液,加面汤粘着剂3者共10ml涂干,施药后7d,苹果蚜虫校正减退率期望防效可达100%,残效期达15d以上,且对蜘蛛、瓢虫、草蛉等主要天敌无明显影响。 相似文献
9.
测定了小麦条锈病不同病级所造成的小麦产量损失率 ,探讨了损失率以及田间产量损失程度的简便测算方法。小麦条锈病病级与小麦穗粒数、千粒重、穗重关系密切 ,其回归方程式分别为:Y1=62.29-3.11X±1.16(r=-0.9920);Y2=44.79-2.74X±1.98(r=-0.9708);Y3=2.68-0.235X±0.08(r=0.9937)。小麦中后期功能叶受害损失较大 ,最终集中表现在穗重降低上 ,损失率回归方程为:Y3′=9.27X-5.76±3.07(r=0.9937)。上穗危害损失率回归方程为:YY3 ′=3.00X+0.64±0.58(r=0.9958) ,经测验相关系数均为极显著。中后期叶片受害病级 1级时损失率为3.5% ,以后每增加1个级别穗重降低0.235g ,损失率增加9.27% ;上穗危害穗部病级增加 1级穗重降低0.1g ,损失率增加3% 相似文献
10.
根据1979~1993年的15a观测结果,组建了三化螟年发生量(Y)与越冬代始蛾期(X,以4月10日为零)的回归预测方程,即Y=6.442-0.201X。该方程回测符合率达100%,1994~1996年预测结果与实际相符,能够应用于测报工作。文中并分析了三化螟越冬代始蛾期与年发生量相关关系产生的直接和间接原因。 相似文献
11.
12.
采用相关分析和通径分析法研究了稻水蝇危害与水稻产量损失的关系。结果表明:水稻产量(y,kg/hm2)与田间虫口密度(x,头 /m2)、穗损失率 (x5,% )间0.01水平显著时的关系符合方程:y^=9433.965-6.6637x1-402.7469x5;产量损失(Y,kg/hm2)与田间虫口密度(x,头/m2)间关系符合下列方程 :Y^=-13.4989+6.0043x(r=0.9647**)。通径分析显示 ,穗损失率和虫口密度对产量建成直接效应最大 ,分别为-0.9218和-0.1422 相似文献
13.
14.
The brown planthopper (BPH) is an important pest in rice. Rice losses due to BPH's damage are often more than 10% of yield. Assessments on loss rates from BPH are now basically dependent on experiential indices. However, early assessments on rice yield losses using hyperspectral data are still rare. In this study, reflectance from rice canopy was measured in net cages after different densities of BPH release. Results showed that reflectance in the near-infrared region (750–1000 nm) from milk grain stage, and in 400–531 nm and 567–705 nm from mature grain stage was closely related to BPH density. These spectral indices: red-edge parameters (λr, Dλr, Sλr), ratio of the maximal reflectance in green (490–560 nm) to minimal reflectance (640–740 nm) in red (RGREEN/RRED), ratio of the near-infrared peak (RNIR) to RRED, normalized difference vegetation index between RNIR and RRED and soil-adjusted vegetation index (SAVI) from both milk and mature grain stages, indicated BPH densities well. As expected, rate of loss in rice grain was higher with increasing BPH density. SAVI, Dλr, Sλr and reflectance at 760 nm (R760) from milk grain stage were significantly correlated with rates of loss in panicle, and 1000-grain weight and multiple-linear regression models for detecting loss rate were established. The hyperspectral reflectance from rice at milk grain stage can be used to assess rice yield losses due to BPH and improve management policies. 相似文献
15.
小麦白粉病反应型和产孢量的关系 总被引:1,自引:0,他引:1
利用小麦的6个品种及小麦白粉菌的3个小种研究了小麦苗期白粉病反应型与产孢量之间的关系。分别用累积单斑产孢量(LBSY)、累积单位面积产孢量(LASY)与反应型组建了反应型-产孢量关系模型:Y_1=exp(1.7178×lnX 0.0256X-2.484)(LBSY法);Y_2=exp(1.5168×lnX 0.052X-2.309)(LASY法)(X为反应型,Y为产孢系数)。通过LBSY方法获得反应型0,1,2,3~-,3,3~ ,4~-,4所对应的产孢系数分别为0,0.09,0.29,0.49,0.60,0.71,0.96,1。 相似文献
16.
稻茎毛眼水蝇生物学特性研究 总被引:2,自引:0,他引:2
稻茎毛眼水蝇是一种水稻害虫。为阐明该虫的发生特点,为防治提供依据,作者采用室内饲养观察和田间定期调查相结合的方法,对其生物学特性进行了研究。结果表明:稻茎毛眼水蝇在江西1年发生7代,以幼虫越冬。成虫羽化、交配、产卵均在白天进行。羽化高峰在7:30~10:00之间。1对成虫一生平均交配7.83次,交配持续时间平均4分48秒,经过交配的成虫比未交配的成虫每雌产卵量多10.77粒,产卵前期和寿命分别缩短68.2小时和42小时。成虫产卵喜选择矮秆品种。卵大多数产在叶片下部,单粒产,卵全天24小时均可孵化,孵化盛期在22:00至次日4:00。幼虫取食叶肉和幼穗,在叶鞘内化蛹。 相似文献
17.
Fusarium ear rot, primarily caused by Fusarium verticillioides, causes losses in grain yield and quality and can result in contamination of grain by mycotoxins, primarily fumonisin B1. Disease severity and fumonisin B1 contamination vary considerably among maize‐growing regions and from year to year. A 2 year field study was conducted in six locations in the USA, to evaluate the roles of planting date, maize hybrid, rainfall, temperature and insect pests in the variation in fusarium ear rot symptoms and fumonisin B1 contamination. Grain samples were inspected to determine percentage of kernels with fusarium ear rot symptoms, categorized as ‘moulded’ or ‘starburst’; grain was also analysed by ELISA for fumonisin B1. Hybrid and planting date frequently had significant effects (P ≤ 0·05) on fusarium ear rot and fumonisin B1 contamination. Earlier planting consistently resulted in lower ear rot severity, fumonisin B1 levels and insect damage. Mould symptoms were highly correlated with thrips populations (Frankliniella occidentalis) (r = 0·78) and with fumonisin B1 concentration (r = 0·89). The starburst symptom was not as closely correlated with thrips (r = 0·33) or fumonisin B1 (r = 0·18). A multiple linear regression model identified highly significant effects on fumonisin B1 for thrips, lower average daily precipitation after flowering, and location. These results strengthen the evidence that locations with high populations of ear‐infesting thrips and dry conditions after pollination have an increased risk of fumonisin contamination, and suggest that high fumonisin levels are much more likely in visibly moulded kernels compared to those with ‘starburst’ symptoms. 相似文献
18.
19.
通过在全膜双垄沟播技术模式下6个耐密型玉米杂交种不同密度(4.5、5.25、6.0、6.75、7.5万株· hm-2)的试验,研究了玉米产量及其性状与种植密度的关系。在本文研究密度范围内,玉米的产量随着密度的增加而增高;当密度达到一定程度之后,随着密度的增加,产量反而下降,二者呈二次曲线模式变化 Y=-6417.314+5501.842 X-396.330 X2。结果表明,6个耐密型玉米杂交种在双垄全膜沟播技术模式下最佳密度为6.941万株· hm-2。此密度下各植株性状指标为:穗粒数为499.9粒、百粒重为38.63 g、出籽率为83.71%、穗长为17.5 cm、株高194 cm、茎粗2.14 cm、秃顶长1 cm。株高与密度之间为正相关,函数曲线是幂模型 Y=140.607 X0.16602,穗粒数、穗粗、茎粗、出籽率4个性状与密度之间为负相关,函数模型均为性状指标随密度的增加而减少的三次曲线。秃顶长、穗长、百粒重与密度的关系呈二次曲线模式变化。密度与秃顶长之间为正相关,与穗长、百粒重之间为负相关。秃顶长随着密度的增大而增加;穗长、百粒重随密度的增加而呈单边下降的变化趋势。穗位高与密度的相关不显著。 相似文献