二阶拟线性椭圓型Euler方程组解的Pohozaev型恒等式及其应用

本文对于二阶椭圆型Euler方程组 -∑D_αF_(q_α~i)(x,u,Du)+F_(ui)(x,u,Du)=0得到了一些积分恒等式,利用这些恒等式证明了某些方程组非平凡解的不存在性。     

河南省杨树材种出材率表的研编

用削度方程和单株带皮—去皮胸径的转换关系式两个模型对河南省杨树进行计算机理论造材．经精度检验，满足要求，方法可行，依此编制了河南省杨树材种出材率表。     

Sporulation of Pyrenopeziza brassicae (light leaf spot) on oilseed rape (Brassica napus) leaves inoculated with ascospores or conidia at different temperatures and wetness durations

In controlled environment experiments, sporulation of Pyrenopeziza brassicae was observed on leaves of oilseed rape inoculated with ascospores or conidia at temperatures from 8 to 20°C at all leaf wetness durations from 6 to 72 h, except after 6 h leaf wetness duration at 8°C. The shortest times from inoculation to first observed sporulation ( l ₀), for both ascospore and conidial inoculum, were 11–12 days at 16°C after 48 h wetness duration. For both ascospore and conidial inoculum (48 h wetness duration), the number of conidia produced per cm² leaf area with sporulation was seven to eight times less at 20°C than at 8, 12 or 16°C. Values of Gompertz parameters c (maximum percentage leaf area with sporulation), r (maximum rate of increase in percentage leaf area with sporulation) and l ₃₇ (days from inoculation to 37% of maximum sporulation), estimated by fitting the equation to the observed data, were linearly related to values predicted by inserting temperature and wetness duration treatment values into existing equations. The observed data were fitted better by logistic equations than by Gompertz equations (which overestimated at low temperatures). For both ascospore and conidial inoculum, the latent period derived from the logistic equation (days from inoculation to 50% of maximum sporulation, l ₅₀) of P. brassicae was generally shortest at 16°C, and increased as temperature increased to 20°C or decreased to 8°C. Minimum numbers of spores needed to produce sporulation on leaves were ≈25 ascospores per leaf and ≈700 conidia per leaf, at 16°C after 48 h leaf wetness duration.     

Genetic analyses of resistance of the wheat differential cultivars Carstens V and Spaldings Prolific to two races of Puccinia striiformis

Genetic analysis of resistance of wheat seedlings to two races of Puccinia striiformis was conducted on F₁, F₂ and F₃ generations from crosses Carstens V (CV) × Lee, Spaldings Prolific (SPA) × Lee and CV × SPA. F₂ generations from crosses of CV and SPA with Strubes Dickkopf (SD) were also studied. The plants were classified into six resistance classes and analysed by factorial correspondence analysis and nonhierarchical classification. The two P. striiformis isolates tested were a French isolate of race 43E138 and a Lebanese isolate of race 2E16, selected for the differences in their virulence spectra for the common differential cultivars Strubes Dickkopf and Nord Desprez. Resistance of CV and SPA was recessive and dominant to races 43E138 and 2E16, respectively. CV possessed three or four resistance genes, one of them being expressed with both races. Two genes of CV had a cumulative effect for resistance to 43E138 and two or three gave dominant resistance to 2E16. SPA had three resistance genes, all of which gave resistance to 2E16 and two of which also gave resistance to 43E138. SPA had one gene in common with CV for resistance to both races. Furthermore, the gene for resistance to race 2E16 in CV and SPA was allelic with a gene in SD, and was probably Yr25 .     

大麦茎秆生长动态模拟模型

通过系统分析甘肃地区不同株型大麦品种茎秆生长的变化动态,以生理发育时间(PDT)为步长,用Richards方程模拟了甘肃大麦茎秆节间伸长和节间增粗的动态过程,并以不同品种不同播期的大麦对模型进行了检验。结果表明:模型对大麦不同品种不同播期节间长度实测值和模拟值的RMSE范围在0.37~1.62 cm之间,节间粗度的RMSE范围在0.011~0.034 cm之间,模型具有较好的预测性。     

云南高海拔粳稻区白叶枯病菌致病型的鉴定

水稻白叶枯病是危害水稻的重要细菌性病害之一,病原为稻生黄单胞菌水稻致病变种Xanthomonas oryzae pv.oryzae (Xoo).近10年来云南省水稻白叶枯病的危害向高海拔粳稻区扩散,在海拔2200m的剑川县,白叶枯病已成为最严重的水稻病害[1-2].开展高海拔粳稻区白叶枯病菌致病型的鉴定、分布和分化研究,对云南高海拔粳稻区稻作生产具有指导意义.     

温室番茄干物质分配及果实生长发育规律的研究

以番茄品种辽园多丽为试验材料,在日光温室内对植株生长期各器官干物质分配及单个果实生长发育进行了研究。结果表明:番茄在开花结果后,地上部分配指数保持在0.9以上,地下部分配指数维持在0.1以下,同化物大多供给地上部用于茎、叶、果的生长;番茄果实横径与发育时间呈"S"形曲线变化规律,并利用Logistic方程建立番茄果实生长的模型。     

适应不同成熟度大豆的差速脱粒滚筒性能试验与分析

针对南方地区大豆草谷比和未成熟豆荚占比高,造成收获机脱粒清选分离质量差、功耗大等问题,设计了一种前后两段组合且两段转速差可调的脱粒滚筒,研究了脱粒滚筒参数变化对豆荚和籽粒的能量、等效形变量等的影响。以脱粒齿类型、前段滚筒转速、两段滚筒转速差为影响因素,以破碎率、未脱净率和夹带损失率为评价指标,得到了差速与非差速脱粒滚筒的最优参数组合,并通过综合性能试验对比了两种脱粒滚筒的脱粒质量、作业油耗和工作效率。结果表明,差速脱粒滚筒最优参数组合是脱粒齿类型为纹杆齿-杆齿组合式脱粒齿,前段滚筒转速为450 r/min,两段滚筒转速差为150 r/min。此时,相较于传统的杆齿式非差速脱粒滚筒,脱粒质量更高,油耗降低了2.7 L/hm2,最大作业效率增大了10.35 %。该研究能够为解决南方地区大豆联合收获机脱粒装置适应性问题提供依据。