钙对水稻旱育秧立枯病的控制作用

用CaSO4 、CaCO3、CaO、CaO2 、CaCl2 和Ca(NO3) 2 混土处理 ,考察了它们对水稻旱育秧立枯病的防治效果 ,其中CaO和CaO2 对该病具有一定的控制作用。用 0 2 5 %～ 2 %CaO水溶液浸种 4 8h可以使水稻旱育秧立枯病病苗率减少 4 0 %左右 ,以土重 0 5 %～ 1%的CaO处理土壤也使水稻立枯病的发病率降低 5 0 %。在降低立枯病发病率的同时 ,CaO处理也延缓了水稻立枯病的发展。

药剂防治棉花枯黄萎病的试验效果

(一)试验材料与方法 1.试验地点 129团11连. 2.试验材料 棉花品种为新陆早6号.供试药剂有克黄枯(深圳产)、990A(河南洛阳产)、代森锰锌(四川产)和甲基托不津(湖南产).

茄果菜苗大棚冷床覆膜假植技术

通过对二叶一心菜苗改冷床露地假植为冷床地膜覆盖假植后 ,菜苗出棚率提高 10 %以上 ,平均达到87.6 % ,病苗株率由 35 %降到 5 %以下 ,节省用节 ,提前出棚 ,从而提早上市 。

五种牧草及三种草坪草种子寄藏真菌检测初探

采用PDA平皿法和滤纸法检测了市售5个牧草品种和3个草坪草品种种子样品寄藏真菌的情况,并就分离获得的真菌对种子出苗及幼苗生长的影响进行了初步研究。结果表明,供试种子样品带菌率为0～70.5%,分离获得的35个真菌分离物大多属于镰刀菌(Fusariumspp.)、链格孢菌(Alternariaspp.)、蠕孢菌(Helminthosporiumspp.)、小核菌(Sclerotiumsp.)、匍柄霉菌(Stemphyliumspp.)和曲霉菌(Aspergillusspp.)。供试样品中假俭草和波多马各(鸭茅)种子带菌率较高,在PDA平皿检测中其未经表面消毒处理的种子带菌率分别为48.4%和70.5%,表面消毒处理种子带菌率分别为40.8%和28.8%,分离获得的种子寄藏真菌对假俭草和波多马各种子出苗及幼苗生长的影响较小。圣地亚哥(南苜蓿)和菊苣种子带菌率较低,但分离获得的真菌对其种子出苗和幼苗生长的影响较大。以镰刀菌与匍柄霉菌接种过的南苜蓿种子出苗率分别比未经表面消毒且未接种真菌的对照低44.0%和21.7%,出苗后的病苗率分别为22.7%和29.7%;以链格孢菌与曲霉菌接种过的菊苣种子的出苗率分别比未经表面消毒且未接种真菌的对照低22.0%和27.5%,出苗后的病苗率分别为2.3%和29.3%。

Study on Seed Breeding of Thuia sutchuenensis

Objective] This research almed to study technical requirements by seed breeding of Thuia sutchuenensis so as to Iay a foundation for the saving and breeding of Thuia sutchuenensis. [Method] The seeds of Thuia sutchuenensis, coI-Iected from Xianyi Town, Chengkou County, Chongqing City, were used as material. The effects of temperature and matrix on germination rate and emergence rate of Thuia sutchuenensis were investigated. In addition, the controI effects of different-type and different-concentration pesticides on seedIing bIight of Thuia sutchuenensis were also studied. [Result] The suitabIe temperature for seed germination of Thuia sutchuenensis was 15-20 ℃, whiIe the optimum temperature was 20 ℃, under which the germination rate couId reach 95%. At temperature of 25 ℃, the seeds of Thuia sutchuenensis almost couId not germinate. The seeds of Thuia sutchuenensis germinated most if soaked in warm water of 40 ℃. After 24 h soaking, the germi-nated seeds were not increased significantIy. Among the matrixes for contalner seedIing, the 18th matrix, composed by sawdust （2/3） and forest topsoiI or general soiI （1/3）, was conducive to the seed germination in contalners. Among the pesti-cides, the controI effect of ferrous suIfate on diseases and pests in Thuia sutchue-nensis was best with cumuIative incidence of 15%, foI owed by those of fe-naminosuIf （17%）, Bordeaux mixture （21%）, KangkuIing （22%） and potassium per-manganate. [Conclusion] Sawdust had great effect on emergence rate of Thuia sutchuenensis in contalner seedIing, which might be reIated to good water retention and permeabiIity of sawdust. However, too much forest soiI was not conducive to the emergence rate of Thuia sutchuenensis in contalner seedIing. Ferrous suIfate had the best controI effect on diseases and pests in Thuia sutchuenensis.

Global stability and vaccination of an SEIVR epidemic model with saturated incidence rate

This study considers SEIVR epidemic model with generalized nonlinear saturated inci- dence rate in the host population horizontally to estimate local and global equilibriums. By using the Rout^Hurwitz criteria, it is shown that if the basic reproduction number R0 〈 1, the disease-free equilibrium is locally asymptotically stable. When the basic reproduction number exceeds the unity, then the endemic equilibrium exists and is stable locally asymptotically. The system is globally asymptotically stable about the disease-free equilibrium if R0 〈 1. The geometric approach is used to present the global stability of the endemic equilibrium. For R0〉 1, the endemic equilibrium is stable globally asymptotically. Finally, the numerical results are presented to justify the mathematical results.