利用核型多角体病毒防治豆天蛾幼虫的研究

室内试验,豆天蛾核型多角体病毒感染3龄幼虫的致死中浓度(LC_(50))为1.4×10~(4(?)8)个多角体/毫升。田间试验,喷施1.6×10~7多角体/毫升的病虫尸匀浆液,对豆天蛾幼虫的防治效果在70％左右。豆天蛾核型多角体病毒与苏云金杆菌或银纹夜娥核型多角体病毒混用,防治同时发生的多种大豆害虫的总效果明显提高,虫口下降率可达90％左右。     

大豆主要食叶害虫为害当量系统与复合防治指标的研究

豆天蛾(Clanis bilineata Walker)、银纹夜蛾(Plusia agnata Standinger)、棉铃虫(He-liothis armigera Hubner)和豆灰蝶(Plebejus argus L.)对黄淮流域大豆生产影响较大,防治指标亟待改进。人工模拟剪叶建立了叶损失率与产量损失的函数方程。逐种测定日食量,求取了每种幼虫不同阶段的校正等量系数,建立了为害当量系统。在考虑多维因素的基础上,建立了大豆不同生育期的复合防治指标。田间调查表明,应用该指标能较好解决4种害虫在田间混合发生,虫龄参差不齐,难以确定防治指标的困难,具有较高实用性。     

饵料对稚幼参生长变色的影响

报告了藻粉,浮泥,人工配合饵料,混合饵料对稚幼长岛县牝一海水育苗场变色的影响。经３个胸月的投喂试验。结果：人工配合饵料组稚幼参体长,体重增长较快,纯藻粉组,浮泥组投喂效果都较差。藻粉中添加部分“海丰”牌饲料预混剂和３０％的浮泥,对稚参有明显的助长作用,日均增长,增重是纯藻粉组的２倍以上,且明显快于人工配合饵料组。     

氮素形态不同配比对黄瓜生长和性别分化的影响（初报）

采用基质培养研究氮素形态不同配比对黄瓜生长及性别分化的影响,结果表明用纯NO3--N营养液处理,黄瓜植株营养生长旺盛,当NH4 -N占25％和50％时,黄瓜的生殖生长明显促进,表现为比纯NO3--N处理第一雌花低0.4、0.6节,雌花率增加了23.9％、31.0％,单株产量增加了35.3％、28.7％。叶片和果实中矿物元素钾增加了0.02％～1.41％,铁增加了11～124,ug/g DW,锌增加了37.6～47.0μg/g DW,镁、锰、铜差异不大。黄瓜在不同生育期对氮素形态的敏感性有差异,幼苗期比生长旺盛期不敏感。     

Bone mineral changes in growing, pregnant and lactating cattle

Bone mineral content (BMC) was determined in one or two coccygeal vertebrae by dichromatic photon absorptiometry in two sets of cattle: A. This set consisted of six fattening bulls. Their increases of BMC and weights were closely correlated. However, BMC increased slightly more than weight. B. There were 28 cows in this set. BMC was measured during lactation and pregnancy. It was found that BMC increased during the dry period and decreased during early lactation. There were great individual variations in BMC, and the skeletal turnover seemed to be great.     

磷肥用量对甜玉米磷素吸收利用的影响

Understanding the phosphorus (P) absorption mechanism is the premise for high P utilization and high crop yield. In this study, the effects of different P rates (0, 37.5, 75, 150, and 300 kg hm^-2, expressed as P0, P1, P2, P3, and P4, respectively) on sweet corn yield, biomass and P accumulation and tissue distribution, P transportation and P utilization were studied using a two-year P gradient positioning field experiment. Our results showed that P application significantly increased the fresh ear yield of sweet corn, but the yield difference among different P application rates (P1-P4) was not significant from 2018 to 2019 compared with P0 treatment. P application significantly increased the biomass and P accumulation of sweet corn plants at jointing, silking and fresh eating stages, respectively. In addition, P accumulation in grain was not significant different, which accounting for 42% of plant P accumulation. With P application, the contribution rate of P assimilation to the ear P accumulation was 57.3%-93.0% after anthesis, while the fresh ear yield per P accumulation, P physiological efficiency, agronomic efficiency, recovery efficiency and partial productivity decreased with P rates. Considering the yield and utilization efficiency of phosphate fertilizer, the supply of 37.5 kg hm^-2 of phosphate fertilizer can meet the needs of high yield and efficient utilization of phosphate fertilizer in sweet corn in this experiment.     

Biochemical study of resistance to imidacloprid in B biotype Bemisia tabaci from Guatemala

Systemic uptake bioassays using excised cotton leaves confirmed resistance to imidacloprid in a Guatemalan population of the tobacco whitefly Bemisia tabaci Gennadius. Polyacrylamide gel electrophoresis of naphthyl esterases identified the insects as B-types. Upon collection from the field, resistance was determined to be 58-fold relative to a susceptible strain originating in the Imperial Valley of California. Resistance levels increased to 126-fold in this population during its continuous exposure to systemically treated cotton. In biochemical investigations, there was no detectable NADPH-dependent mixed function oxidase metabolism of 14C-imidacloprid at any time during the selection process. In contrast, microsomal preparations from housefly abdomens readily produced significant amounts of the mono-hydroxy and olefin derivatives of the parent compound. Detoxification of imidacloprid by housefly MFOs may account for reports of lower toxicity of the insecticide towards this insect compared with whiteflies, despite similar binding properties between imidacloprid and the nicotinic acetylcholine receptors in both species.     

The Effects of Replacing Dicalcium Phosphate with Busumbu Rock Phosphate on Performance and the Mechanical Properties of Bone in Growing Chicks

Three hundred, day-old broiler chicks, with an average initial weight of 41.8±1.79 g, were used in a 15-day study (10 birds per battery cage) to characterize their performance and fluorine status when dicalcium phosphate (DCP) was replaced by Busumbu rock phosphate (BRP) as the source of phosphorus in the chicks' ration. The treatments comprised a standard ration with BRP replacing 0, 25%, 50%, 75% or 100% of DCP. Replacing DCP with BRP significantly reduced the final weight of the chicks (p<0.01), feed intake (p<0.01), weight gains (p<0.01) and dry matter digestibility (p<0.05) but increased (p<0.05) the feed-to-gain ratio. True phosphorus absorption and the percentage of phosphorus in the tibia were not affected by increasing amounts of BRP in the diet. Increasing levels of BRP in the diet linearly reduced (p<0.01) the percentage bone ash, calcium, Ca:P ratio, ultimate breaking force, bending moment, stress, and modulus of elasticity. Leg stiffness, lameness, reduced feed intake, and a decline in general health were recorded in 10–40% of the chicks on 75% and 100% BRP, respectively. These results suggest that excessive ingestion of fluorine from the BRP caused the reduction in the chicks' performance.     

日粮色氨酸水平对生长猪的氮利用效率、血浆类胰岛素生长因子-I、生长激素及胰岛素的影响

本试验旨在研究日粮色氨酸水平对生长猪的氮利用率以及对血浆类胰岛素生长因子-I(IGF-I)、生长激素(GH)、胰岛素浓度的影响。试验以4头大白去势公猪作为试验动物,以色氨酸含量分别为1.2、1.7、2.2和2.7g/kg的4种日粮为试验处理,按照4×4拉丁方进行试验设计。结果表明,色氨酸水平对干物质消化率、有机物消化率和氮消化率没有显著性影响(P>0.05)。氮沉积和氮的生物学利用率随着日粮色氨酸水平由1.2提高到1.7、2.2和2.7g/kg而显著提高(P<0.05),但是试验处理1.7、2.2和2.7g/kg之间的氮沉积和氮的生物学价值没有显著差异(P>0.05)。不同处理之间的血浆IGF-I、GH和胰岛素浓度没有显著差异(P>0.05)。日粮色氨酸水平和血浆IGF-I、GH或胰岛素浓度之间以及氮沉积和血浆IGF-I、GH或胰岛素浓度之间均无显著的相关关系(P>0.05)。综合以上结果,日粮色氨酸水平对生长猪的氮沉积具有显著影响,而对血浆IGF-I、GH和胰岛素没有显著影响。