Plant viruses in irrigation water: reduced dispersal of viruses using sensor-based disinfection

The increasing use of recirculating nutrient solutions and drainage water for irrigation purposes requires effective sanitation methods to minimise the dispersal of plant pathogens. Among these, plant viruses are of particular interest because they cannot be cured. A new disinfection system was tested in regard to its ability to inactivate plant viruses in nutrient solution in greenhouses. Potassium hypochlorite produced onsite by an electrolytic disinfector and injected once weekly into the nutrient solution by a sensor, prevented the dispersal of Pepino mosaic virus in the tomato crop. The management program assures that virus particles released from infected plants do not accumulate, forming an infectious virus reservoir which represents an inoculum potential in the hydroponic system. Both tested applications at 0.2 or 0.5 mg free chlorine/l nutrient solution for 60 or 30 min ensured virus inactivation and did not cause phytotoxicity. The yield of tomato plants grown in KCIO-treated nutrient solution was even significantly higher than that of control plants. PepMV-infected source plants solely bore unmarketable tomatoes showing discoloration. By inhibiting the dispersal of PepMV and the infection of test plants, the amount of unmarketable tomato fruits was reduced rigorously in treated variants.     

Einfluß der VA-Mykorrhiza auf P-Aufnahme und Regenerationsfähigkeit von Mais (Zea Mais L.) unter Wasserstreß

Influence of the VA-Mycorrhiza on P uptake and recovery potential of corn (Zea mays L.) under water stress conditions In a seven week pot experiment the influence of the VA-Mycorrhiza on P uptake and water stress tolerance of corn was investigated. During the eight day water stress period the VAM-plants took up less phosphorus than the control plants. However, during the successive five day recovery period under a normal water regime the VAM-plants showed an increased root growth and an enhanced phosphorus uptake compared with the control plants. The free prolin concentration was lower in leaves of VAM-plants than in those of nonmycorrhizal plants at the end of the water stress period, pointing to a different water stress tolerance.     

挪威云杉林枯枝落叶层元素浸提量的研究

对取自德国Solling的挪威云杉林的不同枯枝落叶层样品进行了一系列浸提实验,结果表明,枯落物分解程度、水∶物的比值和浸提液pH值都是元素浸提的主要控制因素.多数阳离子的浸提受到H+交换机制的很大影响,较低的pH值会导致较高的浸提量;而较高的pH值和稀释作用导致的pH值升高会导致较低的浸提量.在水∶物的比值增加到某一数值之前,水∶物的比值增加会导致浸提液内元素浓度与枯落物元素含量的新平衡,并导致浸提量增大.另外一方面,水∶物的比值增加导致的pH值升高会成为新的限制因素,导致较低的浸提量,尤其对于2、3价阳离子.这两种作用机制的复合效应使浸提量与水∶物的比值的关系曲线非常复杂.建立了森林枯枝落叶层元素含量(T, μmol(+)·kg-1)、浸提液pH值、水∶物的比值(W,kg·kg-1)对元素浸提量(Y,μmol(+)·kg-1枯落物)影响的数学模型.对Na+、K+,Ca2+、Mg2+、Mn2+、Al3+和Fet,模型为Y=A+(T-A)·exp(-B·pH)/[1+C·exp(-W)];对H+,模型为Y＝a+bW c.对严重酸化的枯枝落叶层元素的浸提,不存在所期盼的最优水∶物的比值.水∶物的比值较低时,元素浓度比值变化较大;在水∶物的比值较高时,元素数量比值变化较大.但对严重酸化的枯枝落叶层元素进行浸提时,可把各枯枝落叶层的饱和含水量作为一个折中的水∶物的比值.挪威云杉林枯枝落叶层的未分解层、半分解层、全分解层的饱和含水量分别为3.4、3.2、2.0 kg·kg-1.     

Nonspecific esterase and naphthol-AS-D-chloroacetate esterase in monocytoid and myeloid cells of healthy cattle and cattle suffering from leukosis]

The reaction to non-specific esterase can be used for the identification of the monocytoid cells of the periphery. A negative reaction is exhibited by neutrophile and eosinophile leucocytes and erythrocytes. Varying results are obtained from lymphocytes, rendering it impossible to use this method in the group of lymphoid cells of the periphery or marrow. In the group of large marrow cells (promonocytes), non-specific esterase gave a very strong reaction; this applies both to the marrow of healthy cattle and cattle suffering from leucosis. For the time being, efforts to use this reaction for the solution of the problem of the differentiation of monocytoid cells and cells of similar size in the myeloid series of the bone marrow have not been successful. In neutrophile leucocytes of the periphery, naphtol-AS-D-chloroacetate esterase gives a less intensive reaction than in humans. For this reason, it is less suitable for the differentiation of these cells. Other cell types (eosinophile leucocytes, monocytes, lymphocytes, erythrocytes as well as their bone-marrow stages) give a negative reaction. In the group of large marrow cells of the myeloid series (promyelocytes and neutrophile myelocytes), naphtol-AS-D-chloracetate esterase shows a more intensive reaction in healthy cattle, as compared with cattle suffering from leucosis.     

蛋氨酸和蛋氨酸羟基类似物对猪的生物学效价

蛋氨酸缺乏日粮中添加DL-蛋氨酸和液体蛋氨酸羟基类似物增加了仔猪和生长猪的氮沉积，明显改善了仔猪的生产性能，这表明试验结果是在蛋敏感区域内测得。液体蛋氨酸羟基类似物对猪的相对生物学效价只有DL-蛋氨酸的65%，远低于液体蛋氨酸羟基类似物88%的商业含量。这些结果再次验证在家禽的研究结果，即液体蛋氨酸羟基类似物相对DL-蛋氨酸的效价只有65%。因此，液体蛋氨酸羟基类似物对猪的生物学效价只有65%。     

Hemostatic Disorders in Feline Immunodeficiency Virus-Seropositive Cats

The hemostatic function of 40 feline immunodeficiency virus (FlV) seropositive and 8 FIV and feline leukemia virus (FeLV) seropositive cats was evaluated and compared with reference values from 30 clinically healthy cats. The FIVpositive cats were divided into 3 groups: group I included asymptomatic carriers; group II comprised sick FIV-infected cats with illnesses not likely to influence the hemostatic system; and group III included FIV-positive cats with diseases potentially associated with coagulopathies. Platelet counts in FIV/FeLV-infected cats were significantly lower than in healthy cats (P < .003), whereas the differences in the 3 groups of FIV-positive cats were variable (group I, P= .009; II, P= .05; III, P= .09). Thrombocytopenia (< 145,000 platelets/μL) was present in 4 FIV-positive and 3 FIV/FeLV-positive cats. Platelet aggregation induced by collagen (0.5 and 0.25 μg/mL), adenosine diphosphate (ADP) (1 and 0.6 μmol/L), and thrombin (0.4 and 0.25 IU/mL) was not significantly different from that of healthy cats. The plasma coagulation system was evaluated by measuring one-stage prothrombin time (OSPT), activated partial thromboplastin time (APTT), thrombin time, fibrinogen concentration, coagulation factor assays, fibrinogen and fibrin degradation products (FDP), and plasma exchange test. The OSPT was similar in FlV-seropositive cats and in the healthy control group. Cats with FIV infection, however, had markedly shorter clotting times than healthy cats when using a modified test system (P < .05). In all groups of FIV-infected cats and in those with FIV/FeLV infection, APTT measured with 2 different commercially available tests, and a modified plasma assay was markedly prolonged compared with healthy cats (APTT1 and 2:3 modification: P < .01; APTT2: P < .05 except group III). In 22 of 40 cats with FIV and in 5 of 8 cats with FIV/FeLV infection, plasma samples were beyond the reference range. The thrombin time was also significantly prolonged in cats with FIV and FIV/FeLV infection (P < .01); values in 17 of 40 FIV-positive cats were above reference range. The mean fibrinogen concentration of cats with FIV and FIV/FeLV infection was higher than in the healthy control group (P < .001). Factor VIII activity of 4 cats with FIV infection was 1.5 times higher than that of healthy cats. Factor XII activity of 3 cats from a group of 20 cats with prolonged APTT was between 20% and 35%. Factor IX and XI activities ranged between 70% and 120%. The markedly prolonged APTT in 2 FIV-positive cats could be shortened considerably in a plasma exchange test using 20% feline pooled plasma. The alterations in the coagulogram of FIV-seropositive cats were not related to a clinical stage or concurrent diseases. A definite explanation of the distinct disorder within the intrinsic plasma coagulation system in FIV-infected cats was not found.