Effect of seed manganese content on the growth of wheat (triticum aestivum) under manganese deficiency

Summary The importance of seed manganese (Mn) content for seedling growth of two wheat cultivars under soil Mn deficiency was demonstrated in growth cabinet experiments. Seed was obtained from different field sites (giving a Mn content range of 0.1 to 6.4 μg Mn seed⁻¹), as well as from soaking seed in MnSO₄ prior to sowing. Seed soaking greatly increased the seed Mn content, however, only about 15–20% of this additional Mn was recovered in the seedlings after 26 days growth. In these experiments, the seed rather than the soil provided the major source of plant Mn. Manganese critical deficiency levels (CDLs) were also obtained for leaves, shoots and roots. Increased grain yields from seed soaking were also evident in the field.     

Effect of manganese deficiency on growth and chlorophyll content of algae with and without hydrogenase

Summary Algae without hydrogenase, i.e., Chlorella vulgaris and Chl. saccharophila, become rapidly chlorotic under manganese-deficient conditions, in agreement with the reaction of higher plants. By contrast, the chlorophyll of algae which contain hydrogenase, i.e., Chlorella fusca (=pyrenoidosa), Chl. vulgaris f. tertia (=Chl. III), Ankistrodesmus braunii, and Scenedesmus obliquus, is much more stable in the absence of manganese.     

艾氏剂对连续三个世代多刺裸腹溞生命表统计学参数的影响

利用生命表技术对连续3个世代暴露于不同浓度(20、40、80、160、320μg/L和640 μg/L)艾试剂(aldrin)溶液中的多刺裸腹溞(Moina macrocopa)生命表统计学参数进行了研究.结果表明:艾试剂对3个世代多刺裸腹溞所有生命表统计学参数均有显著性影响(P<0.05).与空白对照组相比,浓度高于80 μg/L的艾氏剂使多刺裸腹溞母代的生命期望和净生殖率显著降低;浓度高于160 μg/L的艾氏剂使母代的世代时间显著缩短,种群内禀增长率显著降低.浓度高于40 μg/L的艾氏剂使多刺裸腹溞F1代的生命期望显著缩短,20μg/L和80～640 μg/L的艾试剂使F1代的净生殖率显著降低,320μg/L和640 μg/L的艾氏剂使F1代的世代时间显著缩短,所有浓度的艾试剂均使F1代的种群内禀增长率显著降低.160～640 μg/L的艾氏剂使多刺裸腹溞F2代的生命期望和世代时间显著缩短,160 μg/L和640 μg/L的艾氏剂使F2代的净生殖率显著降低;除40和320 μg/L外,所有浓度的艾试剂均显著提高了F2代的种群内禀增长率.在实验设置的艾试剂浓度范围内,除F2代种群内禀增长率外,3个世代多刺裸腹溞的所有生命表统计学参数均与艾试剂浓度呈曲线相关.在慢性毒性试验中,污染物对多刺裸腹溞生命表统计学参数的影响因其暴露时所处发育时期和持续暴露世代数的不同而存在着重要的差异.     

Interaction effects of insecticide combinations on the growth ofScenedesmus bijugatus andSynechococcus elongatus

The interaction effects of insecticide combinations involving an organophosphate (monocrotophos or quinalphos) and a pyrethroid (cypermethrin or fenvalerate) were determined on the growth ofScenedesmus bijugatus (unicellular green alga) andSynechococcus elongatus (unicellular cyanobacterium). In general, an organophosphate and a pyrethroid in combinations interacted additively, antagonistically, and synergistically on the growth of the two phototrophic microorganisms. However, combinations of quinalphos and cypermethrin or fenvalerate yielded additive interaction response in onlyS. bijugatus.     

Effect of competition and adverse culture conditions on aflatoxin production by Aspergillus flavus through successive generations

Strains of Aspergillus flavus often degenerate with serial transfers on culture media, resulting in morphological changes and loss of aflatoxin production. However, degeneration does not readily occur in nature as indicated by the wild-type morphological characters of newly isolated strains and the high percentage of aflatoxigenic A. flavus from soil and crops in some geographic regions. In this study, three aflatoxin-producing strains of A. flavus were serially transferred using conidia for 20 generations (three independent generation lines per strain) on potato dextrose agar at 30 C. The rate of degeneration was compared to that of cultures grown in the presence of competing fungi (A. terreus, Penicillium funiculosum, and the yeast, Pichia guilliermondii) and under adverse conditions of elevated temperature, reduced water activity, low pH, and nutrient deprivation. Formation of morphological variants and the associated loss of aflatoxin production over generations varied considerably according to strain and the generation line within each strain. In the strain most sensitive to degeneration on potato dextrose agar, aflatoxin-producing ability was maintained to varying degrees under adverse culture conditions, but not when A. flavus was competing with other fungi.     

Effects of salinity and cadmium interaction on reproduction and growth during three successive generations ofOphryotrocha labronica (polychaeta)

The long-term effects of different cadmium (0.2 and 0.4 ppm) and salinity levels (30, 25, and 20 ‰ S) on growth and egg-mass production ofOphryotrocha labronica (La Greca & Bacci) were investigated over three generations. Low salinity levels and the presence of cadmium resulted in reduced growth rates, prolonged times to reach sexual maturity, and reduced size at maturity. Three-way analysis of variance showed significant interaction effects of generation and cadmium for the different growth processes tested. Using response-surface methods, 0.2 ppm cadmium was shown to have a greater effect on growth rate at the third generation than the first and second generations at the three salinities tested. Increased effects were observed from first to second generation at 0.4 ppm cadmium and 30 and 25 ‰ S, whereas effects decreased from second to third generation. At 0.4 ppm cadmium and salinity of 20 ‰ the first generation was not able to produce viable larvae.     

Effect of manganese and zinc ions on the growth of Rhizobium

Five strains, representing four species of Rhizobium, were grown in specially purified synthetic culture solutions with manganese or zinc ion concentrations ranging from 0 to 10(-5)m. Omission of Mn(2+) restricted growth to 0.4 to 10% of that of controls, depending on the species. Growth was generally maximum with 10(-6)m Mn(2+) and nearly so with 10(-5)m. Omission of Zn(2+) restricted growth to 1 to 20% of that of controls. Growth was generally maximum with 10(-7)m Zn(2+). The 10(-5)m level of Zn(2+) was toxic to a variable degree to all species, suppressing the growth of one strain of R. meliloti to 49% of that of controls, and of R. phaseoli to only 0.4% of that of controls. A Mn(2+) x Zn(2+) interaction was also obtained as evidenced by a higher apparent Zn(2+) requirement with 10(-7)m Mn(2+) than with 10(-6)m Mn(2+).     

The effect of manganese deficiency and cereal cyst nematode infection on the growth of barley

Summary Two factorial pot experiments, each with four rates of soil-applied manganese (Mn), four levels of cereal cyst nematodes (CCN) and four replicates, were conducted under controlled environmental conditions to investigate the interaction of these factors on growth of barley. The experiments were harvested sequentially to count numbers of nematodes at two developmental stages. Development of the nematodes was independent of the Mn status of the host, indicating no effect of Mn on host resistance. In the absence of CCN, decreased Mn had a small effect on vegetative growth, not significantly decreasing dry weight of tops but tolerance at the higher densities of CCN was considerably reduced at low Mn supply, both vegetative growth and grain yield being depressed. Increasing CCN density exerted little effect on the growth of Mn sufficient hosts. Two field surveys supported conclusions from the pot experiments in that increasing nematode densities were correlated with decreasing plant size only at the site where plants were low in Mn. An implication for the field is that crops infected with the nematode and also low in Mn may yield less than expected because the two factors interact to reduce growth and retard development.     

龟纹瓢虫的捕食胁迫作用对连续三代果蝇发育与繁殖的影响

捕食性天敌不仅直接捕食害虫,而且还能改变害虫的生长发育、繁殖,间接地影响害虫的适合度。以常见模式昆虫黑腹果蝇Drosophila melanogaster Meigen及捕食性天敌龟蚊瓢虫为研究系统,研究龟纹瓢虫Propylea japonica Thunberg连续多代直接捕食胁迫、一代捕食胁迫后下一代不捕食胁迫,对果蝇生长发育、繁殖和适合度的影响。结果表明:如果持续地释放瓢虫对果蝇的捕食胁迫作用,显著缩短了第1代、第2代果蝇的幼虫的发育历期,增加了第1代、第2代果蝇的繁殖量。但在第3代的影响却是延长了果蝇的幼虫的发育历期,降低第3代果蝇的繁殖量。如果在上一代胁迫作用得到释放后,下一代不再有瓢虫胁迫,那么连续2代胁迫后去掉胁迫的果蝇比只胁迫一代后去掉胁迫的果蝇幼虫的发育历期明显延长,繁殖量明显下降,后代性比也明显下降。与连续胁迫条件下的处理相比,成虫的寿命明显延长;对果蝇幼虫的发育历期、繁殖量则没有显著影响。结果表明,龟蚊瓢虫的干扰胁迫作用,可以间接的增加果蝇的适合度,促进果蝇种群的增长,使果蝇种群自我维持、调节到相应的水平。     

On the sulfur-source requirement for growth of Thiobacillus intermedius

Thiobacillus intermedius grows in glucose-mineral salts medium supplemented with any or all of seven reduced organic sulfur compounds but does not grow in the absence of the supplement(s). This growth represents a physiological capability of T. intermedius and does not result from contaminated or mutant cultures. T. intermedius is not capable of assimilating sulfate; exogenous ³⁵SO₄ ^-is not incorporated by T. intermedius growing autotrophically or heterotrophically. The demonstrated need for a reduced sulfur source explains the previously reported inability of T. intermedius to grow in glucose-mineral salts medium.     

Effect of calcium carbonate and organic matter on the growth and concentration of iron and manganese in sorghum (Sorghum bicolor)

Summary The effect of CaCO₃ and organic matter on the availability of iron and manganese was studied on sorghum (Sorghum bicolor). Addition of calcium carbonate caused significant decrease in dry matter and grain yield. But yields tended to increase with the addition of organic matter at the rate of 15 t/ha. The iron concentration decreased with the addition of CaCO₃ at all the stages of crop growth. Like iron, concentration of manganese also decreased with the increase in added CaCO₃. Organic matter increased the iron concentration both at seedling and flowering stage. The concentration of manganese was, however, dependent on the stage of the crop.     

Changes of genetic parameters in successive gynogenetic generations and some calculations for carp gynogenesis

Summary In artificial gynogenesis diploidization of the sperm activated zygote is achieved by retention of the second polar body and by this method perfectly normal and fully viable broods can easily be reared. Studying this form of propagation, we determined the coefficient of inbreeding (F), the fixation index (P) and the degree of genotypic identity (I) introduced for characterizing the isogeneity of gynogenetic populations with the help of the parameters of the probability distribution of meiotic recombination between the centromere and the genes.All three parameters were linear functions of the moments of the distribution of recombination probabilities. The theoretical relationships were investigated in the artificial gynogenesis of the carp.It appeared without exception that the progress of inbreeding made by gynogenesis largely depends on the distribution of the recombination probabilities of the genes. The rate of increase of the F value was more rapid only in the first few generations (2–5) compared to sibmating. The increase of the F value slowed in subsequent generations and fell significantly below the values obtained by sibmating. The degree of genotypic identity (I) is not as sensitive to the type of the distribution of recombination probability. In the case of gynogenesis, the value of I abruptly converges to l much more abruptly than in the case of sibmating.Used alone, gynogenesis does not enable the production of homozygous strains to any great extent. However, partly heterozygous, but isogenic, linea can be rapidly produced.