Antimicrobial activity of Psidium guajava L

Psidium guajava aqueous bark and methanolic extracts were found to possess anti-bacterial activity.     

The occurrence of Thysanosoma actinioides Diesing, 1834 (Cestoda: Anoplocephalidae) in a Najdi Camel in Saudi Arabia

The fringed tapeworm Thysanosoma actinioides was recovered from the liver of a Najdi camel (Camelus dromedarius) slaughtered in central Saudi Arabia. T. actinioides is recorded for the first time as a parasite of old world camels.     

An outbreak of neurofilariosis in young goats

An outbreak of cerebrospinal microfilariosis in 23 kids, representing a whole kid crop, occurred on a farm in Qassim, Central Saudi Arabia. The morbidity and mortality rates were 100%. Clinical signs, in kids from the fourth to sixth week of age, manifested as weakness in the hind legs followed by incoordination of movement and feet dragging. Seven to ten days later, the hind legs were completely paralyzed, and within a week the front legs were also paralyzed. The animals continued to feed, drink and suckle normally, and were in good health. Paralyzed kids were helped to suckle by the farm attendants. With time, loss of control of motor functions occurred and the ability to hold the head in upright position was lost, ability to eat or drink was lost. The infected kids health deteriorated and they eventually died. Two dead kids were postmortemed. With the exception of a meningeal haemorrhage seen in one kid, no obvious macroscopic lesions were seen in any of the autopsied animals. Histopathological examination of the spinal cord and brain showed different microfilaria of different sizes between the meninges and the nervous tissue. This indicated that development of the parasite occurred in the nervous tissue. The larger microfilaria contained black deposits, most likely to be digested blood, in their guts. It is likely that the parasites are haematophagus. The main lesions caused by the microfilaria were migratory traumatic haemorrhagic tracts in the spinal cord and the brain. These sometimes contained parts of the microfilariae. In the brain malacic lesions and sporadic aggregates of lymphocytes were also noted.     

Comparing micrometeorology of rain forests in Biosphere-2 and Amazon basin

Micrometeorological variables measured in the BIOSPHERE-2 Center (B2C) enclosed rain forest biome for 1 year were compared with similar measurements made in the Amazon rain forest. In the B2C rain forest, the overlying glass and supporting structure significantly reduces (by approximately a factor of two) the incoming solar radiation. Monthly mean values of above-canopy and within-canopy air temperature, vapor pressure, and vapor pressure deficit are reasonably similar to those of the Amazon rain forest, but there are marked differences in the above-canopy values of these variables in the Arizona summer. Monthly mean diurnal trends also show significant differences. Measurements of vertical air temperature gradient clearly showed two very distinct environments in the 27.4 m high rain forest dome during daylight hours. There is a comparatively cool and fairly well-mixed environment (which is reasonably similar to that found in a natural rain forest) below about 10 m and a hot, thermally stable environment above about 15 m. The nature of the atmospheric turbulence within the B2C rain forest also is significantly different from that normally found in natural rain forests. There is little turbulent mixing above the forest canopy in this enclosed environment. These findings are important for guiding the operation and use of this experimental rain forest facility in future research and for understanding how the rain forest biome functions in an enclosed environment.     

Effect of tillage and contour diking on sorghum establishment and yield on sandy clay soil in Sudan

Sandy clay soils locally known as gardud are less arable despite their better production potential than other infertile and exhausted sand soil in western Sudan due to surface physical constraints such as low infiltration and workability. Field experiments were, therefore, conducted on these soils to determine effect of two relatively new tillage systems to the area and two widely practised systems on soil bulk density, porosity, water storage and sorghum (Sorghum bicolor L.) plant growth and yield. Contour diking at specified spacings was superimposed on the four tillage treatments for impounding surface runoff. These systems were (1) chisel ploughing, (2) broadbed and furrow, (3) ridge-furrow, and (4) traditional no-till (control). Distances of the contour diking were at four levels: zero, 5, 10 and 20 m. Soil bulk density, porosity and water content were significantly affected by the different tillage systems and contour diking. Combined analysis of three successful seasons out of five seasons showed that plant establishment and growth were highly significant. Yield component data (percent of plants reaching physiological maturity, grain and straw) indicated significant differences among treatments tested for the three seasons of the experiment. The 3-year mean grain yield for chisel plowing pooled over the four contour diking distances produced 1448 kg/ha which was greater by 72%, 107% and 384% than broadbed and furrow, ridge-furrow and no-till, respectively. Similarly, the 10-m contour-diking-distance mean grain production (917 kg/ha) over the tillage systems was 16%, 5% and 30% for more than zero, 5-m and 20-m distances, respectively. These results indicate that chisel and 10-m contour diking are appropriate and suitable for gently sloping compacted sandy clay soils of western Sudan, and superior to widely practised ridge-furrow and no-till surface configuration.     

人工诱发条件下玉米自交系对红蜘蛛的抗性鉴定及抗感性分类

在人为控制和创造有利于玉米红蜘蛛发生、又能基本满足玉米正常生长发育需要的条件下,以来自国内外的74个重要玉米自交系为材料,进行了玉米自交系对红蜘蛛抗性的人工诱发鉴定。结果表明:不同的玉米自交系对红蜘蛛的抗性差异很大,其受害指数为0.06~0.91;叶片平均受害面积百分率与受害指数呈极显著正相关(r=0.97,P0.000 01)。这些自交系以其受害指数为基础,通过聚类分析划分为高抗、抗、中感、感和高感5个类群;自交系受害指数在类群间[高抗(0.11±0.02),抗(0.22±0.04),中感(0.35±0.03),感(0.49±0.05),高感(0.75±0.10)]差异极显著(P0.01)。在参试自交系中,ZH4改-1、BSSSS53-B、Q381等20个高抗红蜘蛛,KS2564、B47、1028S等19个抗红蜘蛛,掖478、冀35、PH6WC等18个中感红蜘蛛,郑58、B73、丹340等12个感红蜘蛛,昌7-2、B107、SK59、GNS12059和Mo17-476等5个高感红蜘蛛,其中,Mo17-476对红蜘蛛表现为易感。     

玉米抗螨性的大棚人工诱发鉴定与评价分析

利用大棚条件,在人为控制和创造既能满足玉米正常生长发育,又能促使叶螨发生的条件下,进行了玉米抗螨性的鉴定,并以各自交系的受害指数(DMI)和受害面积比率(DMR)为基础采用聚类法和DMR-直观法划分玉米对叶螨的抗感性。结果表明:DMI、DMR和叶螨结网面积比率(SWR)分别为0.06~0.91、1.12%~93.98%和14.10%~99.50%间,其最高值分别是最低值的15.17、83.91和7.06倍;3者间呈极显著正相关(P0.01)。在2种聚类中,参试自交系均分为抗(占52.70%)和感(占47.30%)两大类群及高抗(占27.02%)、抗(占25.68%)、中感(占24.32%)、感(占16.22%)和高感(占6.76%)等5个亚类群;各类群间的DMI和DMR都存在极显著差异(P0.01)。基于DMI和DMR聚类分析划分的类群及亚类群中所包含的自交系种类及其数量都一致,自交系的抗感划分结果相同。与此相比,基于DMR值直观划分玉米对叶螨的抗感性,抗性自交系数量(占78.38%)偏多、抗性偏高。在参试自交系中,BSSSS53-B、9F592、K10-14-1和铁7922的DMI(0.10)、DMR(≤3.00%)和SWR(20.00%)都最小、抗螨性最强,而GNS12059和Mo17-476的DMI(0.75)、DMR(80.00%)和SWR(98.00%)都最大、抗螨性最弱;其中,Mo17-476对玉米叶螨最为敏感。     

Effects of consecutive applications of gypsum in equal,increasing, and decreasing quantities on soil hydraulic conductivity of a saline‐sodic soil

The objective of this study was to determine the effects of consecutive application of gypsum dissolved in leaching water on hydraulic conductivity of a saline‐sodic soil. Drainage type plastic columns with a 10 cm diameter were used in this laboratory experiment. Soil depth within columns was 30 cm with an average bulk density of 1.38 g cm^–3. Leaching water was applied in six equal portions. Total gypsum was applied at 1, 3, and 5 portions after dissolving in leaching water. In dissolution, equal (1.273 + 1.273 + 1.273 Mg ha^–1), increasing (0.637 + 1.273 + 1.910 Mg ha^–1) and decreasing (1.910 + 1.273 + 0.637 Mg ha^–1) quantities of gypsum were used. Results were compared with the control treatment, in which total amount of gypsum were mixed with surface layer of soil column before leaching. Hydraulic conductivity of soil increased in all treatments. The maximum hydraulic conductivity value was obtained at consecutive application of gypsum at decreasing quantities.