Structure and species richness in wetland continua on sandy soils in subtropical and tropical Australia

Net photosynthetic fixation of wetland plant communities is confined to the period of the year when the surface soil is not waterlogged and is thus well aerated. In the open‐structured vegetation continuum across freshwater wetlands on sandy soils in subtropical and tropical Australia, the sum of the foliage projective covers (FPCs) of the overstorey and understorey strata remains constant, while that of the overstorey decreases to zero as seasonal waterlogging (and anaerobic conditions) in the surface root systems increases. Density and height of the overstorey trees – of only one or two species – and species richness (number of species per hectare) in the understorey decreases along this waterlogging gradient. Melaleuca paperbark trees, possessing surface roots with cortical aerenchyma, may form a closed‐forest at the edge of the wetland continuum wherever there is a continuous flow of aerated water. As global warming progresses, an increase in air temperature in the atmosphere flowing over and through the wetland continuum during the short period of annual foliage‐growth will affect the combined FPCs of overstorey and understorey strata, as well as the leaf‐specific weights of all leaves throughout the plant community. With a reduction in net photosynthetic fixation, species richness of the plant community will slowly decline.     

残茬覆盖与耕作方式对夏玉米叶片衰老代谢和籽粒产量的影响

对小麦机械收获后残茬覆盖与不覆盖两种条件下免耕、翻耕和播种行深松3种土壤耕作方式的夏玉米开花后叶片衰老生理特性和籽粒产量进行了研究。结果表明,残茬覆盖和深松耕作的玉米叶片SOD和POD活性提高、MAD含量降低、叶绿素和可溶性蛋白质含量高、降解速度慢,维持了叶片后期较高的生理功能。最终开花后干物质生产量和玉米籽粒产量表现为：覆盖显著高于不覆盖,深松显著高于翻耕和免耕,残茬覆盖与深松结合效果最好。     

Anthropometric Indices and the Incidence of Hypertension: A Comparative Analysis

Objective: To investigate the association between several anthropometric measurements of obesity with the incidence of hypertension. Research Methods and Procedures: Participants were 592 individuals free of hypertension, selected at random from the community. In the baseline evaluation, they were submitted to completed measures of demographics, anthropometrics, blood pressure, and other risk factors for hypertension. Incident hypertension was defined by blood pressure equal or higher than 140/90 mm Hg or use of blood pressure‐lowering drugs. Results: During a mean follow‐up time of 5.6 ± 1.1 years, 127 developed hypertension. The hazard ratios for the development of hypertension, adjusted for age, baseline blood pressure, gender, and alcohol consumption, were 1.042 (p = 0.091) for BMI, 1.023 (p = 0.028) for waist circumference, 1.042 (p = 0.013) for waist‐to‐height ratio, 1.061 (p = 0.014) for waist‐to‐height² index, 1.079 (p = 0.022) for waist‐to‐height³ index, and 1.033 (p = 0.006) for the waist‐to‐hip ratio. Discussion: The correction of the circumference of waist for stature or hip circumference improves its performance in the prediction of the incidence of hypertension.     

Weight and Height Growth Rate and the Timing of Adiposity Rebound

Objective: Adiposity rebound occurs when the ratio of the velocities of log(weight) to log(height) changes from <2 to >2. This study examined the timing of adiposity rebound in the context of the velocities of weight and height in early childhood because it is not known whether faster weight gain or slower gain in stature is the more important determinant. Research Methods and Procedures: This was a longitudinal study of 406 boys and 397 girls born in Dunedin, New Zealand, in 1972 and 1973. Each child's height and weight were measured at 3 years of age and at least twice more as part of their two yearly assessments until 11 years of age. Results: The mean age of adiposity rebound was 6.6 ± 1.10 years (SD) for boys and 6.0 ± 1.21 years for girls. After adjusting for sex, the correlations between the timing of rebound and z‐scores for BMI, weight, and height at rebound were ?0.35, ?0.30, and ?0.14, respectively. Correlations between the timing of rebound and estimated values of weight and height velocities at 3 years were ?0.48 and ?0.00. The correlations with BMI and waist girth at 26 years were ?0.39 and ?0.35. Discussion: Children with an earlier adiposity rebound were heavier and had above average BMIs. Early rebound is the result of higher rates of weight gain, measured in percentage terms, rather than slower than average accrual of stature. This suggests that restraining weight gain could delay adiposity rebound and prevent obesity in early adulthood.     

辣椒株高遗传分析

以辣椒矮秆自交系B9431（P1）和高秆自交系‘吉林长椒’（P2）为双亲,构建P1、F1、P1、B1、B2和F2 6个家系世代群体,应用植物数量性状主基因＋多基因混合遗传模型对该6个世代群体株高进行多世代联合分析,结果显示：株高遗传符合1对主基因＋多基因遗传模型,高秆对矮秆表现为不完全显性,F1代株高的势能比值为0．39,显性程度为0．91。B1、B2和F2群体主基因遗传率分别为20．35％、17．20％和35．29％,多基因遗传率分别为5．08％、19．75％和0;主基因效应表现为负向加性效应,其值为-6．43,显性效应为0;多基因加性效应值和显性效应值分别为-8．89和9．77。研究还表明,主基因与多基因间的基因效应存在一定差异,主基因加性效应值相当于多基因加性效应值的72．33％,主基因无显性效应,显性效应是由多基因控制遗传。     

Growth development of a balsam fir (Abies balsamea (L.) Mill.) originating from layering

After a disturbance, balsam fir stands (Abies balsamea (L.) Mill.) regenerate primarily by seedlings, but layering is also known to occur and to contribute to the subsequent population base. We examined in detail the lower part of one balsam fir stem, stump and roots in order to: reconstruct the establishment of one mature balsam fir with evidence of layer-origin. The life history of this tree was then reconstructed by measuring tree-ring widths, dating all the sections, and by identifying the presence or absence of pith to differentiate between stem and root structures. We located a pith structure in this tree 51 cm below ground level. This lowest section with pith was characterized by a diameter of only 3 mm and contained 40 concentric tree-rings, suggesting that it originated from a branch. Radial and height growth measured were small until the beginning of 1930s. This period was abruptly followed by an increase in growth in both height and diameter as well as a massive production of adventitious roots, probably produced by partial harvesting of the parent tree/stand.     

Patterns of morphological and genetic diversity of Valeriana jatamansi Jones in different habitats and altitudinal range of West Himalaya,India

Importance to know and understand diversity of Himalayan plants is increasingly recognized considering the fact that various natural and anthropogenic pressures might bring about serious influences to morphological and genetic diversity of the vegetation in the region. In this context, Valeriana jatamansi was investigated in detail, taking into account its importance in various Ayurvedic and modern medicines. Randomly selected mature plants from twenty five different populations (located between 1215 m to 2775 m asl) of V. jatamansi were analysed for their morphological attributes. Further, ISSR markers were used to detect genetic variation among 151 plants of selected 25 populations. Use of 20 primers yielded 125 reproducible polymorphic loci which were used to estimate different parameters of genetic diversity. These parameters were in turn applied to develop relationships with habitat types and altitude range. Significant variation (p < 0.05) in above ground dry weight (AGDW) and below ground dry weight (BGDW) across the populations was observed. Nei's genetic diversity index (He) ranged from 0.25 to 0.37 across the populations, with a mean of 0.31. Genetic diversity exhibited a decreasing trend with increasing altitude, and maximum diversity (He = 0.325) was observed in the range of 1201–1500 m asl. Among the different habitat conditions, highest genetic diversity (He = 0.334; Pp = 84.38) was observed in grassland habitats while minimum in mixed forest habitats (He = 0.285; Pp = 72.433). The genetic diversity (He) had significant negative relationships with AGDW, BGDW and rhizome diameter (Pearson r = −0.359, −0.424 and −0.317, respectively; p < 0.05). The genetic characterization of V. jatamansi from the western Himalaya by this study suggests influences of habitat types and the altitudinal range upon genetic diversity, and based on these proposals for conservation strategies in favour of the species are made.     

MECHANICAL ANALYSIS OF THE ROUNDHOUSE KICK ACCORDING TO HEIGHT AND DISTANCE IN TAEKWONDO

Competition regulation in taekwondo has experienced several changes during the last few years, for example, kicks to the head score more points than kicks to the chest. In addition, some external factors such as the height of target and execution distance seem to affect the kick performance. The aim of this study was to analyse selected biomechanical parameters (impact force, reaction time, and execution time) according to the height and execution distance in two different male groups (experts (n = 12) and novices (n = 21)). Athletes kicked twice from every execution distance (short, normal and long) and towards two different heights of target (chest and head) in a random order. Novices kicked to the head with a longer reaction time than to the chest (p < 0.05) but experts were able to kick with similar performance for both heights. From short and normal distances experts kicked with similar performance; whereas from the normal distance novices had longer reaction and execution time than from the short distance (p < 0.05). In conclusion, in counterattacking situations, experts should perform the roundhouse kick to the head instead of to the chest, because it produces better scores with similar performance; whereas novice athletes should avoid kicking to the head because they are not able to kick with similar performance. Moreover, it is recommended that during counterattacks higher-level taekwondo athletes should intend to kick from normal distances.