若干禾本科牧草在荒漠草原区的适应性及其生产性能和营养价值评价

于2000-2004年,采用小区试验法研究了来源于中国、美国和加拿大的23个禾本科牧草材料在内蒙古高原锡林郭勒盟苏尼特右旗小针茅荒漠草原的适应性、产草量和营养价值。结果表明:内蒙沙芦草、沙生冰草、沙芦草、蒙古冰草新品系、新麦草P2、新麦草P3和错行新麦草的越冬率大于80%,生产性能好,根量大,水平根幅大,垂直入土深,粗蛋白含量高,可作为荒漠草原地区推广种植的优质牧草。     

松嫩草原羊草与其主要伴生种竞争与共存研究

基于对松嫩草原优势物种羊草(Leymus chi-nensis)及其主要伴生种的空间分布格局、植物种间关系对割草的响应,以及羊草、芦苇(Phragmites communis)对营养和胁迫的适应性与种间关系的研究,探讨了植物竞争和共存的潜在机制。     

Molecular genetics of the adrenocortical axis and breeding for robustness

The concept of robustness refers to the combination of a high production potential and a low sensitivity to environmental perturbations. The importance of robustness-related traits in breeding objectives is progressively increasing toward the production of animals with a high production level in a wide range of climatic conditions and production systems, together with a high level of animal welfare. Current strategies to increase robustness include selection for "functional traits," such as skeletal and cardiovascular integrity, disease resistance, and mortality at various stages. It is also possible to use global evaluation of sensitivity to the environment (eg reaction norm analysis or canalization), but these techniques are difficult to implement in practice. The glucocorticoid hormones released by the adrenal cortex exert a wide range of effects on metabolism, the cardiovascular system, inflammatory processes, and brain function, for example. Protein catabolism toward energy production and storage (lipids and glycogen) supports their pivotal role in stress responses aiming at the adaptation and survival of individuals under strong environmental pressure. Large individual variations have been described in adrenocortical axis activity, with important physiopathological consequences. In terms of animal production, higher cortisol levels have negative effects on growth rate and feed efficiency and increase the fat:lean ratio of carcasses. On the contrary, cortisol has positive effects on functional traits and adaptation. Intense selection for lean tissue growth and more generally high protein output during the past decades has concomitantly reduced cortisol production, which may be responsible for the negative effects of selection on functional traits. In this paper, we review experimental evidence suggesting that the balance between production and functional traits was modified in favor of improved robustness by selecting animals with higher adrenocortical axis activity, as well as the molecular genetic tools that can be used to fine-tune this objective.     

Altitudinal and longitudinal variations in Pinus brutia (Ten.) of Crete Island,Greece: some needle,cone and seed traits under natural habitats

Four populations representing the entire natural distribution range of Pinus brutia (Ten.) in Crete (Greece) were sampled to determine: (1) Altitudinal variation within populations of Lassithi, Vorizia, Koustagerako, and Samaria, and; (2) Longitudinal variation among the four populations, based on morphological and anatomical differences in cone, needle and seed characteristics. Samples were collected from 10 trees per altitude, at three altitudes in each population. A total of 12 morphological and anatomical traits from needles, cones and seeds were analyzed to assess the altitudinal and longitudinal variations of the species in the island. The number of teeth per cm showed significant (P<0.01) differences between altitudes in Samaria, Vorizia and Lassithi, while needle length, width and the number of resin canals showed significant differences (P<0.01) between altitudes in Koustagerako. Cone width showed patterns of variation along the altitudinal gradient in Koustagerako, Samaria and Vorizia. Most traits had their highest means at the middle altitudes (650masl) in all the four populations. Overall, no clear altitudinal differentiation was detected, probably due to high rate of gene flow. Longitudinal variability showed a clear pattern of differentiation along the east–west climatic gradient. Needle length, width, sheath length, number of teeth per cm and the number of resin canals were the most useful traits for determining the climatic gradient clines.     

Foliar traits of jasmine plants intercropped in coconut

Shade is one of the important limiting factors in intercropped agro-ecosystems. Objective of this work is to analyze the role of eight foliar traits of juvenile plants of five different species of Jasminum grown under coconut shade. The results reveal the shade tolerant J. pubescence to produce more number of nodes and longer shoots in all the three seasons studied. J. grandiflorum produced longer leaves and internodal distance than other species tested. Winter season shoots were longer with more number of nodes and longer internodal distances than rainy season. Results are discussed in relation to the adaptive behavior of plants to shade.     

Walnut demonstrates strong genetic variability for adaptive and wood quality traits in a network of juvenile field tests across Europe

Adaptive and wood quality trait data were collected and analyzed on commercially available Juglans regia and J. regia×J. nigra provenances and progenies planted across Europe in a multi-site network. A total of 19 seed sources, replicated 35 times per site, were planted at 13 sites from 5 European countries, encompassing the potential distribution area of timber production plantation sites. The following traits were evaluated: survival, height, diameter at breast height, stem form, apical dominance, vegetative budbreak, along with biotic and abiotic damage. Mean values were significantly different both among provenances/progenies and sites. Most common damage was late spring and early autumn frost. Bud break ranking was significantly correlated with provenance and progeny origin. Although J. regia is fast growing, southern European early budbreak plant material should not be planted under most middle European conditions where late spring frost can be expected, as it has a significant negative impact on architectural (and thus wood quality) traits. Hybrid J. regia×J. nigra progeny performed better than J. regia provenances/progenies for most traits measured. Differences were significantly in favor of hybrids at sites with medium to low fertility, although some locally selected seed sources tended to perform as well as hybrids on high fertility sites.     

Stress Reactivity and Coping in Horse Adaptation to Environment

“Coping” or “coping strategy”, defined as the behavioral and physiological efforts of animal to master the situation, is more and more in interest of researchers dealing with applied animal behavior and welfare. Knowledge about “coping styles” may be helpful in understanding individual adaptive capacity to stressful events. At least two types of animal coping strategy (or coping style) can be involved: (1) active copers (proactive) and (2) passive copers (reactive). The individual differences in stress response to threatening situations have been found in horses, and these animals can show specific coping strategies such as other species. This article reviews the set of behavioral, psychoneuroendocrine, and psychoneuroimmune mechanisms involved in animal adaptation to environmental challenges and discusses the relationship between behavioral and physiological factors involved in stress response of the horse. Exploring coping strategies in horses and in any captive animal can be successful when a multidimensional approach including behavioral, neural, hormonal, and hematological measures is considered. Knowledge on stress coping styles can provide valuable information to predict the behavior of individuals during response to specific challenging situations. Moreover, assessing individual differences in adaptation strategies can be useful in horse selection to different exploitation tasks and reproduction.     

The impact of climate change on maize yields in the United States and China

This study analyzes the impacts of climate change on maize yields using an econometric model that incorporates climate, economic, and technology variables. The major finding is climate change will not universally cause negative impacts of maize yields in the United States and China. The results of a simulation of climate change on maize yields over the period 2008-2030 show that a combination of changes in temperature and precipitation can either bring positive or negative effects on maize yields. Furthermore, variation in regional climatic and economic conditions makes the impacts of climatic change on maize yields substantially different in different regions. In this research, the impacts of climate change on maize yields are not simply examined by climate factors. Economic and technology adaptation effects on maize yields are also incorporated. Thus, even with significant changes in climate conditions that alter the maize crop’s growing environment and affect crop yields, a decrease in maize supply due to a decrease in maize yields would lead to an increase in the maize price, which in turn would induce farmers to add more investments in production inputs to raise yields. Thus, the decrease in actual yields may not be as dramatic as predicted in only climate factor considered cases. In this research, findings gained from the study can be used for early-staged policymaking decisions and advanced problem prevention programs. To ensure the continuous increase in maize yields in the future, further studies and research, as well as efficient environmental policies and actions are required.     

Ecophysiological and genetic variation in seedling traits and in first-year field performance of eight <Emphasis Type="Italic">Acacia senegal</Emphasis> provenances in the Blue Nile,Sudan

The genetic variation in seed weight, seed number per kg and seedling traits was compared among eight Acacia senegal provenances originating from the clay plain (east) and sand plains (west) of the gum belt in Sudan. The main objective of this study was to identify germplasm sources of A. senegal that have a good seed germination capacity and seedling traits suitable for reforestation in the clay-soil part of the dryland gum belt in the Blue Nile region in Sudan. A specific objective was to tentatively explore the adaptive strategy of A. senegal populations. Seventeen-week-old seedlings were planted in the field at spacing of 3 m × 3 m, giving 100 trees per plot and replication; within a randomized complete block design with four replications. The experimental site was in the clay plain region. Seed variables showed significant differences. Clay plain provenances showed considerable variation in seed weight and seed number. They had the smallest seed weight but the highest seed number, while the sand (western) provenances had the largest seed weight but lowest seed number. Seedling branch number, root length, root to shoot ratio and shoot dry weight differed significantly among the provenances 12 weeks after germination. Clay provenances had the highest branch number and shoot dry weight but the shortest roots and lowest root to shoot ratio. This was interpreted as showing better adaptation to the site in these local provenances in comparison to those originating from the western sandy soil regions. High positive correlations were observed between seedling variables, such as root nodule and branch numbers; this could be used for early selection. The variation was greater between provenance groups than within them, suggesting that especially selection among groups would yield genetic gain.     

欧亚温带草原东缘生态样带研究探讨

为揭示全球变化与欧亚温带草原东缘生态系统的关系,提出沿着从中国长城至俄罗斯贝加尔湖设置一条经向样带,主要表征欧亚大陆东缘经向热量梯度,反映受大陆性气候控制下的草原地带的生态系列.沿样带开展生物地球化学过程、能量交换、植被结构动态、气候—植被、放牧—草地—牧草驯化、土地利用格局与管理、模型模拟等研究工作,对于加深气候变化和人为影响对草原生态系统的发生、发展、利用及演变规律的影响的认识,增强对气候变化的减缓和适应能力,具有非常重要的意义.