苗木抗旱性综合评价研究——以6种喀斯特造林树种苗木为例

为了评价不同喀斯特苗木的抗旱能力,并建立一个简便、适用的林木抗旱评价指标体系,笔者利用水力结构理论,研究苗木的水势、水力结构、保水力和苗木耗水量等一系列相关参数,探讨苗木的吸水潜能、水分运输与分配效率、保水能力和耗水强度等4个方面的差异,并综合评价不同苗木的抗旱能力,并比较了“隶属函数法”和“多维空间坐标综合评定值累加法”2种不同的苗木抗旱性评价方法。结果表明：应用隶属函数累加法对6种树种苗木的综合抗旱性进行评价,研究结果为：香樟>滇柏>侧柏>刺槐>构树>杜英。且不同树种苗木不同水分运转过程对树种抗旱性的贡献率不同;应用多维空间坐标综合评定法对6种苗木抗旱性的综合评价,其结果为：刺槐>侧柏>香樟>构树>滇柏>杜英。在被评价树种数量较少的情况下,采用多维坐标综合评价法适用性更好。     

油棕叶片4种微量元素含量季节性变化影响研究

选取丹那拉变种(E.guineensis.var.tenera)的成龄树作为研究对象,在2007-2011年间,研究了油棕叶片铁、锰、铜、锌4种微量元素含量在不同季节的变化情况。发现油棕叶片铁含量明显受到季节性影响,冬、春季节含量明显高于夏、秋季节,周年的平均含量为129.05mg/kg,平均变化幅度为55.0mg/kg。油棕叶片锰含量明显受到季节性的影响,冬、春季节含量明显低于夏、秋季节,周年的平均含量为142.8mg/kg,平均变化幅度为25.7mg/kg。研究发现铁锰之间表现出相反的季性变化规律,两者之间存在明显的拮抗关系。油棕叶片的铜、锌含量,虽然也受到一定的季节性影响,但没有表现出明显的规律性,铜的周年平均含量为5.62mg/kg,变化幅度为1.23mg/kg,锌的周年平均含量为19.7mg/kg,变化幅度为2.1mg/kg。     

3种不同代表年份下石羊河流域环境因子对蒸发渗入变化的影响研究

为了揭示石羊河流域蒸发渗入的变化规律,基于LG-I 型大型称重式蒸渗仪,对3 种不同代表年份和不同季节背景下不同环境因子对蒸发渗入变化的影响进行分析研究。通过比较各项环境因子与蒸渗的相关性,结果表明,各项环境因子对蒸渗影响的程度为：降水＞气温＞相对湿度＞风速。降水对蒸渗变化的影响最直接,两者相关性较高,其他3 项因子间接影响蒸渗变化。且降水最多年份蒸渗与各项环境因子的相关性高于其他年份,各个季节中夏季蒸渗与各项环境因子的相关性高于其他季节。     

Feature and risk identification of super karst water burst in deeply buried karst tunnel

With the acceleration of tunnel construction, emerging issue of high-pressure karst water burst becomes more and more complex, and the study subject of analyzing and grasping its features and taking effective risk control measures is still a world-class long-standing puzzle. Based on the feature analysis of the karst water burst disaster during the construction of karst tunnels at home and abroad, the special water burst accompanied with high pressure water burst, earth burst and rock burst is defined as super karst water burst. With the analysis of super karst water burst which happened in Maluqing Tunnel of Yi-Wan Railway, five basic characteristics of super karst water burst are obtained, and its risk sources are also identified from the respects both of geology and human engineering activities. Based on the theoretical analysis, numerical simulation and on-site engineering experience, several threshold conditions for the occurrence of super karst water are identified. In response to implementation plan of risk identification, the method of advanced horizontal drilling with drainage test and closed water test is also proposed.     

Relationships between leaf morpho‐anatomy,water status and cell membrane stability in leaves of wheat seedlings subjected to severe soil drought

The impact of the genotype‐specific leaf morphological and anatomical characteristics on the ability of wheat plants to preserve leaf water balance and cell membranes stability under drought stress was investigated. Seedlings of six modern semi‐dwarf (carriers of Rht, Reduced height genes) and six old tall bread wheat varieties were subjected to soil drought by withholding watering for 6 days. Morpho‐anatomical traits (leaf area, perimeter, thickness, stomata and trichome density) of daily watered (control) plants were characterized by light microscopy, scanning and image analyses. The leaf water status in both control and stressed plants was determined by measuring the relative water content (RWC). The leaf cell membranes stability in stressed plants was estimated by conductometric determination of the membranes injury index. On average, the modern semi‐dwarf varieties had less leaf area and leaf perimeter, and less dissection index, a parameter characterizing the leaf shape. Under drought stress, the modern genotypes maintained better water balance evidenced by significantly higher leaf RWC and better‐preserved the cell membranes stability supported by significantly lower Injury index. The correlations between morpho‐anatomical traits in control plants and drought tolerance‐related traits showed that the higher the leaf dissection index (i.e. more oblong leaves), the greater the water loss and the leaf membrane damages after desiccation were. The effect of shape of the evaporating surface on the water loss was modelled using wet filter paper. Similar to plant leaves, the evaporation and, respectively, water loss from paper pieces of more oblong shape (i.e. higher dissection index) was more intensive. The elucidation of the impact of the leaf shape on transpiration might contribute to better understanding of the mechanisms used by plants to maintain water reserves during drought stress and could be a basis for developing of simple and fast screening methods aiding the selection of drought tolerant genotypes.     

Genotypic Variability in Drought Performance and Recovery in Cowpea under Controlled Environment

Mid‐season drought is a factor frequently limiting crop production in the moist to dry savannah zones of the tropical and subtropical regions of the world. Ten cowpea genotypes were subjected to a cycle of drought at flowering followed by re‐watering to study variation in drought performance and recovery. Drought caused a reduction in leaf assimilation rate, transpiration rate and stomatal conductance with genotypic variances of 75.4, 57.9, and 83.3 %, respectively. Only genotypic variance in stomatal conductance increased appreciably under drought. Reductions in leaf water potential as a consequence of drought positively correlated with a decline in assimilation rate, which was associated with stomatal closure. One week after re‐watering, the three gas exchange parameters of stressed plants recovered fully and attained values 10–30 % higher than the well‐watered plants with increased genotypic variability. Reductions in the total dry matter during the drought interval varied from 11 to 50 % among genotypes, but were of minor importance for the total dry matter at maturity. After stress, the gain in dry matter varied considerably among the stressed genotypes, with stressed plants showing higher gain than the unstressed plants during this interval. This was associated with increased availability of assimilates due to enhanced green leaf area duration after stress release. Variability in drought recovery among genotypes was found, and appears to be more important for final yield than responses during drought.     

Water-Sensitive Periods during the Reproductive Growth Phase of Glycine max L. I. Regression Model for estimating daily leaf water potential

To establish the exact duration of critical periods for plant water stress during the reproductive growth stage of soybeans it is necessary to draw correlations between daily leaf water potential values and crop growth and yield. Different sets of daily leaf water potential values can be induced by different sets of irrigation applications. It is, however, imperative that water stress values are available for each day over the growing season of a large number of irrigation treatments. Since these values were not available, it was decided to calculate it by establishing a relationship between leaf water potential as determined by potential evapotranspiration and soil water content as well as soil water potential for various layers of the root zone. The most reliable regression formula was found to be:      

Water Relations and Transpiration of Quinoa (Chenopodium quinoa Willd.) Under Salinity and Soil Drying

Drought and salinity are the two major factors limiting crop growth and production in arid and semi‐arid regions. The separate and combined effects of salinity and progressive drought in quinoa (Chenopodium quinoa Willd.) were studied in a greenhouse experiment. Stomatal conductance (g_s), leaf water potential (Ψ_l), shoot and root abscisic acid concentration ([ABA]) and transpiration rate were measured in full irrigation (FI; around 95 % of water holding capacity (WHC)) and progressive drought (PD) treatments using the irrigation water with five salinity levels (0, 10, 20, 30 and 40 dS m^?1); the treatments are referred to as FI₀, FI₁₀, FI₂₀, FI₃₀, FI₄₀; PD₀, PD₁₀, PD₂₀, PD₃₀, PD₄₀, respectively. The measurements were carried out over 9 days of continuous drought. The results showed that increasing salinity levels decreased the total soil water potential (Ψ_T) and consequently decreased g_s and Ψ_l values in both FI and PD. During the drought period, the xylem [ABA] extracted from the shoots increased faster than that extracted from the roots. A reduction in Ψ_T, caused by salinity and soil drying, reduced transpiration and increased apparent root resistance (R) to water uptake, especially in PD₀ and PD₄₀ during the last days of the drought period. The reasons for the increase in apparent root resistance are discussed. At the end of the drought period, the minimum value of relative available soil water (RAW) was reached in PD₀. Under non‐saline conditions, Ψ_l decreased sharply when RAW reached 0.42 or lower, but under the saline conditions of PD₁₀ and PD₂₀, the threshold values of RAW were 0.67 and 0.96, respectively. In conclusion, due to the additive effect of osmotic and matric potential during soil drying on soil water availability, quinoa should be re‐irrigated at higher RAW in salt‐affected soils, i.e. before the soil water content reaches the critical threshold level causing the drop in Ψ_l resulting in stomatal closure.     

栽培稻叶结构、水分生理与抗旱性关系研究

摘 要：增强栽培稻品种的抗旱性是稻作节水生产的重要途径。稻作种质资源抗旱相关指标的研究是改良稻作品种抗旱性的重要依据。选择抗旱性差异明显的四种类型稻作种质,采用三种干旱胁迫方式,对孕穗期植株叶片的叶肉厚、中脉粗、叶片相对含水量及叶片保水率进行了考察,分析稻作种质在三种处理下各性状相互之间的内在关联及其与品种抗旱性的关系;结果表明叶肉厚、中脉粗、叶片相对含水量及叶片保水率在干旱胁迫下均表现为旱稻类型高于水稻类型。轻度干旱下的叶肉厚与成熟期生物量抗旱指数DRIm2-B极显著相关,与孕穗期生物量抗旱指数DRIm2-H显著性相关。重度干旱下的中脉粗与DRIm2-B极显著相关,重度干旱下的叶片保水率与重度干旱产量抗旱指数DRIm2-Y显著相关,中脉粗和叶片相对含水量在四种种质类型中差异不明显;孕穗期叶肉厚和叶片保水率可分别作为稻作种质抗旱性研究和评价的两个指标。     

三种槭树抗旱性研究

以采自湖南衡阳的三个槭属树种五裂槭（A. oliverianum）、中华槭（A. sinense）、长柄槭（A. longipes）的幼苗为材料,通过盆栽干旱胁迫,以正常浇水处理为对照,对不同干旱胁迫下的部分生理生化指标进行了测定。结果表明,在干旱胁迫下,3种幼苗的生理生化指标变化趋势基本一致,但变化程度因树种而异。运用坐标综合评定法对3个树种幼苗抗旱能力的初步评价结果表明,长柄槭幼苗的综合抗旱能力最强,中华槭次之,五裂槭较差。从而为北方地区引进园林绿化树种提供依据。     

Functional contribution of two perennial grasses to enhance pasture production and drought resistance under a leaf regrowth stage defoliation criterion

Lolium perenne L. (Lp) is the main pasture species in New Zealand, but climate change increases the likelihood of drought during summer and consequently lowers its growth rates. Bromus valdivianus Phil. (Bv) tolerates better the summer soil water restriction, but its competitiveness in a diverse pasture relates to the defoliation management and soil moisture levels. The performance of both species in terms of production, persistence and feed quality across seasons under different defoliation regimens was evaluated when the species were mixed and in monoculture. The treatments were applied in a randomised complete block design with three blocks. Bromus valdivianus and Lp monocultures and the 50/50 mixture (Mx) were grazed at low and high defoliation frequencies (i.e. based on Bv and Lp optimal leaf regrowth stage [LS], respectively). Herbage mass production was 15% higher in the Mx, mainly due to an increase in production in spring and summer. In spring, there was complementarity growth between the species, while during summer/early autumn, the Mx production relayed in the higher participation of Bv. Root biomass at depth (31–70 cm) was 38% greater for Bv monoculture and the Mx compared with Lp monoculture, which demonstrated the contribution of Bv to a better production of the mixture during and following the dry periods. In addition, the maintenance of the Bv tiller population and the higher growth rate during dry periods demonstrated its better fitness to low soil water availabilities than Lp. Although herbage mass was not modified by the defoliation frequency, forage quality of Bv showed values at low defoliation frequency that could compromise animal production during spring. However, there was an increase in root biomass under low defoliation frequencies, which suggested that a flexible grazing management across seasons would increase the niche utilisation between species in the mixture. The defoliation frequency of the mixture could be based on Lp LS during spring and winter, and slowed down, following Bv criteria, during summer and autumn.     

Characterization and Quantification of Water Stress in Wheat by Soil-Induced Plant Components

Measurements of transpiration rate (TR), leaf diffusive resistance (LDR), leaf water potential (LWP), and canopy minus air temperature (Tc-Ta) were made over four differentially irrigated plots of wheat grown at Pantnagar. The data were analysed to workout functional relationships between these plant parameters. Correlation studies yielded low values of correlation coefficients 'r'. The plotting of the data also showed wide scattering around the lines. For removing the variability of shoot environment the whole data were normalized by subtracting the values of well irrigated (unstressed) plants from the values of the stressed plants. The plotting of normalized data showed close linear relationships. The regression analysis of normalized data provides highly significant correlationships of TR Vs LDR, TR Vs LWP, TR Vs Tc, TR Vs Tc-Ta and Tc-Ta Vs LDR. It indicates that normalization of plant parameters for environmental variability is required in order to better quantify crop responses to soil water deficit.