宁夏地区农村节水系统设计探讨

针对宁夏地区农村居民的生活特点,设计出一套适合宁夏农村地区的节水系统,并在银川的碱富桥村进行示范。通过对节水系统节水率的计算,评价该系统的节水效果。证明实施该节水系统后,该村理论总节水率43.0%,总节水量5.51万m3/a,节水效果明显。由此可知,该节水系统可在宁夏地区乃至干旱地区、半干旱地区推广应用。     

Dynamics of Growth and Water Relations of Fodderbeet and Seabeet in Response to Salinity

A pot experiment was conducted under greenhouse conditions with two subspecies of beet, fodderbeet ( Beta vulgaris cv. Majoral) and seabeet ( Beta maritima ), under saline conditions. Growth and physiological parameters (dry weight, leaf area, water relations and net photosynthesis) were recorded. The two subspecies responded differently in terms of growth parameters. Plant growth was significantly reduced at 400 m m NaCl, while no significant growth reduction occurred at 200 m m NaCl. Fairly high values of relative growth rate were associated with the leaf area of the cultivars. The water content of the shoot decreased with plant age. The fodderbeet cultivar Majoral showed a significant increase in dry matter at 200 m m NaCl after 5 weeks. This growth improvement may be related to the better adaptation of the plants under saline conditions.     

沙地果树水雾微喷灌高效节水技术研究

沙地果树采用水雾微喷灌较大水漫灌节水36.3%;0～20 cm、21～40 cm、41～60 cm土层的土壤容重,水雾微喷比大水漫灌分别降低5.5%、3.0%和1.2%,土壤总孔隙度分别增加8%、2.3%和9.5%;0～20 cm、21～40 cm、41～60 cm土层土壤持水量比大水漫灌分别增加10.9%、17.1%和15.4%;果园中午水雾微喷灌1h后,树下气温从30.7℃降到27.2℃,相对湿度从65.1%提高到75.6%;水雾微喷新梢生长量增加14.0%,树冠投影面积增加14.2%;水雾微喷灌,李子单产与单果重分别增加了22.5%和9.7%,可溶性固型物含量降低2.7%。水雾微喷改善了土壤物理性质,增加了土壤孔隙度,提高了各层土壤持水量,且地表不形成径流,土壤保水保肥作用明显增强。     

Nitrogen Mineralization Characteristics of Disturbed and Undisturbed Soil Samples for Four Main Soil Types on the Loess Plateau

Long-term alternate leaching aerobic incubation was conducted to study nitrogen (N) mineralization in four main soil types under disturbed (D) and undisturbed (UD) conditions from the Loess Plateau (China). Results showed that N mineralization of the UD and D samples decreased from southern to northern Shaanxi Province. Nitrate was the main component of N mineralization during the aerobic incubation for both the D and UD samples. However, net inorganic N in the D samples was less than in UD samples. The average total mineralized N levels were 30% larger for the set of D samples than for the UD samples, and the mineralization potential of the D samples was larger than that of UD samples. Further studies are required to develop predictive methods for quantifying N availability.     

Studies on Mechanisms of Dehydration Postponement in Cassava Leaves under Short-term Soil Water Deficits

Abstract

Cassava (Manihot esculenta Crantz) can produce a high crop yield even in an environment with irregular rains. This is mainly attributed to its abilities to maintain leaf area under drought conditions and rapidly regrow after rain. In this study, we investigated the mechanism of leaf maintenance under water deficits through measurement of photosynthetic rate and water potential changes in leaves. The cassava plants were grown in pots and exposed to water deficits, and the diurnal changes in water potentials, rates of photosynthesis and transpiration and stomatal conductance were measured. The relationship between leaf water potential (ψW) and photosynthetic rate with decreasing soil water, and osmotic adjustment were also investigated. With respect to water supply in leaves, the movement of water in plants was measured using stem heat balance. Under water deficits, photosynthesis occurred only in the early morning. The water loss was reduced by stomatal closure in the mid-day. This was attributed to the complete closure of the stornata during the decrease in ψW to a range between –1.0 and –1.4 MPa. Furthermore, the firm stomatal closure is caused by the consistency of osmotic potential under decreases in soil water, i.e., to a lack of osmotic adjustment. Water stored in the pith parenchyma of stem flowed into leaves in the morning. From these results, we conclude that cassava can consistently maintain an adequate water level in leaves via water storage and the sensitivity of stornata to water deficits, thereby avoiding leaf dehydration.     

Photosynthetic response of white spruce families to drought stress

In the context of climate change, an increased frequency of drought stresses might occur at a regional scale in boreal forests. To assess photosynthetic responses to drought treatment, seedlings of 12 open-pollinated families of white spruce (Picea glauca (Moench) Voss) differing in their growth performance were grown in a controlled environment. Gas exchange and chlorophyll fluorescence parameters as well as shoot xylem water potential (WP) were measured for 21 successive days after watering was stopped. Net photosynthesis decreased as stomatal conductance decreased. Net photosynthesis was not affected by drought until WP reached –2.0 MPa when stomata were closed. Initial fluorescence (F and basic fluorescence after induction (F00) were not affected by drought. A progressive decrease in maximal (Fm) and variable fluorescences (Fv), maximum photosystem II (PS II) efficiency (Fv = Fm), effective quantum yield of PS II (FII), photochemical efficiency of open PS II (Fp), and photochemical quenching (qP) was observed at WP < - 1.0 MPa, whereas non-photochemical quenching (qN) remained high throughout the drought treatment. White spruce families with inferior growth performance showed higher values of Fm, Fv, Fv = Fm, Fp, and qN at WP< - 2.0MPa. The results indicated that chlorophyll fluorescence variables can be used as drought markers in relation to present or predicted climate conditions. These could be used for selecting planting stock adapted to drought periods or dry environments. These markers showed that slow-growing genotypes are better adapted to drought conditions than intermediate or fast-growing genotypes in present and predicted drought conditions.     

Antioxidant and immune potential marker enzymes assessment in the various tissues of rats exposed to indoleacetic acid and kinetin: A drinking water study

In the present study, the influence of two different PGRs, indoleacetic acid (IAA) and kinetin (Kn) on immune potential enzymes, adenosine deaminase (ADA) and myeloperoxidase (MPO), and antioxidant defense enzymes such as glutathione peroxidase (GPx), glutathione reductase (GR), and superoxide dismutase (SOD) in various tissues of rats were investigated during the treatment as a drinking water model. 100 ppm of IAA and Kn as drinking water were administered orally to rats (Sprague-Dawley albino) ad libitum for 21 days continuously. The PGRs treatments caused different effects on the immune potential and antioxidant defense enzymes of experimented rats compared to controls. Results show that IAA caused a significant decrease in GR activity in the lungs and liver and an increase in the spleen. Also, IAA caused a significant decline in GPx activity in the lungs and an increase in the heart. SOD was significantly reduced in the heart, while increased in the lungs. Furthermore, IAA caused a significant decrease in ADA activity in the heart and blood whereas an increase in the kidney and spleen. MPO activity was also significantly increased in the heart by IAA treatment. The activity of enzymes were also seriously affected by Kn; GR activity decreased in the lungs, brain, and blood while GPx activity decreased in the spleen, brain, and heart. ADA activity was also significantly reduced in the blood whereas MPO activity rose in the spleen. In addition, SOD activity lowered in all tissues except for lungs where a significant increment was determined. As a conclusion, the results indicate that PGRs might affect on antioxidant and immune potential enzymes. These data, along with the determined changes suggest that PGRs produced substantial systemic organ toxicity in the erythrocyte, liver, brain, heart, lungs, spleen, and kidney during the period of a 21-day subacute exposure.     

Water status,leaf area and fruit load influence on berry weight and sugar accumulation of cv. ‘Tempranillo’ under semiarid conditions

Berry weight (BW) and sugar concentration (SC) are relevant indices in viticulture since they can be easily measured and, when considered together, give a relatively fair estimation of grape quality. This work aims to evaluate the influence of water availability, leaf area and fruit load on BW and SC, estimating the relative importance of these factors. Leaf area (LA), berry number (BN), yield (YLD), water potential in summer (ψ_pd-s), BW and SC were measured in 16 and 17 ‘Tempranillo’ vineyards in 1999 and 2000, respectively. In all the vineyards, according to local practices, the irrigation amount decreased as summer progressed. The study vineyards comprised a broad range of situations concerning leaf area, fruit load and water status in summer. Average leaf water potential in summer and LA/BN ratio, when considered together, estimated properly BW (R² = 0.91; P < 0.001) and, in a similar way, ψ_pd-s and LA/YLD ratio estimated SC (R² = 0.74; P < 0.001). The relative weight of ψ_pd-s in both relationships was much higher than that of any of the LA:fruit ratios, showing that, under semiarid conditions, water availability plays the main role in regulation of berry growth and sugar accumulation and, therefore, the highest attention should be paid in these areas to irrigation management, seeking the degree of stress that allows optimizing the combination of yield and berry quality in each situation.     

小鼠胚胎玻璃化冷冻保存及保存时间对其体内外发育率的影响

本试验采用乙二醇为主体的ＥＦＳ４０玻璃化溶液,对小鼠扩张囊胚实行二步法玻璃化冷冻保存。结果保存１小时、１年和２年的胚胎,在体内外的发育率无显著性差异（Ｐ＞０．０５）。与对照组相比较也无显著性差异（Ｐ＞０．０５）。     

用酯酶同功酶分析白僵菌的林间扩散能力

在林间人工放菌和挂笼防治光肩星天牛试验的基础上，分离受感染的光肩星天牛白僵菌菌株，对分离的菌株用电泳法进行酯酶同工酶酶谱分析，用聚类分析法对不同分离株进行分类．并进一步分析白僵菌在林间的扩散和交叉感染作用。结果发现：在50m范围内，白僵菌可以有效地感染目标害虫，显示出较强的林间扩散能力和病害流行潜力。