苹果叶幕大小对产量的影响

以6个苹果品种为试材,进行苹果的有效负载面积与产量相关性试验.结果表明:在一定条件下,有效负载面积(EBS)越大,产量相应越高.不同纬度对不同品种的EBS和产量的影响不同.土壤中砾石含量对EBS和产量都有影响,但品种和砧木不同,EBS的减少率不同.不同品种对砾石的耐受能力不同.     

黄土高原人工草地的土壤水分动态及水土保持效益研究

通过９年观测，黄土高原人工草地土壤水分的季节性变化可划分为三个阶段，在此基础上模拟不同人工草地土壤水分的变化规律；随着牧草生育期的延长至第９年，人工草地土壤水分恢复程度逐渐减弱；沙打旺生存能力极强，能够高效地利用深层土壤贮水；用数学模型可以模拟不同人工草地的水土流失，将植被因子引入水土流失方程，可以定量描述对水土流失的影响；反映植被、土壤等因子与水土流失关系的复合因子Ａ￣１值，基本上代表不同人工草地水土流失状况。     

甘肃秦王川灌区土壤盐分特征及次生盐渍化预测

在秦王川灌区水文地质条件和土壤盐分含量特征调查研究的基础上,采用有限差分法建立了预测模型,对灌溉实施后1～5年间地下水位及其埋深变化进行了预测。结果表明,地下水位呈普遍抬升趋势,可导致约2000ha土地产生次生盐渍化。如果不及时采取防治措施,土壤次生盐渍化面积还会进一步扩大。     

Detection and characterization of Clostridium species in soil of Zambia

In the retrospective study of soil-borne diseases of cattle in Zambia, malignant edema and blackquarter were widespread. One hundred and sixty-five cases with malignant edema and 103 cases with blackquarter were reported between 1985 and 1997. It was found that specific soil-conditions associate the emergence of the soil-borne diseases. Soil samples from five areas in Zambia were examined for the presence of genus Clostridium. Direct immuno-fluorescent assay (IFA) examination showed that C. septicum, C. novyi and C. chauvoei were detected in the soil of specific areas in Zambia, respectively. Causal organisms such as C. perfringens were isolated from the soil samples. The information of area-specific distribution of Clositridium species may give an efficient program in protecting cattle and man.     

滩羊尿对典型草原三种草地植物生长的短期作用特性

研究了不同尿液浓度和土壤含水量下，羊尿对典型草原植物茵陈蒿、委陵菜和狗尾草生长的短期作用特性。结果表明，不同施尿量施尿后1个月，狗尾草对羊尿沉积的响应为高尿液浓度负效应，低尿液浓度正效应；茵陈蒿和委陵菜为负效应。土壤含水量越高，羊尿对其分蘖（枝）的负效应越低。不同尿液浓度下，三种植物对羊尿响应的负效应顺序为茵陈蒿〉委陵菜〉狗尾草；且其分蘖（枝）对羊尿和土壤水分互作反应的正效应顺序为狗尾草〉委陵菜〉茵陈蒿。具体放牧过程中，可通过家畜适时饮水降低尿液浓度，以降低畜尿对草地的负效应。     

Allelopathic potential of watermelon tissues and root exudates

Allelopathic potential of watermelon in hydroponic culture was investigated using the continuous root exudates trapping system (CRETS). Laboratory bioassays and high-performance liquid chromatography (HPLC) were used for quantification of phytotoxins in different plant tissues and root exudates collected using XAD-4 resin. Seedling growth of both watermelon and lettuce was significantly inhibited by watermelon root exudates and the degree of inhibition increased with increasing concentration of exudates. Root exudates had inhibitory effects throughout the experiment and these were most pronounced during the period 41–50 days after transplanting. Inhibitory effects of various plant tissues were demonstrated using the bioassay tests. Frulic acid was the dominant component found using HPLC and the amounts of allelochemicals found in the plant extracts were correlated with the bioassay results using the Petri dish test. The results indicate that the allelopathic potential of watermelon may play an important role in the phenomenon referred to as ‘soil sickness’.     

丝茅入侵对高羊茅根系及土壤性状的影响

针对南方地区丝茅(Imperata koenigii (Retz.) P. Beauv.)入侵对冷季型草坪造成严重危害的实践生产问题,通过模拟高羊茅(Festuca arundiacea L.)草坪建植时丝茅入侵形成的混生群落,连续测定群落中根长密度、根干重密度和根体积密度等根系性状指标,土壤容重、土壤含水量及pH等土壤性状指标,分析丝茅入侵对高羊茅草坪根系及土壤性状影响的动态变化。结果表明:丝茅入侵对高羊茅草坪根长密度、根干重密度和根体积密度均有极显著影响(P<0.01);丝茅入侵60 d起影响根长密度,90 d起影响根干重密度,150 d起影响根体积密度;侵入持续时间对高羊茅根系指标影响排序为根体积密度>根干重密度>根长密度;丝茅对草坪分层土壤的含水量、容重和pH均有极显著影响(P<0.01);入侵60 d起首先影响高羊茅根系主要分布的10~20 cm层的土壤性状,影响逐渐向上、向下扩展;持续时间对土壤性状的影响排序为土壤含水量>容重>pH;丝茅入侵使高羊茅根系分生和更新能力下降,使其根系分布土壤层的含水量降低、透气性变差、酸度增高,从而降低高羊茅根系活性与吸收能力,使其竞争力降低而逐渐退化。本试验结果将为草坪中丝茅的防治提供基础数据。     

High concentration of extracellular ATP causes autophagy and apoptosis of SH-SY5Y cells

AIM：To examine the effects of high concentration of extracellular ATP on human neuroblastoma SH-SY5Y cell injury. METHODS：Cultured SH-SY5Y cells were grouped according to the concentrations of ATP and treatment time. The cell viability was detected by CCK-8 assay. The variation of autophagic vacuoles was observed with monodansylcadaverine staining. The cell apoptosis was analyzed by Hoechst 33258 staining. Meanwhile, apoptotic rate was detected by flow cytometry. The levels of caspase-3 and microtubule-associated protein 1 light chain 3-Ⅱ (LC3-Ⅱ) were determined by Western blotting. RESULTS：Compared with control group, the survival rate of SH-SY5Y cells was significantly reduced by ATP at different concentrations (3, 6, 9, 12 and 15 mmol/L for 3 h) and different treatment time (1, 2, 3 and 6 h with 6 mmol/L ATP, peaking at 3 h). The autophagic vacuoles of SH-SY5Y cells were significantly increased at 1 h with ATP treatment, trended to decrease over time and returned to control level at 6 h. The protein expression of LC3-Ⅱ was significantly increased at 1 h with ATP treatment, which was consistent with the time points of increasing autophagic vacuoles. LC3-Ⅱ expression level gradually decreased at 2~3 h with ATP treatment, and returned to control level at 6 h. Compared with control group, the apoptotic rate and the expression level of caspase-3 were enhanced synchronously. The peak of apoptotic rate occurred at 3 h, and kept until 6 h.The level of cleaved caspase-3 expression peaked at 6 h. CONCLUSION：High concentration of extracellular ATP induces the autophagy and apoptosis of SH-SY5Y cells. The increased autophagy shows up, followed by the climax of apoptosis until 6 h. With the prolonged duration of ATP, apoptosis is the main process in the cells.     

阳城县土壤肥力动态监测分析及改良措施

将阳城县 70个土壤肥力动态监测点 1994年的情况与 1984年全国第二次土壤普查结果进行对比分析。结果 ,全县耕作土壤的速效养分含量有所提高 ,但有机质和全氮含量下降。今后应在加强农田水利基本建设的基础上 ,增施有机肥 ,纠正以往重氮轻磷或轻氮偏磷的倾向 ,采取重氮保磷与补钾的措施。并应大力推广平衡配套施肥和施用新型生物菌肥、生物肥料等技术 ,采取用养结合的措施 ,提高土壤肥力     

太阳能土壤加热系统在西瓜反季节栽培中的应用

研究了太阳能土壤加热系统对反季节栽培西瓜的影响.研究结果表明,太阳能土壤加温系统能够增强植株长势,提高西瓜产量和品质,特别是当散热管埋在距地面35 cm处时效果最好.