培养液化学成分变化及其对水培茶树生长的影响

水培过程中营养液中的ＮＨ＿４－Ｎ浓度下降伴随ＮＯ＿３－Ｎ浓度提高，培养过程中溶液活性Ａｌ含量下降，ｐＨ值降低并非活性Ａｌ浓度提高所致，培养液加Ａｌ对ｐＨ下降有缓冲作用。茶树根系分泌物中有咖啡因和儿茶素类物质，利用培养过茶树的营养液再次培养茶苗，即使通过添加速效Ｎ、Ｐ、Ｋ保持其营养水平，茶树生长仍然受到抑制。据此推断，茶树根系分泌物中的咖啡因和儿茶素类物质具有异株克生作用。     

Ni/Al2O3-MxOy催化剂催化松香氢化反应研究

研究了自制非贵金属纳米催化剂Ni/Al2O3-MxOy催化松香的氢化反应。结果表明,松香氢化的最适工艺条件为:反应温度210℃、反应压力4.5 MPa、反应时间2 h、催化剂用量2.5%、搅拌转速500 r/min,在此条件下枞酸转化率可达98%以上,催化剂可重复使用4次。     

Hormonal changes during meiotic maturation and ovulation in the brook trout (Salvelinus fontinalis)

The plasma levels of estradiol-17 (E2), 17, 20-dihydroxy-4-pregnen-3-one (17,20-P) and gonadotropin (GTH) were measured in brook trout (Salvelinus fontinalis) during the period from the end of vitellogenesis to postovulation. Blood samples were taken according to specific stages of maturation, including germinal vesicle breakdown (GVBD) and ovulation. E2 levels were quite high (45 ng/ml) at the end of vitellogenesis (and prior to GVBD) and dropped precipitously by GVBD (2 ng/ml). They remained low through ovulation and postovulation. 17,20-P levels were low prior to GVBD (0.7 ng/ml) and increased dramatically at GVBD (148 ng/ml). The levels of 17,20-P remained high at ovulation (142 ng/ml) and then dropped significantly within 24 h to approximately half of the ovulatory values. They decreased even further by 7 days postovulation. GTH levels rose gradually through GVBD and ovulation from a postvitellogenic level of approximately 3 ng/ml to a 7 day postovulatory value of approximately 10 ng/ml. The overall results; 1) decrease in estradiol prior to GVBD, 2) increase in 17,20-P at GVBD and 3) gradual GTH rise through GVBD and ovulation, are similar to those reported for other salmonids.     

Hypophagic and dipsogenic effect of the 5‐HT1A receptor agonist 8‐OH‐DPAT in broiler chickens

The effects of the 5‐HT_1A receptor agonist 8‐OH‐DPAT on food and water intake in male broiler chickens were investigated. The injection of 25 or 50 μg/kg of 8‐OH‐DPAT 15 min before refeeding in fasted animals produced a decrease in food intake. No effect was observed in drinking. The injection of 25 or 50 μg/kg of the 8‐OH‐DPAT 60 min after the start of refeeding did not produce any significant modification in food intake. No effect on drinking was recorded. The agonist 8‐OH‐DPAT injected 15 min before water presentation in water‐deprived chickens, produced an increased drinking 60 min after the presentation of water. No effect on food intake was observed. The results show that the effect on food intake of the agonist 8‐OH‐DPAT in fasted–refed broiler chickens was similar to those observed in mammals and layer‐strain chickens. However, the agonist did not alter significantly the food intake when the broilers were fed 60 min before the injection. These results are contrary to the observed effects in mammals and in layer‐strain chickens. Probably, the selection for rapid growth rate in broilers causes modifications in the feeding control pattern. The comparison between broilers and layers strain may be a useful tool to elucidate the complex mechanisms involved in food and water intake regulation in chickens.     

粗厚山羊草细胞质对普通小麦耐盐性的遗传效应

以具有粗厚山羊草(Aegilops crassa 6x)细胞质的异源细胞质小麦为材料，采用加盐培养基进行幼穗愈伤组织诱导(生长)、盐溶液种子发芽、盐溶液幼苗培养和戍株模拟盐池生长等方法研究了粗厚山羊草细胞质对小麦耐盐性的遗传效应，旨在为小麦耐盐育种提供理论依据和种质资源材料。结果表明：粗厚山羊草细胞质对小麦的耐盐性具有明显的遗传效应，其效应值的性质、大小与核亲本品种的基因型有关，在特定的核质组合中粗厚山羊草细胞质可明显提高小麦的耐盐性。异质系Ae.crassa 6x-鉴26和Ae.crassa 6x-SMH1694在幼穗愈伤组织诱导、种子发芽阶段和三叶期的耐盐性比相应核亲本明显增强。返青期和成熟期的鉴定结果表明，一些经核基因型改良的粗厚山羊草细胞质小麦的耐盐性超过或接近抗盐对照品种科遗26。进一步研究粗厚山羊草细胞质提高小麦耐盐性的遗传机制，必将拓宽小麦耐盐育种途径。     

Adjustment of soil-surface pH and comparison with conventional fungicide treatments for control of lettuce drop (Sclerotinia minor)

The use of soil-surface applications of finely powdered calcium hydroxide (Ca(OH)₂) to inhibit Sclerotinia minor sclerotial germination and infection at the collar region of lettuce plants is described. In the laboratory, a pH > 8·0 reduced sclerotial germination of the three S. minor isolates tested. In the glasshouse, surface applications of 2–10 t Ca(OH)₂ ha⁻¹ raised the pH of the top 1–2 cm of a duplex sandy loam soil above 8·5 for at least 8 weeks without affecting soil pH within the transplant root zone. There was a linear relationship between the rate of Ca(OH)₂ applied and disease control, with complete disease suppression at 10 t Ca(OH)₂ ha⁻¹. In field trials on two soil types (duplex sandy loam, pH 6·0; and red ferrosol, pH 6·9), a rate of 2·5 t Ca(OH)₂ ha⁻¹, maintained soil-surface pH above 8·5 for 1–3 weeks and provided up to 58% reduction in lettuce drop. Application of polyvinyl alcohol (a soil-conditioning polymer) over the Ca(OH)₂ layer appeared to reduce Ca(OH)₂ loss by wind, but did not improve retention of raised soil-surface pH or disease suppression. Ca(OH)₂ treatment gave similar disease control to the industry standard treatment of a procymidone-based fungicide seedling drench. A combined treatment of Ca(OH)₂ and fungicide drench gave greater control than either individual treatment, and equivalent control to fungicide drench and three procymidone foliar sprays, offering integrated management options. The use of soil-surface-applied Ca(OH)₂ with fungicides, rotation and drip irrigation offers an opportunity for enhanced and sustainable control of lettuce drop.     

Aluminum inhibition of NADH‐linked electron transfer by corn root plasma membranes

Vesicles enriched in right‐side‐out plasma membranes were isolated from corn roots by a modified two‐phase partition method. Using reduced nicotinamide adenine dinucleotide as electron donor, isolated vesicles were capable of reducing both ferricyanide and oxygen. At pH 6.0, the presence of Al inhibited both reduction processes to a similar extent. This result indicates that these two reduction processes share at least one common step that is sensitive to Al. Inhibition was not associated with a change in the structure of the membrane domain, as revealed by fluorescence polarization of membrane incorporated probes. These results are the first indications that the electron transfer processes of plasma membranes are sensitive to the presence of Al.     

Management of strawberry anthracnose by choice of irrigation system,mulching material and host resistance

We studied, by means of field experiments, the combined effects of irrigation system, mulching material and genetic resistance on the incidence of strawberry anthracnose caused by Colletotrichum acutatum. All trials involved artificial inoculation with fruits colonized by the pathogen. One experiment examined the effects of drip irrigation, overhead sprinkler irrigation, and localized low-pressure tape irrigation, and the effects of grass (Brachiaria sp.) and plastic (polyethylene) mulches, in a split plot, randomized complete block design with four replicates. Lower disease incidence, indicating lower pathogen dispersal, was verified with low-pressure tape and drip irrigation. Flower blight and fruit rot incidence in drip-irrigated plots was minimal (ca. 2% of the disease levels in the plots otherwise irrigated). Grass mulch reduced flower blight in the sprinkler system (up to 80%), but had no significant effect when disease levels were already low due to use of other irrigation systems. A second experiment compared the effects of grass mulch, pine (Pinus elliotti) mulch, and plastic mulch with overhead sprinkler irrigation on strawberry cultivars partially resistant (‘Dover’) and susceptible (‘Campinas’) to the disease in a factorial completely randomized design (CRD). Both organic mulches reduced flower blight and diseased fruit incidence by up to 76% compared to the plastic mulch treatment, especially in the early stages of the epidemics. ‘Dover’ had 70% lower incidence of flower blight than ‘Campinas’, and the effects of organic mulches were more pronounced in ‘Campinas’. A third experiment, with all three irrigation systems combined with inoculated and non-inoculated plots, estimated yield effects due to disease and irrigation system. All plots were covered with plastic mulch in a CRD with six treatments. This experiment clearly confirmed the higher flower blight and fruit rot incidences when sprinkler irrigation was used. In inoculated treatments, fruit yield was significantly reduced in tape-irrigated plots, and more so in sprinkler-irrigated plots. In drip-irrigated plots yield was reduced by only 1%. Overall, our results confirm the importance of cultural and genetic factors as valuable means of strawberry anthracnose management. Adoption of localized irrigation systems, the use of organic mulches and choice of a partially resistant cultivar significantly reduced disease levels in field plots. The importance of water splash for C. acutatum dispersal and its dependency on the soil mulch characteristics are the likely causes for the results observed.