两种黄瓜砧木（南瓜）幼苗对NaCl胁迫的渗透调节响应

摘要: 以两种黄瓜砧木中国南瓜(Cucurbita moschata)杂交种“360-3×112-2”和黑籽南瓜（C. ficifolia）的幼苗为试材,在营养液培养的条件下进行80mmol?L-1 NaC1胁迫,研究了南瓜幼苗的生长、相对含水量、各器官的渗透势和叶片中渗透调节物质含量的变化。结果表明,NaCl胁迫后,两种南瓜幼苗的生长显著受到抑制,“360-3×112-2”幼苗的耐盐性比黑籽南瓜强,“360-3×112-2”幼苗的相对含水量降低较少,各器官的渗透势降低较多,叶片中渗透调节物质含量增加较多。较高的耐盐性与它具较强的渗透调节能力有关。     

Fungicidal activity of fluopicolide for suppression of Phytophthora capsici on squash

The efficacy of a new fungicide fluopicolide in suppression of Phytophthora blight caused by Phytophthora capsici was evaluated under laboratory and field conditions. Studies with 51 P. capsici isolates from vegetable crops in Georgia, USA, indicated that 5.9% of the isolates were resistant, 19.6% were intermediately sensitive, and 74.5% were sensitive to 100 μg ml⁻¹ of mefenoxam based on in vitro mycelial growth. EC₅₀ values of fluopicolide in inhibiting mycelial growth of 25 isolates, representing resistant, intermediately sensitive, and sensitive to mefenoxam, ranged from 0.05 to 0.35 μg ml⁻¹ with an average of 0.2 μg ml⁻¹ EC₅₀ values of fluopicolide in suppressing zoospore germination and sporangium production of the 25 isolates ranged from 1.1 to 4.5 μg ml⁻¹ and 0.3–9.0 μg ml⁻¹, respectively. Evaluation of a collection of 150 P. capsici isolates from vegetables and irrigation ponds found none of the isolates were resistant to 10 μg ml⁻¹ of fluopicolide. Field experiments were conducted to determine the efficacy and application methods of fluopicolide for control of P. capsici on squash in spring 2007 and 2009. Fluopicolide applied through drip irrigation or as a foliar spray at 86.6 or 115.4 g ha⁻¹ consistently provided significant disease reduction and increased squash yield. Results with fluopicolide were similar or slightly superior to mefenoxam applied at recommended rate. Fluopicolide applied at 57.7 g ha⁻¹ did not provide consistent satisfactory disease suppression. The results indicated that fluopicolide was effective in suppression of different stages of the life cycle of P. capsici and could be a viable alternative to mefenoxam for managing Phytophthora blight in squash production.     

Phosphorus sorption maxima and desorbability in selected soils with andic properties from the Azores, Portugal

P sorption and desorption capacities were determined on 30 soil horizons (surface and subsurface) of soils with andic properties from the Azores, Portugal, using the Langmuir equation and successive extractions with dilute calcium chloride (CaCl₂), respectively. The proportion of P recovery (Prec) using distilled water (H₂O), CaCl₂, Bray 2 (B2), Mehlich 3 (M3), Egnér–Riehm (ER) and Olsen (OL) extractants was also determined to assess the extent of P release from soils enriched with P at P sorption maxima (Pm). Soils containing very low amounts of organic C and allophane (Vitrandic Haplustepts and Vitrandic Udorthents) showed the lowest values of Pm (48–565 mg kg^− 1) and the highest values of P desorbability (Pdes) (69–100%), indicating that P can be easily lost from these soils. Application of fertilizers to these soils should be restrained in order to minimize eutrophication risk of nearby water bodies. In contrast, allophanic and non-allophanic horizons of Typic Placudands, Alic Hapludands, Acrudoxic Hapludands and Acrudoxic Hydrudands showed much higher values of Pm (2273–52,400 mg kg^− 1) and lower values of Pdes (4–57%).They also showed low proportions of Prec by the used extractants, indicating that large amounts of P can be sorbed in an unavailable form. Thus, these soils may require large amounts of P fertilizers and an efficient method of P application. Other studied soils with high amounts of 1:1 layer silicate minerals and having weak andic properties (Typic and Andic Haplustepts), showed intermediate Pm (1124–8333 mg kg^− 1) and Pdes values (20–63%).

The values of Pm were positively correlated with Al_d, Al_o, allophane, Fe_o, Fe_d and Al_p contents, and with the values of Al_o + 1/2 Fe_o. In contrast, values of Pdes were negatively correlated with these soil constituents. Of the six extractants, the B2 extractant showed generally higher proportions of Prec than the other extractants in most studied soils. The proportions of Prec by the B2, M3, ER and OL extractants were negatively correlated with contents of Fe_o, Fe_d, Al_d, Al_o, Al_p, and Fe_p, and with the values of Al_o + 1/2 Fe_o and PR.     

不同有机肥对西葫芦品种农艺性状和产量的影响

为了明确适宜榆中县种植西葫芦品种,及不同有机肥对西葫芦农艺性状和产量的影响,本文进行了西葫芦品种筛选及有机肥对西葫芦农艺性状和产量比较试验。结果表明,供试的5个西葫芦品种中,实诚SC306、绿蛟龙2号和翠莹5号在瓜型、商品性,产量等农艺性状最为符合商品销售适宜推广,可大面积种植;施用不同有机肥对绿蛟龙2号比较结果表明,施用嘉施宝有机肥西葫芦产量最高,增幅为18.7%。     

柚皮柠檬苦素的提取及其杀虫活性研究

为了探究柚皮中柠檬苦素的最佳提取工艺及其杀虫活性,采用正交试验对柚皮中柠檬苦素的提取工艺进行优化,利用得到的柠檬苦素对夹竹桃蚜虫、吹绵蚧和菜蝽喷雾进行杀虫试验。结果表明：超声波提取法、二氯甲烷和丙酮水浴提取法从10 g柚皮中提取到的柠檬苦素分别是0.9700、1.5860、1.6000 g;二氯甲烷水浴提取法对柚皮中的柠檬苦素提取率为6.08%。10 mg/mL的柠檬苦素能将供试害虫全部杀死,0.625 mg/mL的柠檬苦素依然有较高的杀虫活性。回流法提取柚子皮中的柠檬苦素时,最佳提取工艺是：二氯甲烷为提取溶剂,液料比为1:12,回流提取2次,每次2 h,温度50℃;得到的柠檬苦素对3种供试害虫有较强的杀虫活性。     

Colonisation and histological changes in muskmelon and autumn squash tissues infected by <Emphasis Type="Italic">Acremonium cucurbitacearum</Emphasis> or <Emphasis Type="Italic">Monosporascus cannonballus</Emphasis>

Muskmelon (Cucumis melo cv. Temprano Rochet) and autumn squash (Cucurbita maxima) seedlings were inoculated either with Acremonium cucurbitacearum or Monosporascus cannonballus, two of the soil-borne fungi implicated in ‘melon collapse’. Inoculation was achieved in two different ways: by growing the plants in pots containing infested soil to study the histological changes produced in the infected tissues using light microscopy and by growing seedlings in Petri dishes together with fungal colonies in order to observe the colonisation of the plant tissues using scanning electron microscopy. Both muskmelon and autumn squash roots infected with A. cucurbitacearum showed a suberised layer in the epidermis and the outermost layers of the parenchymatic cortex, but these symptoms developed earlier in the muskmelon plants. Muskmelon plants infected by this fungus also presented hypertrophy and hyperplasia, which led to a progressive separation of the vascular bundles in the lower stems of the affected plants. This response was not observed in autumn squash during the study. On the other hand, few histological changes were observed in tissues infected with M. cannonballus and only a slight increase in the size of cortical intercellular spaces was noted in the lower stems of muskmelon plants, and infected autumn squash tissues remained free of these symptoms throughout the study. The scanning electron microscope observations revealed that both fungi were able to colonise the tissues of the two host plants which were studied. A. cucurbitacearum colonised the epidermis and cortex of both muskmelon and autumn squash. The hyphae grew both inter- and intracellularly, and the density of the colonisation decreased within the endodermis. The same colonisation of host plants was observed as a result of M. cannonballus infection. The xylem vessel lumina of both muskmelon and autumn squash showed hyphae and tylose formation as a result of both fungal infections. However, non-fungal structures were detected in the hypocotyl vascular tissues. The present study demonstrates that both fungi are capable of infecting the tissues of a species which is resistant (autumn squash) and a species which is susceptible (muskmelon) to melon collapse.     

富硒极大螺旋藻整细胞、藻胆体及藻蓝蛋白的光谱特性

对培养富硒极大螺旋藻的最佳硒处理浓度作了研究。结果表明,40mg/L的硒可促进该藻的生长。与对照组相比，富硒极大螺旋藻的整细胞、藻胆体及藻蓝蛋白的光谱特性无显著差异，这表明硒没有影响到极大螺旋藻光能的吸收与传递。     

晋南地区黄瓜、黑籽南瓜死秧的病原菌鉴定及品种抗性研究

经分离、培养对不同菌种培养性状的观察,确定了侵染黄瓜、黑籽南瓜造成死秧的镰刀菌主要为尖镰孢菌黄瓜专化型、尖镰孢菌西瓜专化型、串珠镰刀菌和腐皮镰孢菌4种。经致病性测定,4种镰刀菌均能侵染黄瓜,引起发病造成死秧,可分为强致病类型和中强致病类型。经抗病性鉴定,黑籽南瓜种子只有南瓜4号为耐病品种;黄瓜种子也只有津优31号为耐病品种。     

Studies on the phloroglucinol–HCl reactive material produced by squash fruit elicited with pectinase: Isolation using hydrolytic enzymes and release of p -coumaryl aldehyde by water reflux

Pathological tissues from a variety of plants turn red when treated with the histochemical reagent phloroglucinol (PG)–HCl. This induced PG–HCl reacting material has been termed both wound gum and, more recently, induced lignin or lignin-like material. We are exploring alternative approaches to better identify this induced material. In this report, we describe methods for purifying the PG–HCl reactive material from solvent-washed tissue preparations and measuring the amount of p -coumaryl aldehyde released from the purified material by boiling in water. Acorn squash fruit wall tissue was sliced, sprayed with pectinase to elicit the formation of PG–HCl reactive material and incubated up to 72 h at 27°C. Sampled tissue was washed extensively with water and organic solvents. Insoluble residues were treated with cell wall degrading enzymes to remove cell wall materials, and dimethyl sulfoxide was used to dissolve starch. Yields of residual material increased from 7.5% in the time zero samples to 29.7% after 72 h. Refluxing the purified material in water released <6 μ g p -coumaryl aldehyde g⁻¹ from preparations of tissue at time zero and 8100 μ g p -coumaryl aldehyde g⁻¹ from samples incubated for 48 h. These results suggest that the function of the material is to sequester phytoalexins, but are not consistent with the material being lignin. Published by Elsevier Science Ltd.     

Variation in seed yield components of buffalo gourd (Cucurbita foetidissima HBK.) grown as an annual

Summary Phenotypic variation for parameters of seed yield were examined in 57 buffalo gourd (Cucurbita foetidissima HBK.) plants cultivated as annuals. Among the 52 individuals which bore fruit, seed weight/plant was highly variable (cv=106%); the majority of plants exhibited seed yields below that of the mean (431 g/plant). Values of seed weight/plant were more highly influenced by fruit/plant (r=+0.81) than by seed weight/fruit (r=+0.19). Variation in fruit/plant % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0dh9WrFfpC0xh9vqqj-hEeeu0xXdbba9frFj0-OqFf% ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr% 0-vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaiaacIcaceWG4b% GbaebacqGH9aqpcaaIYaGaaGimaiaaicdacaqGNbGaae4oaiaabcca% caqGJbGaaeODaiaabccacaqG9aGaaeiiaiaabodacaqG3aGaaeyjai% aabMcaaaa!454B!\[(\bar x = 56; cv = 115\% )\] was greater than that displayed for seed weight/fruit and their distribution was also highly skewed. High fruit yields were associated with the duration (in nodes) of the fruiting period (r=+0.64).Values for seed weight/fruit were also highly divergent % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0dh9WrFfpC0xh9vqqj-hEeeu0xXdbba9frFj0-OqFf% ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr% 0-vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaiaacIcaceWG4b% GbaebacqGH9aqpcaaIYaGaaGimaiaaicdacaqGNbGaae4oaiaabcca% caqGJbGaaeODaiaabccacaqG9aGaaeiiaiaabodacaqG3aGaaeyjai% aabMcaaaa!454B!\[(\bar x = 200{\text{g; cv = 37\% )}}\], but considerably less variable than those for fruit/plant or seed weight/plant. A weak relationship existed between fruit/plant and seed weight/fruit (r=–0.28), suggesting the possibility of their simultaneous improvement through selection. Seed weight/fruit was positively associated with fruit size, seed/fruit and 100-seed weight; 4 carpellate fruit displayed significantly greater seed weight/fruit and seed/fruit than 3 carpellate fruit.Journal Paper No. 4219 of the University of Arizona Agric. Expt. Sta., Tucson, AZ 85721, U.S.A.