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91.
92.
《Journal of Sustainable Forestry》2013,32(3):83-93
Abstract Mineralization is the dominant process controlling soil-solution P in the Spodosols of the southeastern United States. Pine trees growing in these soils are typically colonized by ectomycorrhizal (EM) fungi that are known to produce phosphatases. Little, however, is known of the dynamics of EM short roots or phosphatase activity in tree plantations. To address this question, short root densities, EM morphotypes, and associated surface acid phosphomonoesterase in a 12-year-old Pinus elliottii plantation in northern Florida were evaluated. The density of total (living and dead) short roots changed little from February through June, with a mean of 7.6 cm3 soil. The majority of the short roots, however, were inactive or dead with only 14 to 38% appearing viable upon visual inspection. The majority of the viable short roots were mycorrhizal. The most abundant morphotypes were formed by Cenococcum and Thelephora but these had low phosphatase activity. In contrast, less frequently observed morphotypes had substantially higher rates of enzyme production and these may play an important role in sustainable P nutrition of plantation trees. 相似文献
93.
《Communications in Soil Science and Plant Analysis》2012,43(10):1643-1658
Exudation of organic acids by the roots of three rice cultivars grown in three soils of different phosphorus (P) statuses, and their impacts on the rhizospheric P dynamics and P uptake by the rice plants, were investigated. Quantum root exudates from all the rice cultivars were significantly greater at 21 days after transplantation than at panicle initiation or flowering stages. Malic acid was the most predominant organic acid present in the rice root exudates (10.3 to 89.5 μmol plant?1 d?1), followed by tartaric, citric, and acetic acids. Greater exudation of organic acids from rice grown in P-deficient soil by all the rice cultivars suggested response of rice plant to P stress. Results indicate that the release of organic acids in the root exudates of rice plants can extract P from strongly adsorbed soil P fraction, thereby increasing native soil P utilization efficiency and ensuring adequate P nutrition for the growing rice plants. 相似文献
94.
目的:应用野马追克喘散新兽药对呼吸道综合征进行临床疗效试验,为推广野马追克喘散提供科学依据。方法:将自然感染、症状典型、猪呼吸道综合征的140头病猪(杜长大三元杂交),平均体重20~25kg,随机分为7个组,每组20头,其中第Ⅰ、Ⅱ、Ⅲ组用野马追克喘散治疗,分别以高、中、低剂量给药;第Ⅳ、Ⅴ组分别用麻杏石甘散、金花平喘散以常规剂量给药;Ⅵ、Ⅶ组以硫酸卡那霉素注射液(0.2mL/kg体重)和泰乐菌素(0.4mL/kg体重)以常规剂量给药。结果:野马追克喘散的治疗效果较麻杏石甘散和金花平喘散治疗效果好,治愈率也达93.3%。结论:野马追克喘散治疗猪气喘咳嗽疗效较高,收效较快,维持时间较长,是较理想的药物。 相似文献
95.
F. P. Geels J. G. Lamers O. Hoekstra B. Schippers 《European journal of plant pathology / European Foundation for Plant Pathology》1986,92(6):257-272
The effects of a seed tuber treatment with antagonistic isolates of fluorescentPseudomonas spp. were investigated on potato plants from 1981 to 1984. The experimental plots were located in fields in short and long rotations of potato. The short rotations are characterized by serious yield reductions which are caused by unknown microbial factors. The reductions varied from 30% in 1982 to only 3% in 1983 in the 3-year rotations. A statistically significant increase in yield (four to five months after planting) of ware potatoes varying from 9 to 20% was obtained in these plots through tuber bacterization, but only in 1981. In 1982 and 1983 initially significant improvements in shoot or tuber weight of seed potatoes were no longer detectable at ware potato harvest at the end of the growing period. Seed tuber bacterization had no effect on tuber yield in long rotations. Initial colonization of basal root parts by 53×104 colony forming units (cfu) of antibiotic-resistant mutants per gram of root (fresh) dropped significantly to 20×104 cfu per gram after three months. The bacterization effect on tuber yield depended on the development of harmful microbial activity and of introduced antagonists during the growing period. Seed tuber bacterization is more promising for seed potatoes than for ware potatoes in short rotations, the latter being harvested two months later.Samenvatting De invloed van pootgoedbehandeling met antagonistische isolaten van fluorescerendePseudomonas-soorten op de aardappelteelt, werd onderzocht in de periode van 1981 tot en met 1984. De proefvelden maakten deel uit van zowel ruime als nauwe rotaties met aardappelen. Kenmerkend voor de nauwe rotatie is, dat de opbrengst aanzienllijk gereduceerd wordt als gevolg van de aanwezigheid van nog onbekende microbiële factoren. Deze opbrengstverlaging varieerde van 30% in 1982 tot slechts 3% in 1983 in de 3-jarige rotaties. Pootgoedbacterisatie had in deze proefvelden een significante toename van de eindopbrengst (vier tot vijf maanden na pootdatum) van consumptieaardappelen tot gevolg, die varieerde van 9 tot 20%, echter allen in 1981. In 1982 en 1983 werd het effect van bacterisatie ook in de loop van de groeiperiode onderzocht. Aanvankelijk significante toenames van zowel spruit-als knolgewicht waren aan het einde van het groeiseizoen niet meer aantoonbaar. Pootgoedbacteristie bleek geen effect te hebben op aardappel in ruimte rotaties. Aanvankelijk werden de basale wortelgedeelten gekoloniseerd door antibioticum-resistente mutanten met 53×104 kolonievormende eenheden (kve) per gram wortel(vers); dit aantal liep (drie maanden na pootdatum) echter significant terug tot 20×104 kve per gram. Het effect van bacterisatie op de eindopbrengst werd bepaald door de ontwikkeling van de schadelijke microbiële activiteit en de ontwikkeling van de geïntroduceerde antagonisten tijdens het groeiseizoen. Pootgoedbacterisatie in nauwe rotaties biedt meer mogelijkheden voor de teelt van pootaardappelen dan die van consumptieaardappelen, die geruime tijd later geoogst worden. 相似文献
96.
97.
在注射兔病毒性出血症 (RHD)疫苗后 ,30只兔随机分为 2组 ,试验组兔饲喂含 1 5 %黄白散的饲料。从接种到第 1 80天 ,每组取兔 8只 ,每隔 1 5d采血 1次 ,检测血凝抑制 (HI)抗体 ;在接种前 1天及接种后 5、 1 0、 1 7、 2 4、 31、 41、 5 1d ,每组取兔 1 0只 ,采血检测ANAE+淋巴细胞百分率 ;在 1 80、 2 4 0、 30 0d时 ,每组分别取兔 5只做攻毒保护试验。结果表明 :2组兔HI抗体峰值分别为 7 3log2和 9 8log2 ,差异极显著 (P <0 0 1 ) ;试验组疫苗保护期可延长 60d ;试验组ANAE+率从第 1 0天至 5 1天与对照组比较 ,差异极显著(P<0 0 1 )。所以黄白散可增强兔接种RHD疫苗后的特异性免疫功能 ,增强RHD疫苗的免疫效果。 相似文献
98.
Differential phytotoxicity of glyphosate in maize seedlings following applications to roots or shoot
The transport and differential phytotoxicity of glyphosate was investigated in maize seedlings following application of the herbicide to either roots or shoots. One-leaf maize seedlings (Zea mays L.) were maintained in graduated cylinders (250 mL) containing nutrient solution. Half of the test plants were placed in cylinders (100 mL) containing different 14C-glyphosate concentrations; the remainder received foliar appliation of 14C-glyphosate. After 26 h, the roots and the treated leaves were washed with distilled water, and the plants placed again in cylinders (250 mL) containing fresh nutrient solution for 5 days. Plants were weighed, and split into root, seed, cotyledon, coleoptile, mesocotyl, first leaf and apex. The recovery of 14C-glyphosate was over 86%. For both application treatments, the shoot apex was the major sink of the mobilized glyphosate (47.9 ± 2.93% for root absorption and 45.8 ± 2.91% for foliar absorption). Expressed on a tissue fresh weight basis, approximately 0.26 μg a.e. g−1 of glyphosate in the apex produced a 50% reduction of plant fresh weight (ED50) when the herbicide was applied to the root. However, the ED50 following foliar absorption was only 0.042 μg a.e. g−1 in the apex, thus maize seedlings were much more sensitive to foliar application of the herbicide. 相似文献
99.
100.
Hitoshi NAKAMURA Yukari UETAKE Masao ARAKAWA Ikuko OKABE Naoyuki MATSUMOTO 《Journal of General Plant Pathology》2001,67(1):37-40
Basidiocarps of the violet root rot fungus, Helicobasidium mompa, are less frequently used for isolation than are mycelial strands and sclerotia even though the basidiocarps are conspicuously
produced at the trunk base of diseased plants. Basidiocarps are also more suitable for storage. This paper describes an improved
method for obtaining pure cultures from basidiocarps using microcentrifuge tubes to facilitate the awkward steps of rinsing
fungal materials under a dissecting microscope.
Received 28 June 2000/ Accepted in revised form 4 August 2000 相似文献