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941.
灵芝液体发酵培养基筛选研究 总被引:2,自引:0,他引:2
[目的]优选灵芝液体发酵的最优培养基。[方法]以不同碳源的培养基培养灵芝,研究不同碳源对灵芝液体发酵菌丝生长情况及生物量和多糖含量的影响。[结果]玉米粉水解液发酵得到的灵芝菌丝体生物量最大;不同培养基发酵得到的菌丝体生物量大小顺序为玉米水解液〉玉米粉〉葡萄糖+玉米粉〉蔗糖+玉米粉〉麦芽糖+玉米粉〉葡萄糖+麦芽糖〉蔗糖;灵芝菌丝体多糖含量顺序为麦芽糖+玉米粉〉葡萄糖+玉米粉〉玉米粉〉玉米水解液〉葡萄糖。综合各方面因素,选择玉米粉为灵芝液体发酵的最优培养基。[结论]筛选出灵芝液体发酵的最佳培养基为以玉米粉为碳源的培养基。 相似文献
942.
943.
1955-2010年淮北平原冬季农业气候变化基本特征与影响初探 总被引:1,自引:0,他引:1
为了给淮北平原冬季农业生产提供科学依据,利用1955-2010年淮北平原代表站宿州市冬季(12月-次年2月)逐日气候监测资料,采用数理统计方法,研究揭示了冬季农业气候基本要素和相关农业气候指标的演变特征及其对农业的影响。结果表明:(1)55年间,淮北平原冬季气温明显升高,≥0℃的积温明显增多,1986年为冬季气温升高的跃变点,但冬季日照时数减少,年际间冬季降水量波动增大,气象干旱是冬季小麦生产中的主要气象灾害;(2)冬季增暖后,致使冬小麦处于缓慢生长状态,但是冬小麦完成春化阶段的最适宜和适宜的低温天数呈“一少一多”变化态势,以及暖冬促进小麦生育进程相应提前的事实增加了小麦顺利完成春化阶段和后期遭受春霜冻害的风险;小麦育种和引种宜选择春化阶段温度指标范围较宽的品种;(3)虽然冬暖对设施农业生产有利,但是不利于设施农业生产的弱光照天数在增加;同时,现有结构的设施农业生产,在冬季增暖背景下仍然存在较大的低温冻害风险,生产中应注意防范强低温,并科学设计温棚结构来应对日照时数不足。安徽淮北平原冬季气候增暖趋势明显,冬季光、热、水等农业气候基本要素和积温、极端低温、弱光照等农业气候指标呈现诸多变化,对冬季农业生产的影响有利有弊。 相似文献
944.
Roohparvar R Mehrabi R Van Nistelrooy JG Zwiers LH De Waard MA 《Pest management science》2008,64(7):685-693
BACKGROUND: The major facilitator superfamily (MFS) drug transporter MgMfs1 of the wheat pathogen Mycosphaerella graminicola (Fuckel) J Schroeter is a potent multidrug transporter with high capacity to transport strobilurin fungicides in vitro. The data presented in this paper indicate that, in addition to the predominant cause of strobilurin resistance, cytochrome b G143A subsititution, MgMfs1 can play a role in sensitivity of field strains of this pathogen to trifloxystrobin. RESULTS: In a major part of field strains of M. graminicola (collected in the Netherlands in 2004) containing the cytochrome b G143A substitution, the basal level of expression of MgMfs1 was elevated as compared with sensitive strains lacking the G143A substitution. Induction of MgMfs1 expression in wild-type isolates upon treatment with trifloxystrobin at sublethal concentrations proceeded rapidly. Furthermore, in disease control experiments on wheat seedlings, disruption mutants of MgMfs1 displayed an increased sensitivity to trifloxystrobin. CONCLUSION: It is concluded that the drug transporter MgMfs1 is a determinant of strobilurin sensitivity of field strains of M. graminicola. 相似文献
945.
Iray Gell Antonieta De Cal Rosario Torres Josep Usall Paloma Melgarejo 《European journal of plant pathology / European Foundation for Plant Pathology》2008,121(4):487-498
Five field experiments were performed in commercial orchards located in Lleida (Spain) over three growing seasons, 2000–2002,
in order to estimate the relationship between the incidence of latent infection caused by Monilinia spp. in peaches and the incidence of post-harvest brown rot. No latent infection was recorded at popcorn and the maximum
incidence occurred pre-harvest; in some orchards a second peak was detected during the pit hardening period. Monilinia laxa is the most prevalent species isolated from peaches with brown rot. There was a positive correlation between the incidence
of latent infection and that of post-harvest brown rot. The average incidence of latent infection during the crop season explained
55% of the total variation in the incidence of post-harvest brown rot. The effect of temperature (T) and duration of wetness (W) on the incidence of latent infection in peach and nectarine orchards was analysed using multiple regression. The regression
analysis indicated that T and W jointly explained 83% of the total variation in the incidence of latent infection. The model predicts no latent infections
when T < 8°C, and >22 h wetness are required when T = 8°C but only 5 h at 25°C are necessary for latent infection to occur. The incidence of brown rot and latent infection of
peaches caused by M. laxa under controlled experimental conditions were also affected by T and W, as well as by fruit maturity and inoculum concentration. Latent infections were produced in fruit when T was not suitable for the development of brown rot symptoms. In these experiments more than 4–5 h of daily wetness were required
after embryo growth in fruit sprayed to run-off with an inoculum concentration higher than 104 conidia ml−1 of M. laxa for brown rot and latent infections to develop. The fitted model obtained from the field data was able to predict the observed
data obtained under controlled environmental conditions. 相似文献
946.
L. A. Alvarez A. Vicent E. De la Roca J. Bascón P. Abad-Campos J. Armengol J. García-Jiménez 《Plant pathology》2008,57(1):84-91
Considerable losses of citrus trees have been observed in the major citrus-growing areas of Spain. Samples were collected from 132 orchards, and isolations and pathogencity tests were conducted to determine the aetiology of a serious canker disease. Affected trees showed cankers on the scion that frequently began on the branches. Three Phytophthora species were identified based on their morphological, cultural, physiological and molecular profiles. Phytophthora citrophthora was the main species associated with this new syndrome in 114 orchards. Phytophthora nicotianae (syn. P. parasitica ) was isolated from nine orchards as the sole Phytophthora species and in coinfection with P. citrophthora from another nine orchards. Phytophthora citricola was isolated only from one orchard. In stem-inoculation studies conducted under greenhouse conditions, clementine mandarin cv. Hernandina and sweet orange cv. Navel Late were more susceptible to P. citrophthora than sour orange and Carrizo citrange rootstocks. Clementine cv. Hernandina was also highly susceptible in field inoculation experiments. In agreement with field surveys, clementine mandarin cultivars were the most affected, their rootstocks remaining healthy. Phytophthora citrophthora was found to be the predominant species in orchard soils; however, P. nicotianae was also isolated. This information changes the scenario of diseases caused by Phytophthora spp. in Spain and consequently, the present knowledge of epidemiology and the effectiveness of the current control measures should be reassessed. 相似文献
947.
After fifteen years of harmonisation of phytosanitary measures in the European Union, today's legislation has become increasingly stagnant, complex and detailed. The recent finding of Potato spindle tuber viroid in ornamental plants in the Netherlands and other Member States illustrates the struggle to take prompt emergency measures when specific knowledge is not available. It is proposed that the European Commission should take the initiative to organise the process of pest risk analysis from beginning to end. In addition, the Commission should have budgets at their disposal for instantaneous research to generate the required data and fill in knowledge gaps. Such policy enables evaluation of emergency measures and implementation of permanent requirements on the basis of scientific data within a short period, thereby creating a dynamic legislation that focuses on real pest risks. 相似文献
948.
Fabio Minervini Daniela PintoRaffaella Di Cagno Maria De AngelisMarco Gobbetti 《Journal of Cereal Science》2011,54(3):296-304
The use of sourdough, even in combination with cryoprotectant (skim milk, sucrose and trehalose), conventional additives (guar gum, diacetyl tartaric acid esters of monoglycerides, ascorbic acid), honey or fructose and glucose, in frozen dough technology was investigated. After frozen storage, the leavening performance of doughs, and the hardness and texture of breads were compared to those of an unfrozen dough, and to those of a conventional frozen dough. All frozen doughs showed a longer fermentation time and a lower volume increase, with respect to unfrozen dough. When sourdough was combined with cryoprotectant, honey or both, the leavening performance improved compared to the use of sourdough alone. Compared to the conventional frozen dough, higher leavening performance was reached combining sourdough with cryoprotectant alone or together with honey. Sourdough combined with honey, fructose and glucose, honey and cryoprotectant, or conventional additives decreased bread hardness compared to the unfrozen dough bread and to the conventional frozen dough bread. Independently from the use of sourdough, conventional additives allowed to reach a specific volume not significantly different from that of unfrozen dough bread, and breads containing honey were characterized by low values of hardness and by high values of red index. 相似文献
949.
The effect of feeding rate on the growth performance of green sturgeon (Acipenser medirostris) fry 下载免费PDF全文
Four one‐week growth trials were conducted on green sturgeon fry to determine the effect of feeding rate on their growth performance at 18 °C when they were fed a salmonid soft moist feeds containing 445–457 g kg?1 of crude protein and 201–207 g kg?1 of lipid. The fry used in Trials I‐IV were 5–8 weeks after their initiation of exogenous feeding. Their average initial body weights were 1.63 ± 0.01, 2.63 ± 0.03, 5.08 ± 0.08 and 7.49 ± 0.05 g, respectively. Six feeding rates used were as follows: 2.5–15.0% body weight per day (% BW day?1) with a 2.5% increment in Trial I; 1.25–7.50% BW day?1 with a 1.25% increment in Trial II; and 2.0–7.0% BW day?1 with a 1.0% increment in Trials III and IV. Four replicates with 50 fry per tank in Trials I‐III and 30 fry per tank in Trial IV were assigned randomly to each feeding rates. The final body weight, specific growth rate, feed efficiency, protein retention, and whole‐body moisture, lipid, and energy contents were significantly (P < 0.05) affected by the feeding rates. The optimum feeding rates determined by the broken‐line model were 7.1, 5.7 and 5.3% BW day?1 for Trials I, II and IV, when the fry were 5, 6 and 8 weeks after their initiation of exogenous feeding, respectively. 相似文献
950.
Structural development of Pacific red snapper Lutjanus peru from hatching to the onset of first feeding 下载免费PDF全文
Iram Zavala‐Leal Silvie Dumas Edgar O. López‐Villegas Renato Peña Mauricio Contreras‐Olguín Laura Flores‐Montijo José De La Cruz‐Agüero 《Aquaculture Research》2015,46(5):1162-1174
Successful rearing of larval fish requires culture conditions and feeding strategies matching the ontogenetic status of larvae. This study describes the external morphology and development of organs and structures involved in the feeding process (i.e. sensorial organs, mouthparts and digestive system) from hatching until first feeding in Pacific red snapper. Hatching occurred 26 h after fertilization at 26°C and total length (TL) was 2.45 ± 0.08 mm. The larvae showed an undifferentiated eye and digestive tract. At 48 hah, TL was 3.31 ± 0.12 mm. Yolk and oil globule were still present. The mouth was still closed, but the Meckel's, quadrate, hyoid and hyomandibular cartilages were present. The retina was formed by 5 layers, and a thin layer of pigment epithelium was observed in the outer nuclear layer (ONL). At 70 hah, TL was 3.44 ± 0.22 mm. A remnant of oil globule was still present. The mouth and anus were open. At 93 hah, the number of cones in the ONL of the retina have increased and there was more pigment in the pigment epithelial layer. A joint between Meckel's and the quadrate cartilage and also a joint between the hyomandibular cartilage and the skull were present. The presence of live feed was detected in the digestive tract of these larvae. Based on these observations, the Pacific red snapper larvae is functional to start ingesting live feed between the 3rd and 4th day after hatching. 相似文献