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排序方式: 共有657条查询结果,搜索用时 31 毫秒
111.
112.
Olesya I. Zhuravleva Alexandr S. Antonov Vo Thi Dieu Trang Mikhail V. Pivkin Yuliya V. Khudyakova Vladimir A. Denisenko Roman S. Popov Natalya Y. Kim Ekaterina A. Yurchenko Andrey V. Gerasimenko Anatoly A. Udovenko Gunhild von Amsberg Sergey A. Dyshlovoy Shamil S. Afiyatullov 《Marine drugs》2021,19(1)
Seven new deoxyisoaustamide derivatives (1–7) together with known compounds (8–10) were isolated from the coral-derived fungus Penicillium dimorphosporum KMM 4689. Their structures were established using spectroscopic methods, X-ray diffraction analysis and by comparison with related known compounds. The absolute configurations of some alkaloids were determined based on CD and NOESY data as well as biogenetic considerations. The cytotoxic and neuroprotective activities of some of the isolated compounds were examined and structure-activity relationships were pointed out. New deoxyisoaustamides 4–6 at concentration of 1 µM revealed a statistical increase of PQ(paraquat)-treated Neuro-2a cell viability by 30–39%. 相似文献
113.
Viet San Le Laetitia Herrmann Lambert Bräu Didier Lesueur 《Soil Use and Management》2023,39(3):1185-1204
Tea is a very important cash crop in Vietnam as it provides crucial income and employment for farmers in poor rural areas. Unfortunately, the dominance of long-term, conventional tea cultivation has caused severe soil health degradation and environmental pollution. At the same time, as tea production may provide a better net income compared with other annual crops such as rice and vegetables, farmers have been converting parts of their allocated land to cultivate tea plants. Little is known about the benefit of agroecological management as an alternative to conventional tea management practices, and thus, there is a need to understand how it can improve tea yields, quality and the livelihoods of the farmers. Conducted in Northern Vietnam from 2019 to 2022, this study examined the impacts of agroecological tea management practices on soil health indicators, tea yield and quality, and net income of tea farmers. We showed that agroecological management practices significantly enhanced soil organic matter by 0.8% and soil pH by 0.5 units on average. Conversely, conventional management based on chemical fertilizer applications, significantly increased soil total nitrogen by 0.15%–0.2%. No significant differences were observed between soil texture and other soil chemical characteristics. Soil biological parameters were also significantly higher in agroecological tea soil and root samples than in conventional tea plots. Average AMF frequency and intensity of the agroecological tea roots were 98% and 37%, respectively, compared with 73% and 15% of the conventional tea roots. Likewise, soil macrofauna and mesofauna abundance in the agroecological tea plantations was 76 individuals/m2 and 101 individuals/100 g fresh soil on average, respectively, while that of conventional tea farms were 34 and 63 individuals/100 g fresh soil, respectively. Interestingly, a comparison between the converted and nonconverted lands did not show any significant effect of the conversion on soil physicochemical and biological characteristics, apart from tea root AMF colonization. Conventional tea management consistently resulted in higher tea yield and yield components, even though the differences were not always statistically significant. Despite lower tea yields, agroecological tea adopters earned around USD 8400 ha/year more than the farmers still practicing conventional management. This study shows that it is economically and environmentally more sustainable to produce organic tea than conventional tea, and our results should encourage more farmers to adopt such agroecological practices in Northern Vietnam. 相似文献
114.
Takuji Sawamoto Ryusuke Hatano Masato Shibuya Kunihide Takahashi Alexander P. Isaev Roman V. Desyatkin 《Soil Science and Plant Nutrition》2013,59(4):493-501
Abstract The effect of sucrose on the growth of rice plants under gnotobiotic conditions was studied at test tube scale in vinyl isolators under weak or strong light. Under weak light (500 lux) the growth of rice plants on agar medium containing only inorganic nutrients during the 20 days after transplanting stopped at 3rd leaf stage, whereas plants on agar medium containing inorganic nutrient plus 2% sucrose grew to 5th or 6th leaf stage. Under strong light (1.5 × 104 lux) the stage of tillering was promoted by supplying sucrose. The growth of rice plants in pot-hydroculture under weak light had the same tendency as that obtained in test tube culture under weak light. Considering the concentration of inorganic elements in rice shoots, it seems most likely that the uptake of inorganic elements. especially phosphorus and potassium, was enhanced by the supplements of 2% sucrose under weak light. An increase of calcium and manganese uptake was observed in plants grown in medium containing 2% sucrose compared with that of plants grown in inorganic medium alone under strong light. The uptake of inorganic elements from medium containing inorganic nutrients plus 2% sucrose depended chiefly on light energy under strong light in the phytotron used. 相似文献
115.
A. San Bautista S. López-Galarza A. Martínez B. Pascual J. V. Maroto 《Journal of plant nutrition》2013,36(9):1527-1539
To determine their influence on leaf tipburn incidence and yields six nutrient solutions with different proportions of potassium (K), calcium (Ca), and magnesium (Mg) were tested in ‘Camarosa’ strawberry plants. Response models were made to predict tipburn incidence, yields and fruit weight. A high Ca proportion in the nutrient solution was determinant for high yields in the first season, while a high Mg content was fundamental for high marketable yields during the two last seasons. In 2001 and 2002, the average fruit weight was higher with high Mg levels, and in 2000 the lowest fruit weights coincided with low levels of Ca in the nutrient solution. The models for tipburn incidence in 2000 and 2002 indicated that solutions with intermediate to high levels of Mg and intermediate to low levels of Ca resulted in a more frequent incidence of tipburn. Conversely, in 2001, the highest tipburn incidence appeared with high K contents. 相似文献
116.
Comparison of hydroponic and aeroponic cultivation systems for the production of potato minitubers 总被引:1,自引:0,他引:1
Summary Two different cultivation systems, aeroponics and hydroponics in greenhouse beds, were compared for the production of potato
minitubers. Plants in the aeroponic system showed increased vegetative growth, delayed tuber formation and an extended vegetative
cycle of about seven months after transplanting. Therefore in 1999, two production cycles were obtained with the hydroponic
system, but only one with the aeroponic system. However, compared with total production in hydroponics, the tuber yield per
plant in the aeroponic system was almost 70% higher and tuber number more than 2.5 fold higher. Average tuber weight was reduced
by 33% in the aeroponic system. Advantages and possible problems with the aeroponic system for minituber production are discussed. 相似文献
117.
Hernández-Pérez T Carrillo-López A Guevara-Lara F Cruz-Hernández A Paredes-López O 《Plant foods for human nutrition (Dordrecht, Netherlands)》2005,60(4):195-200
Biochemical and nutritional changes were studied during the ripening process of three Opuntia morphospecies with different ripening behavior: Naranjona (O. ficus-indica), Blanca Cristalina (Opuntia sp.), and Esmeralda (Opuntia sp.) of early, early-intermediate, and intermediate-late ripening, respectively. In loss of fresh weight, Naranjona showed
the highest values, while in Blanca Cristalina and Esmeralda, a discrete weight loss was found. No significant differences
were found among morphospecies in soluble solids, total titratable acidity and pH during the postharvest days. Blanca Cristalina
and Esmeralda showed an increase in the content of carotenoids, while these diminished in Naranjona. The cell wall enzymes
evaluated showed particular behaviors during the ripening of each morphospecies suggesting a fine biochemical control and
not a clear relationship between fruit softening and enzyme activity. This study provides basic information on prickly pear
ripening, in order to understand this process for its control and for improving shelf life. 相似文献
118.
M. Villarroel E. Biolly S. San Martin G. Estrada 《Plant foods for human nutrition (Dordrecht, Netherlands)》1993,44(2):131-136
Four formulations of Chilean hazelnut butter were prepared containing Chilean hazelnut paste and 5%, 10%, 15% and 20% margarine. As the level of margarine was increased to 20%, the protein and crude fiber content decreased markedly, while those of moisture, crude fat and calories increased. After 90 days of storage, neither the samples stored at 5°C nor those stored at 15°C showed any objectionable effects both from the bacteriological and chemical point of view. Sensory analyses, including quality and acceptability studies, were performed on the various blends. Flavor, color and taste were improved by the addition of margarine to the butter formulas. It is concluded, therefore, that Chilean hazelnut butter represents a new and interesting alternative for human nourishment. 相似文献
119.
Fire blight is an important disease of hawthorn plants. In this study, the level of susceptibility of three hawthorn species
(Crataegus monogyna, Crataegus laevigata, Crataegus persimilis) to the bacterium Erwinia amylovora was investigated. The results showed that all species were highly susceptible to this pathogen. In addition, the relative
virulence of three different E. amylovora strains on the above species was examined. Variability among the strains was found, with strain 3 being the most virulent
and strain 1 the least. 相似文献
120.
对北京顺义地区有机化梨园中三个不同栽培区节肢动物群落特征进行了系统研究。结果表明,在同一梨园中,稀植区中节肢动物群落物种个体数明显高于密植区和施肥区。各区以同翅目木虱类害虫为最多,稀植区所占比例最高。植食性类群和寄生性类群的多样性指数在稀植区中最小,施肥区最大,优势集中性指数在稀植区中最大;捕食性类群的多样性指数在稀植区最大,施肥区多样性指数最小,优势集中性指数与之相反。由此可知,施肥对于控制害虫数量以及提高植食性类群和寄生性类群的多样性也具有一定的作用。稀植区中害虫数量最大,但其自然天敌个体数比例在各区中最小,今后该区需加大害虫防治力度。 相似文献