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991.
O. Auersch 《Journal of pest science》1961,34(1):7-12
Ohne ZusammenfassungFür die Förderung der Arbeit danke ich Herrn Prof. Dr. H. v. Lengerken. 相似文献
992.
Monicah Mucheru-Muna Daniel Mugendi James Kung’u Jayne Mugwe Andre Bationo 《Agroforestry Systems》2007,69(3):189-197
Soil nutrient depletion as a result of continuous cultivation of soils without adequate addition of external inputs is a major
challenge in the highlands of Kenya. An experiment was set up in Meru South District, Kenya in 2000 to investigate the effects
of different soil-incorporated organic (manure, Tithonia diversifolia, Calliandra calothyrsus, Leucaena leucocephala) and mineral fertilizer inputs on maize yield, and soil chemical properties over seven seasons. On average, tithonia treatments
(with or without half recommended rate of mineral fertilizer) gave the highest grain yield (5.5 and 5.4 Mg ha−1 respectively) while the control treatment gave the lowest yield (1.5 Mg ha−1). After 2 years of trial implementation, total soil carbon and nitrogen contents were improved with the application of organic
residues, and manure in particular improved soil calcium content. Results of the economic analysis indicated that on average
across the seven seasons, tithonia with half recommended rate of mineral fertilizer treatment recorded the highest net benefit
(USD 787 ha−1) while the control recorded the lowest (USD 272 ha−1). However, returns to labor or benefit-cost ratios were in most cases not significantly improved when organic materials were
used. 相似文献
993.
Karen A. Kainer Lúcia H.O. Wadt Christina L. Staudhammer 《Forest Ecology and Management》2007,250(3):244-255
Brazil nut is widely recognized as the cornerstone of the Amazonian extractive economy. Tight linkages between Brazil nut production, regional income, and intact mature forests have thrust this species into focus as a key component of Amazonian conservation and income generation strategies. Nonetheless, a comprehensive synthesis of factors explaining Brazil nut fruit production variation is lacking. We aimed to address this knowledge gap, asking: (1) What are the rates and annual variation of Bertholletia excelsa fruit production at individual and population levels? (2) What factors explain B. excelsa production variation, focusing on spatial and temporal variables, diameter at breast height (dbh), crown attributes, liana loads, and soil attributes? and (3) Does liana cutting affect fruit production? 相似文献
994.
With aid of fluorescein isothiocyanate (FITC) and gold-labelled lectins, together with antibodies against chitinase and β-1,3-glucanases, the spatial distribution of chitin and glucans in hyphal walls of Pythium dimorphum, a causative agent of root die-back disease of conifer seedlings was studied. Contrary to previous reports, this study revealed that chitin, a polymer of N-acetyl-d -glucosamine, is a component of the cell wall of this oomycetous fungus. However, compared with the other amino sugar, N-acetyl-galactosamine, it is not present in significant amounts. Ultrastructural and labelling studies demonstrated that the chitin region is embedded in or masked by glucan residues. 相似文献
995.
Field studies carried out in a forest transition site on a tropical Alfisol in southwestern Nigeria, show that shading by
gliricidia (Gliricidia sepium (Jacq.) Steud) and leucaena (Leucaena leucocephala (Lam.) de Wit) hedgerow species reduced density of speargrass (Imperata cylindrica (L.) Raeuschel) by 67% and 51%, respectively. Shoot biomass of speargrass decreased by 81% and 78% in gliricidia and leucaena
hedgerows, respectively. Reduction in speargrass rhizome biomass in gliricidia plots was 96% while rhizome reduction in the
leucaena plots was nearly 90%. Rhizome mortality was significantly higher in gliricidia plots than in leucaena and control
plots. The bulk of rhizomes was found between 10 cm and 20 cm of soil depth but rhizome did not penetrate further than 30
cm depth in the Alfisol in which this study was carried out. Gliricidia was better than leucaena hedgerow species in suppressing
speargrass. 相似文献
996.
Prof. Dr. O. R. Klimmer 《Journal of pest science》1956,29(1):7-9
Zusammenfassung Die Technisierung der Landwirtschaft und der Einsatz immer neuer chemischer Mittel in immer größerem Umfange zur Steigerung der Erträgnisse und Bewahrung der Ernte vor Verlusten sind, so bedauerlich dies auch aus vielen Gründen sein mag, nicht aufzuhalten.Über die Verantwortung und Verpflichtung aller Beteiligten, alles für den Schutz der mit der Anwendung der chemischen Schädlingsbekämpfungsmittel beschäftigten Menschen und der Masse der Konsumenten zu tun, kann kein Zweifel bestehen.Notwendig ist eine Umstellung im Denken vieler in der Praxis Tätigen, vor allem im Sinne einer Anerkennung der Eigenverantwortung für die eigene Gesundheit und die des Mitmenschen.Die Bearbeitung der vordringlichen Aufgaben und die Lösung der wichtigsten Fragen steht und fällt mit der Bereitstellung größerer Mittel für eigens zu errichtende Untersuchungsstellen, wobei die amerikanischen Verhältnisse in gewissem Umfange als Muster dienen können. Die Dringlichkeit und der Umfang der Probleme lassen eine oberflächliche und zweitrangige Bearbeitung unzweckmäßig erscheinen. Auf dem Gebiet der Gesunderhaltung der Bevölkerung gibt es wohl kaum eine wichtigere Aufgabe als die Bearbeitung der hier umrissenen Fragen. 相似文献
997.
M. A. O. Oladokun 《Agroforestry Systems》1990,11(3):227-241
A survey of cocoa farmers in Bendel, Ogun, Ondo and Oyo States of Nigeria, carried out in 1985, showed that almost all the farmers intercropped other crops with cocoa. The intercrops included food crops such as plantain (92.3), cocoyam (85.7%), cassava (51.3%), yam (41.3%), maize (38.9%), melon (31.4%), cowpea (28.6%) and pineapple (26.0%) and tree crops such as oil palm (71.5%), kola (67.3%), coffee (41.0%), coconut (7.9%) and citrus (7.2%). Other crops are ewe-iran (Sarcophrynium brachystachys) and ewe-gbodogi (Megaphrynium macrostachyum) (45.2%), african walnut (Tetracarpidium conophorum) (42.2%), aligator pepper (Aframomum melegueta) (31.6%), and iyere (Piper guinense) (20.2%). Guava, mango, pawpaw and vegetables such as celosia, okra and solanum occur in cocoa plots at rather low frequencies. As many as six or more other crops can be intercropped with cocoa at the same time. 相似文献
998.
P.O. Anegbeh C. Usoro V. Ukafor Z. Tchoundjeu R.R.B. Leakey K. Schreckenberg 《Agroforestry Systems》2003,58(3):213-218
Domestication of Irvingia gabonensis, a fruit tree grown in agroforestry systems in West and Central Africa, offers considerable scope for enhancing the nutritional
and economic security of subsistence farmers in the region. Assessments of phenotypic variation in ten fruit, nut and kernel
traits were made on twenty-four ripe fruits from 100 Irvingia gabonensis trees in Ugwuaji village in southeast Nigeria, a center of genetic diversity for this species. There were important differences
between the young planted trees of this study and the older unplanted trees of a similar study in Cameroon. Significant and
continuous tree-to-tree variation was found in fruit mass(69.0–419.8 g), flesh mass (59.5–388.8 g), nut mass (9.5–40.6 g),
shell mass (4.9–30.9 g) and kernel mass (0.41–7.58 g); fruit length (49.2–89.3 mm) and width (46.2–100.5 mm) and flesh depth
(12.9–31.4 mm), as well as considerable variation in flesh colour, skin colour, fruit taste and fibrosity. Some fruits were
considerably bigger than those found in Cameroon. These quantitative results will help in the development of cultivars within
participatory approaches to agroforestry tree domestication, and so promote poverty alleviation and sustainable agriculture.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
999.
中国葛藤叶蝉名录及新种、新记录描述(同翅目:叶蝉科) 总被引:3,自引:0,他引:3
本文系统报道我国葛藤上的叶蝉种类,共有11亚科40属50种,其中含3新种、1中国新记录属、5中国新记录种,建立1新组合种,并对折板叶蝉属Paradaevicephalus Ishilhara的属征进行了厘订。新种模式标本保存在安徽农业大学昆虫标本室。 相似文献
1000.
Net photosynthetic rates of developing foliage and one-year-old foliage of loblolly pine (Pinus taeda L.) were measured under field conditions. In the subsequent year, net photosynthesis and dark respiration rates of current-year and one-year-old foliage were measured under controlled environmental conditions. Loblolly pine foliage grows slowly, reaching its final size 3.5 to 4 months after bud burst. Positive rates of net photosynthesis were recorded when the foliage was 13 and 18% of final length, in the controlled-environment and field study, respectively. However, because of high rates of dark respiration during the initial growth period, a positive diurnal carbon balance did not occur until foliage was about a third of final length (40 days after bud burst). Two months after bud burst, when foliage was about 55% of final length, its photosynthetic capacity exceeded that of one-year-old foliage. The highest rates of net photosynthesis were achieved when foliage was more than 90% fully expanded. 相似文献