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91.
Within-stem variations in the mechanical properties of 17–19-year-old Melia azedarach planted in two sites in northern Vietnam were examined by destructive and nondestructive methods. Wood samples were collected from 10, 50, and 90% of the radial length from pith on both sides (North and South) at 0.3, 1.3, 3.3, 5.3, and 7.3 m heights above the ground. The mean values in whole trees of wood density (WD), modulus of rupture (MOR), modulus of elasticity (MOE), and dynamic modulus of elasticity (Ed) at 12% moisture content were 0.51 g/cm3, 78.58 MPa, 9.26 GPa, and 10.93 GPa, respectively. Within the stem, the radial position was a highly (p?<?0.001) significant source of variation in mechanical properties. MOR, MOE, and Ed increased from pith to bark. WD had a strong positive linear relationship with both MOR (r?=?0.85, p?<?0.001) and MOE (r?=?0.73, p?<?0.001). This suggests that it is potentially possible to improve mechanical properties through controlling WD. MOR had also a strong linear relationship with Ed (r?=?0.84, p?<?0.001). This indicates that Ed is a good indicator to predicting the strength of wood if the density of measured element is known. Besides, the stress wave method used in this study provides relatively accurate information for determining the stiffness of Melia azedarach planted in northern Vietnam. 相似文献
92.
Neutral models for testing landscape hypotheses 总被引:5,自引:0,他引:5
Neutral landscape models were originally developed to test the hypothesis that human-induced fragmentation produces patterns
distinctly different from those associated with random processes. Other uses for neutral models have become apparent, including
the development and testing of landscape metrics to characterize landscape pattern. Although metric development proved to
be significant, the focus on metrics obscured the need for iterative hypothesis testing fundamental to the advancement of
the discipline. We present here an example of an alternative neutral model and hypothesis designed to relate the process of
landscape change to observed landscape patterns. The methods and program, QRULE, are described and options for statistical
testing outlined. The results show that human fragmentation of landscapes results in a non-random association of land-cover
types that can be describe by simple statistical methods. Options for additional landscape studies are discussed and access
to QRULE described in the hope that these methods will be employed to advance our understanding of the processes that affect
the structure and function in human dominated landscapes. 相似文献
93.
This paper introduces a combined modelling approach using a simple water budget model (THC-model) and a 3D reservoir sedimentation
model (MOHID Water) to adapt reservoir operation and visualise their effects on the sediment deposition. By this, an effective
combined sediment-water management can be identified under semi-arid conditions for dry, median and wet years. Results are
presented for the reservoirs of the Tuyamuyun Hydro-Complex (THC), which is located in the lower Amu Darya River. The determination
of the actual and usable reservoir storage volume shows that siltation will significantly adversely affect the ability of
the in-stream Channel Reservoir to regulate seasonal demand for both irrigation and municipal water supply. However, modelling
scenarios results confirm the effectiveness of adapted operation rules for the THC reservoirs and show that the operation
of large dams could be modified according to a combined sediment-water management. The experience gained during this study
emphasizes the fact that the concept of a combined reservoir management of sediments as well as water can be an efficient
measure to improve the sustainable long-term use of reservoirs and to contribute towards a safe water supply in water crisis
regions. 相似文献
94.
Seong-Mi Jo Yu Ayukawa Sung-Hwan Yun Ken Komatsu Tsutomu Arie 《Journal of General Plant Pathology》2018,84(6):395-398
RNA silencing pathways in filamentous fungi are composed of multiple component proteins and known to be involved in vegetative growth, virulence or sexual reproduction. We found that the tomato wilt fungus, Fusarium oxysporum f. sp. lycopersici (Fol), carries four homologues genes of Qde-2, an argonaute protein gene and one of the main component protein genes in Neurospora crassa. Gene targeting revealed that FoQde-2, one of the Qde-2 homologues in Fol, is involved in virulence to tomato but not in vegetative growth. 相似文献
95.
José Climent Maria Regina Chambel Marta Pardos Francisco Lario Pedro Villar-Salvador 《European Journal of Forest Research》2011,130(5):841-850
Rooting space is considered as a resource in plants, but comparative studies on the biomass allocation plasticity in response
to rooting volume (RV) are rare. We compared responses in growth, biomass allocation and ontogenetic heteroblasty in nine
hard pine species of contrasted ecology. Seedlings were cultivated in containers of 0.2, 0.5, 1.0, 2.8 and 7 L for two growing
seasons (425 days). Reduction in RV caused a reduction in plant absolute and relative growth rate and biomass allocated to
stems but it increased biomass allocated to roots. RV affected to a lesser extent and in a less consistent direction allocation
to leaves. Species that grew faster (higher relative growth rate) had a steeper decrease in growth with the reduction in RV.
Ontogenetic heteroblasty, evaluated as the proportion of secondary needles in the needle biomass, showed highly different
plasticity patterns in response to RV. Decrease in RV caused negligible or no change either in the most ontogenetically delayed
Mediterranean pines or in the most ontogenetically advanced pines, the mesic Pinus sylvestris and P. uncinata. By contrast, ontogenetically intermediate species showed steep reaction norms in response to reduction in RV. While P. pinaster and P. brutia showed marked rejuvenation, P. nigra accelerated the development of adult foliage. 相似文献
96.
Gaetano Laghetti Girolamo Fiorentino Karl Hammer Domenico Pignone 《Genetic Resources and Crop Evolution》2009,56(8):1163-1170
In 1970s it was thought that two species of ‘farro’, namely emmer (Triticum dicoccon Schrank) and einkorn (T. monococcum L.), were no longer present in Italy, but in 1981, some populations were discovered in a mountain area of the Appennino Sannita
(central southern Italy). In 2006/2007 three monitoring missions were carried out to check the current situation of these
ancient hulled wheats, specifically in the same areas where they were formerly collected. The same zones were also investigated
by both paleo-ethnobotany and agrobiodiversity points of view. The results of this research have shown that nowadays einkorn
is completely extinct while emmer is still cultivated in very few traditional farms, mainly as a fodder crop. A strong genetic
erosion was detected also for emmer and several nowadays samples were contaminated by seeds of modern spelt (T. spelta L.) varieties. In the present study the causes of this genetic erosion and which safeguarding actions to be undertaken are
discussed. 相似文献
97.
Yuanqian Wang Kaixin Zhang Lifang Sun Xiao Han Sujie Fan Xueying Li Yiwei Qu Dan Yao Piwu Wang Jun Zhang 《Euphytica》2018,214(5):85
In order to well understand the molecular basis of heterosis in soybean, the methylation-sensitive amplification polymorphism (MSAP) method based on capillary electrophoresis was used to estimate levels and patterns of cytosine methylation in 15-day post-emergence leaves of four parental lines [Jilin 47 (no. 19), EXP (no. 12), Jilin 38 (no. 3) and Yi 3 (no. 6)] and 12 hybrids [Jilin 38 × Yi 3(3 × ?6), Jilin 38 × ?EXP(3 × ?12), Jilin 38 × ?Jilin 47(3 × ?19), Yi 3 × ?Jilin 38(6 × ?3), Yi 3 × ?EXP(6 × ?12), Yi 3 × ?Jilin 47(6 × ?19), EXP × Jilin 38(12 ×?3), EXP × Yi 3(12 × ?6), EXP × ?Jilin 47(12 × ?19), Jilin 47 × ?Jilin 38(19 × ?3), Jilin 47 × Yi 3(19 × 6), Jilin 47 × EXP(19 × 12)]. In addition, 12 traits of the hybrids and their parents were also analyzed to understand the relationship between DNA methylation variation and heterosis. MSAP results showed that the total relative methylation level of all hybrids was lower than the corresponding middle parent value, indicating that the methylation degree was decreasing. And may express a variety of genes related to the phenotypic variation of hybridization. Moreover, the hemi-methylation levels of Jilin 38 × Jilin 47 and Yi 3 × Jilin 47 hybrids and full-methylation levels of EXP × Yi 3 and EXP × Jilin 47 hybrids was significant higher than the corresponding mid-parent values. In addition, the heredity of methylation from parents in hybrids is more than the variations, in which there were four types appeared great higher: A1, B4, B8, and D2. Furthermore, the results of relationship between genetic variation in DNA methylation and heterosis showed that the hypo-methylation had a promoting effect to increase node number, and the hype-methylation of hybrids was helpful to add to stem thick. Our results may provide new insights into well understanding the molecular mechanisms of heterosis at the epigenetic level in soybean. 相似文献
98.
99.
Ozan Avinc Huw Owens John Bone Mike Wilding Duncan Phillips David Farrington 《Fibers and Polymers》2011,12(7):893-903
Water droplets falling onto finished fabrics can create spots which can spoil the appearance of the fabric. This study compares
the propensity of softened filament polylactic acid and polyester fabrics to exhibit the adverse affects of ‘water-spotting’,
and to identify suitable softeners and methods for their application to minimise and eliminate the problem. The degree of
water spotting was greater on softened polylactic acid fabrics than on softened polyester fabrics. Polylactic acid and polyester
fabrics with hydrophobic properties did not exhibit any water spotting. Softeners applied by an exhaustion process resulted
in a finished fabric which exhibited no water spotting for either dyed polylactic acid or dyed polyester fabrics. The softening
active agent was not responsible for the water spotting. The other components in the softener formulation (such as emulsifier,
wetting agent), which carries the unfixed dyes with water, were found to be responsible. The water spot halo disappeared after
a single machine laundering process. 相似文献
100.
Rogério M. Borges Alcester Mendes Selene S. C. Nogueira Jérôme Bindelle Sérgio L. G. Nogueira-Filho 《Tropical animal health and production》2017,49(7):1353-1359
A nitrogen (N) balance digestion trial was conducted to determine the protein requirement of collared peccaries (Pecari tajacu). In a 4 × 4 Latin square design, four captive adult male peccaries were fed four isoenergy diets containing four different levels of N (11.7, 16.3, 22.8, and 26.7 g N/kg of dry matter—DM). After 15 days of adaptation, a total collection of feces and urine was carried out for five consecutive days. Regression analyses between N intake and N in feces and urine allowed to calculate the metabolic fecal nitrogen (MFN = 2.3 g N/kg of dry matter intake—DMI) and daily endogenous urinary N (EUN = 185 mg N/kg0.75). Likewise, by regression analyses between consumption of nitrogen and the nitrogen balance (NB = N ingested ? N excreted, mg N/kg0.75), a daily requirement of 514 mg N/kg0.75 was calculated. Therefore, if food intake is unrestricted, collared peccaries require a minimum in their diet of about 5.4% crude protein on DM basis. These values are almost as low as those found for browsing and frugivorous wild ruminants, which reinforce the proposition that peccaries’ digestive physiology is nearer to that of domestic and wild ruminants than domestic pigs. This relatively low protein requirement of collared peccary and its great ability to digest protein reveal the relevance of the forestomach for the species on nitrogen/protein metabolism and allow the use of diets with lower crude protein levels than the commercial ones used for the domestic pig, which reduces feed costs. 相似文献