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991.
This paper presents the experimental evidence on the effects of desiccation, low and high temperatures, rough handling, root loss and storage between lifting and planting on plant quality and performance. The review concentrates on the impact of these stresses on outplanting performance; their effect on seedling properties, such as root growth potential and root electrolyte leakage, is also described. Stresses most often happen in combination but there is relatively little information on their interactions. Examples of desiccation plus rough handling, cold storage plus desiccation, frost damage plus freeze storage and the triple stress of desiccation, heating and rough handling are presented. The limited evidence on the cumulative effect of stresses suggests tentatively that damage from rough handling does not accumulate in the same way as damage from desiccation and prolonged storage. Factors affecting stress resistance are briefly reviewed.There are three impediments to producing a critical review of the literature: experimental treatments, particularly of desiccation and rough handling, can rarely be directly compared; the impact of stress treatments can be modified by a large number of factors, and the levels of stress have seldom been quantified in normal forestry practice. The first two problems also make it difficult to formulate general statements concerning critical thresholds for the stresses. However, instruments are now available for measuring and monitoring stresses between lifting and planting and it is, in theory, possible to model the effects of these stresses to take account of the many factors that modify their impact on seedling survival and growth. This offers the possibility of significant improvements in our ability to predict the effect of stresses between lifting and planting on seedling performance. 相似文献
992.
Kouichi Ichihara Tosimi Tanaka Isao Sawaguchi Shuji Umeda Katsumi Toyokawa 《Journal of Forest Research》1996,1(1):45-49
This study examines a method for designing an optimum profile of a forest road in a short matter of time. In this method,
a genetic algorithm (GA) searches for points where the gradient changes and dynamic programing (DP) designs the longitudinal
slope. This method can be applied to the ground heights of an actual forest road. The evaluation function of the DP assesses
the total expenditure. The inverse of this function is the fitness function. Crossover and mutation are operators of an evolution
simulation of a GA. They are each repeated 20 times and 420 profiles are designed and assessed, all within about 10 min. A
comparison of the profile designed by the GA with that of an actual forest road shows only one section where the formation
level differed substantially. Overall, both profiles seem to show a high degree of correspondence. From this result, we believe
that the profile designed by the GA is best, or the one of the best. A conventional method takes about 65 h to calculate all
changing points of gradients. However, by using the GA, the calculation time was reduced to about 1/389 that of the coventional
method, showing that the method which uses the GA through the profile design is very useful. 相似文献
993.
994.
Leaf-water potential and soil-water depletion of walnut mulched with polyethylene and intercropped with alfalfa in Central Italy 总被引:1,自引:0,他引:1
In Italy, new agroforestry cultural models could play an important role in the diffusion of plantation forestry timber species. We studied the stem growth rates and leaf water potentials () of common walnut (Juglans regia L.), and gravimetric soil moisture (DW) depletion during the third and fourth growing seasons in an agroforestry trial in central Italy. Since the establishment of experimental plots in 1992, walnut was intercropped with alfalfa (Medicago sativa L.), with or without polyethylene (PE) mulching along tree rows. By the end of the study period, the unmulched-intercropped walnut was almost 68% smaller in stem diameter and height than the sole-unmulched control, demonstrating walnuts sensitivity to alfalfa competition. The competitive effect of alfalfa on walnut stem growth was effectively controlled/reduced by PE mulching. Stem growth rates of mulched-intercropped walnut were always lower than the control, but much higher (ca. 235% in stem diameter and height) than those of unmulched-intercropped walnut. The higher field performance of mulched-intercropped walnut compared to the un- mulched-intercropped treatment was associated with higher soil moisture and predawn and midday values during the summers driest periods. The presence of PE mulching was also associated with lower levels of soil moisture during the early and late growing season, but this did not negatively affect walnut and growth rates. These results suggest that in the climatic conditions of central Italy, competition for soil moisture between young common walnut trees and alfalfa can be substantially lowered, but not completely eliminated, by PE mulching.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
995.
LIU Lian YU Rong-jie DAI Yun ZENG Zhi-xing GUO Xiao-ling JI Qing-shan ZHONG Jing-xiang 《园艺学报》2015,31(1):135-140
AIM: To construct the prokaryotic expression system containing protein transduction domain (PTD) with heat shock protein 27 (HSP27) in order to prepare and purify the recombinant protein, and to verify whether the recombinant protein PTD-HSP27 has the ability to penetrate the human lens epithelial cell (HLEC) membrane and the rabbit cornea. METHODS: The plasmid pKYB-PTD-HSPB1-6His was constructed by the technique of overlap extension PCR. The plasmid was transformed and PTD-HSP27 was purified through nickel affinity chromatography column and identified by Western blotting. PTD-HSP27-6His was labeled with the fluorescein isothiocyanate (FITC). The penetrating ability of PTD-HSP27 into HLECs and rabbit cornea was tested. RESULTS: The recombinant PTD-HSP27 plasmid was successfully cloned and effectively expressed. The correctness of the recombinant protein PTD-HSP27 was demonstrated. Fluorescence microscopic examination showed that PTD-HSP27-FITC was internalized by HLECs. Fluorescent labeled PTD-HSP27 was then observed in the rabbit aqueous humor. CONCLUSION: The recombined gene PTD-HSPB1 was constructed by overlap extension PCR technique and the PTD-HSP27 fusion protein was prepared and purified by nickel affinity chromatography column. Using the technique of PTD-fusion protein, HSP27 was transduced into HLECs and passed through the cornea. 相似文献
996.
AIM: To develop the cell model of polymer/liquid crystal and to study the effect of their elasticity on the adhesion of rat bone marrow mesenchymal stem cells (rBM-MSCs). METHODS: Using the method of solvent evaporation induced phase separation, the cell model of polymer/liquid crystal was constructed. The surface morphology and phase separation structure were determined by polarized optical microscopy (POM), scanning electron microscopy (SEM) and small angle X-ray scattering (SAXS). rBM-MSCs were separated and expanded by adherent culture. The surface markers of rBM-MSCs were detected by flow cytometry. The cells were induced to osteogenic differentiation and adipogenic differentiation for 2 weeks. After 3 passages, the cells were divided into 4 groups, including total PU control group, 10% membrane group, 30% membrane group and 50% membrane group. The cells were then incubated with rhodamine phalloidin for cytoskeleton staining and were observed under the confocal laser scanning microscope after cultured for 24 h. RESULTS: The cell model of polymer/liquid crystal was constructed successfully using the method of solvent evaporation induced phase separation. Flow cytometry results showed that the rBM-MSCs positively expressed CD29, CD44 and CD90, and negatively expressed CD34 and CD45. After stained with alizarin red S and oil red O, the calcium nodule and lipid droplets in rBM-MSCs were observed obviously. The cytoskeleton staining result indicated that the area in total PU control group, 10% membrane group and 30% membrane group were greater, and the actin microfilaments were also clearer than that in 50% membrane group. CONCLUSION: The cell model with suitable content of liquid crystal made a contribution to the rBM-MSCs' adhesion, but too much liquid crystal inhibits cell adhesion. 相似文献
997.
AIM: To study the effect of idazoxan on the permeability of inflammatory blood-brain barrier (BBB) model in vitro and the expression of tight junction protein ZO-1.METHODS: In vitro BBB model was established by murine brain endothelial cell line bEnd.3 incubated for 7 d. The cells were treated with TNF-α (10 nmol/L) for additional 24 h to establish the inflammatory BBB model, which was pretreated with IDA at doses of 50, 100 and 200 μmol/L, respectively. The permeability was measured using fluorescein isothiocyanate-conjugated dextran (FD-40, MW 40,000), the expression of ZO-1 was detected by Western blot analysis, the distribution of ZO-1 was observed by immunofluorescence, and the mRNA expression of MMP-9/TIMP-1 was measured by RT-PCR.RESULTS: After incubated for 7 d, b.End3 cells converged to be confluent monolayer with low permeability. The inflammatory BBB model induced by TNF-α treatment displayed much higher permeability with decreased expression of tight junction protein ZO-1, destroyed distribution of ZO-1 and increased mRNA expression of MMP-9. When pretreated with IDA, the permeability was greatly decreased, the expression of ZO-1 was greatly increased, the abnormal distribution of ZO-1 was greatly ameliorated and the mRNA expression of MMP-9 was obviously reduced. The effect was most significant in IDA (200 μmol/L)-pretreated group (P<0.01).CONCLUSION: IDA directly acts on brain endothelial cells to reduce the expression of MMP-9, increase the expression of tight junction protein ZO-1 and ameliorate the destroyed distribution of ZO-1 in the inflammatory BBB, thus reversing the abnormally elevated permeability in a inflammatory BBB model in vitro induced by TNF-α. 相似文献
998.
为对水肥一体化在生产上的应用提供数据支持,在河北永年县开展了棚室番茄水肥一体化技术与常规普通施肥对比试验。试验结果表明,采用每667 m2用水250 m3、追肥40 kg的水肥一体化技术,可比常规栽培节水34.2%、节肥20%,番茄增产4.74%。 相似文献
999.
以辣椒超越五号为试材,研究了低温胁迫下施用养殖废弃物生物有机肥对辣椒抗寒性的影响。试验结果表明,与无机肥料(复合肥)相比,施用生物有机肥料之后,辣椒叶片电解质渗透率、丙二醛含量显著降低,施用量越大,下降幅度也越大;脯氨酸(Pro)、可溶性糖、可溶性蛋白含量明显升高,与此同时叶片中的过氧化物酶(POD)和超氧化物歧化酶(SOD)的活性也明显高于无机肥料处理,在适宜的施肥量范围内,肥料施用量越大,酶活性上升幅度也越大。经低温胁迫后,各指标的变化有明显的差异,说明辣椒抗寒性需要结合多个指标进行综合评价。 相似文献
1000.