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71.
72.
电场强度对氯化钠溶液在杉木中渗透能力的影响 总被引:1,自引:0,他引:1
为了研究采用电场手段改良杉木的可行性,将一定含水率的杉木板材置于不同的电场强度(极板间电势差)中,并在杉木板材上部稳定地保持一定量的氯化钠溶液,5 h后,测试板材不同高度(厚度)部位的含水率和钠离子含量,并与未在电场中渗透的杉木的对应值比较分析,研究电场强度对氯化钠溶液在杉木中渗透能力的影响,结果表明:①定向电场的存在,能促进氯化钠溶液在杉木中的渗透;②在本试验范围内,随着电场强度的增加,氯化钠溶液中水分和钠离子在杉木中、下部渗透量增加,并使各渗透层面的含水率均匀性提高. 相似文献
73.
Applications of growth retardants, daminozide and CCC (chlormequatchloride), were studied in order to determine their effects on morphology and post-planting growth of silver birch (Betula pendula Roth) container seedlings. Daminozide was sprayed once (on 28 June at concentrations of 1.0 – 6.0 g l–1) and CCC was sprayed twice (on 29 June and 27 July at concentrations of 0.5–3.0 gl–1). Height growth, morphology of seedlings at the end of the growing season, the shoot and root growth potential the following spring and field performance during the following seasons were measured. During the first summer in the nursery, both daminozide and CCC retarded height growth,but daminozide was more effective. The effects of compounds on stem diameter during the summer of application were small. Neither of the compounds affected the field performance of seedlings. The most suitable applications for retardation of height growth, without negative effects on other morphological variables, were 4 g l–1 (32 mg per seedling) for daminozide and 2 g l–1 (16 mg per seedling), sprayed in two applications, for CCC. 相似文献
74.
Idaho locust (Robinia pseudoacacia 'Idaho') is an exotic multi-purpose tree used in landscaping, soil and water conservation, fodder sources and others. To improve its drought tolerance for reclaiming arid land, five lines of transformed mtl-D gene, as osmotic regulator in plant cells, have been selected and managed to determine their drought tolerance under experimental conditions.Qualitative and quantitative variables of transformed plants were studied. The critical value of drought tolerance was determined by detecting the 2,3,5-triphenyl tetrazolium chloride (TTC) reductants in roots and soil water content (SWC). The critical value for drought tolerance was SWC 6% while for the control plants the critical SWC was 8%; a moderate level of SWC is 13% and the highest SWC for plant endurance was 18%. The method proved to be reliable and sensitive in the evaluation of drought tolerance for forest trees. 相似文献
75.
76.
L. Alpízar Professor H. W. Fassbender Coordinator J. Heuveldop Professor H. Fölster G. Enríquez 《Agroforestry Systems》1986,4(3):175-189
The agroforestry systems of cacao (Theobroma cacao) under laurel (Cordia alliodora) and cacao under poro (Erythrina poeppigiana) were studied at CATIE, Turrialba, Costa Rica. An inventory was taken of the organic matter and nutrients (N, P, K, Ca, and Mg) separating the species into their compartments (leaves, branches, trunks and roots). Studies of the litter and of the mineral soil (0–45 cm) yielded these results:
Patterns of nutrient accumulation are discussed in relation to the characteristics of these agroforestry systems. 相似文献
77.
J. Heuveldop H. W. Fassbender L. Alpízar G. Enríquez H. Fölster 《Agroforestry Systems》1988,6(1-3):37-48
During 7 years (1979–1985) cacao harvests (beans and husks) have been recorded for the agroforestry systems ofTheobroma cacao underCordia alliodora andErythrina poeppigiana shade trees. The mean oven dry cacao yields were 626 and 712 kg.ha−1.a−1 cocoa beans underC. alliodora andE. poeppigiana respectively. Harvests have gradually increased over the years and the plantation has now reached maturity.
Annual extraction of N, P, K, Ca and Mg in fruits, which is relatively small, was calculated on the basis of chemical analyses.
The following average values were found (kg.ha−1.a−1):
At the age of 8 years, theC. alliodora trees have reached 26.7 cm diameter (DBH) and 14.0 m in height. Mean annual growth (from age 5 to 7) is 14.6 m3.ha−1.a−1.
Natural plant residue production has been measured for 4 years (Nov. 1981–Oct. 1985). UnderE. poeppigiana it has reached a value of 8.91 t.ha−1.a−1 and underC. alliodora 7.07 t.ha−1.a−1. The shade trees have contributed 57 and 47% respectively. Transference and decomposition rates are high and important in
the nutrient cycles.
The nutrient content of the litter was analysed and corresponding average yearly transfers were (kg.ha−1.a−1):
For part I see Vol. 4, No. 3, 1986.
Agroforestry Project, CATIE/GTZ (Tropical Agricultural Research and Training Center/Gesselschaft für Technische Zusammenarbeit),
Turrialba, Costa Rica 相似文献
78.
A series of novel 4-O-alkoxytrityl chlorides (1) with different chain lengths was synthesized as a novel reagent for obtaining 6-O-alkylated cellulose with high regioselectivity via trityl groups in one reaction step without the use of any protective groups. These chlorides were reacted with methyl -d-glucoside, which was used as a model compound, to examine the reactivities toward the primary hydroxyl groups of cellulose to afford a series of 6-O-alkylated methyl -d-glucosides in high yields. The product compounds were found to have interesting solubilities and thermal properties. Thus, newly prepared trityl chloride derivatives were found to be useful regioselective derivatization reagents on the primary hydroxyl group in carbohydrates, especially in cellulose. 相似文献
79.
80.
F.M. Trefz A. Lorch J. Zitzl A. Kutschke G. Knubben‐Schweizer I. Lorenz 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2015,29(2):688-695