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41.
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43.
建立刀片在工作过程中的受力模型,得出刀片切土角和安装角的合理选取范围。通过分析螺旋线的形成原理,建立了锥形面螺旋线的统一方程,并对圆锥螺旋钻尖的翼片刀刃部分进行了优化分析。 相似文献
44.
Tissue culture micropropagation of Douglas-fir 总被引:1,自引:0,他引:1
A procedure was developed for plantlet production from embryos of Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco]. The Medium for Conifer Morphogenesis, used at full strength, and supplemented with 10 M benzyladenine for 17 days produced an average of 6.8 shoots on more than 90% of the embryos. The percentage of shoot-forming embryos as well as the average number of shoots per embryo varied significantly among eight seedlots. For secondary multiplication, 89% of the adventitious shoots produced axillary buds on MCM with 5 M benzyladenine. However, 0.5 M BA was more suitable for the elongation of axillaries. Rooting ranged from 0–87% depending upon the treatment. The highest percentage was obtained with a 7-week incubation in peat:perlite containing 1/5-strength medium, 1% sucrose and 2.7 M naphthaleneacetic acid, followed by 5 weeks on peat:perlite with 1/5-strength major and minor salts, full iron and organics, 1% sucrose and 0.1% charcoal. 相似文献
45.
杉木中龄林不同部位和叶龄针叶光合特性的日变化和季节变化 总被引:39,自引:1,他引:39
在不同季节光合最适温度、适宜空气湿度 (70± 5 % )和正常大气CO2 条件下测定了杉木(Cunninghamialanceolata (Lamb .)Hook .)中龄林不同部位和叶龄针叶光合特性及典型天气下净光合速率的日变化。结果表明 ,当年生针叶最大净光合速率 (Pmax)在生长中期 >盛期 >后期 ,1年生和 2年生针叶则从盛期经中期到后期呈下降趋势。从生长盛期至后期 ,光饱和点 (LSP)和暗呼吸速率 (Rd)降低而表观量子利用效率 (α)增加 ,其中尤以盛期与中后期的差别较明显。光补偿点 (LCP)除生长盛期当年生针叶明显高于生长中、后期以外 ,其它差异不明显。Pmax除生长盛期当年生针叶与 1年生接近外 ,均为当年生 >1年生 >2年生。随着叶龄的增长 ,针叶LSP、LCP和Rd 均降低 ,α提高。从上部至中部到下部针叶Pmax、LSP、LCP和Rd 均降低而α增加 ,尤其是上部和中部针叶与下部差异较大。不同季节针叶光合特性的差异与针叶光合生理活性有关 ;不同部位之间的差异则是长时间适应所处光环境的结果 ;而不同叶龄针叶之间的差异除了生理原因外 ,还可能与所处光环境有关。针叶净光合速率 (Pn)的日变化在阴天为单峰型 ,Pn 主要受光合有效辐射通量密度 (PPFD)的影响 ,同时受温度、湿度和CO2 浓度变化的微调。晴天Pn 日变化为双峰型 ,受温度和湿度的强 相似文献
46.
1987年冬和1988年冬二次从浙江引种六个笋用竹种1.56万株,成活率达90%以上,发笋率达80%以上,新竹的秆基粗度已达到母竹的粗度,引种是成功的。本文分析了各引种环节的技术效果。 相似文献
47.
为了给山杏快速繁殖提供理论依据,以山杏茎尖和茎段为外植体,以MS为基本培养基,对消毒方式、初代培养基激素配比、分化培养基激素配比和生根培养基激素配比进行筛选。结果表明,茎尖和当年生茎段经75%酒精处理30 s,0.2%升汞消毒6 min,再用2%Na Cl O处理4 min,其诱导效果最佳。茎尖初代培养最佳激素配比为6-BA 0.5 mg/L+NAA 0.2 mg/L;茎尖愈伤组织分化培养最佳激素配比为6-BA 0.2 mg/L+NAA 0.1 mg/L;茎段初代培养最佳培养基激素配比为6-BA 0.5 mg/L+NAA 0.1 mg/L;1/2MS+IBA 0.2 mg/L为最佳生根培养基。 相似文献
48.
Browse of multipurpose tree species such as black locust could be used to broaden grazing options, but the temporal distribution
of foliage has not been adequately studied. Our objective was to determine effects of harvest date, P fertilization (0 and
600 kg ha−1 yr−1), and pollard height (shoots clipped at 5-, 50-, and 100-cm above ground) on foliar and shoot allometry of black locust.
The experiment was conducted on a naturally regenerated 2-yr-old black locust stand (15,000 trees ha−1). Basal shoot diameter and foliar mass were measured monthly in June to October 2002 and 2003. Foliar and shoot dry mass
(Y) was estimated from basal shoot diameter (D) by the function Y = aD
b
, with regression explaining ≥95% of variance. Allometry of foliar mass was affected by harvest date, increasing at a greater
rate with D in September than in June or July, but not by P fertilization or pollard height. Foliar mass was predicted best by month-specific
equations for the June to October growth interval. Allometry of shoot dry mass was unaffected by harvest date, P fertilization,
or pollard height. These equations could be used as a first approximation of foliar and shoot mass for pollarded black locust. 相似文献
49.
Daniel J. Chmura 《New Forests》2006,32(1):21-31
An investigation of phenological and growth traits was conducted in a lowland plantation, comprised of 23 Norway spruce (Picea abies (L.) Karst.) seed stands from the Istebna region in the Beskidy Mountains of Poland. Significant differences were found among
population in growth initiation, growth termination and the length of shoot elongation period. The two latter traits were
highly correlated and were attributed to the altitude of the maternal stand. The tested populations were grouped based on
phenology. Progeny of lower-alttitude stands ceased growth later, had a longer duration of shoot growth and greater current
leader length compared to progeny of higher-altitude stands. Individual populations, however, did not differ in current-year
growth and total tree height, implying higher within-population variation in growth traits than in phenology. The similar
growth capacity of all tested populations suggests considerable gene flow between maternal stands, although differences in
phenology imply the adaptation of progenies to the altitudinal environment of seed origin. These results suggest that within
tested populations, selection is possible based on phenology alone, without considerable reduction of early height growth;
final decisions, however, should be based on the environmental conditions of the planting site. 相似文献
50.
Variable adventitious rhizogenesis of juvenile shoot cuttings was observed in seven half-sib families (TP-1, BAN-1, AN-3,
JR-3, SL-16, UM-3, and UM-5) of Albizia procera Benth. Treatment with IBA invariably promoted sprouting by 8%, adventitious rooting by 218%, root number by 869%, and root
length by 36.4% compared with the control. Interaction between families and IBA treatment significantly enhanced sprouting
and root length in BAN-1, JR-3, UM-3, and UM-5, and root number in all families, but had a significant suppressive effect
on sprouting in AN-3. Treatment with IBA increased family heritability (h
f
2) 1.38-fold for sprouting, 2.86-fold for adventitious rooting, and 10.86-fold for root number, but reduced family heritability
by a factor of 8.25 for root length. Thus, direct genetic effects seem to have strongly affected sprouting and adventitious
rooting, with IBA playing an auxiliary role, but had little effect on root number and length, for which IBA had a dominant
regulatory role. 相似文献