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Comparison of traditional and improved methods for estimating the stability of organic growing media
Organic growing media employed in hydroponic crops could change their characteristics due to organic matter degradation during culture growing season. Traditional methods for measuring the stability of growing media (Biochemical Stability Index, Lemaire) do not take into account the activity of crop roots, nutrients in the growing media or microorganism presence. Three experiments were performed to determine the stability of six organic substrates. Stability was measured as the percentage of organic matter remaining in substrates. In experiment one (short duration and small scale without plant) 500 ml samples were incubated for 180 days following original methodology proposed by Lemaire (L) and with three modifications: (1) Inoculation with compost (I), (2) watered with nutrient solution (NS), and (3) both combined (I + NS). In experiment two (Long duration, medium scale) 10 l samples were incubated with and without a lolium crop for 720 days in a greenhouse. In experiment 3 stability of each substrate was real measured in 20 l hydroponic bags after use in four cycles of tomato production in a commercial greenhouse (2 years). All incubations were triplicated. Physicochemical properties of substrates were measured. Correlations between stability estimated in experiment one and two and real determinations in experiment three were analyzed. Lemaire methodology modified by adding and inoculum an nutrients (I + NS) was the best method to estimate the stability of organic growing media measured in real conditions in experiment 3. This new method greatly improves the estimation performed with original Lemaire methodology. Long term incubations with lolium also reproduce well the real stability of growing media but this methodology is not feasible because it requires four times longer and the amount of substrate required is 20 times larger for each sample. 相似文献
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试验以玫红景天(Sedum spectabile cv .Borean .)和冰山景天(Sedum spectabile cv .Al-bum )为植物试材,研究了不同基质、不同外源激素浓度对景天新品种嫩枝扦插生根的影响。试验表明:玫红景天和冰山景天均适合在园土+蛭石+珍珠岩(1∶1∶1)、园土+沙土(1∶3)的基质下种植扦插,冰山景天在NAA+IBA(1∶1)浓度为200~400mg/L时,生根率及根长值最大;玫红景天在NAA+IBA(1∶1)浓度为400mg/L时,生根率高、生根效果最佳。为今后研究景天类植物的扦插繁殖提供了科学的理论参考。 相似文献
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不同配比基质对草莓开花结果和果实品质的影响 总被引:1,自引:0,他引:1
[目的]通过设置不同配比的基质,为草莓基质栽培提供理论参考。[方法]采用草炭、蛭石和珍珠岩3种材料,以不同的体积比配成4种不同的混合基质,研究了不同配比基质对立体盆栽草莓开花结果特性和果实品质的影响。[结果]混配基质的各项理化指标均在无土栽培基质的理想范围内,其中以处理Ⅰ草炭+珍珠岩(2∶1)栽培的草莓表现最好。[结论]4种基质处理均适合草莓栽培。 相似文献
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M. Asaduzzaman M.A. Wahab M.C.J. Verdegem S. Huque M.A. Salam M.E. Azim 《Aquaculture (Amsterdam, Netherlands)》2008,280(1-4):117-123
The present research investigated the effect of carbon/nitrogen ratio (C/N ratio) control in ponds with or without substrate addition for periphyton development on production of giant freshwater prawn. C/N ratios of 10, 15 and 20 were investigated in 40 m− 2 ponds stocked with 2 prawn juveniles (5.023 ± 0.02 g) m− 2 with or without added substrates for periphyton development. The various treatment combinations of C/N ratio and periphyton substrate addition are abbreviated as ‘CN10’, ‘CN15’, ‘CN20’, ‘CN10 + P’, ‘CN15 + P’ and ‘CN20 + P’, P representing periphyton substrate. A locally formulated and prepared feed containing 30% crude protein with C/N ratio10 was applied. Tapioca starch was used as carbohydrate source for manipulating C/N ratio and applied to the water column separately from the feed. Increasing the C/N ratio from 10 to 20 reduced (P < 0.001) the total ammonia-nitrogen (TAN), nitrite–nitrogen (NO2–N) and nitrate–nitrogen (NO3–N) in water column and total Kjeldahl nitrogen (TKN) in sediment. The addition of substrates only influenced the NO2–N concentration in the water column (P < 0.001). Increasing the C/N ratio raised the total heterotrophic bacterial (THB) population in the water column, sediment and periphyton (P < 0.001). It also increased the dry matter (DM), ash free dry matter (AFDM), and chlorophyll a content of periphyton (P < 0.001). The lowest specific growth rate (SGR), the highest food conversion ratio (FCR), and the lowest protein efficiency ratio (PER) were recorded in treatment CN10 (P < 0.05). The addition of substrates did not influence size at harvest (P > 0.05) but improved the survival from 62.8 to 72% (P < 0.001). Increasing the C/N ratio from 10 to 20 increased the net yield by 40% and addition of substrate increased the net yield by 23%. The combination of C/N ratio control and substrate addition increased the net yield by 75% from 309 (CN10) to 540 (CN20 + P) kg ha− 1 (120 days)− 1. This 75% higher production concurred with (1) a lower inorganic nitrogen content in the water column, (2) a higher THB abundance supplying additional single cell protein to augment the prawn production, and (3) an improved periphyton productivity and quality. 相似文献
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东方杉系杉科属间杂交新树种,半常绿高大乔木,具有耐水湿、耐盐碱、生长速度快、景观效果好、抗风等优良特性;东方杉不结实,且无性繁殖困难。该文介绍了东方杉温室大棚扦插设施准备,采穗圃营建,扦插育苗方法等育苗技术。应用于大规模苗木生产,平均成活率达到76.3%。 相似文献