芋种子萌发特性的研究

以仰光×乐平及仰光×霞山2种杂交种子为试材,探究消毒方法、光照、温度、播种基质对芋种子萌发和生长的影响。结果表明:8%Na Cl O(无水酒精稀释)处理9min后用无水酒精清洗种子是最佳的芋种子消毒方法;种子或珍珠岩消毒对种子的萌发和子叶的生长无显著影响,但在有菌条件下,生长后期衍生出的细菌或真菌会影响子叶的后续生长;芋种子是喜光性种子,种子萌发的适宜温度为25~30℃;在培养土中,芋种子不萌发,湿润滤纸、无菌水、珍珠岩、沙子和MS培养基中芋种子的发芽率较高,但仅沙子和MS培养基中幼苗生长健壮;移栽于培养土后幼苗生长良好,成活率高达95%。     

Temperature and substrate controls on microbial phospholipid fatty acid composition during incubation of grassland soils contrasting in organic matter quality

Soil incubations are often used to investigate soil organic matter (SOM) decomposition and its response to increased temperature, but changes in the activity and community composition of the decomposers have rarely been included. As part of an integrated investigation into the responses of SOM components in laboratory incubations at elevated temperatures, fungal and bacterial phospholipid fatty acids (PLFAs) were measured in two grassland soils contrasting in SOM quality (i.e. SOM composition), and changes in the microbial biomass and community composition were monitored. Whilst easily-degradable SOM and necromass released from soil preparation may have fuelled microbial activity at the start of the incubation, the overall activity and biomass of soil microorganisms were relatively constant during the subsequent one-year soil incubation, as indicated by the abundance of soil PLFAs, microbial respiration rate (r), and metabolic quotient (qCO₂). PLFAs relating to fungi and Gram-negative bacteria declined relative to Gram-positive bacteria in soils incubated at higher temperatures, presumably due to their vulnerability to disturbance and substrate constraints induced by faster exhaustion of available nutrient sources at higher temperatures. A linear correlation was found between incubation temperatures and the microbial stress ratios of cyclopropane PLFA-to-monoenoic precursor (cy17:0/16:1ω7c and cy19:0/18:1ω7c) and monoenoic-to-saturated PLFAs (mono/sat), as a combined effect of temperature and temperature-induced substrate constraints. The microbial PLFA decay patterns and ratios suggest that SOM quality intimately controls microbial responses to global warming.     

The effects of artificial substrate and stocking density on Pacific white shrimp (Litopenaeus vannamei) performance and water quality dynamics in high tunnel-based biofloc systems

The use of artificial substrates in shrimp aquaculture may allow for production of shrimp at increased densities while providing a growth medium for microbes that assist with water quality processes and provide supplemental nutrition for shrimp. Greenhouse-based shrimp production systems can extend the shrimp production season in temperate climates while conserving water and energy. For this study, we evaluated the effects of providing extra substrate and shrimp density on water quality and shrimp production in greenhouse-based biofloc systems. Four 11-m³, wood framed, and rubber-lined tanks were constructed in each of four high tunnel greenhouses (for a total of 16 tanks). Four treatments were evaluated: high-density stocking with substrate (HDS), high-density stocking with no substrate (HDNS), low-density stocking with substrate (LDS), and low-density stocking with no substrate (LDNS). Each treatment was randomly assigned to one tank in each tunnel to block for location. No artificial heat was used, and shrimp were grown for 120 days. High-density systems were stocked at 200 shrimp/m³ while low-density tanks had 100 shrimp/m³. Adding substrate increased total in-tank surface area by 13.4%. The addition of substrate had no significant effect on any shrimp production or standard water quality parameters. Shrimp had significantly greater final weight, faster growth rate, and lower feed conversion rate in low-density treatments (P ≤ 0.02 for all). Total shrimp biomass production was significantly higher in high-density treatments (HD: 4.0 kg/m³; LD: 2.3 kg/m³; P < 0.05). There were no significant differences in survival between densities (HD: 91.3%; LD: 94.5%; P = 0.43). Peak and overall mean nitrite levels were significantly higher in high-density treatments compared to low-density treatments. Dissolved oxygen levels and pH over the course of the study were significantly lower in high-density treatments, likely due to increased respiration rates in the water column. This project shows the feasibility of shrimp production in temperate climates with no artificial heat using high tunnel greenhouses, few impacts of added substrate on shrimp production, and increased shrimp density can result in much larger harvests with few negative impacts on production metrics.     

激素和基质对黄花远志扦插生根的影响试验

激素和扦插基质是影响扦插生根的重要因素.本试验研究不同激素和扦插基质对黄花远志扦插生根的影响.试验开始于2004年4月15日,7月26日出苗,并统计生根情况.结果表明插条的生根率与激素浓度有关,生根质量与激素的种类有关;插条在400mg·L-1吲哚丁酸十400mg·L-1萘乙酸、800mg/L吲哚丁酸、800mg·L-1萘乙酸溶液中浸泡10min,生根效果较好,生根率分别达到34.0%、29.3%、28.8%;蛭石+珍珠岩、泥炭土+河沙两种扦插基质相比,生根效果以泥炭土+河沙为佳.     

山核桃蒲壳含量对金森女贞容器育苗的影响

通过5种不同山核桃蒲壳(基质)含量(山核桃蒲壳、田园土混合配制体积比分别为0.5∶0.9、1∶9、2∶8、3∶7、4∶6)进行金森女贞育苗比较试验,结果表明:以山核桃蒲壳、田园土混合配制(体积比3∶7)和以山核桃蒲壳、田园土混合配制(体积比2∶8)的基质进行育苗,10个月后的生长效果最好,分别是70.0 cm和67.9 cm,且无显著差异,但以山核桃蒲壳、田园土混合配制(体积比2∶8)的基质比以山核桃蒲壳、田园土混合配制(体积比3∶7)的基质经济效益要好,每盆高0.07元;其它综合效益分别依次为:以山核桃蒲壳、田园土混合配制(体积比4∶6)的基质、以山核桃蒲壳、田园土混合配制(体积比1∶9)的基质、以山核桃蒲壳、田园土混合配制(体积比0.5∶9.5)的基质。表明采用这5种不同山核桃蒲壳含量作为基质进行金森女贞育苗,以山核桃蒲壳、田园土混合配制(体积比2∶8)的基质综合效果最佳。     

适用于西瓜砧木育苗的菌糠基质筛选

以4 种菌糠为复合育苗基质对西瓜砧木进行育苗试验,考察各菌糠品种应用于西瓜砧木育苗的适用性,筛选出适用西瓜砧木育苗的菌糠品种。试验选取海鲜菇、杏鲍菇、金针菇以及茶树菇菌糠分别与蛭石混合配制成复合育苗基质,测定各基质的理化性状并进行西瓜砧木育苗试验。结果表明：杏鲍菇和金针菇菌糠容重相对较小,总孔隙度相对较少;海鲜菇、茶树菇菌糠育苗效果优于杏鲍菇和金针菇处理;海鲜菇菌糠:蛭石=4:1、茶树菇菌糠:蛭石=1:1 基质处理西瓜砧木壮苗指数达0.36、0.37,显著高于对照的草炭:蛭石=2:1处理。建议选择海鲜菇、茶树菇菌糠进行西瓜砧木育苗复合基质的进一步研发。     

不同肥料配方对香石竹生长发育的影响

[目的]筛选适合香石竹生长的最佳肥料配方。[方法]供试香石竹品种为马斯特(R3),栽培基质为陶粒∶草炭=1∶1,共设3个不同肥料配方处理和1个不施肥处理(对照),每处理重复3次,研究不同肥料配方对香石竹的株高、茎粗、叶片长度、花蕾直径、根冠比、干物重的影响。[结果]大量元素水溶性肥料处理的香石竹的株高、茎粗、花蕾直径、干物重分别为82.37 cm、0.79 cm、2.41 cm和0.56 g,均优于其他处理,也可有效促进香石竹的叶片长度和根部发育。[结论]大量元素水溶性肥料是促进香石竹生长的最佳肥料配方。     

Kinetics of substrate oxidation and hydrogen peroxide production by Mycoplasma mycoides subsp. mycoides Large Colony (LC) type and Mycoplasma mycoides subsp. capri

Mycoplasma mycoides subsp. mycoides Large Colony (LC) type is a pathogen of goats causing contagious agalactia and respiratory disease, found on all continents where small ruminants are kept. It shares close genetic characteristics with M. mycoides subsp. capri. Substrate oxidation by 22 strains of M. mycoides subsp. mycoides LC from nine countries was compared with that of eight strains of M. mycoides subsp. capri from five countries. There was considerable similarity in the substrates used, but substrate saturation coefficients (K_s) varied for different substrates. Substrate utilization patterns and K_s values did not (1) significantly differentiate the LC strains from each other, (2) show any correlation with geographical origin, or (3) distinguish the LC strains from the capri strains. These results support previous studies justifying the reclassification of these subspecies as a single species.     

有机废弃物生产园艺基质的研究

以工厂化生产金针菇的菇渣废料为主要原料,以鸡粪、尿素、发酵微生物等为辅料,研究了废弃物菇渣的发酵工艺及发酵后菇渣基质的复配技术,研究结果表明,最佳发酵的温度是50~60℃,最佳水分条件为发酵料含水50%~60%,与菇渣复配的适宜无机基质为蛭石,菇渣与蛭石的体积比为6∶4。     

杏鲍菇培养阶段基质理化特性变化的研究

对杏鲍菇工厂化生产中的培养阶段进行跟踪观察,初步分析了瓶栽杏鲍菇培养期间基质的理化特性变化情况。结果表明：杏鲍菇培养至25-30d时菌丝发满,基质含水量、呼吸产生的CO2量最大;基质pH在菌丝生长阶段前期下降较快,后期基本维持稳定;适宜的后熟时间能提高杏鲍菇的产量和品质。