太空春石斛组培快繁黄苗现象成因初探

以太空春石斛丛生芽为试验材料,初步研究了基本培养基、激素和附加物质香蕉对黄苗现象的影响。试验结果表明:基本培养基以1/2MS培养基最适宜;激素NAA和IBA对黄苗影响差异不显著,NAA0.2mg/L较适宜;而附加物质香蕉对黄苗的影响较大,黄苗较严重。     

浅析汉英语言的称谓

对汉、英两种语言中的亲属称谓语和社交称谓语进行比较,并且阐述了由此所反映出的两种不同的文化内涵。     

不同浓度硫酸盐对水稻土中异化铁还原过程的影响

研究不同电子受体之间的竞争关系对揭示厌氧水稻土中微生物作用导致的氧化还原过程变化机理具有重要的理论意义。本研究采用土壤泥浆厌氧培养、人工合成氧化铁体系接种土壤浸提液厌氧培养及接种铁还原菌纯培养等试验方法,通过向培养体系中添加SO24-,探讨了硫酸盐作为竞争电子受体对不同铁还原体系中Fe（Ⅲ）还原的影响。结果表明,在2种水稻土的泥浆培养过程中,Fe（Ⅲ）还原速率均随着SO24-浓度增加而降低,但Fe（Ⅱ）的最终累积量却较对照处理有明显的增加。添加硫酸盐对Fe（Ⅲ）还原速率（k）的影响表现为：石灰性水稻土〉酸性水稻土;而最终Fe（Ⅱ）累积增加率则为：酸性水稻土〉石灰性水稻土。由接种不同水稻土浸提液的培养试验看出,添加SO24-后Fe（Ⅲ）还原受到显著的抑制,但随着培养时间延长Fe（Ⅲ）还原反应依然可以进行,并且Fe（Ⅱ）累积量最终达到与CK相同的水平。在接种铁还原菌的纯培养试验中,添加SO24-对供试的4株铁还原菌的Fe（Ⅲ）还原过程并未产生抑制效应,表明铁还原菌本身并不受硫酸盐的影响。     

煤矸石等组成的无土栽培基质重金属污染及蔬菜安全评价

利用煤矸石、油菜秸秆等废弃资源为原料,按（煤矸石：腐熟秸秆）体积比为2：8、3：7、4：6、5：5和6：4的比例配制成5种混合基质,在人工光照室内以盆栽的方法栽培白菜、生菜、苋菜、菠菜、茄子、番茄、辣椒和萝卜8种蔬菜,采用尼梅罗综合污染指数和Hakanson潜在生态风险指数法对5种混合基质以及其上生长的8种蔬菜的重金属污染和潜在生态风险进行了综合评价。结果表明,5种混合基质中,煤矸石含量较少的T1、T2、T3基质的重金属污染程度较小,潜在生态风险程度较低,在这3种基质上栽种的蔬菜重金属综合污染评价等级为优良或安全,符合蔬菜绿色食品标准。重金属对混合基质产生的污染中,Cd和Hg是主要的重金属污染及潜在生态风险因子,其他重金属的污染能力较小。另外,在评价由煤矸石为无机原料组成的有机生态型无土栽培基质的重金属污染及潜在生态风险时,应选择国家土壤环境质量一级标准作为参比值,且煤矸石在混合基质中所占的体积比一般不应超过1/2。     

利用组织培养技术提取甘草黄酮

本研究筛选了两种能快速诱导甘草疯长型愈伤组织的培养基MS5和MS7,用微波法提取甘草愈伤组织和野生甘草根中总黄酮。测定结果显示：三年生野生型胀果甘草根中总黄酮的含量约为6.02%,培养3~4周的胀果甘草愈伤组织中总黄酮的含量约为1.1%。结果表明：组织培养生产黄酮在生产效率、工厂化生产、避免季节限制、保护野生甘草资源及实际应用中更具优势。本研究可为从甘草中提取总黄酮提供一条可借鉴的途径。     

红壤溶磷菌的筛选及溶磷机制

采用以磷酸铝为磷源的蒙金娜(PVK)液体培养基研究了从红壤土中筛选出的4种溶磷菌的溶磷效果,选出其中的优势菌株B1,并对其溶磷机理做出初步探讨。结果表明,所筛选出的4株溶磷菌在液体培养条件下均有显著的溶磷效果,其中菌株B1在培养4 d后有效溶磷量最大,达到292.8 mg L-1。各处理培养液pH在培养期间均有显著下降,pH从7.0下降至3.2~4.7。高效液相色谱测定发现,各菌株培养液中有机酸的种类与含量随培养时间变化而不同,其中菌株B1主要分泌草酸和苹果酸,培养1 d后有机酸总量可达到5 mmol L-1;通过添加有机酸对磷酸铝活化的试验表明,分泌有机酸溶磷仅是菌株B1溶磷机制之一,可能还存在其他溶磷机制。菌株B1生长的适宜pH范围为5~9,最适培养温度为30℃,100 ml三角瓶的最适装液量为30~40 ml。经鉴定,菌株B1与苏云金芽孢杆菌有99.9%的相似性。     

液培条件下磷水平对两种磷效率小麦根际特征的影响

为探讨磷高效型小麦(小偃54)和磷低效型小麦(京411)在不同磷水平下根际特征的差异,测定了液培条件下苗期小麦的植株生物量和吸磷量、根际pH值与根系分泌的酸性磷酸酶活性等。结果表明,不同磷水平(P0:0、P1:0.5 mmol/L和P2:1 mmol/L)下,磷高效型小偃54的植株吸磷量和根部生物量从移苗第6 d起明显高于磷低效型京411,在P0水平下尤为明显,且随培养时间的延长两者差距逐渐增大;小偃54的根际pH值在移苗初期与京411并无明显差异,随着培养时间的延长,小偃54的根际pH值显著低于京411,但两者单位根系分泌质子量差异逐渐减小。从移苗第6 d到第18 d,小偃54在不同磷水平下酸性磷酸酶的分泌量均显著高于京411;小偃54在P0水平下根系分泌的酸性磷酸酶量显著高于P1和P2水平,而京411从第12 d起才有相同规律,小偃54比京411对磷胁迫反应快且强度大。由此可见,在不同磷水平下,磷高效型小偃54在苗期的各项测定指标均优于磷低效型京411,在P0水平下两者根际特征差异尤为显著,且两种小麦根际特征差异与苗期生长天数有很大的关系。     

蜡样芽孢杆菌菌株X5强化的生物有机肥能有效控制根结线虫(Meloidogyne sp.)

The efficacy of Bacillus cereus X5 as a potential biological control agent against root-knot nematodes was evaluated in vitro by examining second-stage juvenile mortality and egg hatching rate under addition of culture filtrate and in planta by application of bio-organic fertilizers enhanced with B. cereus X5, B. thuringiensis BTG, or Trichoderma harzianum SQR-T037 alone or together in greenhouse and field experiments. The biofumigation of the root-knot nematode-infested soil with organic materials (chicken manure, pig manure and rice straw) alone or in combination with B. cereus X5 was also conducted in greenhouse experiments. In laboratory, the filtrate of B. cereus X5 more effectively reduced egg hatching rates during the incubation period for 14 d and more effectively killed the second-stage juvenile during the incubation period of 24 h than that of B. thuringiensis BTG. The highest dry shoot weights for greenhouse tomatoes and field muskmelons were found in both the treatment consisting of the bio-organic fertilizer enhanced with the three biocontrol agents and the treatment consisting of the bio-organic fertilizer enhanced only with B. cereus X5. The two bio-organic fertilizers achieved better nematicidal effects than those enhanced only with B. thuringiensis BTG or T. harzianum SQR-T037. B. cereus X5 also enhanced effect of biofumigation, which resulted in increased plant biomass and reduced nematode counts in the roots and rhizosphere soil. Therefore, these results suggested that biological control of root-knot nematodes both in greenhouses and fields could be effectively achieved by using B. cereus X5 and agricultural wastes.     

Nitrogen nutrition,leaf resistance,and leaf photosynthetic rate of the rice plant

The evidence that indicates a close association between nitrogen nutrition and the Photosynthetic rate of single rice leaves (Table 1) shows that the photosynthetic rate is related to the nitrogen content on a dry weight basis or on a leaf area basis, Photosynthesis of single leaves can be analyzed in terms of a series of diffusion resistances, i.e., stomatal, mesophyll, and carboxylation (1, 3, 6). Nitrogen nutrition may affect either one of these or more than two at the same time. Nitrogen nutrition affects mainly the mesophyll resistance, and the stomatal resistance to a lesser extent, in cotton, beans, and maize (10) while it affects both the stomatal and mesophyll resistance in sugar beet (8).     

Effect of nutrient solution salinity and ionic concentration on parsley (Petroselinum crispum Mill.) essential oil yield and content

The growth and essential oil (EO) production of parsley were evaluated in response to salinity and nutrient solution concentrations in a soilless culture. Parsley plants that were 60 days old were potted in a coconut fiber and peat moss medium and were treated with four different nutrient solutions, including T1, T2, T3 and T4. The T1 nutrient solution was the standard, the T2 and T3 solutions contained incremental macronutrient concentrations with an electrical conductivity (EC) of up to 2.2 and 3.2 dS m^?1, respectively, and the T4 solution was the same as T2 but with sodium chloride (NaCl) and an incremental macronutrient concentration with an EC of 3.2 dS m^?1. Next, these plants were grown for 90 days in a greenhouse with natural daylight in Nador, Morocco. Shoot and root growth significant decreased with increasing EC. However, the salinity that resulted from the addition of NaCl did not affect plant growth in the nutrient solutions. The optimum obtained growth and EO production were 1.2 and 2.2 dS m^?1, respectively. Consequently, the optimum EC value (based on the EO production) of parsley in the soilless culture was 1.2–2.2 dS m^?1.