无糖培养条件下大型组培箱内CO2变化规律及对组培苗的影响

该文采用中国农业大学农业部设施农业生物环境工程重点开放实验室研制的设有组培微环境实时监控系统的大型组培箱,分别对矮牵牛、菊花和番茄组培苗移栽后箱体内CO2浓度的变化规律及不同CO2增施浓度对无糖组培苗生长的影响进行了研究.试验表明:移栽后的当天,组培箱内的CO2浓度便开始下降,第2 d下降速度明显加快,均降至100 μL/L以下.在移栽后的第4～5 d,箱体内CO2浓度下降到35 μL/L左右后便不再下降,一直在30～40 μL/L之间波动.因此得出:无糖培养在组培苗移栽后的第2 d就应增施CO2,否则会直接影响组培苗的生长.在不同CO2增施浓度试验中,当光照度控制在80 μmol/(m2·s)时,CO2浓度为(650±50)μL/L时培养出的组培苗生长状况最好.     

组培环境CO2增施监控系统的设计与试验

为改善组培苗的生长发育环境,探索CO₂富集等环境因素的影响,设计制作了CO₂适时增施监控系统,并以葡萄组培苗为对象,利用本控制系统与传统组培方式进行了对比试验。结果表明:系统工作稳定、正常,能够有效地将CO₂浓度控制在设定的(800～1200)μL/L范围内,满足组培苗光合作用的需要;在CO₂富集环境中,组培苗生长健壮、发育良好,光合自养能力显著增强     

增施CO2气肥对温室结球莴苣光合作用影响的综合模型研究

为探讨不同温度和光照条件下增施CO₂气肥对温室作物生长的影响，应用红外线CO₂气体分析仪测定方法，对不同CO₂浓度下结球莴苣光合作用速率的变化进行了深入系统的研究，并分别建立了低温条件下和中、高温条件下增施CO₂气肥对光合作用速率影响的综合模型。研究结果表明，在一定范围内，随着光照度提高和温度上升，增施CO₂气肥对于光合作用的促进效果提高，但是超过饱和点后会有负的效应。本实验条件下，结球莴苣光合作用最佳的生态因子组合为：光照度897.3 μmol·m^-2·s^-1，温度28.9℃，CO₂浓度2160 μL/L，此时的净光合速率(CO₂)Pn为36.0 μmol·m^-2·s^-1。     

高浓度CO2下氮素对小麦叶片干物质积累及碳氮关系的影响

高大气CO₂浓度下植物叶片干物质积累、碳氮关系和糖含量的变化对光合作用的适应性下调有重要的反馈作用,通过研究不同施氮量对高大气CO₂浓度下植物叶片干物质积累、叶氮浓度和糖含量的影响,可进一步明确氮素对植物光合作用适应性下调的调控机制。以不同大气CO₂浓度和氮素水平为处理条件,测定盆栽小麦拔节期叶片鲜重、干重、含水量、还原糖、可溶性糖、全氮含量,研究了氮素对长期高大气CO₂浓度(760μmol·mol-1)下小麦叶片的干物质积累、糖含量及碳氮含量的影响。结果表明,大气CO₂浓度升高使小麦叶片的鲜重和干重增加,含水量下降。大气CO₂浓度升高使N0处理的小麦叶片还原糖含量下降,而可溶性糖含量显著升高;施氮后小麦叶片还原糖含量无显著变化,但可溶性糖含量降低。高大气CO₂浓度条件下小麦叶片全氮含量下降,C/N比增加,而增施氮素后C/N比显著下降。可溶性糖含量和C/N比的下降有利于减轻同化物质对光合作用的反馈抑制,提高大气CO₂浓度增高条件下小麦叶片的P_n。     

空间电场对植物吸收CO2和生长速度的影响

为研究空间电场对植物吸收CO₂和生长速度的影响，首先采用同位素示踪法，分析了不同空间电场调控营养液栽培的番茄秧吸收CO₂气体和HCO^-₃阴离子的能力，证实了 ¹⁴C—HCO^-₃是一种受控于空间电场变化的阴离子，且空间电场强度的变化方向调控着 ¹⁴C—HCO^-₃阴离子流的流动方向。在此基础上以蕹菜(空心菜)为试验材料，采取空间电场与增施CO₂浓度的参数组合，做对比生长试验，通过红外线CO₂分析法揭示了空间电场的极性对植物吸收CO₂的速度有显著影响，且正向空间电场能显著促进植物对CO₂的吸收，并得到正向空间电场与足量的CO₂浓度相配合能大幅度提高温室蔬菜生长速度，使作物产量倍增的结论，为建立空间电场促进植物生长技术提供理论依据。     

水培条件下CO2与NH+4/NO-3配比对番茄幼苗生育的影响

升高CO₂浓度能够促进作物的光合作用，提高作物的生物量和产量，但关于CO₂与NH⁺₄/NO^-₃比及其交互作用对作物影响的研究较少，为探索番茄幼苗生长发育对CO₂浓度升高的响应是否对NH⁺₄/NO^-₃配比有较强的依赖关系，本试验在营养液栽培条件下，以番茄(Lycopersicun esculentum Mill)为试材，研究正常大气CO₂浓度(360 μL/L)和倍增CO₂浓度(720 μL/L)与不同NH⁺₄/NO^-₃配比的交互作用对番茄幼苗生长的影响。结果表明：CO₂浓度升高提高了低NH⁺₄/NO^-₃比例处理中番茄叶片的光合速率和水分利用率，提高幅度随NH⁺₄/NO^-₃比例的降低而增强，光合速率增强最大达55%。在同一CO₂浓度处理下净光合速率与水分利用率均随NH⁺₄/NO^-₃比例的增加而显著降低。这说明CO₂浓度升高对番茄幼苗生长发育的促进作用随NH⁺₄/NO^-₃比例的降低而提高，但并没有减弱全NH⁺₄-N处理中番茄幼苗的受毒害作用。综上所述，CO₂浓度升高能提高植物生产的节水能力和水分生产力；水培条件下，NO^-₃-N是最适合番茄幼苗生长发育的氮源，其它NH⁺₄/NO^-₃比例对番茄幼苗的生长发育有一定的抑制作用，仅以NH⁺₄-N作氮源则番茄幼苗很难生长。     

基于C8051F005的组培CO2微环境调控系统的研制与试验

基于C8051F005芯片设计开发一种新型组培气体微环境控制系统，采用高纯度CO₂定压定量供给和自动箱内循环在线监测技术，成功解决了CO₂气体难以自动精确施放和传感器检测精度及其稳定性的问题，实现了组培微环境CO₂浓度的按需设定和自动控制。该系统能够同时记录CO₂浓度的下降量和时长，既可用于研究不同组培微环境因子对组培苗同化CO₂速率的影响，又能用于规模化组培育苗生产。以驱蚊香草、冬青、大花蕙兰组培苗为实验材料，验证系统可靠性与可行性。结果表明该系统运行可靠，控制精度高，能够满足规模化组培育苗对气体微环境调控的需求和组培微环境建模的科研要求。     

CO2浓度升高条件下不同程度豌豆蚜危害对紫花苜蓿叶片营养物质和次生代谢物质的影响

由于人类大量开采使用石油、煤炭、天然气等化石燃料,使大气CO₂浓度升高,这不但加速全球变暖,还将影响地球上动植物的生存和分布,从而对整个生态系统产生深远影响。为探明CO₂浓度升高与豌豆蚜（Acyrthosiphon pisum）虫口密度对紫花苜蓿（Medicago sativa）叶片内化学物质的影响,明确CO₂浓度升高和蚜虫密度在紫花苜蓿生理生化中的作用,试验在CO₂光照培养箱内设置380 μL·L^-1（对照）、550 μL·L^-1和750 μL·L^-1 3个CO₂浓度培育苜蓿幼苗并接入10日龄成蚜10头·株^-1、20头·株^-1、30头·株^-1,并以0头·株^-1作为空白对照,1周后测定植物体内营养物质和次生代谢物质含量。结果表明,随CO₂浓度升高,蚜虫密度为30头·株^-1时紫花苜蓿可溶性蛋白、可溶性糖以及淀粉含量均上升,在750 μL·L^-1 CO₂浓度下分别比CK上升11.62倍、0.49倍和0.24倍;黄酮、总酚和简单酚含量也显著上升。随蚜虫危害程度加重,同一CO₂浓度下紫花苜蓿淀粉、简单酚含量先上升后下降,高CO₂浓度蚜虫密度为30头·株^-1时比0头·株^-1时可溶性糖、总酚以及单宁含量上升1.66倍、1.49 mg·g^-1和1.09 mg·g^-1,差异均显著（P<0.05）。说明具有固氮作用的豆科植物更易于适应CO₂浓度升高的变化,从而在受到刺吸胁迫后增强自身诱导抗虫性以抵御害虫为害。     

CO2浓度升高和施氮对冬小麦光合面积及粒叶比的影响

利用开顶式气室和盆栽方法, 以冬小麦品种"小偃6号"和"小偃22"为供试材料, 在2种CO₂浓度(375 μL·L^-1和750 μL·L^-1)和3个施氮水平[0、0.15 g(N)·kg^-1(土)和0.30 g(N)·kg ^-1(土)]下分析了小麦抽穗期绿色叶片、非叶光合器官(茎鞘、穗、芒)的形态和光合面积以及粒叶比对CO₂浓度升高和施氮的反应。结果表明, 施氮有助于小麦叶和非叶光合器官伸长和增宽(粗), 增加其光合面积、穗粒数、穗粒重、粒数叶比和粒重叶比。与背景CO₂浓度(375 μL·L^-1)相比, CO₂浓度升高对叶片和茎节长度、茎叶和芒光合面积具有明显的正向效应(P<0.05), 但对叶宽、茎节直径、穗面积影响不明显(P>0.05), 使"小偃6号"和"小偃22"单茎光合面积分别增加8.1%~15.1%和2.8%~13.2%, 且均以0.30 g(N)·kg^-1(土)施氮水平下增幅最大。CO₂浓度升高后, 穗粒数和粒数叶比在3个施氮水平下均不同程度增加, 其中2个品种粒数叶比分别在0.30 g(N)·kg^-1(土)和0.15 g(N)·kg^-1(土)施氮水平下增加最明显, 增幅分别为44.2%和41.4%; 穗粒重和粒重叶比在不施氮时下降, 在施氮时显著增加, 其中2个品种粒重叶比平均增幅分别为43.6%和20.7%。由于芒面积远小于其他源器官面积, 在单茎光合面积中所占比例较小(3%左右), 因此认为CO₂浓度升高主要通过促进小麦茎叶伸长生长来增加光合面积, 同时提高单位叶面积库承载力和物质调运能力, 改善源库关系, 增加氮素供应有利于小麦源库生长对CO₂浓度升高的反应。     

组培育苗气体微环境自动调控系统的研制与试验

为改善组培苗生长发育的气体环境，降低育苗成本，在综合分析已有气体环境控制系统的基础上，基于以流量控制组培环境CO₂浓度和以压力控制混合罐CO₂浓度和气体压力的控制策略，建立了相应控制的数学模型，设计了新型组培育苗气体微环境自动综合调控系统，对组培气体环境中CO₂浓度和相对湿度实施适宜参数组合调控。以叶用甘薯组培苗为试验材料，依据有关文献，取适宜光合光量子通量密度、CO₂浓度和相对湿度的参数组合为(250 μmol·m<     

An examination of the total analysis of major elements in soil samples

Recently conventional chemical analyses were mostly replaced by instrumental analysis. Although results from both methods were examined in details after the samples had been solubilized or extracted by appropriate techniques, the solubilization method was considerably altered so as to be convenient for the following analysis. In atomic absorption spectrophotometry (AAS), for example, fusion technique was mostly inadequate because of the higher salts concentration in the obtained solution. The use of H₂SO₄ must also be avoided in acid digestion for SO₄ ^2- precipitates with Sr²⁺ or La³⁺ which must be added to eliminate interferences in the succeeding procedure. Therefore, it is essential to consider the whole scheme including sample treatments to evaluate the suitability of instrumental analysis. In this experiment, the suitability of the methods which have been employed in our laboratory was examined by analyzing 9 rock standards.     

Absorption and transport of Na and Cl in rice cultivars differing in their tolerance to salinity: An examination of the effects of ammonium and potassium salts

The absorption and transport of Na and Cl from 0.1 mM and 10 mM ²²Na labelled NaCl or ³⁶Cl labelled KCl were examined in 15 days old seedlings of 3 cultivars of rice differing in their tolerance to salinity. Furthermore, the effects of 10, 100 and 1000 ppm (N)₂S on their uptake were studied. It was found that in general, the salt‐tolerant cultivars BR and PNL‐1 absorbed more Na and translocated a lesser proportion of it to the shoot, compared to the salt‐sensitive IR‐8, from 0.1 mM NaCl. The presence of (N)₂S reduced the uptake of Na in all the cultivars. It was also found that the presence of 100 ppm K, KN or NNreduced Na absorption from 0.1 mM NaCl significantly in all the cultivars, and the translocation to shoot in BR‐ Chloride transport from 0.1 mM NaCl was reduced by (N)₂S in all the cultivars. The 3 cultivars differed significantly in the rates of absorption and transport of Na and Cl. The results indicate that PNL‐1 which is a cross of IR‐8 X BR, has inherited the salt tolerance trait from BR. Lower rates of Na translocation to the shoot can be used as an index of salt tolerance in rice.     

Gaseous nitrogen losses from fertilized soil during nitrification and denitrification using the acetylene blockage technique

Summary A sandy soil amended with different forms and amounts of fertilizer nitrogen (urea, ammonium sulphate and potassium nitrate) was investigated in model experiments for N₂O emission, which may be evolved during both oxidation of ammonia to nitrate and anaerobic respiration of nitrate. Since C₂H₂ inhibits both nitrification and the reduction of N₂O to N₂ during denitrification, the amount of N₂O evolved in the presence and absence of C₂H₂ represents the nitrogen released through nitrification and denitrification.Results show that amounts of N₂O-N lost from soils incubated anaerobically with 0.1% C₂H₂ and treated with potassium nitrate (23.1 µg N-NO ₃ ^– /g dry soil) exceeded those from soils incubated in the presence of 20% oxygen and treated with even larger amounts of nitrogen as urea and ammonium sulphate. This indicates that nitrogen losses by denitrification may potentially be higher than those occurring through nitrification.     

Microbial diversity in three floodplain soils at the Elbe River (Germany)

Microbial communities in floodplain soils are exposed to periodical flooding. A long-term submerged Eutric Gleysol (GLe), an intermediate flooded Eutric Fluvisol (FLe), and a short-time flooded Mollic Fluvisol (FLm) at the Elbe River (Germany) with similar organic carbon contents (C_org) between 8.1% and 8.9% were selected to test the quality of phospholipid fatty acids (PLFA), soil microbial carbon (C_mic), basal respiration (BR), metabolic quotient (qCO₂), and C_mic/C_org ratio to characterize and discriminate these soils with microbial parameters.The three floodplain soils can be differentiated by C_mic and by total PLFA-biomass. Due to the different flooding durations and the time since the soils were last flooded C_mic and PLFA-biomass increase in the order GLe<FLe<FLm. Both parameters correlate significantly (r=0.999;p<0.05). The C_mic/C_org ratios are low in comparison to terrestrial soils and revealed the same ranking over the three soils like C_mic. Contrary, qCO₂ and BR are highest in GLe and lowest in FLm according to inundation regime. The diminished C_mic, high BR, and high qCO₂ values in GLe seem to be an unspecific response of aerobic soil microorganisms on the long flooding period and the resulting short time for developing after last flooding as well as the low pH value. Different plant communities and their residues may influence the microbial diversity additionally.The PLFA profiles were dominated by the group of saturated fatty acids that together constituted almost 62-72% of the total fatty acids identified in the soils. In GLe all groups of PLFA, inclusive monounsaturated fatty acids, are lowest and in FLm highest, while in FLe the PLFA fractions show an intermediary amount of the three soils. The FLm had most of the time aerobic conditions and revealed therefore the highest C_mic, PLFA-biomass, especially monounsaturated fatty acids, C_mic/C_org ratio as well as relatively low BR and qCO₂ value. These indicate that microorganisms in FLm are more efficiently in using carbon sources than those in GLe and FLe.All 26 identified PLFA were found in FLe and FLm, while the polyunsaturated fungi biomarker 18:2ω6,9c could not be detected in GLe. In this long-time submerged soil the environmental conditions which microorganisms are exposed might be disadvantageous for fungi.     

Assessing the depletion of soil P following sequential extractions with Mehlich-3 and Olsen solutions

We analyzed in soils with contrasting cultivation histories the depletion of P following sequential extractions with soil testing solutions. Soil samples were collected in three experiments in eastern Canada (L’Acadie, Lévis, and Normandin) and P was sequentially extracted 16 times, once daily, using Mehlich-3 (M3) or Olsen (Ol) solution. The cumulative amount of P extracted was 252 mg P_M3 kg^?1 and 77 mg kg^?1 P_Ol for L’Acadie, 212 mg P_M3 kg^?1 and 66 mg P_Ol kg^?1 for Lévis, and 424 mg P_M3 kg^?1 and 83 mg P_Ol kg^?1 for Normandin. The depletion of P was described by a logarithmic function (Y = a ln (N) + b) for P_M3, and a power function (Y = αN^β) for P_Ol. The inorganic P pool decreased in the three soils. The organic P pool did not decrease possibly because soil testing solutions did not directly extract P from this pool. This study demonstrated that laboratory soil testing analysis using M3 or Ol solution principally target P from the inorganic pool, suggesting that P fertilizer recommendations to mineral soils relying on these methods do not account for the potential of the organic P pool to contribute to soil P availability.     

Changes in the fungal-to-bacterial respiratory ratio and microbial biomass in agriculturally managed soils under free-air CO2 enrichment (FACE) - A six-year survey of a field study

In soil ecology, microbial parameters have been identified as sensitive indicators of changes in the soil environment. The Braunschweig FACE project provided the opportunity to study the effects of elevated CO₂ (550 μmol mol⁻¹) as compared to ambient CO₂ (370 μmol mol⁻¹) on total microbial biomass (C_mic), C_mic-to-C_org ratio and the fungal-to-bacterial respiratory ratio together with total C_org, N_t, C:N ratio and pH over a six-year period. Field management followed a typical crop rotation system of this region with either a crop-related full nitrogen supply (N100) or 50% reduced N supply (N50). The soil microbial parameters responded to the elevated CO₂ treatment in varying intensities and time spans. The fungal-to-bacterial respiratory ratio was the most sensitive parameter in responding to an elevated CO₂ treatment with highly significant differences to ambient CO₂-treated control plots in the third year of CO₂ fumigation. After six years bacterial respiratory activity had increased in ascending order to 34% in FACE-treated plots (N50 and N100) as compared to control plots. Soil microbial biomass (C_mic) responded more slowly to the FACE treatment with highly significant increases of >12% after the fourth year of CO₂ fumigation. The C_mic-to-C_org ratio responded very late in the last two years of the CO₂ treatment with a significant increase of >7.0% only in the N100 variant. Total C_org and N_t were slightly but significantly increased under FACE around 10.0% with ascending tendency over time starting with the second year of CO₂ treatment. No significant FACE effects could be recorded for the C:N ratio or pH.These results suggest that under FACE treatment changes in the soil microbial community will occur. In our study the fungal-to-bacterial respiratory ratio was superior to total C_mic as microbial bioindicators in reflecting changes in the soil organic matter composition.     

Specific ion effect on the accumulation of abscisic acid in wheat

Studies were carried out in the glass house using sand culture to find out the specific ion effect on the accumulation of abscisic acid in wheat. Seeds were sown in sixteen different solutions of chloride, sulphate, nitrate, carbonate salts of sodium, potassium, calcium and magnesium used each at ‐2 bar osmotic potential. The leaf samples taken after 25 days of sowing indicated that osmotic as well as salt stress increased significantly the accumulation of abscisic acid. The accumulation of abscisic acid was significantly less under potassium and calcium salt ions as compared to that under sodium and magnesium salts ions. Overall effect of anions showed that accumulation of abscisic acid was more under PEG (osmotic stress and chloride salts but it was less under sulphate and nitrate salts and was the least under carbonate salts. The accumulation of abscisic acid was exceptionally high under potassium dihydrogen phosphate. In general, the accumulation of abscisic acid‐a growth inhibitor varied not only with the type of the cation but also depended on the accompanying anion indicating differential growth response of plants under different types of saline conditions having dominance of different salt ion(s).     

Yield and nutritional evaluation of the banana hybrid ‘FHIA-18’ as influenced by phosphate fertilization

Abstract

The ‘FHIA-18’ hybrid banana is an alternative for producers as it is resistant to Black Sigatoka and Panama disease. However, few studies report the nutritional requirement of this hybrid, especially phosphorus. It is known that the efficiency of phosphorus use can be improved, reducing the need for application, depending on the genotype cultivated. Therefore, this study aimed to evaluate the yield and mineral nutrition of ‘FHIA-18’ hybrid banana on phosphate fertilization. A banana orchard with the cultivar ‘FHIA-18’ was conducted on a Typical Red Latosol. Then, triple superphosphate fertilizer was applied on plants at 0, 20, 30, 40, 50, and 60?kg ha^?1?year^?1, over three productive seasons. At the time of flowering the macro and micronutrient contents of the leaves were evaluated. Subsequently, the nutrient contents of the fruits were evaluated. For this, fruit pulp samples from the third and fourth hands were collected. In addition, yield was estimated considering cluster mass and plant density. The following dose 36?kg ha^?1 of P₂O₅ year^?1 increased the content of phosphorus in the leaf, despite that banana hybrid cultivar FHIA 18 demanded 50% of the recommended fertilizer to achieve its maximum yield (29.4 t ha^?1?year^?1). Phosphate fertilization promoted significant changes in P, Ca, Cu, and Zn contents of leaves and fruits. Therefore, it is concluded that the mineral nutrition of banana ‘FHIA-18’ is affected by phosphate fertilization, as well as requiring less P than recommended to achieve higher yield.     

Determination of top-dressing for rice in the field by the detection of asparagine

It is well known that an increase of and better grain can be obtained by the application of an adequate amount of quick-acting nitrogen fertilizers such as ammonium sulphate, thirty to twenty five days before heading, and this is a common practice of top-dressing, being called “Hogoe” in Japanese. It is also well known that excess of nitrogen supplied at this time makes plants weak against mechanical injury, insects and disease. For the application of “Hogoe”, therefore, an accurate diagnosis of the nitrogen nutrient condition of rice is required. In a series of investigations on the nitrogen metabolism, the author found that asparagine appeared in parallel with the increase of nitrogen concentration in rice plants, and considered that the detection of asparagine would be a good indicator for assessing the nitrogen requirement of rice lantst^l).     

Background level of nitrous oxide in the atmosphere in relation to flux from soil

According to Broadbent and Clark (3), there are numerous data indicating that denitrification leads to the emission of N₂O together with N₂, whereby loss of N is developed from soils. Nitrous oxide is also released from soils to the atmosphere during the nitrification of ammonium and ammonium-producing fertilizers under aerobic conditions (1). Relatively few attempts have been made to directly measure N₂O evolution under field conditions (6, 7, 10–12), although a number of laboratory studies have been reported. These studies are essential for determining the N balance between additions and losses of soil N.