Lettuce response to organic and phosphate fertilizers and root mycorrhization

The response of lettuce to production system, organic and phosphate fertilizers and root mycorrhization, was evaluated in two pot trials with factorial treatment combination of: (i) soil type (from organic and from conventional production systems) and organic fertilizer (0, 2 and 4 t ha^?1) in the first trial; and (ii) mycorrhizal inoculation (mycorrhized and non-mycorrhized plants) and Gafsa phosphate (0, 100 and 200 kg P₂O₅ ha^?1) in the second. Lettuce growth decreased with increasing rates of the organic fertilizer because of its very high electrical conductivity (50.1 dS m^?1) and lack of maturation. However, the fertilizer harmful effects were minimized in the soil from organic production. The application of Gafsa phosphate significantly increased lettuce yield and nutrient uptake. However, for the highest rate of phosphate, mycorrhized lettuce yield decreased compared to non-mycorrhized lettuce, suggesting that high soil available P may have harmful effects on the activity of mycorrhizal fungi.     

Natural variation of Arabidopsis thaliana root architecture in response to nitrate availability

Root system architecture (RSA) plays a crucial role in nutrient and water uptake in plants. RSA can be modulated to improve nitrogen use efficiency (NUE) of crops, decreasing the need for fertilization. In this study, we analyzed 12 root parameters in 48 Arabidopsis accessions grown in media with low or high nitrogen (N). Low N repressed six root traits and enhanced six others. A principal component analysis showed that six components contributed to 90.08% of N availability. The primary component contributed to 35.64% of the variation and was associated with LR characteristics. The 48 Arabidopsis accessions were divided into five response groups. Stw-0 had the highest biomass production and a high N concentration in both roots and shoots, independent of growth conditions. H55 had numerous LRs at low N. Our results provide N-responsive parameters suitable for mapping of quantitative trait loci related with root morphology.     

氮、磷、钾对小白菜产量和硝酸盐含量的影响及最优配方的选择

采用416-B最优混合设计，以珍珠岩作为保护地基质栽培小白菜．研究NO3^--N、P、K和NH4^ -N对保护地无土栽培小白菜产量和硝酸盐含量的影响。结果表明．氮素是影响小白菜产量和硝酸盐含量的主要因素；磷、钾的单效应作用较氮素小，主要通过对氮的互作效应影响产量和磷酸盐含量；最优的小白菜营养液配方为：NO3^--N、P、K和NH4^ -N的浓度分别为6．98,1．08，6．45和2．76mmol／L。     

固、液态磷源在石灰性土壤中的移动性及其对土壤有效磷含量影响的研究

采用同心圆扩散法对固体和酸性液体磷肥在石灰性土壤中的移动性与有效性进行研究。结果表明,土壤Olsen-P含量随施肥点圈层由内向外层而递减,液肥处理的Olsen-P量在施肥点以外的3个土壤圈层中均高于固肥处理。固体肥料大部分停留在距施肥点0~7.5 mm圈层,占施磷总量的55%~70%;液体肥料虽在0~7.5 mm层的含量低于固体肥料(约占15%~40%),但在远离施肥点的后3个圈层(7.5~43 mm)中均高于固体肥料处理,其中7.5~13.5 mm最为明显(液肥占35%,固肥占20%)。3种施磷量在砂土、壤土及粘土上均表现出一致的变化规律。肥料对土壤pH值的影响仅限制在距施肥点最近的0~7.5 mm范围,该层的pH值显著低于后层。本研究说明在石灰性土壤中液体磷的移动性、有效性明显高于固体磷,但对土壤pH值无显著影响。     

低磷胁迫下马尾松无性系磷效率性状对氮沉降的响应

【目的】剖析不同类型低磷胁迫下马尾松应对大气氮沉降的生长表现和适应机制,为在大气氮沉降背景下选育营养高效利用的马尾松速生优质新品种提供理论依据。 【方法】以来自马尾松 (Pinus massoniana) 全同胞子代的 5 个优良无性系 1 年生扦插幼苗为材料,分别在同质低磷 (介质表层与深层均缺磷) 和异质低磷 (介质表层磷丰富、深层缺磷) 两种土壤磷素环境下设置两种浓度梯度的模拟氮沉降试验,以研究低磷胁迫下马尾松无性系苗木生长、根系发育及氮、磷效率对模拟氮沉降的响应差异和规律。 【结果】1) 不同类型低磷胁迫下马尾松苗高和干物质积累量均表现出显著的无性系变异,且在同质低磷下存在明显的无性系 × 氮交互效应 (P < 0.05)。2) 马尾松无性系在不同类型低磷胁迫下应对氮沉降的适应机制有所差异。同质低磷、高氮环境下,33-4 和 19-5 等生长势较强的无性系,其根系长度、根表面积以及根分泌的酸性磷酸酶活性显著高于生长势较弱的无性系,干物质积累量与酸性磷酸酶活性之间的相关性增强,表明根系可通过增加在土壤中的分布面积和提高酸性磷酸酶活性来应对高氮、低磷的外界环境;异质低磷下,生长势较强的无性系,其根系长度和表面积在高氮沉降下显著增加,但比根长反而显著下降,意味着根系在高氮下增加吸收面积的同时,降低自身内部消耗可能是马尾松高磷效率的重要生物学基础之一。3) 马尾松无性系的磷吸收效率受氮沉降影响较大,在不同氮、磷水平下,其磷吸收效率与氮吸收效率均呈极显著正相关 (P < 0.01),表明模拟氮沉降有利于马尾松无性系对土壤中磷素的活化吸收,但磷利用效率无显著差异。4) 马尾松无性系的干物质积累量、根系长度、根表面积以及根分泌的酸性磷酸酶活性等指标的变幅较大,且无性系重复力均达到 0.75 (P < 0.05) 以上,这为高氮、低磷环境下马尾松耐受型植株的选择提供了可能。 【结论】以马尾松根系形态和根分泌的酸性磷酸酶活性变异为突破口,选育氮沉降下具有高磷效率的马尾松无性系将有利于遗传效益的提高。     

适宜施氮量保证滴灌日光温室黄瓜番茄产量降低土壤盐分及氮残留

农民传统过量肥水供应可能导致土壤氮素和盐分积累,滴灌施肥能在根区精确供应肥水以满足作物需求。为明确膜下滴灌日光温室黄瓜-番茄轮作体系氮素供应对土壤氮残留、电导率及作物产量和根干质量的影响,该研究设计空白(NN)、有机肥对照(MN)、优化供氮(RN)、高量供氮(HN)、传统供氮(CN)5个处理,进行了2008-2010年6季田间试验。结果表明,随着氮素供应量的增加,根层土壤硝态氮和电导率显著增加,CN处理加快并加剧了土壤硝态氮和盐分积累。3个黄瓜-番茄轮作周期,氮素供应RN、HN、CN处理的土壤硝态氮平均分别为176.9、346.6、500.8 kg/hm2,CN处理是RN处理的2.83倍(P0.05)。3a黄瓜季RN、HN、CN处理的土壤硝态氮积累量平均分别为-1.87、-49.61、-3.52 kg/hm2、番茄季分别为74.89、225.23、343.15 kg/hm2,CN处理积累量是RN处理的4.58倍(P0.05)。3个轮作周期后,RN、HN、CN处理比试验前的土壤硝态氮残留增加了219.1、526.9、1 018.9 kg/hm2,平均每个轮作周期增加73.0、175.6、339.6 kg/hm2,CN处理是RN处理的4.65倍(P0.05)。3个轮作季后,NN、MN、RN、HN、CN处理土壤电导率分别为433.8、681.5、824.5、927.5、1 120.0μS/cm,RN、HN、CN处理显著高于MN、NN处理(P0.05)。2008年番茄季、2009黄瓜季、2009番茄季、2010番茄季拉秧后的土壤电导率差异显著,CN处理是RN处理的1.15、1.29、1.40、1.36倍(P0.05),表明RN处理可显著降低土壤次生盐渍化的风险。每个轮作周期的土壤硝态氮、电导率动态变化均存在2个积累时期,分别在7月初-8月初的夏季休闲和9月初-11月中旬的番茄结果期。总之,优化供氮比传统供氮减施氮肥66.7%,显著降低土壤硝态氮残留和土壤电导率,保证黄瓜番茄产量不减,将为日光温室黄瓜番茄轮作体系滴灌施肥制度提供科学依据。     

长期施用磷肥对冬小麦根际磷、锌有效性及其作物磷锌营养的影响

以中国农业大学昌平试验站长期定位试验为基础,研究了长期施用磷肥对冬小麦根际磷锌有效性及其对作物磷锌营养的影响。结果表明,长期施用磷肥[P2O5,135.kg/(hm2.a)]导致土壤有效磷含量逐年提高;对根际和非根际土壤有效锌含量没有显著影响,但是根际土壤有效锌含量显著高于非根际土壤;长期施用磷肥冬小麦抽穗期植株锌含量显著低于不施磷处理;无论拔节期和抽穗期,植株含磷量和植株磷锌比(P/Zn)都随着施磷量的增加而显著增加。长期施用磷肥处理(P1和P2)在显著提高了冬小麦子粒含磷量的同时,显著降低了其含锌量;冬小麦子粒磷锌比(P/Zn)随着施磷量的增加也显著增加,子粒含磷量与含锌量呈极显著的负线性相关关系。     

Carbon availability regulates soil respiration response to nitrogen and temperature

The response of soil CO₂ fluxes (R_soil) to interactions between carbon (C) and nitrogen (N) availability or C and temperature conditions is not well understood, but may increasingly affect future C storage under the combined anthropogenic impacts of N deposition and climate change. Here we addressed this uncertainty through a series of laboratory incubation experiments using soils from three contrasting ecosystems to investigate how changes in C, N, and temperature regulate R_soil through changes to Michaelis–Menten parameters (i.e. V_max and K_m). Results of this study demonstrate that R_soil response to N enrichment and changes in temperature are dependent on the C availability of soil substrates. N addition influenced R_soil through both the maximum rate (V_max) and the half saturation constant (K_m). The increase in K_m corresponded to a decrease in R_soil when C was limited. Alternatively, when C was abundant, N enrichment increased R_soil, which corresponded to an increase in V_max. Regulation of temperature sensitivity through V_max and K_m was also dependent on C availability. Both V_max and K_m demonstrated positive temperature responses, supporting the hypothesis of a canceling effect at low C concentrations. While temperature sensitivity was influenced by both C quantity and C complexity, our results suggested that C quantity is a stronger predictor. Despite strong differences in climate, vegetation, and management of our soils, C–N and C-temperature interactions were markedly similar between sites, highlighting the importance of C availability in the regulation of R_soil and justifying the use of Michaelis–Menten kinetics in biogeochemical modeling.     

Residual effects of organic acid-treated phosphate rocks on some soil properties and phosphate availability

The effects of the application of organic acid-treated phosphate rocks on the growth and nutrient uptake of Italian rye grass (Lolium multiflorum Lam. cv. Tachiwase) and some properties of the soil were evaluated in a greenhouse pot experiment. Phosphate rocks (PRs) collected from six countries; China, Florida (USA), Jordan, Sri Lanka, Togo, and Tanzania, were treated with 1 M oxalic or tartaric acid at the ratio of 2.5 mL g^-1 PR. The organic acid-treated PRs, containing 12–31% water soluble P, were applied to a granitic regosol (pH 5.8) at 200 mg P pot^-1 (4 kg soil). Untreated PRs and single superphosphate (SSP) were included in the treatments. Italian ryegrass was grown for 175 dafter planting (DAP) with ample supply of other nutrients and water. Shoots were harvested at 56, 119, and 175 DAP and the soils were analyzed for pH and Olsen-P after the experiment. Application of organic acid-treated PRs consistently increased the dry matter yield and P uptake of the plants compared with the application of untreated PRs at each harvest, but they were less effective than SSP. A larger amount of P (calculated per unit water-soluble P applied) was recovered from the organic acid-treated PRs than from SSP. The amount of residual extractable P in the soils with the organic acid-treated PRs was about the same as or significantly larger than that in the soil treated with SSP. Soil pH was also significantly higher than in the control and SSP soils. The results suggest that organic acids could be used to improve the P availability of PRs to plants with favorable residual effects in terms of available P and soil pH, without exerting any adverse effects on plant growth or nutrient acquisition.     

磷矿粉的超微细活化及磷释放动态研究

以无机、有机材料为活化剂,用振动磨湿法研磨和连续提取的方法,研究了不同活化剂对磷矿粉的超微细活化作用及磷素动态释放特性。结果表明,添加活化剂能够显著提高磷矿粉的粉碎效率,缩短研磨时间。对磷矿粉进行超微细活化处理能显著提高磷矿粉有效磷的含量,胶磷矿加入无机,有机活化剂和无机、有机活化剂并用的处理2h样品的有效磷含量是粗胶磷矿的1.82、1.86、1.83倍。 2%柠檬酸连续浸提试验表明,各微细处理的胶磷矿6次累积磷总量分别是粗胶磷矿粉的1.90、1.86、1.64、1.69倍。     

Variation of nitrogen accumulation and yield in response to phosphorus nutrition of soybean (Glycine max L. Merr.)

Phosphorus (P) is essential macronutrient for soybean [Glycine max (L.) Merr.] growth and function. The objective of this study was to determine effect of phosphorus nutrition (including phosphorus nutrition level and interruption of phosphorus supply) on nitrogen accumulation, nodule nitrogen fixation and yield of soybean plants by ¹⁵N labeling with sand culture. The results showed that they all presented a single peak curve with improvement of phosphorus nutrition level, when phosphorus concentration of nutrient solution was about 31 mg/L, they all reached the maximum and effect of phosphorus nutrition level on nodule nitrogen fixation was lower than that on yield formation level. Interruption of phosphorus supply during soybean growth period, nitrogen accumulation and nodule nitrogen fixation were seriously inhibited, and yield was decreased significantly when interruption of phosphorus supply during V₃-R₁ and R₁-R₅ period, while interruption of phosphorus supply during R₅-R₇ period had no significant effect on nitrogen accumulation, nodule nitrogen fixation and yield. So soybean nitrogen metabolism and yield were sensitive to phosphorus nutrition in the V₃-R₅ period, those were not sensitive to phosphorus nutrition after R₅ period.     

超微活化条件对磷矿粉磷素形态及肥效的影响

采用化学分析、红外光谱分析以及盆栽试验研究了活化剂添加量及研磨时间对超微活化磷矿粉磷素形态及生物有效性的影响.结果表明,与普通磷矿粉相比,磷矿粉经超微活化处理后有效磷提高了45.1％～58.7％,活性磷提高了169.4％～203.6％,水溶性磷含量随活化剂添加量的增加也明显提高;当活化剂添加量达到5％时,3次水溶性磷的累积释放量较相同条件下制得的超微细磷矿粉提高84倍以上.适当延长研磨时间有利于磷矿粉磷素的释放,但效果不显著.红外光谱分析结果表明:超微细活化磷矿粉中与PO3-、HPO2-相关的特征吸收峰强度较普通磷矿粉显著增强,且生成了与PO43-、HPO42-相关的新特征吸收峰,使磷矿粉中的磷向有效状态转变.盆栽试验结果进一步表明,超微活化磷矿粉处理的玉米生物量、磷素利用率均显著高于磷矿粉、普通超微细磷矿粉以及过磷酸钙和磷酸二铵等常规水溶性磷肥,可增强抗固定能力而显著提高土壤有效磷含量.超微活化磷矿粉较高的活性磷总量和水溶性磷持续适度的供磷强度是其生物有效性高的原因.     

黄瓜幼苗干物质积累、膨压及光合速率对铵态氮和硝态氮的响应

采用溶液培养方法,研究了氮素形态及水平对黄瓜干物质积累、膨压及光合速率的影响。结果表明,同一氮素水平时,NO3--N处理黄瓜干物质重量、叶片面积、叶片含水量、水势、膨压等均高于NH4+-N处理。低水平NH4+-N(5mmol/L)对黄瓜光合速率影响不大,甚至高于同水平NO3--N处理的,叶片面积稍有减小;高水平NH4+-N不仅显著抑制黄瓜干物质的积累,叶片面积仅是同水平NO3--N处理的12.7%,最小光合速率（Pn）为CO2 1.6mol/（m2·s）,仅为同水平NO3--N处理的10%左右。NH4+-N处理引起黄瓜叶片面积的减小与叶片膨压降低相关性较大,相关系数为0.98;膨压与叶片水势直接相关,而渗透势对此影响不大。高水平NO3--N对黄瓜产生了渗透胁迫,抑制黄瓜生长,表现在渗透调节物质的大量积累。不同黄瓜品种对氮素形态及水平响应差异较大,所有处理中新泰密刺长势均好于吉尼罗。低水平的NH4+-N对黄瓜干物质的积累影响不大,高水平则明显抑制其生长。说明高浓度铵态氮对植物产生了毒害,而高浓度的硝态氮则是渗透胁迫。     

Surface soil hydraulic properties in four soil series under different land uses and their temporal changes

The concepts of “genoform” and “phenoform” distinguish the genetically-defined soil series and the variation of soil properties resulted from different land uses and management practices. With the repeated field measurements over time, we attempted to understand the difference of soil hydraulic properties among different land uses for a given soil series, and their temporal dynamics. Four soil series (Glenelg, Hagerstown, Joanna, and Morrison) in Pennsylvania with contrasting textures, structures, and parent materials were investigated. Within each soil series, four common land uses (woodland, cropland, pasture, and urban) were examined. At each site of soil series–land use combination, field-saturated and near-saturated hydraulic conductivities, K(ψ), were measured at the soil surface using standard tension infiltrometers at water supply potentials (ψ) of − 0.12, − .06, − 0.03, − 0.02, − 0.01, and 0 m. Surface infiltration measurements were repeated at each site in May and October from 2004 to 2006. The analysis of variance indicated that the measurement time (May or October) had the greatest impact on all measured hydraulic conductivities (p < 0.001), followed by the land use (p < 0.05 for K_ψ = 0 and K_{ψ = − 0.06}) and soil series (p < 0.06 for K_{ψ = − 0.01} to K_{ψ = − 0.03}). The interactions between the time and land use and between the soil series and land use were statistically significant for K_ψ = 0 and K_{ψ = − 0.01.} When separated by the measurement time, land use showed greater impacts in October than in May, while soil series had greater impacts in May than in October. Among the four land uses, woodland showed less obvious temporal change compared to the other three land uses because of less human-induced impacts and more consistent ground cover. Other three land uses generally showed a higher hydraulic conductivity in May than in October due to the drier initial soil moisture condition and related management practices in the spring that gave rise to more significant macropore flow. The results suggested that the initial soil moisture is an important variable that drives the temporal variation of the surface soil hydraulic properties.     

低磷胁迫下箭筈豌豆和毛叶苕子根际过程的差异比较

采用我国北方两个豆科绿肥品种: 箭筈豌豆（Vicia sativa L.）与毛叶苕子（Vicia villosa Roth）,在控制条件下通过不同供磷处理的营养液培养,研究了不同绿肥作物适应低磷胁迫根际过程的差异,并揭示其高效利用磷的机理。试验通过分次取样的方法,测定了两种豆科作物在缺磷与供磷条件下的生物量、根系质子释放速率、根系有机酸分泌速率以及根表酸性磷酸酶活性的动态。结果表明,箭筈豌豆与毛叶苕子在生长前期对低磷胁迫的响应存在明显差异。箭筈豌豆主要靠增大质子释放量和提高酸性磷酸酶活性来适应低磷胁迫; 而毛叶苕子主要通过提高根冠比、扩大根系生物量来对外界环境中的缺磷状况做出响应,在缺磷时其根表酸性磷酸酶的活性显著提高。箭筈豌豆与毛叶苕子可通过协调根系形态和生理的适应性变化提高对磷的吸收。     

不同磷效率小麦对低铁胁迫的基因型差异

用营养液培养方法研究了不同磷效率小麦幼苗对低铁胁迫的基因型差异。结果表明,低铁胁迫(-Fe)对磷高效基因型小麦生长的抑制作用显著大于对磷低效基因型。低铁处理下,磷高效基因型81(85)-5-3-3-3、Xiaoyan54和Taihe-5025的植株地上部干重平均比正常供铁(+Fe)处理下降55.2%;磷低效基因型Jinghe90-Jian-17、NC37和Jing41平均33.0%。低铁胁迫显著降低了磷高效基因型小麦的叶片叶绿素含量,3个磷高效基因型的叶绿素a、叶绿素b和叶绿素a+b含量分别降低了35.6%、35.3%和35.3%,磷低效基因型分别降低了16.8%、7.7%和11.9%。低铁胁迫对小麦的根系生长、根系吸磷量和磷利用效率均未产生明显的影响,但显著降低了磷高效基因型小麦的植株地上部吸磷量和根效率比。与正常供铁的处理相比,磷高效和磷低效基因型小麦的地上部吸磷量和根效率比在低铁处理中平均降低了55.0%、54.9%和32.5%、36.4%。磷高效基因型小麦植株体内积累的磷量明显高于磷低效基因型,这是磷高效基因型不耐低铁的主要原因。磷效率越高,对低铁的反应越敏感。     

氮素形态对解磷细菌发酵液解磷效果及小白菜生长和品质的影响

采用盆栽试验,研究了施用硝态氮、铵态氮对解磷细菌发酵液不同组分解磷活性及其对小白菜产量、品质的影响。结果表明,施用相同氮肥时,浇灌解磷细菌原发酵液处理 T3的作用效果明显优于菌体悬浮液T2及菌液上清T1;以硝态氮为底肥时,施用发酵原液的土壤有效态磷含量较高,小白菜产量最高,品质明显优化,即硝态氮含量下降, Vc、可溶性糖、可溶性蛋白、纤维素以及植株磷含量显著增加,且增加变幅均高于以铵态氮为底肥的效果。由此可知,硝态氮与解磷细菌发酵原液配施时, W1菌株解磷效果更好,可能是解磷菌株W1最适的氮源。因此,种植小白菜时直接向其根际施用解磷细菌发酵液并配施硝态氮肥,更有利于提高小白菜的品质及产量。     

Phosphorus and potassium availability from cattle manure ash in relation to their extractability and grass tetany hazard

ABSTRACT

Due to a decrease in phosphorus (P) and potassium (K) mining, manure is incinerated to concentrate P and K in ash. To understand the alternative use of manure-derived ash as P and K sources, laboratory and greenhouse experiments were conducted to determine the relationship between extractability and P and K uptake in cattle manure ash (CMA) and that between CMA application and a grass tetany hazard. The results showed that more P was extracted with 2% citric acid (90% of the total P) than with 2% formic acid (72–84% of the total P). Ninety-one percent of the total K was soluble in water. A greenhouse pot experiment was conducted to test P and K availability to Guinea grass (Megathyrsus maximus). Cattle manure ash or calcium dihydrogen phosphate (CF) was incorporated into sandy soil at 10, 20, and 50 g P₂O₅ m^?2. Two combinations of CMA and CF were tested at 20 g P₂O₅ m^?2. Potassium rates followed K content in CMA applied at different rates of P equivalent to 19, 38, or 96 g K₂O m^?2. In four harvests, there was no significant difference in the total yields between CMA and CF treatments. The total P uptake was significantly lower in the CMA treatment than in the CF treatment, while it was not in the combined CMA and CF treatments. The P uptake in response to different extraction methods indicated that the extraction of P by 2% formic acid without sonication is recommended to predict P availability in CMA. The potassium uptake from CMA application was comparable to that from the KCl application, and excessive K occurred at 38 and 96 g K₂O m^?2. The grass tetany hazard ratio higher than 2.2 was observed at the beginning period at the lowest application rates of CMA and CF. In conclusion, the combination use of CMA and CF was better than the single use of CMA. Moreover, CMA would be an available K source, but the grass tetany hazard still needs to be considered in application rates and pretreatments.