Influence of Phosphorus and Endomycorrhiza (Glomus Intraradices) on gas exchange and plant growth of Chile Ancho Pepper (Capsicum Annuum L. cv. San Luis)

Seedlings of chile ancho pepper were grown in pots containing a pasteurized mixture of sand and a low phosphorus (P) sandy loam soil, and either inoculated (VAM) or not inoculated (NVAM) with the endomycorrhizal fungus Glomus intraradices. Long Ashton nutrient solution (LANS) was modified to supply P to the seedlings at 0, 11, and 44 g(P) m^-3 (P₀, P11, P₄₄, respectively). Low P depressed net photosynthetic rate (P_N), stomatal conductance (gs), phosphorus use efficiency (P_N/P), and internal CO₂ concentration (C_i). The mycorrhiza alleviated low P effects by increasing P_N, g_s, P_N/P, and decreasing C_i. At P₀, C_i of NVAM plants was equal to or higher than that of VAM plants, suggesting nonstomatal inhibition of photosynthesis. Gas exchange of VAM plants at P₀ was similar to that of NVAM plants at P11. Endomycorrhiza increased leaf number, leaf area, shoot, root and fruit mass at P₀ and P₁₁ compared to NVAM plants. Reproductive growth was enhanced by 450 % in mycorrhizal plants at P₄₄. Root colonization (arbuscules, vesicles, internal and extraradical hyphae development) was higher at lower P concentrations, while sporulation was unaffected. The enhanced growth and gas exchange of mycorrhizal plants was in part due to greater uptake of P and greater extraradical hyphae development. This revised version was published online in June 2006 with corrections to the Cover Date.     

高粱和地球囊霉联合修复锶污染土壤研究

本研究选用高粱(Sorghum bicolor(L.) Moench)为修复植物用于治理土壤锶污染,接种地球囊霉(Glomus geosporum),比较不同锶浓度(0、75、725、975 mg/kg)处理下,地球囊霉对高粱修复锶污染土壤的调控作用。结果表明:在所有锶处理下,接种地球囊霉的侵染率都高于50%。与无菌根处理相比,在75、725 mg/kg锶处理,接种地球囊霉的高粱的生物量、株高和根长都显著增加(P0.05)。接种地球囊霉的高粱表现出显著的菌根依赖性(P0.05)。其中最显著的是75 mg/kg处理,菌根依赖性为136.92%,并且在0—975 mg/kg锶处理中菌根依赖性都大于100%。地球囊霉侵染的高粱,叶片和根中的锶含量与无菌根处理组相比显著增加(P0.05),接种菌根组的转运系数都高于与无菌根组。接种地球囊霉,土壤中的全磷含量和速效磷含量显著降低(P0.05)。全磷减少了6.52%—18.77%,速效磷减少了12.38%—27.43%。接种AMF显著增加了土壤磷酸酶活性(P0.05),与无菌根组相比,增加了19.67%—32.56%。综上所述,地球囊霉能够促进高粱对锶的富集能力和耐受性,在锶污染(75—725 mg/kg)时接种地球囊霉的效果最好。     

一株耐盐日本曲霉的筛选及其溶磷促生作用

【目的】从内蒙古种植葵花的盐碱地中筛选高效溶磷真菌,为盐碱地增产节肥开发生物肥料提供溶磷菌种资源。【方法】利用ITS r DNA序列鉴定菌株、固体培养基测定耐盐性,液体摇床培养与盆栽试验结合分析菌株溶磷能力,盆栽和田间试验明确菌株M1促进作物生长和增产作用;LC-MS技术测定菌株M1在液体培养基中分泌有机酸和植物激素含量,明确菌株M1的溶磷和促生机理。【结果】溶磷菌株M1鉴定为日本曲霉(Aspergillus japonicus)。液体培养基接种菌株M1培养6 d,以Ca_3(PO_4)_2为磷源时上清液有效磷达1020.89 mg/L,溶解率为63.30%;以AlPO_4为磷源时有效磷达995.69 mg/L,溶解率为48.59%;以贵州开阳磷矿粉、江苏锦屏磷矿粉、云南晋宁磷矿粉、河北钒山磷矿粉和云南昆阳磷矿粉为磷源接种菌株M1,从晋宁磷矿粉释放的有效磷浓度最高,达到363.64 mg/L。菌株M1可耐受10%NaCl。将M1制备的菌剂分别接种于施用Ca_3(PO_4)_2、AlPO_4和开阳磷矿粉3种磷源的4种盆栽试验土壤包括北京石灰性潮土、安徽黏性潮土、安徽水稻土和山东沿海盐潮土。结果显示,菌株M1对玉米植株促生效果显著,玉米植株鲜重比对照提高2.14%–90.91%、干重增加22.15%–268.28%;土壤有效磷提高21.81–24.27 mg/kg。菌株M1与4种土壤的适配性均高于对照菌株DSM 821。田间小区花生产量结果显示,接种溶磷菌剂M1增产效果最好,花生果实产量达4.46 t/hm~2,比不接种菌剂的对照处理增加0.81 t/hm~2,增产22.19%。菌株M1在含有磷酸三钙、磷酸铝和开阳磷矿粉3种难溶磷培养液中经过6 d培养,均产生7种有机酸,其中草酸和柠檬酸含量最高,分别为616.16 mg/L和413.69 mg/L;培养液均能检测到吲哚乙酸(IAA)和玉米素,IAA含量为15.45–77.58 mg/L,玉米素浓度为0.06–0.11 mg/L。【结论】获得了一株高效溶解多种难溶磷的日本曲霉菌M1,它能显著增加土壤有效磷、促进玉米生长和花生增产,与4种典型土壤适配性好,具有良好的农业应用前景。     

Growth effects of the vesicular-arbuscular mycorrhizal fungusGlomus constrictum on maize plants in pot trials

Maize plants were inoculated withGlomus constrictum in soil of low phosphorus content amended with five rates of P in the form of Ca₃(PO₄)₂. Maize dry matter yield was increased by addition of P up to 30 and/or 60 mg P/kg soil, above that it began to decrease to reach at 100 mg P/kg a value similar to that of the control. At all P levels used, the shoot and root (total plant) dry mass of inoculated plants was significantly increased compared with the non-inoculated controls and this increment ranged in some cases between 50 and 70%. Development of vesicular-arbuscular mycorrhizal fungus (VAM) monitored in terms of P contents in dry matter of maize revealed that the P content of plants not inoculated withG. constrictum was not influenced by P addition to soil. On the other hand, P content of maize plants inoculated with VAM was dramatically increased by increasing P levels of soil and was maximum at 30 mg P; above that it began to decline. Mycorrhizal root infection (expressed as percentage of root length infected) increased by increasing the P concentrations above the soil basal level up to 80 mg P where the infected root length was 72% of the total root length after 28 d of planting. The increase in VAM spore formation in soil was similar to that of root infection except that the highest spore number was sieved from soil at 60 mg P/kg soil.     

Uptake of phosphate from soils and fertilizers as affected by soil P availability and solubility of phosphorus fertilizers

Fertilizers labelled with ³²P were used to measure amounts of phosphorus, P_s and P_F, taken up by Lolium perenne from available soil P and from P fertilizer respectively, when applied at a rate of 66 mg P·(kg soil^–1) in greenhouse experiments. The quantity P_s of phosphorus taken up from soil in the presence of P fertilizer was compared to the quantity P_o taken up from soil without P fertilizer. The quantity (P_s–P_o) is positive for low P_o values, i.e. in soils poor in available phosphorus, but is negative for high P_o values indicating that an input of P fertilizer can induce a decrease in the utilization of available soil phosphorus. Moreover, for a given soil, the quantity (P_s–P_o) depends on the chemical form of the fertilizer. The standard method of evaluation of P fertilizer efficiency is based on the assumption that P_s=P_o, but P_s can differ from P_o. This result can explain the contradictory data published from field experiments about the efficiency of the various P fertilizers.     

中亚热带森林更新方式对土壤磷素的影响

为了深入了解磷(P)在中亚热带森林生态系统内的有效性,在三明市梅列区陈大采育场黄坑工区,选择天然林采伐后采取不同更新方式的多种森林,以米槠天然林为对照,研究森林不同更新方式对中亚热带森林土壤全磷、有效磷及可溶性有机磷的影响。结果显示:在0—100 cm土层,(1)土壤全磷平均含量大小顺序依次为米槠天然林(NF)(0.49±0.09)g/kg,米槠轻度干扰人促更新林(LAR)(0.35±0.04)g/kg,米槠强度干扰人促更新林(HAR)(0.34±0.03)g/kg,马尾松人工林(PIM)(0.32±0.02)g/kg,杉木人工林(CUL)(0.3±0.03)g/kg,人促更新林比人工林高,NF显著高于其它的林分(P0.05);(2)土壤有效磷(Na HCO3提取)平均含量大小顺序依次为NF(0.41±0.39)mg/kg,LAR(0.26±0.2)mg/kg,HAR(0.23±0.16)mg/kg,PIM(0.17±0.05)mg/kg,CUL(0.13±0.06)mg/kg,NF显著高于其它林分,LAR显著比人工林高(P0.05)。(3)在0—10 cm土层,各林分可溶性有机磷含量在夏季最高,冬季最低,温度和降水量的季节变化是影响其重要因子之一;同一季节,人促更新林比人工林高,NF显著高于人工林(P0.05)。结果表明,全磷、有效磷和可溶性有机磷含量随人为干扰强度的增强呈降低趋势,其与年凋落物量和土壤有机碳储量呈显著正相关,与土壤容重呈显著负相关,全磷和有效磷在土壤剖面呈表聚性特征。相比于人工林经营,采取人促天然更新的方式,更有利于中亚热带森林养分的贮存和转化,有利于森林的长期经营和管理。     

低磷和干旱胁迫对大豆植株干物质积累及磷效率的影响

土壤缺磷和季节性干旱已经成为南方酸性红壤地区大豆生产的主要限制因素之一。选取2个大豆品种巴西10号(磷高效)和本地2号(磷低效),研究其在不同磷素(0,15, 30 mg/kg P)和水分处理(分别在开花期和结荚期进行干旱胁迫)下的反应,从植株生物量、叶绿素含量、磷效率指标等方面研究不同基因型大豆对水磷耦合胁迫的适应机制。研究结果表明,随着土壤磷素水平的增加,两个品种的生物量和叶片叶绿素含量显著增加,根冠比则显著下降。在同一磷素水平处理下,干旱胁迫则导致较高的根冠比,对叶片叶绿素含量影响不大,两个品种表现一致。两个基因型大豆受到干旱胁迫后,其产量均显著低于正常水分处理。中等施磷能显著提高两个大豆品种的产量,但高磷处理对产量的增加幅度有限,甚至高磷处理还造成本地2号减产。巴西10号的产量随土壤中磷素的增加而增加,而本地2号的产量则为中磷>高磷>低磷,不管是磷处理还是水分处理,巴西10号的产量均高于本地2号。无论是花期干旱还是结荚期干旱,巴西10号和本地2号的根磷效率比、磷吸收效率及磷转移效率均随土壤磷浓度的增加而增加,磷利用效率则降低。总体上来讲,巴西10号的磷吸收效率和利用效率高于本地2号,而根磷效率比、磷转移效率则小于本地2号。     

Impact of mineral fertilizers on mineral nutrients in the ginger rhizome and on soil enzymes activities and soil properties

Ginger is used as one of the important ingredients in traditional as well as modern medicine besides as a spice. It boosts immunity and is a rich source of many biologically active substances and minerals. Although it is a medicinally important crop, its productivity is, however, affected due to poor nutrient management and therefore it requires an adequate supply of nutrients in the form of inorganic fertilizers or organic manuring, or a mixture of both. In this context, the present study was aimed to investigate the effect of mineral fertilizers on the content of mineral elements in the ginger rhizome, on soil enzyme activity, and soil properties. Lysimeter experiments were conducted at the Institute of Genetics and Plant Experimental Biology, Kibray, Tashkent region, Uzbekistan. The experiment comprised of four treatments T1 – Control, T2 - N₇₅P₅₀K₅₀ kg/ha, T3 - and T4 - N₁₀₀P₇₅K₇₅ + B₃Zn₆Fe₆ kg/ha. The results showed that the application of N₁₂₅P₁₀₀K₁₀₀ kg/ha increased rhizome K content by 49%, P content by 20%, and Na content by 58% as compared to control without fertilizer. While the application of N₁₀₀P₇₅K₇₅ + B₃Zn₆Fe₆ kg/ha showed a significant enhancement in rhizome K, Ca, P, Mg, Na, Fe, Mn, Zn, Cu, Cr, Mo, and Si contents over the control. This treatment also improved active P content by 29%, total P content by 80%, total K content 16%, and N content by 33% content, and the activities of urease, invertase, and catalase activities as compared to control of without mineral fertilizer and control respectively. Thus the application of NPK + BZnFe at the rate of 100:75:75:3:6:6 kg/ha helps in improving macroelements and microelements in the ginger rhizome and activities of soil enzymes that helps in mineral nutrition of the rhizome.     

施磷对川西北高寒草地土壤磷形态及有效性的影响

以川西北高寒草地为研究对象,采用随机区组设计,设置0、10、20、30、40、50、60 g/m²的过磷酸钙(P₂O₅,16%)施肥试验,分析土壤不同形态磷含量和有效磷(Olsen-P)含量变化特征,探究施磷对川西北高寒草地土壤磷形态及有效磷的影响。结果表明：(1)随施磷量增加,土壤总磷(TP)含量先增加后趋于平稳而Olsen-P含量减少。高水平(50、60 g/m²)施磷下氢氧化钠有机磷(NaOH-Po)及残留磷(Residual-P)是高寒草地主要的磷素累积形态,其含量显著高于不施磷处理;(2)树脂交换态磷(Resin-Pi)、碳酸氢钠无机磷(NaHCO₃-Pi)、碳酸氢钠有机磷(NaHCO₃-Po)和氢氧化钠无机磷(NaOH-Pi)含量随施磷量增加整体呈先增加后降低趋势,表层土壤30 g/m²磷肥用量下其值均为最高,分别为21.54、22.94、65.86、64.48 mg/kg。酸溶性无机磷(HCl-Pi)随施磷量增加整体呈下...     

生物炭对菜园土壤微生物功能多样性的影响

研究生物炭的施用及其与不同肥料混施对菜园土壤中微生物群落功能多样性的影响,为农业废弃物的合理利用和菜园土优化培肥提供科学依据和理论指导。以清远市连州县代表性菜园土(属肥熟旱耕人为土)为研究对象,通过盆栽试验,利用BIOLOG方法对10个施肥处理(对照CK(0%生物碳+无肥)、T1(0%生物碳+0.1%商品有机肥)、T2(0.1%生物碳+无肥)、T3(0.25%生物碳+无肥)、T4(0.5%生物碳+无肥)、T5(1%生物碳+无肥)、T6(100(N)+30(P_2O_5)+75(K_2O)mg/kg干土)、T7(0.1%生物碳+0.1%商品有机肥)、T8(0.1%生物碳+100(N)+0(P_2O_5)+75(K_2O)mg/kg干土)、T9(0.1%生物碳+100(N)+30(P_2O_5)+75(K_2O)mg/kg干土)、T10(0.1%生物碳+0.1%商品有机肥+100(N)+0(P_2O_5)+75(K_2O)mg/kg干土))的土壤微生物群落功能多样性进行分析。结果表明:(1)T1和T3处理比其它处理显著提高土壤微生物对碳源的利用率(P0.05),但生物炭施用量增加会降低平均颜色变化率(AWCD值);(2)T1处理可以显著提高土壤微生物的群落物种均匀度(Mclntosh指数),而T3处理显著提高土壤微生物的物种丰富度和均匀度(Shannon和Mclntosh指数);(3)T1和T3处理对聚合物类、碳水化合物类、羧酸类、氨基酸类和酚类碳源利用率最高;(4)添加化肥处理中磷肥的施用可以提高土壤微生物活性,增加土壤微生物碳源利用能力,而氮肥和钾肥的添加显著降低了土壤微生物的碳源利用能力;(5)主成分分析表明,T1、T2和T3处理的微生物碳代谢功能群结构相似;单施有机肥或适量生物炭对土壤微生物群落结构的影响较混合施用更为显著;化学磷肥的添加及在施用化肥的基础上配施适量生物炭改变了土壤微生物对碳源种类的利用。     

The effects of elevated atmospheric CO2 and soil P placement on cotton root deployment

Root proliferation into nutrient rich zones is an important mechanism in the exploitation of soil nutrients by plants. No studies have examined atmospheric CO₂ effects on cotton (Gossypium hirsutum L.) root distribution as affected by localized phosphorus (P). Cotton plants were grown in a Troup sand (loamy, thermic Grossarenic Kandiudults) using 17.2-l containers placed in open top field chambers (OTC) under ambient (360 mol mol^–1) or enriched (720 mol mol^–1) atmospheric CO₂ concentrations for 40 days. Equivalent amounts of P were added (150 mg P per kg of soil) to 100, 50, 25, 12.5, and 6.25% of the total soil volume; control containers with no added P were also included. Under extremely low P (controls), cotton was unresponsive to CO₂ enrichment. In treatments with both fertilized and unfertilized soil volumes, root proliferation was greater in the unfertilized soil under elevated CO₂ conditions. Stimulation of root growth occurred in the P-fertilized soil fraction; the pattern of stimulation was similar under both CO₂ levels. Under ambient CO₂, cotton plant response was positive (shoot mass, and total root mass and length) when soil P was confined to relatively small proportions of the total soil volume (6.25 and 12.5%). However, elevated CO₂ grown plants tended to respond to P regardless of its distribution.     

东北丘陵区林地转型耕地对土壤编码碱性磷酸酶基因的细菌群落的影响

【目的】通过研究林地转型耕地对土壤编码碱性磷酸酶基因的细菌群落丰度、多样性和结构的影响,为丘陵区耕地长期施肥下农田土壤微生物多样性丧失的影响机制以及未来的退耕还林过程中土壤微生物多样性的提升和土地可持续利用研究提供一些基础数据和技术支撑。【方法】采用实时荧光定量PCR (real-time quantitative PCR,qPCR)和高通量测序技术解析土壤编码碱性磷酸酶基因的细菌群落的丰度、多样性和结构变化,并耦合土壤化学性质分析,明确土壤编码碱性磷酸酶基因的细菌群落丰度和多样性与土壤化学性质的关系以及关键的驱动因子。【结果】林地垦殖为农田后,长期施肥导致土壤酸化,pH从5.58降至4.72,而土壤速效磷则从2.49 mg/kg增至49.3 mg/kg。相应地,耕地土壤编码碱性磷酸酶基因的细菌群落的丰度和Shannon指数均显著低于林地。基于编码碱性磷酸酶的phoD基因(alkaline phosphatase-encoding gene)序列的物种分类表明,丘陵区土壤编码碱性磷酸酶基因的细菌群落的优势门为变形菌门(Proteobacteria)、蓝藻门(Cyanobacteria)、浮霉菌门(Planctomycetes)、放线菌门(Actinobacteria)、厚壁菌门(Firmicutes)和疣微菌门(Verrucomicrobia),其中林地土壤的蓝藻门的相对丰度显著高于耕地。耕地土壤的慢生根瘤菌属(Bradyrhizobium)和芽孢杆菌属(Bacillus)的相对丰度显著高于林地,而中慢生根瘤菌属(Mesorhizobium)、假单胞菌属(Pseudomonas)、Chlorogloea属、Gemmata属、Phormidesmis属和Pseudolabrys属的相对丰度显著低于林地。土壤编码碱性磷酸酶基因的细菌群落结构因林地转型耕地而发生显著改变。phoD基因丰度和Shannon指数与pH显著正相关,而与总磷、速效磷、硝态氮和铵态氮均显著负相关,其中土壤速效磷是这些影响因素中影响最强烈的,长期施用无机磷肥导致含碱性磷酸酶的土壤细菌群落对有机磷分解的能力退化。【结论】林地转型耕地加之长期施肥改变了土壤pH和速效磷,并在其他理化因子的协同驱动下,导致土壤编码碱性磷酸酶基因的细菌群落丰度、多样性和结构的显著变化。     

秸秆还田配施不同比例化肥对晚稻产量及土壤养分的影响

在不同秸秆还田方式对早稻的效应研究确定的最佳还田方式和还田量(粉碎还田3000 kg/hm2)基础上,以单施秸秆为对照,研究了秸秆还田配施不同比例化肥对晚稻产量、干物质积累与分配及土壤养分的影响。结果表明:(1)与对照相比,秸秆3000 kg/hm2+N 150 kg/hm2+P2O575 kg/hm2+K2O 37.5 kg/hm2增产效果最为显著,在水稻的每穗粒数、千粒重、结实率、充实度和产量等方面增加幅度最大,分别为9.32%、4.28%、13.70%、2.74%和26.38%。(2)各处理的干物质茎鞘比例随着生育进程不断降低,从孕穗期的66.68%—77.00%降低至成熟期的25.97%—34.79%,除SNPK1外,叶片比例从孕穗期的23.00%—33.32%降低至成熟期的7.41%—21.03%;秸秆还田配施不同比例化肥处理的茎鞘比例在孕穗期、抽穗期和成熟期高于对照,而叶片比例与茎鞘比例呈相反趋势。(3)与对照相比,秸秆还田配施不同比例化肥处理提高了土壤pH值、有机碳、全氮、碱解氮、全磷、有效磷、全钾、速效钾,降低了土壤C/N比。研究结果说明,秸秆还田配施不同比例化肥可以提高植株干物质积累速率、群体生物量,合理改善土壤养分,保证较高的水稻增产潜力,其中秸秆3000 kg/hm2+N 150 kg/hm2+P2O575 kg/hm2+K2O 37.5 kg/hm2效果最为显著。     

蚯蚓活动对红壤磷素主要形态及有效磷含量的影响

通过盆钵生物试验和采用Hedley磷素分级方法研究了秉氏环毛蚓(Pheretima pingi)对红壤磷素主要形态和红壤有效磷含量的影晌.结果表明,在蚯蚓和有机物料(稻草、花生秸、油菜秸)的共同作用下,经过100d培养后土壤有效磷含量显著提高.统计分析结果表明,花生秸接种蚯蚓处理与不接种蚯蚓处理和油莱秸接种蚯蚓处理与不接种蚯蚓处理之间的土壤有效磷含量差异均达显著水平.采用Hedley磷素分级法测得的树脂磷由原土的痕量增加到10.5～17.8 mg·kg^-1,NaHCO₃溶解态磷由原土的14.5 mg·kg^-1增加到23.5～53.6 mg·kg^-1,微生物细胞磷由原土的1.0 mg·kg^-1增加到6.8～9.7 mg·kg^-1,土壤有机磷含量由原土的37.9 mg·kg^-1增加到50.7～59.3 mg·kg^-1,而土壤中活性最低的残留磷含量则有所降低.蚯蚓活动对红壤磷素具有较强的活化作用.     

Evaluation of the effects of pharmacological zinc oxide and phosphorus source on weaned piglet growth performance,plasma minerals and mineral digestibility

Crossbred pigs (n=720; average age=28±3 days and weight=9.5±0.3 kg) were used in a 20-day trial in order to determine the influence of phosphorus (P) source and various doses of pharmacological zinc (Zn) on growth performance, plasma minerals and mineral digestibility. Pigs (five intact males and five females per pen) were randomly allotted to treatments in a 3×3 factorial arrangement with three sources of dietary P (4.5 g/kg digestible P, 4.5 g/kg digestible P plus 2500 phytase units (FTU)/kg, or 5.5 g/kg digestible P) and three dietary levels of supplemental Zn (0, 1750 or 3500 mg/kg) from ZnO (82% Zn) with eight pens per treatment. Diets were formulated to exceed all nutrient requirements, including calcium (Ca), P and Zn from day 0 to 20. Zn supplementation increased (quadratic P<0.05) average daily feed intake. There was a significant Zn level×P source interaction on average daily gain and feed conversion ratio (FCR). Pigs fed 4.5 g/kg digestible P without or with 2500 FTU/kg phytase gained more per day (quadratic P<0.05) and had better FCR (quadratic P<0.05) when they were fed 1750 mg/kg supplemental Zn. However, pigs fed 5.5 g/kg digestible P gained more per day (linear P<0.05) and were more efficient (linear P<0.05) when they were fed 3500 mg/kg supplemental Zn. Plasma Zn and Zn digestibility increased (linear P<0.05) as pharmacological Zn supplementation increased from 0 to 3500 mg/kg, irrespective of P source. However, Ca, P, sodium (Na), potassium (K) and copper (Cu) digestibility were reduced (P<0.05) as pharmacological Zn supplementation increased, and this was mitigated or exacerbated by the supplementation of 5.5 g/kg digestible P or phytase. In conclusion, increasing the dietary inclusion of pharmacological Zn may impact growth performance in young pigs through the interaction with minerals such as Ca, P, Na and K. Pharmacological Zn may reduce Na or K digestibility and indirectly reduce water secretion into the lumen, resulting in an increase in faecal dry matter as pharmacological Zn supplementation in the diet increased.     

Interactive effects of molybdenum and phosphorus fertilizers on photosynthetic characteristics of seedlings and grain yield of Brassica napus

A pot experiment with acid yellow–brown soil was conducted to investigate the interactive effects of molybdenum (Mo) and phosphorus (P) fertilizers on the photosynthetic characteristics of seedlings and grain yield of Brassica napus which is sensitive to soil P and Mo deficiency. Both Mo and P fertilizers were applied at three levels (0 mg Mo kg^?1, 0.15 mg Mo kg^?1, 0.30 mg Mo kg^?1 soil; 0 mg P kg^?1, 80 mg P kg^?1, 160 mg P kg^?1 soil). The results showed that P fertilizer application increased grain yield, soluble sugar concentrations of seedling leaves, DM and P accumulation of seedling shoots of Brassica napus in the absence or presence of Mo fertilizer. In contrast, Mo fertilizer increased these parameters only in the presence of P fertilizer. Mo accumulation in shoots, chlorophyll concentrations and net photosynthesis rate (P _n) of seedling leaves were increased by both Mo and P fertilizers, particularly with the combination of the two fertilizers. The results also showed that the Mo and P fertilizers increased photosynthetic rate through two different mechanisms, with Mo increasing photosynthetic activity of mesophyll cells, and P increasing stomatal conductance. The results demonstrate that there was a synergetic effect on photosynthesis and grain yield between Mo and P fertilizers and it is conducive for Brassica napus growth to co-apply the two fertilizers.     

Interaction of phosphorus fertilizer form and soil medium on Douglas-fir seedling phosphorus content,growth and photosynthesis

Douglas-fir seedlings were grown in containers in peat-vermiculite or mineral soil each amended with different levels of concentrated superphosphate (CSP) or a granulated North Carolina phosphate rock (RP). Media dilute acid-fluoride extractable phosphorus (DAP), seedling photosynthesis, weights, and tissue P concentrations were measured at 65±3 and 105±3 days. DAP was highly correlated with soluble fertilizer P (but not total P) added at the beginning of the experiment. Considerable soluble P was lost from peat-vermiculite but not from the mineral soil. Seedling total P content was proportional to the amount of soluble P per container at both harvests, but was greater for a given level of soluble P in the organicversus the mineral medium. Added soluble P increased foliar P concentrations, plant P content, and dry weight. Net carbon uptake was highly correlated with added levels of soluble P, foliar P concentrations, and with total P content. The internal efficiency of P from the RP source was less than P from CSP with respect to P contentversus growth, net CO₂ uptake, and net photosynthesis rates. At the end of the experiment, seedling P content plus DAP remaining in the media for the higher fertilizer rates accounted for 75% of the originally added soluble P in the mineral soils, but only 15% of the originally added soluble P in the organic media.     

甘肃白银铜矿矿坑土壤细菌和古菌的多样性及坡度分布特征

【背景】甘肃白银铜矿作为西部地区的重要矿区,探究其细菌和古菌多样性及坡度分布特征对明确矿区微生物多样性分布具有关键意义。【目的】通过分析白银铜矿矿坑不同坡度的土壤细菌群落多样性和古菌群落多样性,探究不同坡度土壤样品细菌及古菌多样性与理化性质之间的关系。【方法】以不同坡度的白银铜矿土样为材料,采用Illumina HiSeq测序技术,分析样品的细菌多样性和古菌多样性。【结果】α和β多样性分析表明,ACE、Chao1、Shannon和Simpson等多样性指数在样品间存在显著差异。白银铜矿矿坑土壤的细菌排名前十的纲是Gammaproteobacteria、Oxyphotobacteria、Alphaproteobacteria、Bacteroidia、Actinobacteria、Clostridia、Nitrospira、Bacilli、Mollicutes和Acidimicrobiia,相对丰度最高的是Gammaproteobacteria。在纲水平上,白银铜矿的古菌由Thermoplasmata、Nitrososphaeria、Methanomicrobia、Halobacteria、Methanobacteria、Group_1.1c和Bathyarchaeia组成,相对丰度最高的是Thermoplasmata。冗余分析(redundancy analysis,RDA)得出,pH和速效磷是影响土壤多样性的最重要因素。【结论】白银铜矿为强酸性铜矿,其土壤铜离子含量最高。从坡顶到坡底,pH呈现先降低再升高的趋势(2.18-4.75),铜离子(20-150mg/kg)和总铁(2.5-50mg/kg)呈现先升高后降低的趋势,铵态氮(3.61-44.90mg/kg)、速效磷(0-56.79mg/kg)和速效钾(9.07-35.65mg/kg)含量低且呈现波动趋势,硫化物(1mg/kg)无明显变化。白银铜矿矿坑土壤细菌相对丰度最高的属为Acidithiobacillus,古菌相对丰度较高的属为uncultured_bacterium_f_Ferroplasmaceae和uncultured_bacterium_f_Nitrososphaeraceae。其中,细菌多样性受到pH驱动,古菌多样性受到速效磷的驱动。本研究有助于我们进一步了解白银铜矿土壤微生物群落的变化。     

Humus stock degradation and its impact on phosphorus forms in arable soils – a case of the Ukrainian Forest-Steppe Zone

Soil humus degradation strengthens nutrient mining, especially phosphorus. This study was carried out on the Ukrainian Forest-Steppe Zone (UFSZ). A total of 21 soil profiles have been investigated: 11 Phaeozems, 6 Luvisols, and 4 Chernozems. Soils were tested for particle size distribution, calcium carbonate (CC), pH, and organic carbon (C_org). The evaluation of humus degradation as a reason of P depletion was performed based on indicators such as Humus Stock Gap (HSG), Humus Stability Index (S), and Yield Gap/Gain (YG/G). In order to evaluate the degree of P depletion, total phosphorus (P_tot) and its five fractions: water soluble – P_H2O, exchangeable – P_EX, bound to Fe and Al – P_Fe/Al, bound to Ca – P_Ca, and residual P – Pres, have been determined.

Data revealed that in 14 of 21 investigated soils, S indices were below the threshold its value of nine, considered as the balanced content of humus with respect to soil texture. Next, in 11 of 21 cases, the negative humus balance indicates the yield gap in Phaeozems and Chernozems. The first three P pools (P_H2O, P­EX and P_Al/Fe) in Phaeozems were exhausted, constituting less than 10% of the P_tot. In Phaeozems, P_Al/Fe, in Luvisols, P_EX, and in Chernozems, P_H2O fractions were basic indicators of available P status. Their pools were directly or indirectly controlled by PCa. Humus content in Phaeozems and Chernozems revealed as the key factor impacting both total P and/or its available resources. Amelioration of P depletion requires efforts oriented on restoration of soil humus stock, concomitant with P fertilization.     

西南喀斯特区坡耕地秸秆覆盖对土壤生态化学计量特征及产量的影响

土壤养分亏缺是限制作物生长的关键因素,同时也是制约作物产量的重要影响因子。为提高西南喀斯特区坡耕地土壤肥力和作物产量,于2018—2019年连续两年在贵州省黔西县开展了野外原位径流小区观测试验。通过该试验探讨不同秸秆覆盖率下土壤碳(C)、氮(N)、磷(P)、钾(K)含量及其生态化学计量特征,揭示不同秸秆覆盖率下土壤养分状况及土壤改良效果。共设6个秸秆覆盖梯度,玉米单作+秸秆覆盖(SM₀—SM₅,0,1111、2222、3889、5556,6944 kg/hm~2),其中SM₀为对照组(CK)。结果表明：(1)秸秆覆盖不同程度增加了土壤有机碳(SOC)、全氮(TN)及全磷(TP)含量,总体上随覆盖量的增加而增加,尤其是覆盖量较多的情况下(SM₄,SM₅),均显著高于对照(P<0.05),但两者之间差异不显著(P> 0.05),而全钾(TK)则随着覆盖量的增加而减少。(2)在高秸秆覆盖条件下(SM₄,SM₅),除了N∶P外,两...