Linking leaf elemental traits to biomass across forest biomes in the Himalayas

Plants require a number of essential elements in different proportions for ensuring their growth and development.The elemental concentrations in leaves reflect the functions and adaptations of plants under specific environmental conditions.However,less is known about how the spectrum of leaf elements associated with resource acquisition,photosynthesis and growth regulates forest biomass along broad elevational gradients.We examined the influence of leaf element distribution and diversity on forest biomass by analyzing ten elements(C,N,P,K,Ca,Mg,Zn,Fe,Cu,and Mn)in tree communities situated every 100 meters along an extensive elevation gradient,ranging from the tropical forest(80 meters above sea level)to the alpine treeline(4200 meters above sea level)in the Kangchenjunga Landscape in eastern Nepal Himalayas.We calculated communityweighted averages(reflecting dominant traits governing biomass,i.e.,mass-ratio effect)and functional divergence(reflecting increased trait variety,i.e.,complementarity effect)for leaf elements in a total of 1,859 trees representing 116 species.An increasing mass-ratio effect and decreasing complementarity in leaf elements enhance forest biomass accumulation.A combination of elements together with elevation explains biomass(52.2%of the variance)better than individual elemental trait diversity(0.05%to 21%of the variance).Elevation modulates trait diversity among plant species in biomass accumulation.Complementarity promotes biomass at lower elevations,but reduces biomass at higher elevations,demonstrating an interaction between elevation and complementarity.The interaction between elevation and mass-ratio effect produces heterogeneous effects on biomass along the elevation gradient.Our research indicates that biomass accumulation can be disproportionately affected by elevation due to interactions among trait diversities across vegetation zones.While higher trait variation enhances the adaptation of species to environmental changes,it reduces biomass accumulation,especially at higher elevations.

基于“三教”改革的职业教育活页式教材开发研究

校企“双元”协作开发活页式教材是职业院校深化“三教”改革急需解决的问题。通过对职业教育活页式教材形态、编写机制、内容组织模式、育人模式及教学模式变革的分析与归纳,提出活页式教材正朝着形态“活”、教师“活”、内容“活”、思想“活”、教法“活”的方向发展。在对“活页式”教材实践探索的基础上,设计职业教育活页式教材开发流程,构建融“三教”为一体的活页式教材建设框架,提出活页式教材体例格式,详解案例活页内容。

基于缺铁诊断指标筛选的猕猴桃叶片黄化诱因分析

[目的]筛选适宜的缺铁诊断指标,据此分析导致陕西关中地区猕猴桃园叶片黄化的主要因子,并利用施肥矫治试验对该因子进行验证,为猕猴桃叶片黄化防控提供理论依据。[方法]在陕西关中地区,依据叶片黄化后土施Fe-EDDHA可以复绿确定了3个缺铁猕猴桃果园,采集当年强旺营养枝顶端第2~3个叶片,共采集不同黄化度叶片64份,缺铁叶片样品的黄化度以SPAD值表征,将SPAD值与5个缺铁诊断指标进行相关分析。在关中地区选择5个健康果园、80个出现不同程度黄化症状的猕猴桃果园,采集叶片样品,将黄化果园叶片按照黄化程度分为绿叶、轻度黄化叶和重度黄化叶,测定12种元素、活性铁和硝态氮含量及SPAD值,并将其与SPAD值进行相关分析。在85个果园各采集1份土壤样品,分析其基础理化性状。选择两个黄化果园进行施肥矫治效果验证。[结果]64份缺铁黄化叶片中,鲜样邻二氮菲浸提铁与其SPAD值的相关性明显高于干样全铁、0.1 mol/L盐酸浸提铁、1 mol/L盐酸浸提铁和鲜样1 mol/L盐酸浸提铁,说明鲜样邻二氮菲浸提铁最适于猕猴桃缺铁的黄化诊断。健康园绿叶和黄化园绿叶中所测的12种元素、活性铁和硝态氮含量均无显著差异。SPAD和邻二氮菲浸提铁含量的顺序为黄化园绿叶>轻度黄化叶>重度黄化叶,而叶片硝态氮、磷、钾和硼含量则相反。轻度和重度黄化叶钙、全铁和锰含量低于绿叶。相关分析表明,猕猴桃叶片SPAD与叶片邻二氮菲浸提铁、全铁、锰和钙含量正相关,而与叶片钾、磷、硝态氮、全氮、硼、铜等含量负相关。随机森林和通径分析进一步表明,与猕猴桃叶片黄化关系最密切的指标为邻二氮菲浸提铁、钾及硝态氮。线性加平台函数拟合表明,邻二氮菲浸提铁5.084 mg/kg是猕猴桃叶片缺铁黄化诊断的临界值。土壤分析结果表明,黄化园土壤pH和碳酸氢根含量均偏高,而速效钾和硝态氮含量均适宜,说明土壤重碳酸盐诱发缺铁很可能是导致叶片黄化的主要原因。与健康园相比,黄化园土壤阳离子交换量偏低,说明叶片黄化还与土壤阳离子交换能力不足有关。施用Fe-EDDHA和蓝铁矿[Fe_(3)(PO_(4))_(2)·8H_(2)O]均可提高叶片SPAD和邻二氮菲浸提铁含量,降低叶片钾和硝态氮含量,从而矫治猕猴桃叶片缺铁黄化。[结论]叶片鲜样中邻二氮菲铁最适于猕猴桃缺铁黄化诊断,其临界浓度为5.084 mg/kg。陕西关中地区猕猴桃园叶片黄化主要是由土壤重碳酸盐诱发缺铁所致,且与土壤阳离子交换能力不足有关;黄化叶中钾和硝态氮的累积是由缺铁造成的。因此,生产上应注意黄化园铁肥的补充和土壤阳离子交换能力的提升。

不同海拔的大别山山核桃林地土壤性质和叶片营养元素分析

为了比较不同海拔大别山山核桃林地土壤性质和叶片营养元素的差异及相关性,为大别山山核桃林地科学施肥和养分管理提供参考,采用酸度计法、重铬酸钾容量法、半微量凯氏定氮法、碱解扩散法、盐酸氟化铵浸提-分光光度法和醋酸铵-火焰光度计法分别测定了不同海拔大别山山核桃林地0~30 cm土层p H、有机质、速效氮、速效磷、速效钾,采用原子吸收分光光度法测定了土壤和叶片的氮、磷、钾、钙、镁、锌含量,并进行显著性分析和相关性分析。结果表明:(1)不同海拔大别山山核桃林地土壤速效磷、全氮、全磷、全钾、钙、镁和锌含量存在显著性差异(P<0.05),大别山山核桃叶片钾、钙和镁含量存在显著性差异(P<0.05)。(2)不同海拔大别山山核桃林地土壤p H随着海拔升高而降低,而有机质和氮含量随着海拔升高而升高;叶片钾含量随海拔升高而升高,钙和镁含量则是随着海拔升高而降低,其余营养元素受海拔影响较小。(3)大别山山核桃叶片营养元素之间、土壤营养元素之间、以及叶片与土壤之间存在一定相关性,其中土壤间相关性达到显著水平的有2对,叶片间相关性达到显著水平的有4对,土壤和叶片间相关性达到显著水平的有2对(P<0.05)。大别山山核桃林地土壤平均p H值为5.18,偏酸性;有机质含量均值为5.07%;速效氮、速效磷含量较高,速效钾较匮乏;微量元素平均含量依次为Mg>Ca>Zn。建议增施生石灰进行土壤改良,减少氮肥施用,增施磷钾肥,尤其是钾肥,将化学肥料和有机肥料混合增施,保持土壤养分平衡。

无患子媛华不同物候期养分需求特征研究

为了解无患子媛华无性系原料林叶片矿质元素在不同关键物候期动态变化规律,揭示该无性系养分需求特征,为科学制定营养管理制度提供理论依据。以福建省建宁县树龄5、6、7 a的无患子媛华无性系原料林为研究对象,测定展叶期、花序抽生末期、花期末、果实膨大初期、果实转色期、果实成熟期N、P、K、Ca、S、Mg、Fe、Zn、B等含量指标。无患子媛华无性系原料林不同关键物候期叶片中N、P、K、Ca、Mg含量总体呈先降低、再上升、后降低趋势,均在果实膨大初期达到最高;N和P的含量在花序抽生末期和果实膨大初期之间存在显著差异,其K含量在果实膨大初期显著高于其他关键生育期,且在其余生育期之间无显著差异,而Ca含量和Mg含量在展叶期和果实膨大初期存在显著差异(P<0.05),Fe、B含量呈先上升后降低趋势,Fe含量在果实转色期显著高于其余生育期,B含量在花期末急剧降低,且显著低于其余生育期(P<0.05),Zn含量和S含量全年总体无明显变化。3个树龄叶片中N含量和K、P、Mg含量分别呈显著正相关,Ca含量和K、Fe含量分别呈显著正相关,S含量和Zn含量呈显著负相关,Zn含量和S、B含量分别呈显著负相关。坐果期(6—7月底)可作为叶片营养诊断的适宜时期;施肥应考虑各元素间的关联;在花序抽生末期时,此时应及早追施N、P和B肥;在坐果期要适量追肥,同时结合追施微肥。

烟草薄片剪切断面形貌有限元仿真模拟优化

本研究对烟草薄片精密剪切过程进行了仿真研究,获得了材料力学性能和相互作用参数,为有限元仿真模拟提供了必要数据。建立了烟草薄片的力学模型,并构建了相应的有限元仿真模型。在仿真模拟过程中,重点分析了烟草薄片剪切断裂的形成过程及静水应力随时间的变化趋势。采用有限元仿真模拟与实验测量相结合的方法,综合分析剪切间隙对烟草薄片断面质量的影响。结果表明,随着剪切纵向间隙的增加,烟草薄片的塌角高度逐渐增加,剪切带高度总体呈现减小趋势,而断裂带高度则呈现增加趋势。然而,当剪切间隙为0.15 mm时,由于上、下剪刃的重合,导致剪切带高度略微增加,断裂带高度略微减小。有限元仿真模拟结果与实测结果相吻合,验证了本研究的可靠性和准确性。

Leaf stoichiometry of Leontopodium lentopodioides at high altitudes on the northeastern Qinghai-Tibetan Plateau,China

Altitude affects leaf stoichiometry by regulating temperature and precipitation,and influencing soil properties in mountain ecosystems.Leaf carbon concentration(C),leaf nitrogen concentration(N),leaf phosphorous concentration(P),and their stoichiometric ratios of Leontopodium lentopodioides(Willd.)Beauv.,a widespread species in degraded grasslands,were investigated to explore its response and adaptation strategy to environmental changes along four altitude gradients(2500,3000,3500,and 3800 m a.s.l.)on the northeastern Qinghai-Tibetan Plateau(QTP),China.The leaf C significantly varied but without any clear trend with increasing altitude.Leaf N showed an increasing trend,and leaf P showed a little change with increasing altitude,with a lower value of leaf P at 3500 m than those at other altitudes.Similarity,leaf C:P and N:P exhibited a little change with increasing altitude,which both had greater values at 3500 m than those at other altitudes.However,leaf C:N exhibited a decreasing trend with increasing altitude.Soil NH^(+)_(4)-N,soil pH,soil total phosphorus(STP),mean annual temperature(MAT),and mean annual precipitation(MAP)were identified as the main factors driving the variations in leaf stoichiometry of L.lentopodioides across all altitudes,with NH^(+)_(4)-N alone accounting for 50.8%of its total variation.Specifically,leaf C and N were mainly controlled by MAT,soil pH,and NH^(+)_(4)-N,while leaf P by MAP and STP.In the study area,it seems that the growth of L.lentopodioides may be mainly limited by STP.The results could help to strengthen our understanding of the plasticity of plant growth to environmental changes and provide new information on global grassland management and restoration.

叶面喷施微生物制剂对苹果树体生长、果实表型性状和叶片营养元素的影响

为了分析叶面喷施微生物制剂对苹果树体生长、苹果果实表型性状和叶片营养元素的影响,设置了3种常用微生物制剂(T_(1):巨大芽孢杆菌菌剂、T_(2):枯草芽孢杆菌剂、T_(3):密旋链霉菌剂),分别按照不同剂量(10、20、30 g/667 m^(2))进行叶面喷施,对比分析了不同微生物制剂在不同施用剂量下对苹果生长、果实及营养指标的影响。结果表明:当T_(1)微生物菌剂的施用剂量为20 g/667 m^(2)时,苹果树冠径、干径、新梢长度、新梢粗度、百叶鲜重、百叶干重等树体的生长情况最佳;当T_(1)微生物制剂的施用剂量为20、30 g/667 m^(2)时,苹果果实单果重、果实横径、果实纵径、果柄粗度等表型性状指标较高,而果柄长度较低;T_(1)、T_(3)微生物制剂的施用剂量为30 g/667 m^(2)时,苹果叶片中的N、P、K含量均较高,且前者的Ca和Mg含量更高;T_(2)微生物制剂在果树树体生长、果实表型性状和叶片营养元素含量方面均低于T_(1)、T_(3)微生物制剂。综上,巨大芽孢杆菌菌剂的施用效果在3种微生物菌剂中最为理想,最佳施用剂量为20 g/667 m^(2)。

木棉树形结构和叶性状对生境要素的响应研究

植物形态结构是植物本身与外部环境共同作用的结果。为了分析木棉树形结构与叶性状的相关关系,探索地形、土壤和气象要素对木棉生长的影响,以及揭示木棉的生长策略和适应机制,该文以云南省西双版纳国家级自然保护区内230棵木棉为研究对象,测定6个树形结构指标,8个叶性状指标以及所在区域地形、气象、土壤养分等生境要素,使用结构方程模型和变差分解分析各生境要素对木棉树形结构和叶性状的影响和解释度。结果表明:(1)木棉树形结构各观测指标之间、叶性状各观测指标之间存在相关性(P<0.05)。(2)生境要素各观测指标对木棉生长具有较强影响,其中年均降雨量、坡度、平均温度对木棉生长指标的解释率较高,是影响木棉生长的主要生境指标。(3)从标准化路径系数看,3个生境要素对木棉树形结构和叶性状影响具有一致性,均表现为地形要素>气象要素>土壤要素。(4)3个生境要素叠加解释了树形结构和叶性状分别为43.5%和12.3%,表现出树形结构对生境环境的响应大于叶性状对环境响应的特点。研究结果初步探明了木棉不同生长指标对环境要素的适应策略,为木棉在异质生境的培育、繁殖以及木棉人工林高效经营等提供了理论依据和实践参考。

Soil and Leaf Micronutrient Composition in Contrasting Habitats in Podzolized Sands of the Amazon Region

Plant macronutrient distribution in podzolized sands of the Amazon caatinga has received attention in several studies;however, the distribution of micronutrients has not been assessed. Soil micronutrient availability has been hypothesized to reflect contrasting habitat characteristics as well as fundamental differences in substrate, and leaf micronutrient composition may reflect the macronutrient content needed to maintain balance for leaf cell functions. In this study, soil and leaf samples were obtained in a toposequence (valley, slope, and mound). Available soil micro- and macronutrients as well as total leaf content were measured by inductively coupled plasma-atomic emission spectrometer and mass spectroscopy. Soil Zn (-1) and B (-1) as well as Cu (-1) levels were very low. Soil Mn was low in the valleys and slopes (0.62-0.87 mg·kg-1), but higher in the mound (6.59 mg·kg-1). Soil Fe (11.48-21.13 mg·kg-1) was well above the critical level in all of the habitats. Leaf micronutrients Cu, B, Zn, and Fe were below the critical levels for tropical crops of 3-7, 20-70, 15-20, and 72 mg·kg-1, respectively. Leaf Mn (88 mg·kg-1) and Al (<50 mg·kg-1) were below the accumulators level. A strong relationship between leaf micro- and macronutrients suggests the maintenance of a homeostatic elemental composition, which may favour photosynthetic function. Therefore, the local distribution of species may be shaped by their abilities to maintain a balance of micronutrient collected through roots under critically low levels of available Zn, B, and Cu whilst excluding potentially deleterious ions of Mn, Fe, and Al.

Physicochemical characteristics of ambient particles settling upon leaf surfaces of urban plants in Beijing

Particulate pollution is a serious health problem throughout the world, exacerbating a wide range of respiratory and vascular illnesses in urban areas. Urban plants play an important role in reducing particulate pollution. Physicochemical characteristics of ambient particles settling upon leaf surfaces of eleven roadside plants at four sites of Beijing were studies. Results showed that density of particles on the leaf surfaces greatly varied with plant species and traffic condition. Fraxinus chiuensis, Sophora japonica Ailanthus altissima, Syringa oblata and Prunus persica, had larger densities of particles among the tall species. Due to resuspension of road dust, the densities of particles of Euonymus japonicns and Parthenocissus quinquefolia with low sampling height were 2-35 times to other taller tree species. For test plant species, micro-roughness of leaf surfaces and density of particles showed a close correlation. In general, the larger micro-roughness of leaf surfaces is, the larger density of particles is. Particles settling upon leaf surfaces were dominantly PM30 （particulate matter less than 10 μm in aerodynamic diameter; 98.4%） and PM2.5 （particulate matter less than 2.5 μm in aerodynamic diameter; 64.2%） which were closely relative to human health. Constant elements of particles were C, O, K, Ca, Si, Al, Mg, Na, Fe, S, Cl and minerals with higher content were SiO2, CaCO3, CaMg（CO3）2, NaCI and 2CASO4. H2O, SiO2. CaCO3 and CaMg（CO3）2 mainly came from resuspension of road dust. 2CaSO4. H2O was produced by the reaction between CaCO3 derived from earth dust or industrial emission and SO2, H2SO4 or sulfate. NaCl was derived from sea salt.

An Analysis on Leaf Traits of 22 Helianthus tuberosus Germplasm Resources Introduced from Abroad

Atomic absorption spectrophotometry,sulfuric acid and potassium dichromate oxidation method and ultraviolet spectrophotometry,were used to determine mineral elements,fiber,the content of chlorogenic acid and flavones in leaves of 24 Helianthus tuberosus Linn.resources,and the characteristics of the leaf introduced from abroad were evaluated.The results showed that the highest water content of 22 species was F12(27.58%),and the lowest was F16(19.02%).The difference in mean water content between the species from Denmark and France was small,but it was lower than that of Qingyu 3 and Qingyu 4.There were 3 orbicular leaves,1 long oval-shaped leaf and 18 oval leaves.The highest K content in the leaves was F19(30.62 mg/g),which was 2.5 times than Qingyu 3.The highest Mg content was D8(14.17 mg/g).The Fe content hadlittledifference,ranging from 0.09 mg/g to 0.19 mg/g.The highest Ca content was D8(26.87 mg/g).The highest level of chlorogenic acid and flavones was F7,2.55%and 1.24 g/100 g respectively.The highest fiber content was F9(16.7%),and the lowest was F19(7.36%).Through the analysis of the main component and the clustering analysis,when the genetic distance was 0.65,the 24 resources can be divided into three major categories.The first category of leaves were mainly oval and orbicular;the second category of leaves were long oval-shaped;the third category of leaves were oval.There was a difference between the various indexes in the leaf of different kinds of H.tuberosus Linn.resources.Finally,F19,D8,F9,F7,D14 and D11,6 specific species(F19,D8,F9,F7,D14 and D11)were screened out for further studies in the future.

Determination of Nutrient Contents in the Leaf Litter of <i>Diospyros crassiflora</i>S. (Hiern-FWTA) Plantation in Okwuta-Ibeku, Umuahia, Abia State, Nigeria

Determination of nutrient contents in Diospyros crassiflora leaf litter was carried out in the Forestry Research Institute of Nigeria (FRIN), Okwuta-Ibeku, Umuahia, Abia State, Nigeria in 2016 and 2017. Three 1 m × 1 m trays were randomly positioned for collection of leaf litter production from 4/5 years old Diospyros crassiflora species in each block (10 m × 25 m) within the plantation totaling 1.5 ha. A Randomised Complete Block Design (RCBD) with three replicates was used to study the mean monthly leaf litterfall of Diospyros crassiflora. Leaf litter was collected from each of the three litter trays per block and placed in paper bags every 28th day of each month from January-December in 2016 and in 2017. Fifteen grammes (15 g) of properly mixed and oven-dried samples of D. crassiflora leaf litter were milled and sieved in 1 mm sieve;0.3 g was used to determine nutrient elements and their concentrations. The data obtained from mineral nutrient contents of D. crassiflora leaf litter was analysed using analysis of variance. Result reveals the mean concentrations of nitrogen (1.41 and 1.41 mg·l-1), phosphorus (0.18 and 0.18 mg·l-1), potassium (0.68 and 0.68 mg·l-1), sodium (0.35 and 0.30 mg·l-1), calcium (1.57 and 1.56 mg·l-1), magnesium (0.32 and 0.31 mg·l-1), chlorine (0.25 and 0.24 mg·l-1), Organic carbon (0.03 and 0.03 mg·l-1) and Organic matter (1.17 and 1.18 mg·l-1) etc. in D. crassiflora leaf litter in January-December (2016 and 2017). The study shows almost uniform distribution of mineral elements concentrations in 2016 and 2017.

山药叶片黄化与生理指标、矿质元素含量的相关性研究

为探究叶片生理指标及矿质元素含量与山药叶片黄化的相关性,以山药品种‘雅山药1号’为试验材料,分别对不同黄化程度山药叶片的鲜重、干重、叶绿素含量、超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性以及叶片的矿质元素含量进行测定。结果表明,随着叶片黄化程度加剧,叶片的鲜重、干重、干物质含量、POD活性明显下降,叶绿素a(Chla)、叶绿素b(Chlb)含量明显下降,但Chla/Chlb呈上升趋势,SOD活性呈现先上升后下降再上升的趋势,CAT活性呈现出双峰曲线变化趋势;N、S、B含量均上升,Ca、Mg、Fe、Mn含量明显下降。相关性分析表明,Chla、Chlb与Ca、Mg、Fe、Mn、POD活性呈极显著正相关,与N、S、B呈显著或极显著负相关。研究结果初步确定山药叶片黄化与叶片叶绿素含量及Ca、Mg、Fe、Mn元素含量下降密切相关。

Finite Element Analysis of Elastic Deformation in Blade Machining

In the process of milling the half-open impeller, the milling force ACTS on the half-open impeller will cause the machining deformation error of the half-open impeller. The impeller material studied in this paper is 7050-t7451 aluminum alloy, whose elastic modulus is 70.3 GPa, with low stiffness. Therefore, during milling, it is easy to cause elastic deformation of the cutter, thus causing machining errors and reducing machining surface quality. In addition, due to the low stiffness of blade surface, the deformation of blade surface is much larger than that of hub surface. Therefore, this paper only studies the deformation law of blade surface in the process of milling.

韶关贡柑园植株叶片矿质元素特征及其与土壤养分的相关性

研究韶关市贡柑叶片矿质元素以及果园土壤养分状况,为贡柑果园平衡施肥提供依据.2021年在广东省韶关市南雄贡柑果园布设20个采样点,采样测定贡柑叶片9种营养元素含量及土壤5种养分,同时分析两者的相关性.结果表明,贡柑叶片氮元素和磷元素均处于缺乏水平;钾、钙、镁元素以及微量元素铁、锰、铜、锌元素处于适量及适量以上水平,锌元素处于适量以下水平比例为85.71%.贡柑果园土壤pH介于4.00~4.69,均处于偏酸性状态;土壤有机质、碱解氮和速效钾含量较高,均值分别为53.58 g·kg^(-1)、286.41 mg·kg^(-1)和595.89 mg·kg^(-1),均处于过量状态;土壤有效磷含量均值为78.38 mg·kg^(-1),均高于适量状态.叶片钾元素与土壤碱解氮、有机质和速效钾呈显著正相关,叶片锰元素、锌元素与土壤pH均呈显著正相关;叶片铬、镉和汞元素与土壤碱解氮、有效磷和速效钾均呈显著正相关.贡柑果园整体土壤养分含量偏高,存在土壤养分和叶片元素需求不平衡问题,要注意科学合理施肥.

增施镁肥对富川烟区烤烟养分吸收及产质量的影响

以K326为供试烤烟品种,以中量元素水溶肥(含镁9%)为供试镁肥,在土壤有效钾镁比值和有效钙镁比值均偏高的富川烟区开展肥效试验,探索增施镁肥(67.50、135.15、270.30 kg/hm^(2))对平衡烟叶营养元素和提高烤烟产质量的效果。结果表明:增施镁肥能够显著提高烤烟的产量与产值,显著提升上部、中部、下部烟叶的镁含量;高水平镁处理(270.30 kg/hm^(2))显著提高了上部烟叶、中部烟叶的氮含量;施镁水平与烟叶磷和钙含量呈负相关关系,增施镁肥显著降低了上部、中部烟叶中的钾含量;与不施镁肥相比,增施镁肥显著降低了烟叶的钾镁比和钙镁比,虽然该植烟区仍处于缺镁状态,但是在一定程度上缓解了烤烟缺镁的严重程度;增施67.50 kg/hm^(2)镁肥的处理提高了烤烟中烟碱、粗蛋白质、总糖、总氮的含量,烟叶品质较佳。因此,综合烤烟经济性状、养分吸收及烟叶产质量考虑,在富川植烟区施用67.50~135.15 kg/hm^(2)的镁肥较为适宜。

脐橙幼苗新老叶片养分含量对大、中量元素短期缺乏的差异性响应

【目的】对比大、中量养分短期缺乏下脐橙新、老叶片中11种必需元素含量及变化,并分析缺素导致的营养元素间的相互影响。【方法】以一年生枳砧纽荷尔脐橙幼苗为试材进行了砂培试验。以完全营养液为对照(CK),设置缺氮(-N)、缺磷(-P)、缺钾(-K)、缺钙(-Ca)和缺镁(-Mg)处理,测定不同处理脐橙叶片(老叶和新叶)生长指标及矿质元素含量。【结果】所有缺素处理均导致叶片叶绿素含量降低,生物量减少,以缺氮处理最为显著。缺氮降低了叶片N、Ca、Cu、Mo含量;缺磷降低了叶片P、K、Mo含量;缺钾降低了叶片K含量;缺钙降低了叶片N、Cu、Zn、Mo含量但增加了P含量;缺镁降低了叶片Ca、Mg、Zn、Mo含量但增加了K含量。以必需矿质元素为变量分别对各处理老叶和新叶进行主成分分析,老叶中第一主成分(PC1)明显将缺钾处理与其他处理区分开,与对照相比,缺钾老叶离子组成变化为N(-3%)、P (+1%)、K (-71%)、Ca (+11%)、Mg (+39%)、B (+16%)、Mn (+11%)、Fe (+32%)、Cu (-7%)、Zn (+14%)、Mo (-63%);新叶中PC1明显将缺氮处理与其他处理区分开,缺氮新叶离子组成变化为N (-53%)、P (+8%)、K (+7%)、Ca (-14%)、Mg (+11%)、B(+55%)、Mn (+51%)、Fe (-14%)、Cu (-57%)、Zn (+4%)、Mo (-25%)。老叶和新叶中元素含量呈正相关的元素是N-Cu、N-Ca、Mg-Mn和Cu-Mo,呈负相关的是K-Zn。【结论】脐橙幼苗老叶对钾的短期缺乏反应最敏感,缺钾会显著降低老叶中K和Mo含量并增加Mg和Fe含量,而新叶对氮素的短期缺乏最敏感,缺氮显著降低新叶中N、Ca、Cu和Mo含量。短期缺少P、Ca和Mg对脐橙幼苗叶片中的养分含量影响较小。

土壤pH值与雪茄烟叶矿质元素和化学成分的关系

为了探究土壤pH值对雪茄烟叶矿质元素和常规化学成分含量的影响,在来凤雪茄烟区采集土样和对应烟叶样各89份,采用相关性分析和灰色关联分析探讨了土壤pH值与雪茄烟叶矿质元素和常规化学成分的关系。结果表明,来凤雪茄烟区土壤pH值平均为5.99,在5.5~7.0的适宜范围样本占比为80.9%。雪茄烟叶钙、钾含量较高,分别为7.71%和5.16%;总糖和还原糖含量偏低,仅为0.46%和0.19%。土壤pH值与雪茄烟叶钙、总糖、还原糖呈显著或极显著正相关,与硼、锰、钾呈极显著负相关。灰色关联分析表明土壤pH值与雪茄烟叶总氮含量关联系数最高,其次为硼和磷,再次为钾、总糖、烟碱。来凤雪茄烟区可科学合理调控土壤酸碱度、均衡烟叶矿质元素营养,以提高雪茄烟叶品质。

光碳核肥对石榴叶片矿质元素含量的影响

研究叶面喷施不同浓度光碳核肥对石榴各生育时期叶片中矿质元素含量变化的影响,确定石榴合理施肥时间和用量,为石榴的科学精准施肥和优质丰产提供理论依据。在云南省永胜县以‘突尼斯’软籽石榴为材料,在常规施肥的基础上研究不同浓度光碳核肥处理(1.3%、1%、0.7%、0.5%)下石榴生育期内叶片矿质元素变化规律。随着石榴生长发育,石榴叶片中N、P、Ca、Zn元素含量呈现上升趋势,K、Mg、Fe元素含量呈现下降趋势。1.3%处理抑制了石榴叶片中N、P的含量;0.7%处理对石榴叶片N、P、K含量有明显的促进作用,较对照(清水喷施)分别提高了22.3%、47.6%、121.9%,且显著提高了石榴成熟期叶片Fe含量;0.5%处理石榴叶片Ca、Zn含量显著增加,最高分别为19.72、144.54 g/kg,较对照分别增加了5%、1.05倍,同时对石榴营养生长期叶片P、K含量有一定促进作用。可以通过叶面喷施一定浓度光碳核肥调控石榴叶片中矿质元素的含量,其中喷施浓度0.7%处理能显著提高石榴叶片N、P、K、Fe含量,0.5%处理对Ca、Zn、P、K含量的提高有促进作用,可根据不同生育时期矿质元素含量的差异制定合适的施肥方案,满足石榴生长发育的营养需求,从而改善石榴品质。