Seedling emergence,growth, and mineral concentration of three citrus rootstocks under salt stress

Salt tolerance of Carrizo citrange (CC), sour orange (SO), and Cleopatra mandarin (CM) rootstocks during emergence and early seedling stage of development was studied under greenhouse conditions. Increasing salt concentration in the nutrient solution delayed and depressed seedling emergence (SE), increased time to 50% emergence, reduced seedling growth (SD) but did not affect emergence spread. At the first salinity level (5 mmol), emergence of the first seedling (EFS) was delayed by 2–3 days in CC and one day in SO but was not affected in CM. At the two lowest salinity levels (5 and 10 mmol), final percent emergence (FPE) was not affected in CC but was reduced in SO and CM while shoot biomass was reduced in CC but was not affected in SO and CM. This study showed a non‐consistent trend among citrus rootstocks concerning whether the delay in emergence is more sensitive to salt stress than final percent emergence. However, SG was generally more affected by salinity than SE, particularly at high salinity levels. Shoot and root N and Cl concentrations generally increased with increasing salt concentrations. Shoot Cl concentration was found to be a better tool than root Cl concentration in evaluating the extent of the injurious effect of salt stress and a better parameter in ranking salt tolerance of citrus rootstocks. This study also showed that salt tolerance is not a constant character in citrus rootstocks but varies with the stage of seedling development.     

Leaf mineral element concentrations and growth of sweet sorghum subjected to acid soil stress

Abstract

The nutritional profile of sweet sorghum [Sorghum bicolor (L.) Moench] cultivars grown under acid soil field stress conditions is a critical consideration when developing plants which are adapted to these infertile soils. Uptake and accumulation of macro‐ and micronutrients vary among genotypes and ultimately Influence plant growth and development. This study compared fourteen sweet sorghum germplasm lines and varieties for their Individual patterns of leaf nutrient concentrations and productivity when grown under acid soil field conditions (pH 4.45 to pH 4.85) at three locations over a two‐year period. Significant year x location interactions were found for Fe, K, and Ca concentrations at both Blairsville and Calhoun and for Mn and P levels at Blairsville and Calhoun, respectively. Data from Calhoun on plant height, dry weight, visual stress ratings, and rainfall indicate a possible association between drought tolerance and acid soil tolerance in sorghum. No significant differences in A1 concentrations were found among these sweet sorghum lines and varieties, which indicate that their acid soil tolerance mechanisms are probably not related to A1. MN 1054 accumulated the highest levels of Mn in the three acid soils. The highest concentrations of Mg and P were found in Brandes. MN 960 had the highest visual stress ratings (highest susceptibility) while Brandes, Ramada, Roma, and Wray were the most tolerant. All fourteen cultivars apparently have some tolerance to acid soil stress conditions.     

Differential response of citrus rootstocks to aluminum levels in nutrient solutions: II. Plant mineral concentrations 2

The objective of this study was to determine relations between Al effects and mineral concentrations in citrus seedlings. Six‐month‐old seedlings of five citrus rootstocks were grown for 60 days in supernatant nutrient solutions of Al, P, and other nutrients. The solutions contained seven levels of Al ranging from 4 to 1655 μM. Al and similar P concentrations of 28 μM P. Aluminum concentrations in roots and shoots increased with increasing Al concentration in the nutrient solution. Aluminum concentrations in roots of Al‐tolerant rootstocks were higher than those of Al‐sensitive rootstocks. When Al concentrations in nutrient solution increased from 4 to 178 μM, the K, Mg, and P concentrations in roots and the K and P levels in shoots increased. Conversely, Ca, Zn, Cu, Mn, and Fe in the roots and Ca, Mg, Cu, and Fe in the shoots decreased. The more tolerant rootstocks contained higher Fe concentrations in their roots than did the less tolerant ones when Al concentrations in solution were lower than 308 μM. Concentrations of other elements (Ca, K, P, Mg, Zn, and Mn) in roots or shoots exhibited no apparent relationship to the Al tolerance for root or shoot growth of the rootstocks. Calcium, K, Zn, Mn, and Fe concentrations in roots and Mg and K concentrations in shoots of all five rootstocks seedlings had significant negative correlations with Al concentrations in corresponding roots or shoots.     

Nitrogen availability to citrus seedlings from urea and from mineralization of citrus leaf or compost

A pot experiment was conducted using a Candler fine sand (hyperthermic, uncoated, Typic Quartzipsamments) amended with either citrus leaves or compost, to measure the nitrogen (N) mineralization and its availability to two citrus rootstock seedlings. A rapid increase in NH₄‐N concentration was evident in the soil amended with citrus leaves as compared to compost during the initial 14 to 20 d. Subsequently, the concentration of NH₄‐N decreased in the citrus leaves amended soil. The extractable NO₃‐N concentration was greater in the soil amended with citrus leaves as compared to compost, throughout the 270 d duration of the study. The N concentrations and N uptake by Cleopatra mandarin (CM) and Swingle citrumelo (SC) seedlings grown in citrus leaf amended soil were very similar to those in urea amended soil. Therefore, mineralization of N from dry ground citrus leaves was quite rapid. The N concentrations in both rootstock seedlings were much lower in the compost amended and unamended soils as compared to those in either citrus leaves or urea amended soils. Rapid mineralization of N from cirrus leaves added to sandy soil, resulting in an increased availability of N, suggested that the contribution of N from shed leaf mineralization must be considered while developing N rate recommendations for improving N use efficiency.     

矿质营养对柑橘品质的影响

本文简述了柑橘所需主要营养元素对品质的重要作用,讨论了不同种类肥料对柑橘品质的效应,提出了改善我国柑橘品质现状的主要措施,为科学调控柑橘营养代谢、平衡施肥和开发多养分柑橘缓/控释专用肥料提供依据。     

Irrigation water salinity affects soil nutrient distribution,root density,and leaf nutrient levels of citrus under drip fertigation 1

The purpose of this study was to determine the effects of irrigation water salinity on soil nutrient distribution, citrus leaf nutrition and root density. Irrigation water, salinized to an EC of about 0.3,1.6, or 2.5 dS/m using a 3:1 ratio of NaCl:CaCl₂ plus uniform weekly applications of liquid fertilizer, was applied through a drip system. Soil samples were taken at depths of 0–15 and 15–30 cm, both directly under the drippers and 45 cm outward from the drippers, near 8‐year old ‘Valencia’ orange trees on either Carrizo citrange or Sour orange rootstocks growing in a Candler fine sand in lysimeter tanks.

In both undisturbed and uniformly mixed soil profiles, soil pH and concentrations of Na, Ca, and P were higher under the dripper than 45 cm outward from the dripper at both depths regardless of salinity level. Soil N and Cl tended to be higher outward from the drippers than near the drippers, except in undisturbed soil at the 0–15 cm depth. Increasing salinity levels in the mixed soil profile not only increased soil EC, Na, Cl, and Ca, but also increased the concentration of P and decreased the concentration of Mg.

Root density of both rootstocks were increased by high salinity. Root densities and organic matter percentages were higher in soil sampled under drippers than that sampled outward from drippers. Leaf nutritional values and responses to salinity were dependent on rootstock as trees on sour orange had higher K and Ca, but lower Mg and Cl than trees on Carrizo. Although there were no nutrient deficiencies, K of trees on Carrizo citrange and Mg of trees on sour orange were rereduced by high salinity. An increase in leaf Ca concentrations when irrigated with salinized irrigation water likely minimized the effects of salt stress.     

Interaction of soil boron application with leaf B concentration,root length density,and canopy size of citrus affected by Huanglongbing

Abstract

Good and balanced citrus nutrition is important for high fruit yields and improved tree performance. A study was conducted for 2?years to investigate the effect of soil application of boron (B) on leaf nutrient content, canopy size, and root length density (RLD). The study was conducted on 10-year-old Candidatus Liberibacter asiaticus (CLas)-infected Vernia sweet orange on Rough Lemon rootstock in a commercial grove east of St. Cloud, FL planted at 375 trees ha^?1 on a traditional soluble dry nutrition and spray programs. Treatments were supplied with various ground-applied controlled-release fertilizer treatments containing B. Boron was applied at 0×, 2×, and 4× current University of Florida recommendation where 1×?=?1.12?kg ha^?1. Data collected included leaf B nutrient content, soil B concentration, trunk diameters, canopy volumes, soil electrical conductivity, and soil pH. The 0×, 2×, and 4× application rates corresponded with leaf nutrient contents ranging from 56?mg kg^?1 and 88?mg kg^?1 in March 2017, 162?mg kg^?1 and 288?mg kg^?1 in September 2017, and 122?mg kg^?1 and 320?mg kg^?1 in May 2018. Temporary, RLD decreased with time from March to September 2017 by 13, 30, and 37% at the 0, 2.24, and 4.48?kg B ha^?1 and increased by 309, 258, and 306% at the 0, 2.24, and 4.48?kg B ha^?1, respectively, from September 2017 to May 2018. No consistent pattern was established between soil B application with canopy size.     

柑桔叶片黄龙病光谱特征选择及检测模型

为探索高光谱技术诊断黄龙病及分类的可行性,通过变量筛选方法组合为高维数据实用化提供参考。采集柑桔叶片高光谱图像并进行普通(polymerase chain reaction,PCR)鉴别分为轻度、中度、重度、缺锌和正常5类样品。用无信息变量消除算法(uninformative variable elimination,UVE)剔除无关信息,组合遗传算法(genetic algorithm,GA)和连续投影算法(successive projections algorithm,SPA)筛选变量,对数据进行降维。结合极限学习机(extreme learning machine,ELM)和最小二乘支持向量机(least squares support vector machine,LS-SVM)构建柑桔黄龙病判别模型。对预测样品进行诊断分类,来评价模型判别能力。经对比发现,UVE组合SPA筛选变量后的LS-SVM模型效果最好,该模型以Link_kernel函数为核函数,惩罚因子(γ)最小为1.07,误判率最低为0。用全谱作输入变量时LS-SVM模型复杂程度最高且预测能力最差,误判率最高为11.9%,可能是包含无用信息和冗余信息变量造成的。研究显示,UVE组合SPA筛选变量,结合LS-SVM对柑桔黄龙病诊断并分类具有一定可行性,为高维度数据实用化提供一定参考价值。     

外源 GSH 对 NaCl 胁迫下番茄幼苗叶片及根系离子微域分布的影响

【目的】盐胁迫是限制新疆番茄生长的重要障碍因子之一,而外源喷施谷胱甘肽 (GSH) 是解决这一问题的有效措施。探讨外源 GSH 缓解番茄盐胁迫的效应和作用机制,可为该措施的有效应用提供理论依据。 【方法】采用营养液栽培法,选用番茄品种‘中蔬四号’为试材。在营养液中加入 NaCl 100 mg/L,使其产生盐胁迫,以不加 NaCl 作为对照 (CK),试验处理包括不喷施 GSH (NaCl)、喷施 GSH (+ GSH)、喷施 GSH 合成酶抑制剂 (+ BSO) 以及喷施 GSH 和 BSO (+ BSO + GSH)。测定番茄幼苗叶片和根系中与耐盐性相关的 K+、Ca2+、Mg2+、Na+ 和 Cl– 的离子微域分布状态和平衡。 【结果】NaCl 胁迫下番茄叶片和根系所有组织细胞中 Na+ 和 Cl– 相对含量显著提高,K+ 相对含量和 K+/Na+、Ca2+/Na+、K+/Cl– 比值降低,说明 NaCl 胁迫使细胞中 Na+ 和 Cl– 有害离子积累及胞内离子稳态严重破坏;外源 BSO 施用进一步加剧了 NaCl 胁迫下番茄叶片和根系细胞的 K+/Na+ 失衡。而外源 GSH 施用抑制了 NaCl 胁迫下番茄叶片和根系对 Na+ 的吸收,降低了 Cl– 的相对含量,提高了 K+/Na+、Ca2+/Na+、K+/Cl– 比值。外源 GSH 亦使 NaCl+BSO 胁迫下番茄叶片各组织及根系中皮层、内皮层和中柱的 Na+ 未检出,根系和叶片各组织中 Cl– 相对含量显著降低,K+ 和 Ca2+ 相对含量及 K+/Na+、Ca2+/Na+、K+/Cl–、Ca2+/Cl– 比值显著提高。 【结论】外源 GSH 通过抑制盐胁迫下番茄叶片和根系对 Na+ 的吸收,降低 Cl– 吸收,改善细胞中离子的微域分布和维持离子平衡, 从而缓解了盐胁迫对番茄的毒害作用,提高了番茄的耐盐性。     

Growth,mineral composition,leaf chlorophyll and water relationships of two cherry varieties under NaCl-induced salinity stress

Abstract

Growth, mineral nutrition, leaf chlorophyll and water relationships were studied in cherry plants (cv. ‘Bigarreau Burlat’[BB] and ‘Tragana Edessis’[TE]) grafted on ‘Mazzard’ rootstock and grown in modified Hoagland solutions containing 0, 25 or 50 mmol L^?1 NaCl, over a period of 55 days. Elongation of the main shoot of the plants treated with 25 or 50 mmol L^?1 NaCl was significantly reduced by approximately 29–36%, irrespective of the cultivar. However, both NaCl treatments caused a greater reduction in the dry weight of leaves and scion's stems in BB than in TE plants. Therefore, BB was more sensitive to salinity stress than TE. The reduction of leaf chlorophyll concentration was significant only when BB and TE plants were grown under 50 mmol L^?1 NaCl. Osmotic adjustment permitted the maintenance of leaf turgor in TE plants and induced an increase in leaf turgor of BB plants treated with 25 or 50 mmol L^?1 NaCl compared with 0 mmol L^?1 NaCl. Concerning the nutrient composition of various plant parts, Na concentrations in all plant parts of both cultivars were generally much lower than those of Cl. For both cultivars, leaf Cl concentrations were much higher than the concentrations in stems and roots, especially in the treatments containing NaCl. Finally, the distribution of Na within BB and TE plants treated with NaCl was relatively uniform.     

Iron deficiency stress responses amongst citrus rootstocks

Seedlings of citrus rootstocks differing in lime tolerance were grown in nutrient solution with and without Fe. Proton efflux, release of phenolic compounds and Fe reducing substances and root-mediated reduction of Fe^III in FeEDTA and freshly precipitated Fe(OH)₃ in response to Fe deficiency were determined. Sweet orange, Carrizo citrange and trifoliate orange, the three least tolerant rootstocks used in the study, did not decrease nutrient solution pH in response to Fe deficiency. The more lime tolerant rootstocks, rough lemon, Cleopatra mandarin and sour orange, did decrease nutrient solution pH. But in CaSO₄ solution only sour orange increased H⁺ efflux significantly under Fe deficiency. In response to Fe deficiency, the release of phenolic compounds was increased significantly in rough lemon and Cleopatra mandarin seedlings, while the release of reducing substances was increased significantly in rough lemon, sour orange and trifoliate orange. Rough lemon was the only rootstock to respond to Fe deficiency with an increase in root-mediated reduction of chelated Fe^III at pH 6.5. At pH 8.0, both Fe-deficient rough lemon and Cleopatra mandarin roots reduced higher amounts of Fe^III from freshly precipitated Fe(OH)₃ than Fe-sufficient seedlings. Iron reduction by detached roots of Fe-deficient and Fe-sufficient rough lemon did not follow Michaelis-Menten kinetics at high substrate concentrations. Rates of Fe reduction at low substrate concentrations were inconsistent with the existence of an inducible ferric reductase in response to Fe deficiency.     

Avocado rootstock influences scion leaf mineral content

ABSTRACT

To test the influence of avocado rootstocks on the scion leaf ionome, the nutritional status of avocado cultivars Hass and Ettinger grafted onto 15 rootstocks was compared over 3 years. The rootstocks were of different genetic origins (West Indian or Mexican) and were clonally or reproductively propagated. The trees were grown in a high-density orchard, and were continually fertigated as is common in modern avocado orchards. Leaf mineral composition was analysed and found to be correlated with crop load. ‘Hass’ leaves had significantly higher levels of B, Ca, Mg, Na, P and K than ‘Ettinger’ leaves. Rootstocks of Mexican origin produced higher foliar Cl levels, but lower levels of Mg and Mn. Rootstocks grown from seedlings conferred higher foliar K and lower B, Ca and Mg. The results demonstrate that avocado rootstocks affect the nutritional status of the tree, by a differential mineral transport, which is indicated by the scion leaf ionome.     

基于高光谱的柑橘叶片氮素含量多元回归分析

快捷、准确、无损地检测柑橘叶片氮(N)素含量,对柑橘树N肥施用的精准动态管理有重大现实意义。以117株园栽罗岗橙为试验研究对象,在不同生长期用ASD公司的FieldSpec3采集柑橘树健康叶片的高光谱反射值,以高光谱反射数据或其变换形式作为柑橘树样本多元矢量描述;用凯氏定氮法同期检测出柑橘树叶的真实N素含量值;在用PCA对高维光谱矢量降维的基础上,利用支持矢量回归算法(SVR)建立高光谱多元表达和N素含量间的映射关系,以实现任意柑橘树N素含量的预测分析。试验结果表明,测试集上预测值和真实值间的平方决定系数R2为0.9730,平均相对误差为0.9033%,均方误差MSE为0.090343,证明了该方法的有效性,为利用高光谱技术进行柑橘树N素含量的无损检测提供了参考。     

Seasonal changes in durian leaf and soil mineral nutrient element content

The 3–4 year monitoring study showed that fluctuations in durian (Durio zibethintts Murray) leaf and soil nutrient element levels were closely related to seasonal changes in the crop phenology. The leaf sampling method was standardized taking the 5th and 6th mature green leaf from the shoot tip. The best sampling time was determined to be in November where the coefficient of variability for most nutrient elements were the lowest at or lower than 20%. Tentative standards for durian leaf nutrient elements were set up taking the 95% confidence interval of the means at this sampling stage. All the leaf macro elements, nitrogen (N), phosphorus (P), potassium (K), sulfur (S), and the micro elements, zinc (Zn), manganese (Mn), copper (Cu), and iron (Fe) declined or were lower during fruit set and development from September to end of fruit harvest in January. Leaf N was also the lowest in July and leaf P at the tail end of harvest. Soil N, P, and the bases K, Ca, and Mg also exhibited similar trends, lower during fruit development especially in October‐November and were lower during active leaf flushing from March to May.     

进口与国产PEG对拟南芥种子萌发和幼苗主根生长影响的比较

干旱是造成作物减产的主要原因,我国每年因干旱造成的粮食损失达300亿kg。目前全球干旱缺水的状况日益加剧,世界各国都加强了植物水分胁迫响应遗传机理和分子改良作物抗旱新品种培育的研究,我国也开展了作物抗旱节水分子机制的研究。在实验室内聚乙二醇（PEG）6000或者聚乙二醇（PEG）8000被认为是目前模拟水分胁迫最好的大分子化合物,     

Effects of nitrogen,boron and potassium on boron deficiency,leaf mineral concentrations,and yield of table beets (Beta vulgaris L.)

Abstract

Application of 11.2 kg B/ha and/or of 224 kg N/ha reduced the number of table beet (Beta vulgarisL. cv Detroit Dark Red) roots with B deficiency compared to low rates or no N or B application in three field experiments. In two of the three experiments, the 224 kg/ha N rate decreased B concentration in leaves when no B was added yet B deficiency of roots was reduced compared to the 56 kg/ha N rate. B application increased B concentration in leaves. Calcium concentration in leaves was higher at 224 kg N/ha than for 56 kg N/ha. Nitrogen concentration in leaves was increased by increasing the rate of N while K concentration was decreased at the higher N rate. Average number of roots with B deficiency was significantly higher for the Morse strain than for the Harris strain of ‘Detroit Dark Red’ in one experiment where the two strains were compared. There were no differences between the two strains in leaf B concentration but Ca concentration was higher in the Morse strain than for the Harris strain. Yields were higher at the 224 kg/ha rate of N than at 56 kg N/ha but were not consistently affected by B and K applications. There was no clear relationship of leaf N, Ca and K concentrations to B deficiency of roots     

采用柑橘叶片功能性氮含量无损监测模型的调控施氮方法

为实现柑橘氮素管理的定量化，该研究以5年生‘春见’橘橙为试验材料，设置不同对照施氮处理N₀、N₁、N₂、N₃(施氮量分别为0、50、100、200 g/株)和调控施氮处理Nr₁、Nr₂、Nr₃(分别根据N₁、N₂、N₃进行调控)，在试验开展的第1年利用高光谱技术，分别建立柑橘果实膨大期和转色期的叶片功能性氮含量无损监测模型；第2年利用叶片功能性氮含量无损监测模型与追氮量公式计算调控施氮处理的实际追氮量，比较分析对照施氮和调控施氮对柑橘果实产量、品质及氮肥利用率的影响。结果表明，利用反向传播神经网络构建的叶片功能性氮含量模型精度较高，决定系数R²为0.78(果实膨大期)和0.77(果实转色期)。调控施氮处理Nr₁和Nr₃比对照施氮N₁和N₃分别增产5.49和4.4...     

Effects of nucleo-cytoplasmic interactions on leaf volatile compounds from citrus somatic diploid hybrids

Three diploid citrus somatic hybrids (cybrids) were produced by fusions combining nucellar callus-derived protoplasts of Willow Leaf mandarin (Citrus deliciosa Ten.) and Commune clementine (Citrus clementina Hort. ex Tan.) with, respectively, leaf protoplasts of Eureka lemon [Citrus limon (L.) Burm.] and Marumi kumquat [Fortunella japonica (Thunb.) Swing.] and leaf protoplasts of Marumi kumquat. Ploidy and origins of the nuclear, chloroplastic, and mitochondrial genomes were investigated by flow cytometry and nuclear and cytoplasmic simple sequence repeat analyses. Volatile compounds were extracted from the leaves of the three cybrids by a pentane/ether (1:1) mixture, analyzed by GC-MS, and compared to those of their parents. The cybrids were found to be very close to their nucleus-giving parent, suggesting that the main information for volatile compounds biosynthesis is contained in the nucleus. However, nucleo-cytoplasmic interactions occurred: the (mandarin + lemon) cybrid, possessing nucleus and chloroplasts of lemon and mitochondria from mandarin, synthesizes more monoterpene alcohols and esters than its nucleus-giving parent; the (clementine + kumquat) cybrid, possessing nucleus from kumquat and organelles from mandarin, synthesizes more monoterpene and sesquiterpene hydrocarbons and sesquiterpene alcohols than its nucleus-giving parent.