Sap Nitrate Concentration Research Articles

CHLORIDE CHANNEL-b mediates vacuolar nitrate efflux to improve low nitrogen adaptation in Arabidopsis.

The vacuole is an important organelle for nitrate storage, and the reuse of vacuolar nitrate under nitrate starvation helps plants adapt to low-nitrate environments. CHLORIDE CHANNEL-b (CLC-b) in the vacuolar membrane is a nitrate transporter; however, its regulation and effects on nitrate efflux have not been established. Here, we evaluated CLC-b expression and its effects on physiological parameters under low nitrate conditions. CLC-b expression increased significantly in the roots of wild-type Arabidopsis (Arabidopsis thaliana) Col-0 under nitrate starvation. Under low nitrate, clcb mutants showed reductions in chlorophyll content and xylem sap nitrate concentration, shoot/root nitrate ratios, shoot/root total N ratios, and biomass. CLC-b-overexpression yielded opposite phenotypes and increased nitrogen use efficiency. CLC-b mutants showed elevated chlorate tolerance and an increased proportion of vacuolar nitrate relative to the total protoplast nitrate content as compared to the wild type. Yeast 1-hybrid, EMSA, and chromatin immunoprecipitation (ChIP) experiments showed that HRS1 HOMOLOG2 (HHO2), the expression of which is downregulated under low nitrate, binds directly to the promoter of CLC-b. clcb/hho2 double mutants and HHO2-overexpressing clcb plants had similar phenotypes under low nitrate to those of clcb single mutants. Thus, CLC-b mediates vacuolar nitrate efflux and is negatively regulated by HHO2, providing a theoretical basis for improving plant adaptability to low nitrate.

Effect of cultivar on measurements of nitrate concentration in petiole sap and leaf N content in greenhouse soil-grown cucumber, melon, and sweet pepper crops

Excessive N fertilizer applications in intensive vegetable production in soil is commonly associated with appreciable N losses causing negative environmental impact. Measuring petiole sap [NO3−‒N] and leaf N content (%) are simple and practical monitoring methods to assess crop N status for improving N fertilizer management. The effect of cultivar on petiole sap [NO3−‒N] and leaf N content was evaluated. One cucumber, two melon, and two sweet pepper crops were grown in different cropping periods, with three cultivars in each crop. Three N treatments, deficient (N1), sufficient (N2) and excessive (N3) N supply, were applied by combined fertigation with drip irrigation. For a given N supply, there were often significant differences between cultivars in petiole sap [NO3−‒N] and leaf N content in cucumber, the two melon crops and one pepper crop. This was, particularly so with the sufficient (N2) and excessive (N3) N supply. In the cucumber and two melon crops, there were consistent differences in petiole sap [NO3−‒N] between cultivars in two or three of the different N treatments. In some crops, very little petiole sap [NO3−‒N] was measured with deficient (N1) N supply. In the two pepper crops, the differences between cultivars were less clear than with cucumber and melon. In general, for the three species examined, petiole sap [NO3−‒N] was subject to more consistent and larger effects between cultivars, than was leaf N. Average differences between cultivars in petiole sap [NO3−‒N] of 200‒450 mg NO3−‒N L−1 were observed during periods of 4‒6 weeks in cucumber and melon. The differences between different cultivars of the same species in petiole sap [NO3−‒N] and leaf N content, when receiving the same N supply, has implications for the practical applications of these methods for monitoring crop N status.

Comparison of SPAD-based leaf greenness and paralleled petiole sap nitrate concentrations for monitoring potato vine nitrogen status

Comparison of SPAD-based leaf greenness and paralleled petiole sap nitrate concentrations for monitoring potato vine nitrogen status

Evaluation of real-time nutrient analysis of fertilized raspberry using petiole sap.

The time delay in receiving conventional tissue nutrient analysis results caused red raspberry (Rubus idaeus L.) growers to be interested in rapid sap tests to provide real-time results to guide immediate nutrient management practices. However, sap analysis has never been conducted in raspberry. The present work aimed to evaluate the relationship of petiole sap nitrate (NO3–), potassium (K+), and calcium (Ca2+) concentrations measured using compact ion meters and leaf tissue total nitrogen (TN), potassium (K), and calcium (Ca) concentrations measured using conventional tissue nutrient analysis. The relationship of petiole sap NO3– and leaf tissue TN concentrations with plant growth and production variables was also explored. Fertilizer treatments of urea were surface applied to raised beds of established “Meeker” floricane red raspberry plots at control, low, medium, and high rates (0, 34, 67, and 101 kg N ha–1, respectively) in 2019 and 2020. The experiment was arranged in a randomized complete block design with three replications. Whole leaves were collected from representative primocanes in mid- and late- July and August 2019 and 2020 (i.e., four sampling time points per year). At each sampling time point, a subsample of leaves was used for petiole sap analyses of NO3–, K+, and Ca2+ concentrations using compact ion meters, and conventional tissue testing of leaf tissue TN, K, and Ca concentrations, respectively. There were no interactions between N fertilizer rate and year nor between N fertilizer rate and sampling time. No significant differences were found due to N fertilizer rate for petiole sap NO3–, K+, Ca2+ nor leaf tissue TN, K, Ca concentrations. However, significant year and sampling time effects occurred in measured petiole sap and leaf tissue nutrient concentrations. Overall, the correlations between petiole sap NO3– and leaf tissue TN, petiole sap Ca2+ and leaf tissue Ca, petiole sap K+ and leaf tissue K concentrations were non-strong and inconsistent. Future research is warranted as the interpretation of correlations between raspberry petiole sap and leaf tissue nutrient concentrations were inconclusive.

Why is phloem sap nitrate kept low?

Since the first description of phloem sap composition nearly 60 years ago, it is generally assumed that phloem sap does not contain nitrate and that there is little or no backflow of nitrate from shoots to roots. While it is true that nitrate can occasionally be absent from phloem sap, there is now substantial evidence that phloem can carry nitrate and furthermore, transporters involved in nitrate redistribution to shoot sink organs and roots have been found. This raises the question of why nitrate may or may not be present in phloem sap, why its concentration is generally kept low, and whether plant shoot-root nutrient cycling also involves nitrate. We propose here that phloem sap nitrate is not only an essential component of plant nutritional signaling but also contributes to physical properties of phloem sap and as such, its concentration must be controlled to ensure proper coordination of plant development and nutrient transport. This article is protected by copyright. All rights reserved.

Petiole sap nitrate concentration to assess crop nitrogen status of greenhouse sweet pepper

Vegetable production requires improved nitrogen (N) management practices. Monitoring petiole sap nitrate concentration ([NO3−–N]) is a simple and cheap method to evaluate crop N status. The sensitivity of petiole sap [NO3−–N] to assess crop N status of sweet pepper was evaluated. Three sweet pepper crops were grown in different cropping seasons, each with an autumn-winter growing period. The crops commenced in 2014, 2016, and 2017. Combined fertigation and drip irrigation frequently applied (every 1–4 days) complete nutrient solution throughout each crop. The crops were grown in a greenhouse in soil. Five N treatments as N concentrations were applied throughout each crop: N1 (2.0–2.4 mmol L−1); N2 (5.3–6.2 mmol L−1); N3 (9.7–12.6 mmol L−1); N4 (13.1–16.1 mmol L−1); N5 (16.7–20.0 mmol L−1). These corresponded to very deficient, deficient, conventional, excessive and very excessive N supply. Petiole sap [NO3−–N] was determined every 1–2 weeks and related to Nitrogen Nutrition Index (NNI), which was used as an indicator of crop N status. For each of the N treatments in each crop, petiole sap [NO3−–N] was relatively constant throughout the crop. The relationship between petiole sap [NO3−–N] and NNI, for pooled data from the three pepper crops, was described by (a) the polynomial equation NNI=−1.10E−07×Sap2+0.000473×Sap+0.5514 with an R2 of 0.84, and (b) the segmented linear equations NNI=0.00034×Sap+0.572 and NNI = 1.04, with an R2 of 0.83. Sufficiency values for maximum growth of sweet pepper were obtained by (a) solving the polynomial equation for NNI = 1.0, and (b) using the intercept value of the horizontal line of the segmented linear regression. The corresponding sufficiency values for the duration of a complete crop cycle were 1441 and 1367 mg NO3−–N L−1, respectively. A sufficiency value of 1400 mg NO3−–N L−1 was rounded-off and suggested for the duration of a complete crop cycle of greenhouse-grown sweet pepper in SE Spain. The relationships between petiole sap [NO3−–N] and NNI, and the derived sufficiency values for the flowering and early fruit growth, and harvest phenological stages were similar to those determined for the entire crop. Petiole sap [NO3−–N] is a sensitive and effective method to monitor crop N status of sweet pepper.

Development of Nitrogen Fertilizer Topdressing Model for Winter Wheat Based on Critical Nitrogen Dilution Curve

Critical nitrogen (Nc) dilution curve and its extended N nutrient index (NNI) in previous study was only be applied to wheat for N status diagnosis. This research improved this model and further established the N topdressing model which can be quantify the N topdressing rate when NNI < 1. To facilitate the estimate of the Nc concentration, the determination of basal stem tissue sap nitrate (Nit) concentration as a rapid and operational way was used to characterize N status in this study. The results revealed that N dilution curve in this study specific to winter wheat could be used to establish the N nutrition status. There was significantly positive relationship between the Nit concentration and whole plant N concentration at each growth stage. Moreover, the Nit concentration linearly and positively correlated to the N fertilizer application rate, then deducing the N fertilizer topdressing rate per 100 Nit unit, which finally established the N fertilizer topdressing model: N topdressing rate = (critical Nit − actual Nit) × N topdressing rate per 100 Nit unit. The N dilution curve-based model will offer technical support for managing the precise application of N during the growth period of wheat crops.

Natural abundance (δ¹⁵N) indicates shifts in nitrogen relations of woody taxa along a savanna-woodland continental rainfall gradient.

Water and nitrogen (N) interact to influence soil N cycling and plant N acquisition. We studied indices of soil N availability and acquisition by woody plant taxa with distinct nutritional specialisations along a north Australian rainfall gradient from monsoonal savanna (1,600-1,300 mm annual rainfall) to semi-arid woodland (600-250 mm). Aridity resulted in increased 'openness' of N cycling, indicated by increasing δ(15)N(soil) and nitrate:ammonium ratios, as plant communities transitioned from N to water limitation. In this context, we tested the hypothesis that δ(15)N(root) xylem sap provides a more direct measure of plant N acquisition than δ(15)N(foliage). We found highly variable offsets between δ(15)N(foliage) and δ(15)N(root) xylem sap, both between taxa at a single site (1.3-3.4 ‰) and within taxa across sites (0.8-3.4 ‰). As a result, δ(15)N(foliage) overlapped between N-fixing Acacia and non-fixing Eucalyptus/Corymbia and could not be used to reliably identify biological N fixation (BNF). However, Acacia δ(15)N(root) xylem sap indicated a decline in BNF with aridity corroborated by absence of root nodules and increasing xylem sap nitrate concentrations and consistent with shifting resource limitation. Acacia dominance at arid sites may be attributed to flexibility in N acquisition rather than BNF capacity. δ(15)N(root) xylem sap showed no evidence of shifting N acquisition in non-mycorrhizal Hakea/Grevillea and indicated only minor shifts in Eucalyptus/Corymbia consistent with enrichment of δ(15)N(soil) and/or decreasing mycorrhizal colonisation with aridity. We propose that δ(15)N(root) xylem sap is a more direct indicator of N source than δ(15)N(foliage), with calibration required before it could be applied to quantify BNF.

Diagnosis of N nutrient status of corn using digital image processing technique

基于6个不同水平的氮肥田间试验, 采用数码相机获取夏玉米6叶期和10叶期的冠层图像, 分析了不同供氮水平下夏玉米冠层图像色彩参数指标与施氮量、叶片SPAD值、植株硝酸盐浓度、植株全氮含量、0~90 cm土壤硝态氮含量之间的关系。结果表明: 在6叶期, 玉米冠层数字图像色彩参数指标B/(R+G+B)、G/B、R/B、B/L均与施氮量、叶片SPAD值、植株硝酸盐浓度、植株全氮含量、0~90 cm土壤硝态氮含量存在极显著的线性相关关系, 其中B/(R+G+B)与各营养参数的相关关系最好, 其次是B/L。因此, 运用数字图像技术进行玉米的氮素营养诊断是可行的。夏玉米6叶期冠层图像色彩参数指标与上述营养参数间的相关性明显高于10叶期, 可作为应用数字图像技术进行氮素营养诊断的关键时期, 而蓝光标准化值[B/(R+G+B)]是进行夏玉米氮素营养诊断的最佳冠层图像色彩参数指标。

TheArabidopsisNitrate Transporter NRT1.8 Functions in Nitrate Removal from the Xylem Sap and Mediates Cadmium Tolerance

Long-distance transport of nitrate requires xylem loading and unloading, a successive process that determines nitrate distribution and subsequent assimilation efficiency. Here, we report the functional characterization of NRT1.8, a member of the nitrate transporter (NRT1) family in Arabidopsis thaliana. NRT1.8 is upregulated by nitrate. Histochemical analysis using promoter-beta-glucuronidase fusions, as well as in situ hybridization, showed that NRT1.8 is expressed predominantly in xylem parenchyma cells within the vasculature. Transient expression of the NRT1.8:enhanced green fluorescent protein fusion in onion epidermal cells and Arabidopsis protoplasts indicated that NRT1.8 is plasma membrane localized. Electrophysiological and nitrate uptake analyses using Xenopus laevis oocytes showed that NRT1.8 mediates low-affinity nitrate uptake. Functional disruption of NRT1.8 significantly increased the nitrate concentration in xylem sap. These data together suggest that NRT1.8 functions to remove nitrate from xylem vessels. Interestingly, NRT1.8 was the only nitrate assimilatory pathway gene that was strongly upregulated by cadmium (Cd(2+)) stress in roots, and the nrt1.8-1 mutant showed a nitrate-dependent Cd(2+)-sensitive phenotype. Further analyses showed that Cd(2+) stress increases the proportion of nitrate allocated to wild-type roots compared with the nrt1.8-1 mutant. These data suggest that NRT1.8-regulated nitrate distribution plays an important role in Cd(2+) tolerance.

Potato Crop Nitrogen Status Assessment to Improve N Fertilization Management and Efficiency: Past–Present–Future

Improving nitrogen use efficiency is important for the potato crop, because of its relatively low ability to take up available soil mineral nitrogen (N). Splitting of N fertilizer application is a suitable approach to better match N need and supply. In-season crop N monitoring methods are therefore required to support such strategies. This paper deals with the state of the art and potential development of characteristics, use and implementation of well known and more recent methods aimed to assess in-season potato Crop Nitrogen Status (CNS). A short overview of this concept is given for the potato crop. The most important and available methods for CNS assessment are evaluated for their accuracy, precision, sensitivity, sensibility and feasibility. These are: the petiole sap nitrate concentration test; the leaf chlorophyll concentration measurement using a hand-held chlorophyll meter; the measurement of crop light reflectance through a hand-held radiometer using passive sensors. More recent methods still under investigation based on near, ground-based, air-borne or space-borne remote sensing are discussed for their scientific and practical interest in the near future. The current and potential use and implementation of these methods into decision support systems for potato N fertilization management aimed at improving the potato crop nitrogen use efficiency are analysed by: comparing relative and raw data; establishing threshold values of CNS; and combining or integrating the CNS values into models dedicated to N recommendation or to crop growth simulation.

Diagnosis tool for plant and crop N status in vegetative stage: Theory and practices for crop N management

The environmental constraints to agriculture imply that nitrogen (N) fertilizer management should be adjusted to crop N requirements determined by target yields. Nowadays for environmental and economical reasons target yield of farmers can be lower than the potential crop yields as permitted by soil and climatic conditions. So it is important to provide farmers crop N status diagnostic tools in order to decide the rate and the timing of N fertilizer applications. Theory on crop N uptake and allocation allows the determination of a diagnostic tool, the Nitrogen Nutrition Index, based on the determination of the critical N dilution curve for each crop species considered. During the vegetative growth period of all the crop species studied, including C3 and C4 species and monocots and dicots, plant N concentration decreases monotonically as crop grows because of (i) the ontogenetic decline in leaf area per unit of plant mass, and (ii) the remobilisation of N from shaded leaves at the bottom of the canopy to well illuminated leaves at the top. NNI appears then as an indicator well connected with the physiological regulation of N uptake at canopy level. So this indicator can be used as the basis for determination of crop N nutrition status, and then for decision making on the necessity of an N application for achieving target yield. Nevertheless despite its high physiological relevance, NNI cannot be used directly in farm conditions because its determination is very time consuming. So it is necessary to develop indirect methods for NNI estimation through more operational procedures. Several methods have been proposed in literature, such as nitrate concentration in sap or chlorophyll meter. But the calibration or validation of these methods with NNI have not been always made and, when they have been, they did not give univocal relationships, showing a strong dependence of the relationship with cultivar and environment, that limits considerably the relevance of such diagnostic tools in a large range of situations. Easier to use is the indirect estimation of crop NNI by remote sensing measurements. This method allows the estimation of both actual crop mass, through LAI estimation and crop N content, through crop chlorophyll content. The possibility to have repeated estimations of crop NNI during the period of vegetative growth would allow a dynamic diagnostic tool of crop N status. The coupling of indirect measurements of crop N status with dynamic models of crop growth and development should allow a very promising method for crop N diagnostics for decision tools in N fertilization.

Using High-Resolution Satellite Imaging to Evaluate Nitrogen Status of Winter Wheat

ABSTRACT Nitrogen (N) applications often increase crop yields significantly, but N needs vary spatially across fields and landscapes. The color of the wheat plant is sensitive to N status and may provide a means to accurately predict N fertilizer rates matching spatial variability. Previous researches have reported that remote sensing may contribute to N management decisions by collecting spatially dense information. The objective of this study was to determine the feasibility of using high-resolution satellite imaging for evaluating N status of winter wheat in the North China Plain. High-resolution images from a QuickBird satellite were taken on April 1, 2002 at booting stage of wheat with multi-spectral wavelengths (blue, green, red, and near-infrared). Correlation analyses indicated that all the broadband indices derived from the satellite images correlated well with sap nitrate concentration, SPAD readings, total N concentration, and aboveground biomass. The individual band reflectance values R, G, B correlated well with sap nitrate concentration, SPAD readings, total N concentration, and aboveground biomass. These results demonstrated the potential of using new generation high-resolution satellite imaging for large area wheat N status diagnosis.

Establishment of Critical Sap and Soil Nitrate Concentrations using a Cardy Nitrate Meter for Two Carrot Cultivars Grown on Organic and Mineral Soil

Nitrate (NO3 −) meters have been used effectively for crop nitrogen (N) management in many crops, including corn and cabbage. The use of a Cardy NO3 − meter to assess the N status of the carrot crop could improve the utilization of applied N, but critical NO3‐N concentrations are required. Two carrot cultivars were grown on mineral and organic soils over 3 years at five N application rates to establish critical sap and soil NO3‐N concentrations and to identify the effects of soil type and cultivar. Although a yield response to N application occurred on mineral soil in 2 of 3 years, consistent critical sap NO3‐N concentrations could not be established because of variability among years, cultivars, and soil types. Critical soil nitrate concentrations were highly variable, but values of 31 to 36 mg · L−1 NO3‐N could be established for the early sampling date to 30 cm deep. Sap NO3‐N concentrations cannot be used alone for N analysis of carrots, but early‐season soil NO3‐N assessment could be useful in adjusting N‐fertilization practices.

Optimum Nitrogen Fertilization of Winter Wheat Based on Color Digital Camera Images

Site‐specific nitrogen (N) fertilizer management based on soil Nmin (soil mineral N) and the plant N status (sap nitrate analysis and chlorophyll meter (SPAD) reading test) has been shown to be effective in decreasing excessive N inputs for winter wheat in the North China Plain, but the multiple sampling of soil and plants in individual fields is too time‐consuming and costly for producers and farmers. In this study, a color digital camera was used to capture wheat canopy images at a specific growth stage to assess N needs. Treatments included a farmer's N treatment (typical farmer practice), an optimum N treatment (N application based on soil–plant testing), and four treatments without N (one to four cropping seasons without any N fertilizer input). Digital images were analyzed to get red, green, and blue color‐band intensities for each treatment. Normalized intensities of the red, green, and blue color bands were well correlated with soil Nmin, SPAD readings, sap nitrate concentration, and total N concentration of winter wheat. This research indicated the potential of using a digital camera as a tool combined with an improved Nmin method to make N fertilizer recommendations for larger fields.

Current Topics: Diagnosis of nitrogen nutrition of satsuma mandarin based on nitrate concentration in petiole sap

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Diagnosis of Nitrogen Nutrition of Satsuma Mandarin Based on Nitrate Concentration in Petiole Sap

Diagnosis of Nitrogen Nutrition of Satsuma Mandarin Based on Nitrate Concentration in Petiole Sap

Use of Digital Camera to Assess Nitrogen Status of Winter Wheat in the Northern China Plain

The most widely used methods to assess the nitrogen (N) status of winter wheat (Triticum aestivum L.) are the determination of plant total N by combustion, the testing of nitrate in the leaf tissue and the use of SPAD readings. However, due to their labor requirements or high costs these methods can hardly be applied to the huge wheat growing areas of the Northern China Plain. This study therefore examined an alternative method to measure the N status of wheat by using a digital camera to record the visible green light reflected from the plant canopy. The experiment was conducted near Beijing in a multi-factorial field trial with three levels of N. The intensity of green light reflected from the wheat canopy was compared to the total N concentration, to the nitrate concentration of the basal stem, and to the SPAD readings of leaves. The results show significant inverse relationships between greenness intensity, canopy total N, and SPAD readings at booting and flowering. At booting, sap nitrate <2000 mg L−1 was inversely related to greenness intensity and to sap nitrate concentration in the basal stem. At sap nitrate ˜2000 mg L−1, the greenness intensity reached a plateau. At booting and flowering, significant inverse relationships between greenness intensity and shoot biomass were found. The results show the potential of the new method to assess the N status of winter wheat.

Rapid Determination of Nitrogen Status in Pansy

Two experiments were conducted with pansy (Viola ×wittrockiana Gams `Bingo Yello') to determine the relationship between foliar nitrogen (% of dry weight) (FN) and either sap nitrate concentration (SN) in petioles or SPAD readings of foliage. FN was highly correlated to SN throughout both experiments (r = 0.80 to 0.91). FN was poorly correlated to SPAD readings early in both experiments (r = 0.54 to 0.65), but more highly correlated later when visual symptoms of N deficiency were apparent (r = 0.84 to 0.90). SN determined with the Cardy sap nitrate meter was a reliable predictor of FN in pansy, while SPAD readings were only reliable after symptoms of N deficiency were visually evident. FN can be predicted with SN using the following equation: log(SN) = 0.47*FN + 1.6 [r2 = 0.80, n = 132]. Growers and landscape professionals can use SN readings to predict FN levels in pansy, and thus rapidly and accurately diagnose the N status of their crop.

Rapid Determination of Nitrogen Status in Annual Vinca

Abstract Three experiments were conducted to develop a method for rapid determination of nitrogen (N) status in ‘Pacifica White’ vinca (Catharanthus roseus (L.) G. Don). In experiment 1, N was applied to potted vinca at 40, 80, 120, or 160 ppm N to produce plants ranging from N deficient to N sufficient. Data were collected 14, 28, and 42 days after treatment (DAT) and included flower number, growth index [(height + width + width) ÷ 3], and from recently matured foliage the following parameters: SPAD-502 readings, petiole sap nitrate (SN) concentration, and total-N (percent of dry weight) (FN). Experiment 2 was similar with the exception that N rates applied were 30, 60, 90, 120, 150, or 180 ppm N, and data were collected 14, 29, and 42 DAT. In experiment 3, N was applied at 0, 90, or 180 ppm N and data were collected 0, 4, 7, 10, and 14 DAT. In experiments 1 and 2, SPAD readings were poorly correlated to FN (correlation coefficients ranged from 0.35 to 0.88) and the relationship between FN and SPAD readings changed at different collection dates. Petiole sap nitrate concentration determined by a Cardy nitrate meter was highly correlated throughout the three experiments. Above 380 ppm SN, the relationship between FN and SN was determined to be: SN/1000 = 2.3 × FN-4.8 (r2 = 0.73, n = 104). In experiment 3, FN and SN readings were able to detect N deficiency in vinca by 4 DAT, despite lack of visual symptoms until 14 DAT. SPAD readings were not suitable for predicting FN and plant N status. SN was a reliable predictor of FN and thus could be used to rapidly determine plant N status.