Leaf Nutrient Concentrations Research Articles

A New Curve of Critical Leaf Potassium Concentration Based on the Maximum Root Dry Matter for Diagnosing Potassium Nutritional Status of Sweet Potato.

Critical leaf nutrient concentrations have often been used to diagnose the nutritional status of crops. Determining critical leaf potassium (K) concentrations for the maximum root dry matter (RDM) will provide a reliable means of linking leaf K nutrient concentrations to the yield of sweet potato. Three field experiments, using varying K application rates (0–300 kg K ha−1) and two sweet potato cultivars, were performed in the Zhejiang Province of China. A new critical leaf K curve (Kleaf) based on the maximum RDM was determined to assess K nutrition in sweet potato and described by the equation . A critical root K curve (Kroot) based on the maximum RDM was also determined to assess K nutrition and described by the equation . The K nutrition index (KNI) was constructed to identify the situations of K-limiting and non-K-limiting treatments. The leaf KNI (KNIleaf) ranged from 0.56 to 1.17, and the root K KNI (KNIroot) ranged from 0.52 to 1.35 during the growth period of sweet potato. The results showed that the critical leaf K concentration curve can be used as an accurate leaf K status diagnostic tool at critical growth stages that connected leaf nutrient concentration and sweet potato tuber yield. This K curve will contribute to K management of sweet potato during its growth period in China.

Can Early-Period Fruit Analysis be Performed for Timely Interventions Against Physiological Disorders In Apple Trees?

Apple is grown in various parts of the world and consumed year-long in four seasons. The nutrient contents of fruit constitute the bases for several disorders experienced in storages. Although leaf analyses are used worldwide to assess the nutritional status of fruit trees, they may not yield accurate outcomes for assessment of fruit nutrient contents. Even if leaf nutrient contents are enough or quite high, various physiological disorders on fruits may be resulted from nutrient deficiencies. Fruit analyses should be performed to determine fruit nutrient contents and accordingly to improve flesh quality and to take relevant measures in early periods.In this study, fruit samples were collected for 2 years from 260 apple orchards in Isparta province of Turkey in 6 different periods covering the timeframe from June drops to harvest and fruit nutrient contents were determined from these samples. Firstly, seasonal variations of nutrients were examined. It was observed that fruit nutrient contents decreased periodically and this decreasing was quite faster through the early periods of the vegetation. Secondly, correlations between nutrient contents of the fruits sampled at the last period and the nutrient contents of the fruits sampled at earlier periods were also investigated in this study. Significant correlations revealed that fruit nutrient contents could be traced between the relevant periods and reference values could be established for these periods. Positive outcomes were observed for investigated nutrients except for N, Fe and Zn.

Nutrient Management in Underutilized Vegetable Crop Ivy Gourd [Coccinia grandis (L.) Voigt

Background: Ivy gourd is the most nutritious and healthy vegetable among the underutilized vegetable crops. To increase the production effective nutrient management is key tool.
 Methods: The experiment on growth and yield improvement in ivy gourd through integrated nutrient management was conducted in a randomised block design with three replications at Regional Horticulture Research Station in ASPEE College of Horticulture and Forestry, Navsari Agricultural University, Navsari, Gujarat.
 Results: An application of 50% RDF (Recommended Dose of Fertilizer) + Bio-compost had a beneficial effect on growth parameters like minimum days to flowering (35.83 days) and fruit harvest (47.11), maximum dry biomass of shoot (8.41 kg) and dry biomass of root (840 g) with near to neutral fruit pH (6.8). Maximum length of fruit (5.12 cm), diameter of fruit (1.80 cm), weight of fruit (4.57 g), maximum fruit yield plant-1 (1.64 kg), highest fruit yield (16.60 t ha-1), maximum leaf nutrient content (N - 1.753 ppm, P - 0.456 ppm, K - 1.653 ppm) and soil nutrient status (N - 211.77 kg ha-1, P2O5 - 69.52 kg ha-1, K2O - 498.96 kg ha-1) were also noted in 50% RDF + Bio-compost as compared to other treatment.

Open field soilless system using cocopeat substrate bags improves tree performance in a young Mediterranean persimmon orchard

The effect of installing cocopeat substrate bags either lying on the soil surface or buried in the soil was evaluated on a newly-established persimmon orchard growing under semi-arid conditions with conventional irrigation and fertilization practices. Tree growth and leaf water and nutrient status were determined for four seasons after tree planting. Compared to the control, cocopeat substrate bags increased vegetative growth and, in the third year, increased fruit yield by 40%. In the fourth year, fruit yield was not significantly affected by cocopeat substrate bags, but bags increased fruit fresh weight by 21% and accelerated fruit ripening. Rapid and substantial root colonization of the cocopeat bags was observed regardless of placement. Trees with the cocopeat substrate bags had improved water status compared with the control for some monitoring dates, which could explain the improved tree performance. Except for an increase in P and Cl, leaf nutrient concentrations were not affected by the cocopeat substrate treatments. We concluded that the open field soilless system technique is a viable option for enhancing persimmon tree performance during orchard establishment. Further research is needed to optimize fertilizer practices when using cocopeat substrate bags and to test their use with other fruit crops grown under similar environmental conditions.

Evaluation of Lettuce (Lactuca sativa L.) Production under Hydroponic System: Nutrient Solution Derived from Fish Waste vs. Inorganic Nutrient Solution

Organic fresh products are appreciated and are gaining a good reputation regarding human health and environmental concerns. Despite the fact that hydroponics are commonly used in vegetable production, growers are looking for sustainable cultivation systems. Therefore, the objective of this study was to investigate the effect of using an organic-based nutrient solution (NS) derived from fish waste in a hydroponic system on the vegetative growth and production of lettuce compared to a conventional inorganic NS. Plant growth, yield, physiological and nutrient content parameters were determined. The results revealed that the overall growth and fresh biomass of the organic NS grown lettuce were relatively lower than those of the inorganic NS. Stomata density was significantly higher in inorganic grown lettuce compared to the organic one. However, the total chlorophyll, carotene, phenolic compounds, and flavonoid contents, as well as antioxidant activity were significantly higher in lettuce grown in organic NS compared to the inorganic one. Leaf nutrient content at harvest was significantly impacted by the type of used fertilizer. Based on these findings, in hydroponic system, organic liquid fertilizer derived from fish waste (as an alternative NS source) requires further improvements to achieve optimal growth and yield comparable to that of conventional inorganic NS.

Ameliorasi Rizosfer Kedelai Menggunakan Jerami, Abu Sekam, dan Dolomit

Successful saturated soil culture practices in tidal land to increase soybean production needs to be supported by amelioration. The rhizosphere is an area where the intensive reciprocal relationship between plants, soil, and soil microorganisms occured. However, the effect of amelioration through the rhizosphere is still unclear. This research aimed to study the effect of amelioration using rice straw, rice husk ash, and dolomite on the rhizosphere on the growth and production of soybean. The research was conducted in tidal swamp land type B overflow from May to August 2019. The experimental design used was a split-split plot design with rice straw, rice husk ash, and dolomite as the main plot, subplots, and sub subplots, respectively. Rice straw was applied by embedding in the soil, while rice husk ash and dolomite were applied to the rhizosphere during planting. The observations included plant biomass dry weight, leaf nutrient concentration of P, Fe, and Al, number of filled pods, and soybean productivity. The application of rice husk ash with rice straw or with dolomite increased soybean growth and production. The combination of 400 kg ha-1 of rice husk ash and 4 ton ha-1 of rice straw yielded the highest productivity with the value of 2.94 ton ha-1.
 Keywords: abiotic stresses, rhizosphere, saturated soil culture, tidal land

Effects of NPK Fertilizer and Vine Care on Soil Chemical Properties and Cucumber (Cucumis sativus L.) Growth and Yield Parameters

Cucumber yield in Nigeria is limited by low soil fertility. Therefore, field fertility and vine care experiments that have ability to moderate yield were conducted in the year 2015 cropping seasons. The experiment was located on farmer’s field at Abeokuta, Ogun State, Southwestern Nigeria to study the effects of NPK fertilizer and vine care on soil chemical properties, leaf nutrient content, growth and yield of cucumber (Cucumis sativus L.). It was a 4 x 3 factorial experiment arranged in a Randomized Complete Block Design (RCBD) with three replicates. Four levels of NPK nutrient formulations (control, NPK15-15-15, NPK 20-10-10 and NPKMg 12-12-17-2) and three vine care types (unstaked, staked and trellised) were applied. Pre-experiment soil samples and soils from each plot at the end of the experiment were collected for soil chemical analysis. Leaf nutrient contents were determined. Plant growth and yield data were measured. Data collected were subjected to statistical analysis and the interaction between factors combined separated. NPK fertilizers significantly (P ≤ 0.05) increased soil N, P, K, Ca, Mg and leaf P, K, Ca and Mg concentrations, Cucumber fruit yield was increased by NPKMg 12-12-17-2 (90.5%), NPK 15-15-15 (60.4%) and NPK 20-10-10 (30.0%) compared with control. Application of vine care enhanced performance of cucumber, fruit yield was increased by trellised (34.0%) and staked (17.3%) compared with control. Combined application of NPKMg 12-12-17-2 and trellising was found most suitable for cucumber production.

The Effectiveness of Composted Green Waste Amended with Vermiculite and Humic Acid Powders as an Alternative Cultivation Substrate for Cornflower Cultivation

ABSTRACT Green waste (GW) is gradually increasing with the rapid development of urban greening and China’s flower industry. Using composted green waste (CGW) as acultivation substrate can effectively save peat resources to achieve environment-friendly and sustainable development. This study improved the physical and chemical properties of CGW by adding different proportions of vermiculite and humic acid powders to CGW and used the improved CGW as acornflower cultivation substrate. In this experiment, the single-factor analysis of variance, the multiple comparisons, and the orthogonal test multi-index matrix analysis were used to analyze cornflowers’ growth indicators in different treatments. The main indicators were cornflower biomass, leaf nutrient content, and leaf pigment content. Through the comprehensive matrix analysis of the above indicators, it was concluded that the total weight of different treatments was T5> T8> T6> T4> T9> T7> T2> T3> T1. The test results showed that the growth status of cornflowers treated with T2~ T9 was better than that of T1 treatment. It is feasible to improve CGW using vermiculite and humic acid powders and to use the improved CGW for cornflower cultivation. The addition of vermiculite and humic acid powder together in cornflower cultivation was more effective than the single addition of vermiculite or humic acid powders cultivation substrate. The results of this study not only provided insight into the improvement of CGW, but also offered an alternative substrate for cultivating high-quality cornflowers, which had ecological and economic values.

Performance of ‘Galia’ melon grown under different soil cation ratios

The northeast region of Brazil stands out in the production and export of melon. In this region, where this crop is mostly grown, part of the soil is of limestone origin, as is the irrigation water used. Over successive cultivations, these conditions can lead to soil alkalinization due to the accumulation of basic cations of the exchange complex, such as Ca, Mg, K and Na, in soils that are already rich in bases, thus influencing nutrient availability and, consequently, crop yield. On this basis, this study was developed to identify the cation ratios (K:Mg:Ca) of the soil that best correlate with attributes indicative of ‘Gália’ melon production. Two experiments were carried out in two consecutive years (2017 and 2018), in a randomized-block design with five treatments and five replicates. Treatments consisted of the following cation ratios (K:Mg:Ca) for experiment I, whose soil had a K content of 0.40 cmolc dm-3: T1 (1:3:34), T2 (1:3:21), T3 (1:3:9), T4 (1:0.8:9) and T5 (1:11:34); and experiment II, where the soil had 0.56 cmolc dm-3 of K: T1 (1:1.6:29.8), T2 (1:1.4:13.3), T3 (1:1.4:8.5), T4 (1:0.5:8.5) and T5 (1:4.8:29.8). The following traits were evaluated: chemical analyses of the soil during the flowering phase and at the end of the cycle, nutrient concentration in the diagnostic leaf during the fruiting phase, total yield, marketable yield, average total weight, average marketable weight, total number of fruits and number of marketable fruits per plant. The cation ratios influenced the average total and marketable fruit weights only in experiment I, but not yield. Therefore, when associated with irrigation water from the Açu sandstone aquifer and fertigation, the high absolute K and medium to high Mg contents are sufficient to meet the K and Mg nutrient requirements, dispensing with correction of the cation ratio.

Foliar nitrogen as stimulant fertilization alters carbon metabolism, reactive oxygen species scavenging, and enhances grain yield in a soybean–maize rotation

AbstractStimulant fertilization isthe supplementary application of low doses of foliar fertilizers to otherwise well‐fertilized crops, and literature suggests that it may increase grain yield. However, the physiological mechanisms behind this potential yield increase are not well understood. This study investigated the effect of supplementary foliar nitrogen (N) in soybean [Glycine max (L.) Merr.] and maize (Zea mays) nutrition, photosynthetic parameters, antioxidant metabolism, agronomic parameters, and grain yield. We tested the presence or absence of low rates of late season (R3 and V10 of soybean and maize, respectively) foliar N fertilization in a main season soybean followed by an off‐season maize. While there were no effects of N application on leaf nutrient concentration, the net photosynthetic rate, stomatal conductance, water use efficiency, and carboxylation efficiency increased due to foliar N fertilization in both crops. The improvement in photosynthesis occurred due to a concomitant increase in Rubisco activity and in the concentration of sugar in the leaves prior to grain filling. Foliar N fertilization also improved antioxidant metabolism, suggesting that fertilized plants were less affected by environmental stresses during their cycle. The improvement in the metabolic activity due to foliar N did not affect grains per plant but increased a hundred grain mass and grain yield of both soybean and maize. Our results suggest that foliar N applied as stimulant fertilizer is a promising strategy to increase yield of maize and soybean crops.

Correlation Between the Growth of Young Rubber Trees and Nutrient Content of Leaves

Correlation Between the Growth of Young Rubber Trees and Nutrient Content of Leaves

Genetic diversity in Coffea canephora genotypes for leaf nutrient concentration


 This study analyzed the genetic diversity in Coffea canephora genotypes by univariate and multivariate statistical analysis, based on concentrations of macro- and micronutrients in coffee leaves in the stages of pre-flowering and grain filling. The experiment was arranged in randomized blocks with three replications, in a 42x2 factorial design, in which factor one represented the evaluated genotypes and factor two the periods of leaf sampling, i.e., pre-flowering and grain filling. The data of leaf nutrient concentrations were subjected to analysis of variance by the F test (p <0.01), and genetic parameters were estimated. For the study of genetic diversity, the genotypes were grouped by the hierarchical unweighted pair-group method using arithmetic averages (UPGMA). The relative importance of a trait to predict genetic diversity was also studied. There is genetic divergence for leaf nutrient concentration in C. canephora genotypes. With a maximum limit of 60% of dissimilarity between genotypes, four groups were also formed by UPGMA. For the 42 evaluated genotypes, leaf S concentration was the most important trait for genetic diversity; this genotypic variability should be investigated to enhance the efficiency of nutritional diagnosis.
 Highlights
 
 There is genetic variability for leaf nutrient concentration in Coffea canephora
 The leaf concentration of nutrients in the phenological stage of pre-anthesis is different from the leaf concentration of nutrients in the coffee bean filling period.
 Leaf concentration of sulfur was the characteristic that contributed most to the genetic diversity among the 42 genotypes, followed by the concentration of copper, boron and magnesium.
 Genotypic variability for leaf nutrient concentration should be considered for better nutritional management.

Detrimental effects of copper and EDTA co-application on grapevine root growth and nutrient balance

Continuous application of Cu-based fungicides and molluscicides may lead to Cu accumulation in vineyard soils. Grapevine (Vitis vinifera L.) inoculation with arbuscular mycorrhizal fungi (AMF) can be a suitable strategy to increase plant tolerance to the excessive levels of this element in the soil. However, the simultaneous use of EDTA-based fertilizers or phytosanitary products in those vineyards can affect metal mobility in the soil, with potential negative consequences for plants. Therefore, this study aimed to elucidate the effect of AMF inoculation on grapevine performance in Cu contaminated soils, in the presence or absence of EDTA chelates.Two-year-old plants growing in pots filled with an Arenosol, previously inoculated or not with two different AMF, were subjected to three soil treatments: control, Cu addition; Cu and FeNaEDTA addition. Four months later, at the end of the growing season, plant vegetative growth parameters, root colonization as well as soil, root and leaf nutrient contents were analyzed.In the soil where Cu was applied, Rhizoglomus irregulare- and Funneliformis mosseae-inoculated plants showed significantly higher root biomass than the non-inoculated ones, and R. irregulare-inoculated plants were the ones with the highest root P and Fe concentrations. However, when Cu and FeNaEDTA were applied together to the soil, AMF inoculation was no longer an asset for grapevines, and overall, root biomass decreased, translocation of Cu to leaves was stimulated, and a significant decrease in leaf Mn concentrations was detected, below the levels found in control soils. For this reason, in soils with high Cu-concentrations, although mycorrhizal inoculation can be a suitable strategy to improve plant growth and nutrition, the use of EDTA-based products should be avoided, as it can lead to an amplification of the toxic effects commonly caused by the excess of Cu in plants.

High Nutrient Concentrations of Hydroponic Solution Can Improve Growth and Nutrient Uptake of Spinach (Spinacia oleracea L.) Grown in Acidic Nutrient Solution

Hydroponic leafy green production offers high productivity and quality of crops but requires good management of pH and electrical conductivity (EC) to optimize the nutrient uptake. Nutrient solution pH is typically managed between 5.5 and 6.5, whereas lowering pH to more acidic range (e.g., <5.0) can potentially mitigate problematic waterborne diseases. Plant response to low pH is species specific and generally involves direct effect of increased hydronium ions and indirect effects of pH-dependent factors, such as low cations availability. To develop a new hydroponic nutrient management strategy, ‘Corvair’ spinach plants were grown under pH 4.0, 4.5, 5.0, and 5.5 of a hydroponic nutrient solution using a deep-water culture system in a growth chamber. Spinach shoot and root mass after 19 to 20 days declined with lowering pH. At the lowest pH of 4.0, plants displayed stunted overall growth and severely inhibited root development. Plant growth and morphology at pH 4.5 or 5.0 were normal but small, suggesting that growth reduction at these pH was likely a result of reduced nutrient uptake. Plant tissue analyses showed decreased N, P, K, Mg, S, Cu, Fe, Mn, and Zn concentration as pH decreased. When the strength of nutrient solution was increased three times at a low pH 4.5 to improve the overall nutrient availability, spinach shoot and root fresh weight with high nutrient concentrations (EC 3.4 dS·m−1) significantly improved but was still lower than those in the control (pH 5.5 and EC 1.4 dS·m−1), respectively. Plant tissue analysis showed that lowering pH to 4.5 significantly reduced tissue concentrations of P, K, Ca, Mg, S, Cu, Mn, and Zn compared with those in the control. Under low pH and increased EC treatment (pH 4.5 and EC 3.4 dS·m−1), all dry leaf nutrient concentrations were similar or higher than those of the control, except Mg and Zn, which showed a lower concentration than the control with a weak significance (P < 0.06). This suggests that additional optimization of nutrient formula might further improve the spinach growth at low pH. Together, our results will help to develop a new and low-cost nutrient management methodology to produce leafy greens hydroponically.

English

A superimposed experiment was conducted at Gircha, Chencha district, Southern Ethiopia to determine the effect of four rootstocks on leaf nutrient concentration of five apple cultivars. The experiment was laid out in a randomized complete block design (RCBD) with three replications. Data on leaf nutrient concentrations were collected and analyzed using SAS software. Results revealed that scion-rootstock interaction significantly (p<0.05) affected leaf nutrients (nitrogen - N, phosphorus - P, potassium -K, calcium- Ca and magnesium - Mg) contents. The maximum N  (2.32%), P  (0.43%), K  (2.09%), Ca (1.88%) and Mg (0.45%) were recorded for combination of Local + Saturn, Local + Scarlet, Begidu + Scarlet, TT-Gala + Mlerose and TT-Gala + Scarlet, respectively; while the lowest values of N (1.3%), P (0.12%), K (1.02%), Ca (0.42%) and Mg (0.11%), were recorded for the combination of Gircha + Saturn, Gircha + Saturn, Begidu + Nela,  Gircha + Mlerose and Gircha + Mlerose, respectively. Under Gircha soil condition, Mlerose, Saturn, Alkmen and Scarlett O’Hara cultivars grafted on Begidu, TT-Gala and Local rootstocks were confirmed better in acceptable leaf nutrient concentration. Based on leaf nutrient concentrations TT-Gala, Begidu and Local rootstocks were selected as best compatible with most cultivars grafted. Key words: Apple, scion-rootstock, nutrient and cultivar.

Short-Term Effects of Spent Mushroom Substrate Mulching Thickness on the Soil Environment, Weed Suppression, Leaf Nutrients, and Nut Characteristics in a Hazelnut Orchard

Worldwide, a huge amount of solid fermented waste is produced every year during mushroom production. The rational utilization of spent mushroom substrate (SMS) is conducive to environmental protection and the sustainable development of agriculture. The aims of this work were to analyze the effects of the SMS mulching thickness on the soil environment, weed suppression, leaf nutrients, and nut traits in a hazelnut plantation and provide a theoretical basis for the scientific and reasonable utilization of SMS. An SMS mulching experiment with four mulching thickness treatments (MT1: 5 cm, MT2: 10 cm, MT3: 15 cm, and CK: 0 cm) was conducted in a semi-arid area of North China in 2019. The soil properties, weed control efficiency, leaf nutrient content, and nut yield and quality characteristics of these treatments were all measured and analyzed. The results showed that (1) the average soil temperatures of MT2 and MT3 at different soil depths were 0.73–1.78 °C and 1.18–2.50 °C lower than when no mulch was used in warm weather and 0.67–1.05 °C and 0.99–1.56 °C higher than when no mulch was used in cold weather. The average soil moisture content of MT1, MT2, and MT3 at different soil depths was 6.27–8.13%, 10.66–17.23%, and 7.26–12.81% higher than that of CK, respectively. There were no significant differences in the soil bulk density or porosity among the four treatments. The average soil nutrient contents (soil organic matter and available N, P, and K) of MT1, MT2, and MT3 were 7.05–15.23%, 14.90–38.93%, and 17.42–40.11% higher than those of CK, respectively. Soil enzymatic activities of these treatments followed the order MT3 ≈ MT2 > MT1 > CK. (2) MT2 and MT3 both had high levels of weed control efficiency: 55.66–92.93% and 70.43–97.90%, respectively. (3) The leaf N, P, K, and SPAD increased significantly under MT2 and MT3 by about 10% compared with the CK. (4) MT2 effectively increased the nut size, nut and kernel mass, and crude fat content of the nut (CFC). In general, the short-term field experiment clearly showed that SMS is a superior mulching material for improving the soil environment and plant growth, and 10 cm thickness is suitable for mulching practice.

Improvement of water and nutrient efficiencies oil palm through bio-silicic acid application

Crop water use efficiency is critical for high yields in conditions of limited water supplies. This study aims at determining the effect of application bio-silicic acid (BioSilAc) on water use efficiency and nutrient availability for immature (2 years after planting) and mature (5 years after planting) oil palms in sandy soil during a period of low rainfall. A field experiment was conducted on sandy soil at an oil palm plantation in Central Kalimantan. The experiment was arranged in a randomized block design with seven treatments and three replicates using a combination of composted empty fruit bunches of oil palm (CEFBOP) and BioSilAc applications. The treatments (tree-1 year-1) were as follows (tree-1 year-1): (T1) 100% NPK standard dosage; (T2) T1 + 1.5 kg quartz sand; (T3) 75% (T1) + 1.5 kg quartz sand; (T4) T1+ 4 tablets BioSilAc; (T5) 75% (T1) + 4 tablets BioSilAc; (T6) T1 + 50 kg CEFBOP + 2 tablets BioSilAc; and (T7) 75% (T1) + 50 kg CEFBOP + 2 tablets BioSilAc. The parameters observed were soil and leaf nutrient contents, average weight, and number of fresh fruit bunch (FFB), and daily water usage and water potential using a sap flow meter and stem psychrometer to calculate water use efficiency in T1 (control) and T5 which represents the application of BioSilAc. The results indicated that the application of 75-100% NPK + 4 tablets BioSilAc tree-1 year-1 in mature oil palm was capable of improving yield of11.9% (T5) and 12.1% (T4) and water use efficiency of 31.3% (mature) and 50.4% (immature) of the control treatment.

The Effect of Foliar and Ground-Applied Essential Nutrients on Huanglongbing-Affected Mature Citrus Trees.

The fate of foliar and ground-applied essential nutrients is the least studied topic under citrus greening or Huanglongbing (HLB)-affected citrus, which is inherently suffering from severe root decline because of HLB-associated problems. The objective of this study was to evaluate if ground-applied coupled with foliar spray of essential nutrients can reverse the decline in tree growth and understand the fate of the nutrients in the soil-root-tree interfaces. The treatments were arranged in a split-split plot design in which nitrogen (N) was ground-applied in 20 splits biweekly and Mn, Zn, and B were foliar and /or ground-applied in three splits following the spring, summer, and late summer flush seasons. Soil nutrients in three depths (0–15, 15–30, and 30–45 cm), root, and leaf nutrient concentrations of the essential nutrients, leaf area index (LAI), and tree canopy volume (TCV) data were studied twice (spring and summer) for two years. A significantly higher soil NH4-N and NO3-N concentrations were detected in the topsoil depth than the two lower soil depths (15–30 and 30–45 cm) indicating lesser nutrient leaching as trees received moderate (224 kg ha−1) N rate. Except for soil zinc (Zn) concentration, all the nutrient concentrations were significantly higher in the topsoil (0–15 cm), compared with two lower soil depths indicating that Zn was intricate by changes in soil environmental conditions, root acquisition, and/or leaching to lower soil depth. Leaf N concentration significantly increased over time following seasonal environmental fluctuations, tree growth, and development. Thus, leaf N concentration remained above the optimum nutrient range implying lower N requirement under irrigation scheduling with SmartIrrigation, an App used to determine the daily irrigation duration to meet tree water requirement and split fertigation techniques. Root Manganese (Mn) and Zn concentrations were significantly higher in the root tissues of the treated than the control trees and translocated to the leaves accordingly. Meanwhile, a significantly higher LAI for trees budded on Swingle (Swc) rootstock however, larger TCV for trees budded on Volkameriana (Volk) rootstocks. The trees had significantly larger TCV when the trees received a moderate N rate during early study years and under foliar 9 kg ha−1 coupled with the ground 9 kg ha−1 Mn and Zn treatments during the late study years. Therefore, split ground application of 224 kg ha−1 of N, foliar applied 9 kg ha−1 coupled with ground-applied 9 kg ha−1 Mn and Zn were the suggested rates to sustain the essential leaf nutrient concentration within the optimum ranges and improve the deterioration of vegetative growth associated with HLB-induced problems of citrus trees.

Influence of rootstocks on scion leaf mineral content in mango tree (Mangifera indica L.)

Grafting is an important practice in mango (Mangifera indica L.) orchard management for propagating elite germplasm but there is limited information on the effect of rootstock-scion interactions on the mineral nutrition of mango. Here, we analyzed the variations in leaf nutrients of commercial (‘B74’ and ‘Kensington Pride’ [KP]) and newly developed cultivars from the National Mango Breeding Program (NMBP) (‘NMBP1243’, ‘NMBP1201’, and ‘NMBP4069’) grafted onto six different rootstocks (‘B’, ‘KP’, ‘Mallapunyah’, ‘SabahBRF’, ‘Vellaikulamban’, and ‘Watertank’) to determine the influence of the rootstock on the scion leaf nutrient content. Deviation from the optimum percentage (DOP and ΣDOP indexes) was calculated to compare nutrition status/balance among the different rootstocks. Leaf nutrient concentrations and their DOP index were affected by the rootstocks and scions. None of the rootstocks or scions had consistently higher or lower nutrient levels, and interaction effects between rootstock and scion factors were insignificant. The DOP index indicated an imbalance of nutrients in the leaves, but scions grafted onto rootstocks ‘Vellaikulamban’ and ‘SabahBRF’ were more nutritionally balanced, indicating that they are preferred rootstocks for propagation. Principal component analysis showed a clear separation among rootstocks according to their differences in nutrient concentrations, such that ‘Vellaikulamban’ and ‘SabahBRF’ (Group 1) were different from ‘Watertank’ and ‘B’ (Group 2) as well as from ‘KP’ and ‘Mallapunyah’ (Group 3). Scions were clustered based on their similarities with ‘B74’ and ‘NMBP1201’ in Cluster 1, ‘NMBP 4069’ in Cluster 2, ‘NMBP 1243’ in Cluster 3, and ‘KP’ in Cluster 4. This study provides valuable information to understand the potential impact of the rootstock on the nutritional status of scions as well as for the selection of rootstock-scion combinations for variety improvement.

Global resorption efficiencies of trace elements in leaves of terrestrial plants

Abstract Leaf nutrient resorption is a critical nutrient conservation strategy. Previous studies focus mainly on resorption patterns of macronutrients, but resorption patterns of trace elements remain poorly understood. A meta‐analysis was conducted to explore the general patterns of the leaf resorption of eight trace elements [i.e. copper (Cu), molybdenum (Mo), zinc (Zn), boron (B), manganese (Mn), sodium (Na), aluminium (Al) and iron (Fe)], and a macronutrient [i.e. sulphur (S)] using data collected from 53 published studies. Sulphur (49.6%) had the highest average resorption efficiency followed by Cu (30.3%), Mo (29.5%), Zn (19.5%) and B (17.6%). Two structural elements, Na and Mn, were not resorbed, whereas two potentially toxic elements, Al (−55.6%) and Fe (−25.4%), were accumulated in senesced leaves. Both climatic factors and growth types affected leaf nutrient resorption efficiency, but the magnitudes and directions of the effects differed greatly between S and the trace elements. The resorption efficiencies of S, Cu, Mo and Zn decreased as leaf nutrient concentrations increased, but the structural or potentially toxic elements (i.e. B, Mn, Na, Fe and Al) presented no response or opposite trends. Our results provide global mean resorption efficiencies of trace elements for the first time, and highlight that structural and potentially toxic elements have relatively lower or no leaf resorption, which should be fully considered in biogeochemical models. A free Plain Language Summary can be found within the Supporting Information of this article.