Tree Nutrient Status Research Articles

The Use of the Normalized Difference Red Edge (NDRE) Vegetation Index from Multispectral Cameras Mounted on Unmanned Aerial Vehicle to Estimate the Nutrient Content in Oil Palm Leaves

This study aimed to develop a prediction model for the nutrient content of N, P, K, Mg, and Ca in oil palm leaves using the Normalized Difference RedEdge (NDRE) vegetation index derived from multispectral camera data. Data acquisition was carried out by an unmanned aerial vehicle (UAV), which was correlated to leaf sample analysis of the 17th frond number. Results showed that simple regression analysis successfully represented nutrient content (N, P, K, Mg, and Ca) based on NDRE values. Based on the MAPE and Correctness values, the nutrient content prediction model for N and P yields reliable results, while for K, Mg, and Ca, they are considered good, with Correctness values of 95.5%, 96.6%, 88.8%, 87.3%, and 90.0% for N, P, K, Mg, and Ca, respectively. The study found that the NDRE vegetation index can be used to predict the nutrient content of oil palm leaves with reliable results in accuracy for N and P, and good accuracy for K, Mg, and Ca. This is a promising finding, as it could lead to the development of a non-destructive and rapid method for monitoring the nutrient status of oil palm trees, with the validation models for N, P, K, Mg, and Ca are yN = 1.1089x - 0.2497, yP = 0.99x + 0.002, yK = 1.204x - 0.1576, yMg = 0.9149x + 0.0183, and yCa = 1.0418x - 0.0218. Keywords: Multispectral Cameras, Oil Palm, Leaf Nutrient Contents, Prediction.

Impacts of aquaculture wastewater irrigation on soil health, nutrient availability, and date palm fruit quality

Water scarcity and droughts are among the most challenging issues worldwide, particularly in arid and semi-arid regions like Saudi Arabia. Date palm (Phoenix dactylifera L.), a major crop in Saudi Arabia, is being significantly affected by water scarcity, soil salinity, and desertification. Alternative water sources are needed to conserve freshwater resources and increase date palm production in Saudi Arabia. On the other hand, Saudi Arabia has a significant number of aquaculture farms that generate substantial amounts of wastewater, which can be utilized as an alternative source of irrigation. Therefore, this study aimed to assess the potential of aquaculture wastewater as an alternative irrigation source for date palm orchards. Aquaculture wastewater was collected from 12 different farms (Al-Kharj, Al-Muzahmiya, and Al-Qassim regions, Saudi Arabia) and its quality was analyzed. The impacts of aquaculture wastewater irrigation on soil quality, nutrient availability, nutrient status of date palm trees, and dates fruit quality were assessed in comparison to source water (freshwater) irrigation at Al-Kharj, Al-Muzahmiya, and Al-Qassim regions. The water quality analyses showed higher salinity (EC = 3.31 dSm−1) in farm Q3, while all other farms demonstrated no salinity, sodicity, or alkalinity hazards. Moreover, the aquaculture wastewater irrigation increased soil available P, K, NO3−–N, and NH4+–N by 49.31%, 21.11%, 33.62%, and 52.31%, respectively, compared to source water irrigation. On average, date palm fruit weight, length, and moisture contents increased by 26%, 23%, and 43% under aquaculture wastewater irrigation compared to source water irrigation. Further, P, K, Fe, Cu, and Zn contents in date palm leaf were increased by 19.35%, 34.17%, 37.36%, 38.24%, and 45.29%, respectively, under aquaculture wastewater irrigation compared to source water irrigation. Overall, aquaculture wastewater irrigation significantly enhanced date palm plant growth, date palm fruit quality, and soil available nutrients compared to freshwater irrigation. It was concluded that aquaculture wastewater can be used as an effective irrigation source for date palm farms as it enhances soil nutrient availability, date palm growth, and date fruit yield and quality. The findings of this study suggest that aquaculture wastewater could be a viable alternative for conserving freshwater resources and increase date palm production in Saudi Arabia.

Regeneration of post‐mining and post‐fire soil function by assessment of tree nutrient status: Evidence from pioneer and N‐fixing species

AbstractNutrient concentrations in the foliage of particular tree species can identify growth‐limiting factors. Therefore, the adaptability and usefulness of certain trees in the afforestation of barren soils after disturbances could be based on nutrient supply and stoichiometry. In this study, we investigated the macronutrient supply to (i.e., nitrogen [N], phosphorus [P], potassium, sulfur, calcium [Ca], and magnesium [Mg]) and C:N:P (carbon:nitrogen:phosphorus) stoichiometry of the foliage of black alder (Alnus glutinosa), common birch (Betula pendula), and Scots pine (Pinus sylvestris) in two different regeneration scenarios—a reclaimed mine site with primary succession and an afforested post‐fire (PF) site with secondary succession. The control plot was on an undisturbed forest site hosting stands of the studied tree species. The lower concentrations of elements in the post‐mining soils developed from “point zero” were enough to supply the trees with a similar level of nutrition to those in the PF and undisturbed soils. The studied tree species differed in their foliage chemistry and had different effects on the soil properties. The alder and birch foliage contained more nutrients than the pine foliage. In particular, the birch foliage contained the highest concentrations of Ca, Mg, and P, thus enhancing the biogeochemical cycling of these elements. The alder foliage had the highest N concentration, albeit the soil total N contents under this species were not higher than those under birch. Thus, its phytomeliorative effect may have been overestimated. The pine foliage contained the lowest concentrations of nutrients, indicating the high nutrient use efficiency of this species. On the sites degraded after disturbance, pine and birch grew under N‐limitation stress, while the alder—a N‐fixing species—grew under P‐limitation stress, especially at the PF site. The PF soils under alder were also characterized by higher acidity, P depletion, and higher C:P and N:P ratios compared to the PF soils under the other studied species. We found that birch should be the most common tree species in the first phase of area regeneration after disturbances. Introducing alder into afforestation should take place in admixtures, especially at the PF site.

Effect of Municipal Mulch and Poultry Litter Amendments on Soil and Tree Parameters of a Mature Peach Orchard in a Humid Subtropical Climate

Applying organic matter (OM) amendments in mature peach orchards with low organic matter content (Prunus persica (L.) Batsch.) may improve tree nutrient and water status during the growing season and enable growers to reduce synthetic fertilizer inputs. Three treatments were applied to “Juneprince” and “Scarletprince” peach trees: (1) grower standard of bare soil (GS), (2) municipal mulch (M), and (3) poultry litter with municipal mulch (PLM). Synthetic fertilizer was reduced within the M and PLM treatments each year. Soil samples were taken from under the amendments, and the nutrient and water status of the soil and trees were monitored over 3 years. Fruit yield and tree growth measurements were also recorded. Soil OM did not increase, but soil P increased in all three treatments over time. Soil Cu was reduced by adding OM amendments, while PLM increased soil Na and increased leaf K in “Scarletprince” trees. The PLM and M treatments buffered soil water compared to GS, but tree water status between treatments was largely similar. The elevated N status over time from the PLM and M treatments delayed fruit maturity and reduced cumulative yield in “Juneprince” trees. The PLM treatment increased “Scarletprince” fruit size and mass over 3 years, as well as tree size compared to GS. Covering the soil with mulch allowed for reduced synthetic fertilizer use, but further reduction of supplemental synthetic fertilizer or adjustment of amendment rates is needed to limit N and ensure desired fruit harvest windows and long-term production.

Seasonal trends in leaf and fruit nutrient concentrations of apple (Malus x domestica Borkh.) grafted on different clonal rootstocks and their effect on fruit quality

Effective nutrient management necessitates monitoring of nutrient requirement, extent and timing of nutrient supply during the fruit development. To achieve a good nutrient balance and its impact on fruit quality, study of nutrient dynamics is of utmost importance as it provides an intriguing stratagem to control tree nutrient status. The research aimed at investigating seasonal patterns of nutrient concentrations in leaves and fruits of apple (Malus × domestica Borkh.) cv Silver Spur on various clonal rootstocks (MM106, M4 and M9) during the year 2019–2020 and their impact on fruit quality. For this purpose collection of leaf and fruit samples commenced from one month after full bloom (May 15) until harvesting (September 18) at an interval of twenty one days and samples were evaluated for both macro and micro-nutrients {Nitrogen (N), Phosphorus (P), Potassium (K), Calcium (Ca), Magnesium (Mg) and Boron (B)} and quality characteristics. In general, concentration of N, P, K and B declined continuously in both leaf and fruit toward the end of fruit maturation, whereas leaf Ca and Mg augmented along the cycle, however fruit Ca and Mg increased up to first fruit development stage and then decreased again signifying nutrient dilution along growing season and its effect on fruit quality. With respect to rootstocks, semi-vigorous rootstock MM106 recorded higher values for leaf and fruit nutrient concentrations as compared to dwarf M9 and semi-dwarf M4 rootstocks specifying a significant effect of rootstocks on nutrient absorption.

A New Small-Size Camera with Built-In Specific-Wavelength LED Lighting for Evaluating Chlorophyll Status of Fruit Trees.

To produce high-quality crops, not only excellent cultivation techniques but also accurate nutrient management techniques are important. In recent years, many nondestructive tools such as the chlorophyll meter "SPAD" and the leaf nitrogen meter "Agri Expert CCN" have been developed for measuring crop leaf chlorophyll and nitrogen contents. However, such devices are still relatively expensive for individual farmers. In this research, we developed a low-cost and small-size camera with built-in LEDs of several specific wavelengths for evaluating the nutrient status of fruit trees. A total of 2 camera prototypes were developed by integrating 3 independent LEDs of specific wavelengths (Camera 1: 950 nm, 660 nm and 560 nm; Camera 2: 950 nm, 660 nm and 727 nm) into the device. In addition, a simple software tool was developed to enable the camera to capture leaf images under different LED lighting conditions. Using the prototypes, we acquired images of apple leaves and investigated the possibility of using the images to estimate the leaf nutrient status indicator SPAD (chlorophyll) and CCN (nitrogen) values obtained using the above-mentioned standard tools. The results indicate that the Camera 1 prototype is superior to the Camera 2 prototype and can potentially be applied to the evaluation of nutrient status in apple leaves.

Annual compost amendments can replace synthetic fertilizer, improve soil moisture, and ensure tree performance during peach orchard establishment in a humid subtropical climate.

The application of organic matter (OM) to peach orchards is currently uncommon in commercial operations but could potentially replace synthetic fertilizers and improve long-term orchard sustainability. The purpose of the study was to monitor how annual applications of compost to replace synthetic fertilizer would change soil quality, peach tree nutrient and water status, and tree performance during the first four years of orchard establishment within a subtropical climate. Food waste compost was incorporated before planting and added annually over four years with the following treatments: 1) 1x rate, applied as dry weight at 22,417 kg ha-1 (10 tons acre-1) incorporated during the first year and 11,208 kg ha-1 (5 tons acre-1) applied topically each year after; 2) 2x rate, applied as dry weight at 44,834 kg ha-1 (20 tons acre-1) incorporated during the first year and 22,417 kg ha-1 (10 tons acre-1) applied topically each year after; and 3) control, with no compost added. Treatments were applied to a virgin orchard location, where peach trees had never previously been grown, and to a replant location, where peach trees had been grown previously for more than 20 years. Synthetic fertilizer was reduced in the 1x and 2x rates by 80 and 100% during the spring and all treatments received the summer application according to standard practice. Soil OM, phosphorus and sodium all increased with the addition of 2x compost in the replant location at 15cm depth, but not within the virgin location compared to the control treatment. The 2x rate of compost improved soil moisture during the growing season, but tree water status was similar between treatments. Tree growth was similar between treatments in the replant location, but the 2x treatment had larger trees compared to the control by the third year. Foliar nutrients were similar between treatments over the four years, while 2x compost rate increased fruit yield in the virgin location compared to the control the second year of harvest. The 2x food waste compost rate could be considered as a replacement for synthetic fertilizers and to potentially increase tree growth during orchard establishment.

Relationships between the Water Uptake and Nutrient Status of Rubber Trees in a Monoculture Rubber Plantation

Rubber cultivation is primarily rainfed agriculture, which means that water supplies are not stable in most rubber cultivated areas. Therefore, improving the water use of rubber trees through fertilization management seems to be a breakthrough for enhancing the growth and latex yield of rubber trees and carrying out the intensive management of rubber agriculture. However, the relationships among the nutrient status of rubber trees, their water uptake, and soil resources, including water and nutrients, remain unclear. To address this issue, we measured C, N, P, K, Ca, and Mg concentrations in soil and leaves, stems, and roots in a monoculture rubber plantation and distinguished the water uptake depths based on stable isotope analysis throughout the year. We found that the rubber trees primarily absorbed water from the 5–50 cm depth layer, and soil water and nutrients (usually N, P, K) decreased with depth. In addition, the water uptake depth of rubber trees exhibited positive correlations with the nutrient status of their tissues. The more water the rubber trees absorb from the intermediate soil layer, the more nutrients they contain. Therefore, applying fertilizer to intermediate soil layers, especially those rich in C content, could greatly promote rubber tree growth.

Effects of organic matter amendments on soil nutrient availability and tree nutrient status in California almond

Effects of organic matter amendments on soil nutrient availability and tree nutrient status in California almond

Mitigation of soil acidification in orchards: A case study to alleviate early defoliation in pear (Pyrus pyrifolia) trees

Long-term application of chemical fertilizers has aggravated red soil acidification and caused severe early defoliation in pear-growing region of southern China. To investigate the effects of BIO and HA on the growth and activity of fine roots, and in turn the effect on leaf nutrient status and early defoliation of pear trees, we conducted a 2-year pot experiment (2018–2019) using 1-year-old pear (Pyrus pyrifolia) seedlings in a pear orchard in southern China. Four fertilization treatments were included: chemical fertilizer as control (CF), CF with humic acid (CF-HA), BIO, and BIO mixed with HA (BIO-HA). Results showed that BIO and BIO-HA treatments significantly decreased the early defoliation rate of pear trees about 18%–27% compared with CF and CF-HA treatments. For the growth status of the aboveground, the relative growth rate of pear trees treated by BIO and BIO-HA was 1.2 times higher than the CF treatment at 180 days after budding, and it was accompanied by an increase of leaf thickness, microelements content (e.g. calcium, manganese, iron and zinc), and a decrease of leaf temperature. Compared with CF treatment, BIO or BIO-HA significantly improved soil pH value by 0.9–1.1 units, and increased soil exchangeable calcium content by 50%–83%. BIO and BIO-HA treatments also significantly increased total lateral root number, length and root activity, which were negatively correlated with the early defoliation rate by the network analysis. Furthermore, structural equation model showed that root traits were the core factor to alleviate the early defoliation rate, which was directly or indirectly driven by the application of bioorganic fertilizer. In conclusion, BIO or BIO combined with HA can alleviate the early defoliation rate of pear trees by mitigating soil acidification to stimulate the lateral root growth and activity, and in turn increase leaf micronutrients content and aboveground growth. Our study shows that measuring root traits are at the core of plant responses to soil nutrient status and pH.

Influence of Branch Death on Leaf Nutrient Status and Stoichiometry of Wild Apple Trees (Malus sieversii) in the Western Tianshan Mountains, China

The wild apple tree Malus sieversii is a tertiary relict species and a key ancestor of the commonly cultivated apple trees today. In recent years, many M. sieversii individuals have died or have severe dead branches. Whether branch death would lead to the change in nutrient stoichiometry of M. sieversii remains unclear. In this study, the nitrogen (N), phosphorous (P), and potassium (K) stoichiometric traits of M. sieversii individual trees with different proportion of dead branches divided into three classes (Class I [< 20%], Class II [40–60%], and Class III [> 80%]) during annual growth period, elemental scaling relations, and the possible influencing factors were systematically analysed. Leaf N, P, and K decreased during growing season, and N and P did not show significant differences among the three classes; however, the Class III wild apple trees had the lowest K contents in both photosynthetic and reproductive organs. Flowers had higher P and K contents than leaves, whereas fruits had low N content. The growth of M. sieversii was always limited by N due to low N:P ratio and N resorption efficiency. The scaling exponents of leaf N–P, N–K, or P–K among the three classes did not show any significant differences, revealing an inherent property of M. sieversii. Most soil variables showed weak correlations with leaf nutrient parameters (except for K). Precipitation and relative humidity, rather than temperature, showed significantly positive effects on leaf nutrients. These findings suggest that increasing water input and plant K content may be conducive to enhance the resistance and recovery ability of diseased wild apple trees.

Hyperspectral Estimation of Apple Canopy Chlorophyll Content Using an Ensemble Learning Approach

HighlightsMonitored the canopy chlorophyll content of apple trees using hyperspectral reflectance information.Constructed support vector machine combination regression model (C-SVR) based on five-fold cross validation and support vector machine regression approach.Compared estimation accuracy of ensemble learning models (C-SVR, RF), machine learning models (SVR, ANN), and PLSR models for apple canopy chlorophyll content.Abstract. Rapidly and effective monitoring of the canopy chlorophyll content (CCC) of apple trees is of great significance for crop stress monitoring in precision agriculture. This study attempted to use hyperspectral vegetation indices (VIs) to estimate the CCC of apple trees based on ensemble learning approach. In this study, vegetation indices combined by any two wavelengths from 400 to 1100 nm were constructed to calculate the correlation coefficient with the CCC in apple. We constructed a partial least squares regression model (PLSR), artificial neural network regression model (ANN), support vector machine regression (SVR), random forest regression (RF) model and support vector machine combination regression model (C-SVR) based on combinations of VIs to improve the estimation accuracy in apple CCC. The results showed that the correlation coefficients between NDVI (949,695), OSAVI (828,705), RDVI (741,725), RVI (716,707), DVI (572,532), and apple CCC were all above 0.76. The CCC estimation model using the RF and C-SVR approach constructed by the NDVI (949,695), OSAVI (828,705), RDVI (741,725), RVI (716,707), and DVI (572,532) achieved the better estimation results, and the R2V, RMSEV, and RPDV values of models were 0.76, 0.131(mg . g-1), 2.04 and 0.78, 0.127(mg . g-1), 2.12, respectively. Compared with the PLSR, ANN, and SVR model, the R2V and RPDV values of C-SVR model were increased by 4%, 1.2%, 3.8%, and 5.0%, 28.4%, 7.1%, respectively. The results show that using C-SVR approach to estimating the apple CCC can realize high accuracy of quantitative estimation. Ensemble learning approach is an effective method for monitoring the nutrient status of fruit trees based on hyperspectral technique. Keywords: Apple tree canopy, Chlorophyll content, Crop stress monitoring, Ensemble learning, Hyperspectral, Vegetation index.

Concentraciones críticas nutrimentales y normas DRIS para árboles de medio turno de Cedrela odorata L.

El diagnóstico nutrimental ayuda a mejorar la eficiencia del uso de fertilizantes en plantaciones forestales y a incrementar tanto las utilidades económicas, como los beneficios ecológicos. Dos métodos comúnmente usados, para tal efecto, son las concentraciones críticas y el Sistema Integrado de Diagnóstico y Recomendación (DRIS); sin embargo, no existen estudios que aporten los valores críticos o normas DRIS para Cedrela odorata (cedro rojo), especie importante en las regiones tropicales. El objetivo del presente estudio fue desarrollar un conjunto de concentraciones críticas y uno de normas DRIS para C. odorata en su etapa de medio turno. El estudio se realizó con 74 árboles localizados a lo largo del área de distribución natural del taxon en México, a los cuales se les determinó el incremento diamétrico y la concentración nutrimental entre julio de 2017 y enero de 2018. Se derivó un conjunto de concentraciones críticas y uno de normas DRIS. Una segunda fase fue la verificación de las concentraciones críticas y normas DRIS generadas, mediante un experimento en una plantación de cedro rojo de medio turno. El ensayo fue completamente al azar con arreglo factorial 3 × 4, en el que los factores correspondieron a la aplicación de P y K, respectivamente. Se presenta un conjunto de concentraciones críticas y uno de normas DRIS para árboles de C. odorata de medio turno. El proceso de verificación indica que ambos conjuntos de valores de referencia predicen correctamente el estado nutrimental de los árboles de medio turno del cedro rojo.

REUTIVAR: Model for Precision Fertigation Scheduling for Olive Orchards Using Reclaimed Water

Olive orchard is the most representative and iconic crop in Andalusia (Southern Spain). It is also considered one of the major economic activities of this region. However, due to its extensive growing area, olive orchard is also the most water-demanding crop in the Guadalquivir River Basin. In addition, its fertilization is commonly imprecise, which causes over-fertilization, especially nitrogen. This leads to pollution problems in both soil and water, threating the environment and the system sustainability. This concern is further exacerbated by the use of reclaimed water to irrigate since water is already a nutrient carrier. In this work, a model which determines the real-time irrigation and fertilization scheduling for olive orchard, applying treated wastewater, has been developed. The precision fertigation model considers weather information, both historical and forecast data, soil characteristics, hydraulic characteristics of the system, water allocation, tree nutrient status, and irrigation water quality. As a result, daily information about irrigation time and fertilizer quantity, considering the most susceptible crop stage, is provided. The proposed model showed that by using treated wastewater, additional fertilization was not required, leading to significant environmental benefits but also benefits in the total farm financial costs.

Soil and Tree Nutrient Status of High Elevation Mixed Red Spruce (Picea rubens Sarg.) and Broadleaf Deciduous Forests

Anthropogenic and industrial emissions have resulted in historically high levels of acidic deposition into central Appalachian forests. Despite the reduction in acidic inputs due to legislation curbing industrial emissions in the United States, continued N deposition may impact forest ecosystems. Soil and foliar samples were collected from four high elevation red spruce sites along a modeled gradient of historic N deposition. The three most abundant tree species at all sites, Acer rubrum L., Betula alleghaniensis Britt., and Picea rubens Sarg., were sampled. Bulk soil beneath the canopies of individual trees were collected from the top 15-cm and separated into organic and mineral fractions for analysis. Mehlich-III soil extracts of soil fractions and foliar digests from these trees were subjected to elemental analysis. Soil N concentrations supported the presence of a N deposition gradient: in organic horizon soil fractions, N concentrations were driven by precipitation volume and elevation; whereas in mineral soil fractions, N concentration was explained by modeled N deposition rate and elevation. In organic fractions, significant reductions in Ca, K, and P were evident as N deposition increased, whereas the Ca:Sr ratio increased. Foliar Ca, K, and Sr declined in foliage with increasing N deposition, with concomitant increases in foliar Ca:Sr ratios. Although the three species were sympatric in mixed stands at all four sites, the foliar–soil nutrient associations differed among them across the gradient, indicating differential uptake and cycling of nutrients/metals by these forest tree species.

Nutrient Status and Root Density of Huanglongbing-Affected Trees: Consequences of Irrigation Water Bicarbonate and Soil pH Mitigation with Acidification

The Candidatus Liberibacter asiaticus bacterium, associated with Huanglongbing (HLB) disease of citrus trees, moves downward in the phloem and infects the roots soon after transmission by the Asian Citrus Psyllid (Diaphorina citri) vector into shoots. Before canopy symptoms appear, 30–50% of the roots are damaged. Without aggressive management to reduce abiotic and biotic stress, root loss increases to 70–80%. An extensive survey of HLB-affected groves in central and south-central Florida indicated that a greater decline in fibrous root health as well as a greater expression of HLB symptoms is observed where irrigation water is high in bicarbonates (&gt;100 mg L−1) and soil pH is &gt;6.5. Over three seasons of survey, acidification of irrigation water in the central and south-central citrus growing regions of Florida reduced the decline in root density associated with HLB. Irrigation water treatment with sulfuric acid and soil amendment with elemental sulfur for 36 months to establish a soil pH range from 4.0 to 7.0 increased root growth, soil nutrient availability, and the uptake of Ca, Mg, Mn, and Zn in response to a gradual reduction in soil pH in young and mature Valencia orange groves on Swingle citrumelo rootstock. The reduction in soil pH increased yield and soluble solids in fruit and so would improve citrus production.

Compost and Geneva® series rootstocks increase young ‘Gala’ apple tree growth and change root-zone microbial communities

Rootstocks are used in commercial apple (Malus ×domestica Borkh.) orchards to create dwarf trees that are highly precocious, but there are gaps in understanding how soil fertility management practices may affect soil health, tree nutrient status, plant associated soil microbial communities, and orchard productivity when different rootstock genotypes are used. For three consecutive years, we tested six fertilizer treatments, on five rootstock genotypes (each was scion grafted with ‘Brookfield Gala’). The fertilizer treatments included, (1) a no fertilizer control, 40 kg/ha plant available N from (2) calcium nitrate Ca(NO3)2 fertigation, (3) chicken litter compost, or (4) yard waste compost, and, two integrated compost-Ca(NO3)2 treatments, which were comprised of 20 kg/ha N from either (5) chicken litter or (6) yard waste compost and 20 kg/ha from Ca(NO3)2. The rootstock genotype treatments included, ‘Budagovsky 9’, ‘Geneva® 41’, ‘G.214’, ‘G.935’, and ‘Malling 9’. Trees were planted into 38 L pots containing local soil and Stalite®. After three years, total tree biomass was greater in the chicken litter, chicken litter-Ca(NO3)2, yardwaste, and yardwaste-Ca(NO3)2 treatments than the non-fertilized control, regardless of the rootstock genotype. In 2015, the Ca(NO3)2, chicken litter, and the two integrated compost-Ca(NO3)2 treatments had greater leaf tissue N than the control and yardwaste treatments. Leaf tissue P and B were consistently greater in the Geneva® rootstocks than B.9 or M.9. In the third year of the experiment, the compost and integrated treatments had greater soil organic matter, cation exchange capacity, potentially mineralizable soil nitrogen, and soil microbial respiration than the control. Additionally, bacterial and fungal microbial community compositions were affected by rootstock genotype, fertilizer treatment, and time and these effects were correlated with changes in tree growth and soil properties. These results suggest that compost and integrated compost-Ca(NO3)2 nutrient applications can be used to increase plant growth, leaf mineral content, soil fertility, and microbial activity in newly established apple orchards. Additionally, the Geneva® rootstocks that we tested appear to be more effective at acquiring soil minerals than other dwarfing genotypes and, therefore, may be well suited for use in fertility management plans that derive all or part of their nutrients from compost. Further research into the roles played by microbial communities in apple tree growth and soil fertility is supported.

Soil physicochemical properties, tree nutrient status, physical, organoleptic and phytochemical characteristics and antioxidant capacity of clementine mandarin (Citrus clementine cv. SRA63) juice under integrated and organic farming

Two mandarin orchards old trees, the first cultivated as organic farm and the second adapting integrated farming approach were assessed, regarding soil properties, plant nutrition and fruit quality attributes. Organic cultivation enhanced some of the soil properties, mainly by increasing the levels of exchangeable potassium, magnesium and phosphorus, while potassium, magnesium and zinc were also higher in the leaves of organically cultivated trees. Yield was higher under integrated cultivation, with fruits of lower diameter and length. Peel color was advanced under organic cultivation, which induced higher maturity index and total soluble solids in the juice. The individual carbohydrates and organic acids assessed did not differ between the two cultivation systems, while fruits produced under integrated system exhibited higher hesperidin content and higher antioxidant capacity than the organic ones. The principal component analysis resulted in a clear distinction between the two systems, based mainly on the yield, peel and flesh participation in the whole fruit and leaf potassium and sodium concentrations. Overall, the two systems did not differ considerably, but their few significant differences were enough to be clearly distinguished. The integrated produced fruits with higher antioxidant capacity, justified the aspect that organically produced food cannot be “a priori” characterized as better than the integrated one. On the other hand the superiority of organic food can be surely based on the low or zero pesticide residues and on preserving environmental and economic sustainability.

Diagnostic tools for nutrition status in Eucalyptus globulus: changes in leaves, xylem and phloem sap compounds according to N-, P-, and K-withdrawal or salt application

The results presented here demonstrate the capacity for phloem sap as a diagnostic tool for monitoring the nutritional status of plants and highlight the processes of remobilisation and source–sink dynamics. It is essential to develop methods that accurately reflect plant nutritional status for growth. In a greenhouse experiment with potted eucalyptus, we studied the effects of withdrawing single macronutrients N, P, or K, or salt application on the abundance of components in phloem, xylem and leaves to identify and refine methods to rapidly and effectively assess the nutrient status of Eucalyptus globulus trees. Clear effects on growth (and photosynthesis) were found for “−N” treatment and NaCl application. Effects of nutrient withdrawal were detected indicating our methodologies are useful for nutrient availabilities below the threshold of growth responses. While “−P” resulted in significantly lower P in xylem sap, the corresponding effect for “−K” on K in xylem sap was not found, although Ca and Na increased. Salt application increased Na in xylem sap sixfold. In leaf material “−N” reduced N. Surprisingly, “+NaCl”, “−P” and “−K” did not change the corresponding elements in leaves. Additionally, “−P”-treatment had the tendency to affect C-, N-, K- and particularly P-increment (n.s.). In phloem sap, “+NaCl” resulted in several effects, most prominently doubling Na concentration. Importantly, “−N” increased amino acids in phloem sap (n.s.). Statistically significant relationships between concentrations in leaves and phloem sap were found for δ13C and amino acids. Within the results obtained from phloem sap, sugars and bivalent cations (Ca and Mg) are correlated with that obtained from the leaves as well as Na and P. The role and comparative advantages of phloem sap as a diagnostic tool for nutritional status are discussed.

Effects of mulching on soil temperature and moisture variations, leaf nutrient status, growth and yield of pistachio trees (Pistacia vera.L)

Abstract The objective of this study was to investigate the response of leaf nutrients concentration, growth and yield of pistachio trees affected by changes in soil moisture and temperature as a result of different mulching. The experiment was conducted in a randomized complete block design with five replications in Feyzabad, Khorasan Razavi, Iran, for two years in 2014 (‘off’ year) and 2015 (‘on’ year). Treatments included sub-soil plastic (SPM1 and SPM2), up-soil plastic (UPM), woodchips (WM), barley residue (BM) mulches and control (CK). Treatment of SPM2 recorded the highest shoot growth and nut splitting, and lowest bud abscission in ‘off’ year. However, in ‘on’ year, maximum bud abscission was found in SPM2. Treatments of BM and WM were effective in decreasing flower bud and fruit abscission than other treatments during ‘on’ year. Mulching affected leaf P concentration in ‘off’ year and N, P and Mg in ‘on’ year, with the highest rate of these nutrients recording in BM treatment. Yield variations were not significantly affected by treatments in ‘off’ year, but in ‘on’ year, SPM2, WM, BM and SPM1 treatments increased yield by 29.2%, 28.7%, 19.8% and 10.5% compared to CK, respectively. Unlike other treatments, UPM had negative effect on leaf N concentration, and yield during ‘on’ year. This difference is attributed to high soil temperature in this treatment, so that yield reduced in soil temperature ranges over 36–37 °C in mean depth of 20–60 cm. In general, sub-soil plastic mulches, despite increasing yield in ‘on’ year, could not control flower bud abscission in that year. Thus, due to the increase of leaf nutrient concentration, regulation of alternate bearing phenomenon and improvement of yield, organic mulches are better options in arid and semi-arid regions with traditional irrigation methods.