Search

Girdling is an ancient agronomic technique that causes a change in the distribution of photosynthates, mineral nutrients and plant hormones. The aim of this study was to assess the effect of girdli...

In order to best nutrient use efficiency, as required by the increasing food demand for the future global population, in this work an innovative hybrid nanocomposite was designed as an alternative nanoscale fertilizer. An environmentally friendly chemical preparation based on polyelectrolyte complexation was used. A chitosan and sodium alginate complex was selected as a biodegradable shell to release the nanoscale nutrient, CuO nanoparticles. By optimizing the synthesis conditions, i.e. pH and polymer/cross-linker ratio, good stability and accurate size control of the resulting nanocomposites were achieved. The morphology features were evaluated using scanning and transmission electron microscopy, and chemical characterization was performed using X-ray diffraction, thermogravimetric analysis, Fourier-transform infrared spectroscopy, dynamic light scattering and inductively coupled plasma optical emission spectrometry. All the collected data confirmed spontaneous polymeric aggregation in nanostructures of sperical shape, having a mean diameter of about 300 nm, as well as CuO encapsulation inside the polymeric coating. Moreover, the role of the biopolymer shell in the significant slowing of copper release from the hybrid nanocomposite was reported. Finally, the nanocomposite efficacy in seeding and germination was evaluated on Fortunella margarita Swingle seeds. The tests demonstrated the benefits in the seedling growth together with a synergic effect in developing both the epigean and hypogean parts. The obtained results indicated that the proposed hybrid nanocomposite could be a potential alternative to realize a smart delivery nanofertilizer using an eco-sustainable method.

In this study, the adaptation characteristics of orange trees, related to the application over a decade of deficit irrigation (DI) strategies, have been explored. To this purpose, the analysis of a minimal dataset composed of physiological information (stem water potential - Ψ and sap flow - SF measurements), yield (fruits number and weight) and qualitative parameters (titratable acidity, TA; and total soluble solids, TSS) was performed with reference to the last irrigation seasons (i.e. 2018–19). The applied irrigation treatments were the following: sustained deficit irrigation (SDI); regulated deficit irrigation (RDI); partial root-zone drying (PRD), each distributing a water deficit of about 19%, 29% and 52%, respectively, compared to the control treatment (FI) supplying the full irrigation level (100% ET). In general, higher water use efficiencies (WUE) have been obtained in DI treatments, which guarantee greater water savings (up to 50%), without affecting yield and quality characteristics. In particular, the most stressed treatment (PRD), while reaching the lowest Ψ values (− 1.8 to − 2.0 MPa), as also shown by SF versus Ψ clusters, resulted in WUE values for yield (WUE), TA (WUE) and TSS (WUE) parameters of approximately 2.6, 2.9, and 3.1 times greater than FI, respectively. Overall, this study allowed identifying the cumulative adaptation characteristics of the orange trees under study to the application of long-term DI strategies and showing that trees were able to achieve yields and qualitative features similar to those obtained with FI, even after 10 years of application of deficient irrigation regimes., The work was carried out in the frame of Programma Operativo Nazionale (PON) “Attraction and International Mobility” (AIM) 1848200-2 initiative (D.V.) and within the project “Strategie per migliorare l’efficienza d’uso dell’acqua per le colture mediterranee” (SaveIrriWater) Linea 2 Ricerca di Ateneo 2020–22 (Universit` a degli Studi di Catania). J.M.R.-C. acknowledges the postdoctoral financial support received from Juan de la Cierva Spanish Postdoctoral Program (FJC2018-037196-I)

(1) Background: The commercial sustainability of the citrus nursery industry involves cutting costs by using alternative planting substrates to replace (or partially replace) the conventional black peat. Conifer wood biochar was evaluated as a component of the growth medium in a commercial citrus nursery for Carrizo citrange seedlings. (2) Methods: Seven growth media mixtures (A&ndash, G) were tested. Each mixture consisted of 50% sandy volcanic soil with the remaining 50% made up as follows: A = black peat and perlite 1:1, B = biochar 1, C = black peat, perlite, and biochar 0.5:1:0.5, D = black peat and biochar 1:1, E = black peat, compost, and biochar 0.5:0.5:1, F = black peat, perlite, compost, and biochar 0.5:0.5:0.5:0.5, G = black peat and lapillus 1:1, this substrate, previously adopted by the hosting nursery, was the control. (3) Results: The best media for the rootstock studied here were those containing 25% biochar (mixtures D and E). In the deeper layers the substrate was more compact, and the roots were limited to the shallow layers of the pot. (4) Conclusions: Conifer wood biochar can be partly added in place of peat in growth media mixtures, thus reducing costs and ameliorating sustainability.

The effect of basal zone defoliation on vines influences yield and ripening depending on the phenological stage and its intensity. Early basal defoliation (EBD) was carried out at flowering on the autochthonous Vitis vinifera (L.) cultivar ‘Nerello mascalese’ grown on the eastern slopes of Mount Etna, Sicily. The effects were evaluated over a two-year period. In the first year, the canopy retained 67 % of its original leaf area after EBD and in the second year, 58 %. Compared with control vines, mid-day leaf water potentials in the EBD vines enjoyed higher water status throughout the growing seasons in both years. EBD had no significant negative effects on yield but did have significant positive effects on the levels of total polyphenols, total flavonols and total anthocyanins. Yield and its components are conditioned by a number of factors mainly linked to climate and to the vines’ general condition during berry growth and ripening. Even after two consecutive years of treatment, EBD does not have any negative effects on yield. However, EBD does have strong positive effects on berry quality attributes as a consequence of the following: greater exposure of the cluster to sunlight, higher vine water status and avoidance of high temperature stresses in the last phase of ripening during the analysis of anthocyanin.

The selection process has caused modern durum wheat cultivars to achieve higher yields with different protein quality but also to have low micronutrient amounts. In order to evaluate the suitability of germplasm for the recovery of such nutrient content, macro- and microelements concentrations in twelve ancient Sicilian durum wheat landraces and in three modern cultivars were compared. According to the results, the substantial differences in macro- and micro-element concentrations between the two groups of wheat genotypes suggest ancient Sicilian landraces can effectively represent a suitable genetic material for biofortification plans of micronutrients in modern varieties.

To be economically and environmentally sound, the nitrogen (N) supply in orchards needs to be finely tuned according to crop needs. This requires knowledge of the amount and the dynamics of N uptake by roots and of its allocation. This paper reports two experiments, carried out on the same set of trees, in order to: 1) study the uptake dynamics of N derived from fertiliser (N dff ) and its allocation to tree organs and, 2) quantify its N remobilization in spring from storage organs to new growth. The study was carried out using field-grown adult orange trees (cv. Tarocco nucellare grafted on Troyer Citrange), one of the most important fruit tree crops in the Mediterranean area. Nitrogen was supplied as ammonium nitrate in 10 applications with equal doses evenly distributed from March to November 2009. Four groups of 5 trees each received 15 N-enriched N starting from March, July, September, and November, respectively, while they received unlabelled N in the remaining periods. The results show that trees absorbed roughly 30% of the fertiliser N. Fertiliser-N use efficiency (NUE) was generally low in spite of the fact that readily available N sources were regularly supplied and the trees were irrigated; the later the fertiliser N was supplied, the lower was the NUE. Uptake rate was rather constant from April to November, but relatively less N was partitioned to fruits when the fertiliser was supplied later in the season. Remobilization of N from one-year-old leaves provided more than 60% of the N required by shoots in spring. By the end of April, most of the N had already been transferred from storage to growing organs. We estimated that, during the vegetative season, trees absorbed 94 kg N ha −1 from the soil and half of this amount derived from fertiliser. Spring remobilisation of winter stored N contributed for additional 40 kg N ha −1 to the N needs.

Blood oranges have been cultivated in Italy since the early 19th century. Growers and breeders were able to identify and collect many somatic mutants, which differed in their major pomological traits, such as fruit size and firmness, pulp and peel pigmentation, and ripening period. Recently, in the framework of a genetic resource conservation program, most of the accessions collected at CREA in recent decades were planted in a single block to evaluate their characteristics. The presence of many selections in the same block, of the same age and grafted on the same rootstock is extremely important for a reliable characterization of the pomological characters, particularly pigmentation, which is strongly influenced by both the environment and the rootstock. The collection consists of 88 genotypes, including old lines and nucellar selections. Some commercial Tarocco, Moro and Sanguinello varieties were also included in the collection to facilitate comparison among clones. Moreover, the pomological features of 20 elite Tarocco clones cultivated nearby in the same experimental station were used as a further reference. The pomological characterization, based on 13 traits and performed in two consecutive years, revealed significant variability. Some genotypes showed strong year-to-year variability, mainly in fruit pigmentation, probably due to different climatic conditions during winter. Similarly, other traits such as fruit size, total soluble solids and acidity also varied among and within the varietal groups. These findings have a potential utility in identifying promising clones, which might fulfil the growing market needs such as higher anthocyanin content and longer shelf life.

We investigated long-term (18 years) effects of three organic (cow manure (CM), poultry manure (PM), compost from agro-industry orange wastes (OW)) and one inorganic fertilization (IF) on various soil biological indicators (microbial biomass C, soil respiration, total phospholipid fatty acids (PLFAs), total bacteria, Gram-positive and Gram-negative bacteria and fungi) and nutrient contents (total and extractable organic C, total and mineral N, available P and K) along the profile of a Typic Haplustept under orange Mediterranean orchards. All fertilizers were added on the same N content basis (190 kg N ha−1 per year). Variables related to carbon cycling gradually worsened with depth, regardless of treatment, but at any soil depth they improved according to IF < PM < OW < CM. Similarly, mineral nutrient availability decreased with increasing soil depth, according to CM > OW > PM > IF. Organic manures favoured Gram-negative bacteria, especially between 35 and 55 cm depth, whereas Gram-positive bacteria flourished better under inorganic fertilization up to 55 cm. Organic fertilizers increased microbial biomass C, compared with IF, with CM being the most efficient, i.e. inducing the greatest C use efficiency, in turn coupled with a greater amount of fungi compared to bacteria. This is crucial from the environmental viewpoint, since fungi better contribute to soil C storage. PLFAs signatures of microbial communities reflected the differences in resources availability determined by soil depth and fertilizer type; indeed, fungi and Gram-negative bacteria responded more promptly to nutrient contents than other microbial groups. Oligotrophic conditions in deeper soil horizons increased the metabolic quotient, an indicator of stress conditions.

The aim of the present paper was to investigate the agronomical responses of a fertilizer able to release nutrients on the basis of plant-demand, glass-matrix based fertilizer (GMF). Nutrient release was stimulated by mixing the glass-matrix with organic components such as digested vine vinasse (DVV) or meat-meal (MM), added with the aim to increase GMF biological affinity toward roots. Laboratory tests and short-term pots trials showed that the mixture GMF+DVV increased nutrient availability and plant growth. In the following stage these mixtures were tested for their ability to contrast in calcareous soils citrus iron chlorosis, one of major abiotic stresses affecting fruit tree crops in the Mediterranean area. Three year studies were conducted: i) in pots, on ‘Tarocco ScirA¨â€™ orange trees [Citrus sinensis (L.) Osbeck] grafted on Swingle citrumelo and ii) in field, on Tarocco grafted on sour orange rootstock [C. aurantium (L.) Osbeck], by comparing GMF and its mixtures with DVV and MM to a synthetic Fe chelate application. The GMF+DVV mixture was able to supply adequately micronutrients, particularly iron, reducing the chlorosis symptoms, increasing the leaf SPAD index and Fe concentration, and decreasing the "Fe index".

Several citrus orchards develop symptoms of Fe deficiency when cultivated in calcareous and alkaline soils. In a field trial a new type of fertilizer, the glass-matrix based fertilizer (GMF, a by-product from ceramic industries) was applied. GMF is able to release nutrients, particularly Fe, on the basis of plant-demand, being nutrients not soluble in water, but only in acidic or metal complexing solutions. In our experiment, the effectiveness of GMF was tested on “Tarocco” orange trees of twenty years, severely suffering from Fe chlorosis, also by mixing GMF with meat meal (MM) or digested vine vinasse (DVV), thus comparing these treatments to the conventional Fe-chelate fertilization and the Fe-unfertilized control. The GMF + DVV mixture showed to be able to supply adequately micronutrients (particularly Fe) on long term, reducing the chlorosis symptoms, increasing the leaf SPAD index, Fe concentration and decreasing Fe index. No significant effect on yield and fruit quality was noticed. Our results indicated that these innovative formulates, and in particular glass-matrix based fertilizer mixed with digested vine vinasse, could be used as an “environmental friendly” fertilizer, allowing not only to reduce the use of chemicals (such as Fe-chelate), but also to re-use industrial wastes and organic residues which gave an “adding value” to these novel organo-mineral formulates.

Mineral nutrients applied to crops are a cost to growers and could represent a cause of air and water contamination, especially when supply exceeds nutrient needs. Assessing the amount of nutrients that trees need to absorb in order to successfully complete a vegetative and reproductive growth is therefore a fundamental step for developing rational fertilization strategies in orchards. In this paper, the estimation of cumulative yearly nutrient needs and the dynamics of nutrient uptake along the vegetative season in “Tarocco” orange [Citrus sinensis (L.) Osbeck] orchards in Southern Italy were studied. In a first experiment, allometric relationships between branch circumferences and wood or leaf biomass were obtained. These relationships were used to quantify the growth patterns of the above ground organs. Woody organs accounted for the majority of the above ground biomass (AGB). Although the leaves accounted in total for less than 21% of AGB biomass, they included more than 38% N, 31% P, 44% K, 32% Ca and 33% Mg. In a case-study represented by a mature citrus orchard, most AGB annual increase was accounted by the fruits and the shoots. Calcium was the nutrient absorbed with the highest rate, followed by N, K, Mg and P. Most Ca and Mg were recovered in the abscised leaves, while most P and K were recovered in fruits. Nitrogen was distributed more equally among fruits, pruning wood and abscised leaves. Seasonal uptake data indicate that N, P and Ca are absorbed from April to November, while the net uptake of K and Mg is almost complete by the summer. From December to February the amount of nutrients present in the tree canopy either remained stable or decreased, therefore indicating no net nutrient uptake during this period, and, as in the case of N and K, internal nutrient translocation to perennial organs.

To investigate the influence of different types of fertilizers on quality parameters, N-containing compounds, and the δ15N, δ13C, δ2H, δ 34S, and δ18O values of citrus fruit, a study was performed on the orange fruit cv. ‘Valencia late’ (Citrus sinensis L. Osbeck), which was harvested in four plots (three organic and one conventional) located on the same farm. The results demonstrated that different types of organic fertilizers containing the same amount of nitrogen did not effect important changes in orange fruit quality parameters. The levels of total N and N-containing compounds such as synephrine in fruit juice were not statistically different among the different treatments. The δ15N values of orange fruit grown under fertilizer derived from animal origin as well as from vegetable compost were statistically higher than those grown with mineral fertilizer. Therefore, δ15N values can be used as an indicator of citrus fertilization management (organic or conventional), because even when applied organic f...

Two different ‘omics’ approaches were performed to a better comprehension of biological mechanisms involved in citrus iron (Fe) deficiency. Tips roots from Swingle citrumelo and Carrizo citrange (sensitive and tolerant rootstocks, respectively), growing in pots with control and chlorotic soil, were used for transcriptomic and proteomic analysis. CombiMatrix array was performed to isolate differential genes, among which glutathione peroxidase (GPX), SAUR gene and glutamate dehydrogenase (GDH) showed to be the most involved ones. They were switched on Swingle grown on calcareous conditions compared to Carrizo (in the same soil) and to the same stock in the control soil. The over-expression of GPX could be the effort of plants to neutralize the oxidative environment produced by stress. The involvement of auxin (and as consequence of SAUR gene) in the regulation of Fe deficiency responses is also well known. Both genes were considered in association to peroxidase, ferric chelate reductase activities, iron and chlorophyll content, to monitor the degree of suffering of rootstocks. Among differentially expressed proteins, identified by means of 2D-PAGE and RP-HPLC/nESI-MSMS, a strong down-regulation of cytosolic pyrophosphate-dependent phosphofructokinase I²-subunit and NADPH-isocitrate dehydrogenase could produce plant inability to sustain the energetic request of cell roots.

Two citrus rootstocks, one sensitive to iron deficiency [Swingle Citrumelo (SC)] and the other tolerant [Carrizo Citrange, (CC)], were studied to characterize variation in their root protein profile induced by iron-deficient conditions. Plants of both rootstocks were grown in two different soils, one volcanic (v) and the other calcareous (c), containing 0% and 10% active lime, respectively. To evaluate the effects of the calcareous soil on the protein accumulation of both rootstocks, the root protein profiles (SCc vs SCv and CCc vs CCv) were characterized by two-dimensional gel electrophoresis, thus obtaining, for the first time, a reference map of this previously uncharacterized proteome. A total of 219 spots, significantly changed in abundance, were analyzed by high-performance liquid chromatography nano electrospray ionization tandem mass spectrometry. The identified proteins were classified according to their putative function and known biosynthetic pathways. Principal component analysis, comparing the four sets of data, indicated that each group clustered together with low variance and that CCv and CCc data sets were well differentiated, whereas SCv and SCc were similar.

To investigate the influence of different types of fertilizers on quality parameters, N-containing compounds, and the delta(15)N, delta(13)C, delta(2)H, delta (34)S, and delta(18)O values of citrus fruit, a study was performed on the orange fruit cv. 'Valencia late' (Citrus sinensis L. Osbeck), which was harvested in four plots (three organic and one conventional) located on the same farm. The results demonstrated that different types of organic fertilizers containing the same amount of nitrogen did not effect important changes in orange fruit quality parameters. The levels of total N and N-containing compounds such as synephrine in fruit juice were not statistically different among the different treatments. The delta(15)N values of orange fruit grown under fertilizer derived from animal origin as well as from vegetable compost were statistically higher than those grown with mineral fertilizer. Therefore, delta(15)N values can be used as an indicator of citrus fertilization management (organic or conventional), because even when applied organic fertilizers are of different origins, the natural abundance of (15)N in organic citrus fruit remains higher than in conventional ones. These treatments also did not effect differences in the delta(13)C, delta(2)H, delta(34)S, and delta(18)O values of fruit.

A 6-year study was conducted in an organically managed orange orchard located in Sicily (Southern Italy) to assess the effect of compost and organic fertiliser utilisation on soil quality. Adopting a randomised-block experimental design with three replicates, four treatments were carried out. In treatments 1 and 2, two different composts (C1 from distillery by-products and C2 from livestock waste) were applied. The plots of treatment 3 were fertilised using dried poultry manure. The control treatment was fertilised by mineral/synthetic fertilisers. In order to verify the hypothesis that composts and organic fertilisers improve soil fertility, soil quality was evaluated by selecting dynamic soil parameters, as indicators linked to C and N cycles. Total organic C, total N, C/N ratio, humified fraction, isoelectric focussing (IEF) of extracted organic matter, microbial biomass C, potentially mineralisable N under anaerobic conditions, potentially mineralisable C, C mineralisation quotient and metabolic quotient were determined for each sample. Moreover, the Community Level Physiological Profile (by Biolog technique) was defined, calculating derived functional biodiversity and versatility indexes. Parameters related to IEF and potentially mineralisable C showed significant differences among the treatments. Moreover, total C, total N and humification parameters tended to increase, while no differences were observed in biodiversity indexes. On these findings, it was concluded that composts and poultry manure only weakly affected soil properties, though they increased soil potentially available nutritive elements to crops.

In a study realised over a three year period on orange bearing trees (Citrus sinensis (L.) Osbeck) ‘Valencia late’, grafted on sour orange (C. aurantium L.), the effect of organic fertilisers (OF) on plant nutrition and performance was verified. In a randomized block experimental design, four treatments were compared, namely: mineral fertiliser (MF) treatment adopted as control, citrus byproduct compost (CB), poultry manure (PM) and livestock waste compost (LW). The trees, with the exception of (MF) treatment, were organically grown since 1994 in the experimental farm of CRA-ACM in Lentini, Sicily, and received the same N input every year. Significant differences for micronutrients (Fe, Mn, Zn) were noticed in leaf analyses, whereas no difference was found between treatments for leaf macronutrient content. The δ 15 N detected in leaves, proteins of pulp and amino acids of juice showed the lower level in MF, an intermediate value in CB and the highest level in animal derived fertilisers treatments (PM and LW). Fruit of the CB treatment showed values of total soluble solids and total acidity significantly lower than other treatments. Orange peel Chroma C* in CB and MF was higher than in PM and LW treatments. Discriminant analysis of the leaf and fruit analytical data set successfully separated treatments. First discriminant canonical function explains the 96,9% of the variability, with highly significant Wilks’ lambda. Cross validation classified correctly all MF and CB samples, whereas PM and LW in few cases were mixed up.

Iron chlorosis is one of the most serious abiotic stresses affecting citrus (Citrus sp.) culture in the Mediterranean Basin. A trial was performed with potted tolerant and sensitive rootstocks that were grown in volcanic and calcareous soils. Microarray analysis allowed for the identification of differentially expressed genes putatively involved in iron (Fe) deficiency. Most of the differentially expressed genes isolated from the root tips were of unknown function; the remaining genes were related to the oxidative stress response (e.g., glutathione peroxidase), hormone metabolism and signaling (e.g., small auxin up RNA family protein genes), biological regulation, protein turnover, and the tricarboxylic acid cycle (e.g., aconitase). Additionally, the majority of the Fe stress-related genes expressed in the sensitive Swingle citrumelo (Citrus paradisi × Poncirus trifoliata) and tolerant Carrizo citrange (Citrus sinensis × P. trifoliata) rootstocks identified using real-time reverse transcription–polymerase chain reaction (RT-PCR) were related to regulation, the oxidative stress response, and hormone metabolism and signaling, thereby confirming the array data. Furthermore, validation of the differentially expressed genes in seven tolerant and sensitive rootstocks grown in a field trial under chlorotic conditions was performed. In general, the gene expression profiles reflect the different responses of rootstocks, possibly as a result of the various genetic mechanisms involved in the response to Fe deficiency. Moreover, the expression of aconitase was analyzed in the roots and juice to evaluate the implication of the different aconitase isoforms (Aco), which are derived from specific cellular compartments, in the different tissues. The involvement of the mitochondrial isoform (Aco2) was directly correlated with the acidity of the juice, whereas the cytosolic one (Aco3), which corresponds to the aconitase isolated during the microarray analysis, was found specifically in the roots.