F. Intrigliolo’s research while affiliated with Council for Agricultural Research and Agricultural Economy Analysis and other places

Within the Project MO.NA.CO was evaluated the Environmental effectiveness of GAEC cross-compliance standard 2.2 “Maintaining the level of soil organic matter through crop rotation” and economic evaluation of the competitiveness gap for farmers who support or not the cross-compliance regime. The monitoring was performed in nine experimental farms of the Council for Agricultural Research and Economics (CREA) distributed throughout Italy and with different soil and climatic conditions. Were also evaluated the soil organic matter and some yield parameters, in a cereal monocropping (treatment counterfactual) and a two-year rotation cereal-legume or forage (treatment factual). The two-years application of the standard “crop rotations” has produced contrasting results with regards to the storage of soil organic matter through crop rotation and these were not sufficient to demonstrate a statistically significant effect of treatment in any of the farms considered in monitoring, only in those farms subjected to more years of monitoring was recorded only a slight effect of the standard as a trend. The variations of organic matter in soils in response to changes in the culture technique or in the management of the soil may have long lag times and two years of time are not sufficient to demonstrate the dynamics of SOM associated with the treatment, also in consideration of the large inter annual variability recorded in different monitored sites.

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 -subunit and NADPH-isocitrate dehydrogenase could produce plant inability to sustain the energetic request of cell roots.

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.

During the last decade, the organic food and farming (OFF) sector has grown considerably worldwide. Citrus play an important role in organic farming systems, being one of the most highly demanded products on the market for organic produce. In this chapter, the criteria for citrus orchards fertility management and plant nutrition in the organically managed agroecosystems are discussed in the light of the most relevant scienti fi c literature. Moreover, two case studies carried out in Southern Italy and aimed at comparing onventional and organic orange management in terms of yield, yield quality and long-term impact on soil fertility are reported. The body of knowledge available and the results presented demonstrate that organic citrus management is a technically feasible option for citrus growers. In addition, the shift to organic farming could contribute to enhance the environmental sustainability of citrus productions in the long term.

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 δ15N 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.

During three consecutive years, in a citrus orchard planted with Tarocco ‘Meli’ and ‘Scirè’ on sour orange (C. aurantium L.) were verified the differences of the plant water status and the possibility to build an empirical model to estimate the Ψpd utilizing stem water potential (Ψmd) and vapor pressure deficit (VPDmd) measured at midday. The first results showed statistical differences during the irrigation season in the two clones water potential. These difference permitted to separate the data of Tarocco ‘Meli’ and ‘Scirè’. As a result, two empirical models were built. The 2nd degree equation (Ψpd=a+b1Ψmd+b2VPDmd) was obtained by considering the Ψpd as dependent variable, the Ψmd and the VPDmd as explanatory variables. ANOVA applied to the multiple regression resulted highly significant with P-value <0.000, indicating highly predictive capacity of the equation. The multiple coefficients of correlation were R=0.783 for Tarocco ‘Meli’ and R=0.825 for Tarocco ‘Scirè’. The two models were tested with the method of the cross-validation, a technique for estimating the performance of a predictive model. The observed data showed no statistical differences when compared to the fitted data. The results were discussed in a relation to the application of the empirical model which estimates the Ψpd that seems to be the best indicator of tree water status, without measuring it before dawn.