Hyperspectral (HS) data represents an extremely powerful means for rapidly detecting crop stress and then aiding in the rational management of natural resources in agriculture. However, large volume of data poses a challenge for data processing and extracting crucial information. Multivariate statistical techniques can play a key role in the analysis of HS data, as they may allow to both eliminate redundant information and identify synthetic indices which maximize differences among levels of stress. In this paper we propose an integrated approach, based on the combined use of Principal Component Analysis (PCA) and Canonical Discriminant Analysis (CDA), to investigate HS plant response and discriminate plant status. The approach was preliminary evaluated on a data set collected on durum wheat plants grown under different nitrogen (N) stress levels. Hyperspectral measurements were performed at anthesis through a high resolution field spectroradiometer, ASD FieldSpec HandHeld, covering the 325-1075 nm region. Reflectance data were first restricted to the interval 510-1000 nm and then divided into five bands of the electromagnetic spectrum [green: 510-580 nm; yellow: 581-630 nm; red: 631-690 nm; rededge: 705-770 nm; near-infrared (NIR): 771-1000 nm]. PCA was applied to each spectral interval. CDA was performed on the extracted components to identify the factors maximizing the differences among plants fertilised with increasing N rates. Within the intervals of green, yellow and red only the first principal component (PC) had an eigenvalue greater than 1 and explained more than 95% of total variance; within the ranges of red-edge and NIR, the first two PCs had an eigenvalue higher than 1. Two canonical variables explained cumulatively more than 81% of total variance and the first was able to discriminate wheat plants differently fertilised, as confirmed also by the significant correlation with aboveground biomass and grain yield parameters. The combined approach proved to be effective, being able to synthesise the redundant radiometric information in a reduced number of indicators of plant nutritional status, which could be utilized to delineate homogeneous within-field areas to be submitted to site-specific fertilization.

Hyperspectral (HS) data of vegetation provide a wealth of detailed information to identify plant nutritional status, but data analysis is fundamental for exploiting their full potential. The discrete waveband approach (Heege, 2013), through computation of narrowbands vegetation indices (VIs), is the most straightforward strategy used to synthetize information from plant spectral signatures. However, saturation effects are known to occur for some VIs over specific LAI values; in addition, bands capturing most of information of crops characteristics may vary across growing cycle modifying VI efficacy. Conversely, full spectrum approach, through multivariate analysis, could synthetize whole plant spectral response. In any case, the statistical function is still depending on growth stage and plant health. In the study of the relationship between HS data and biochemical parameters, ordinary least squares models (OLS) are commonly employed but their use requires important assumptions to be satisfied. However, residuals are often spatially correlated and, when spatial dependence is not taken into account, type I error tends to increase leading to results misinterpretation and improper management decisions. Generalized least squares models (GLS) with correlated errors allow spatial correlation components to be assessed and filtered from the residual term (Rodrigues et al., 2013). The aim of this study was to investigate the efficacy of different approaches for HS data analysis in estimating leaf N in wheat. To reach this aim, models accounting for spatial correlation were used and compared to OLS models.

Emmer (Triticum dicoccum Schu¨ bler) and spelt (Triticum spelta L.) are two ancient cereal crops which have been traditionally grown in the semiarid areas of the Mediterranean basin. The renewed interest in these species has its origin in favorable quality parameters of grain. Unfortunately, there is a lack of information on hulled wheat characteristics when a whole plant is used as forage. Therefore, a field trial was carried out in southern Italy during 2010-2011 to evaluate the effect of N applications (0, 40, and 80 kg ha-1) and harvest period (cut at boots just swollen and cut at early dough) on forage yield and quality of two emmer varieties (‘‘Padre Pio’’ and ‘‘Giovanni Paolo’’) and one of spelt (‘‘Altamura’’) on their biomass yield and nutritional traits as well as carbohydrates fractionation. Data indicated that the harvest stage and genotype affected forage yield and quality significantly, while N fertilization has influenced some qualitative parameters. Old wheat cultivars tested had considerable yield and forage quality, and they seem to be adapted to marginal lands in the absence of N fertilization. Therefore, from our findings we can conclude that the emmer could be recommended for hay production harvested at booting stage given its valuable nutritional characteristics, whereas spelt results to be more adaptable for silage production when harvested at the early dough stage.

White lupin (Lupinus albus L.) is an important source of plant protein for both humans and livestock, due to high protein content, low alkaloids level, high level of unsaturated fatty acids, price and market availability in many countries. In this paper is reported the effect of S fertilization on white N fixation capability of lupin, grain yield and chemical characteristics in terms of protein fractions, fatty acid and mineral composition. Randomized complete block design with three replicates was used, and three S applications (0, 30 and 60 kg ha-1, respectively) for white lupin were used. The S fertilization was split into two: 50 % before sowing and 50 % in the early of March as K2SO4. At the same time, both the legume and oat crops were fertilized uniformly with solution of 10 kg N ha-1 15N NH4 15NO3 (10 % 15N atomic excess). Data indicated that under Mediterranean environment on sub-alkaline soil, white lupin produces low grain and protein; however, S application increased plant yield and N fixation. In conclusion, it seems that S fertilization to white lupin should be recommended to soils with sub-optimal S levels to obtain maximum seed and protein yields. Moreover, S fertilization enhanced the protein quality increasing its degradable fraction, and improved the lupin oil quality through the increase in oleic and linolenic acids and the remarkable decrease in erucic acid.

Table grape vines (Vitis vinifera L.) grown in arid regions require irrigation to achieve optimum fruit yield and quality. Quality is usually considered as a combination of appearance, physical and chemical characteristics at harvest and during storage. Irrigation management, undoubtedly, represents a key strategy to optimize vine performance, in relation to both quantitative and qualitative response. The objective of this research was to evaluate the effects of three different water regimes on berry growth and fruit quality of 'Italia' table grape. To reach this aim, a field trial was carried out on an experimental vineyard located in Apulia region, on 'Italia' table grape (grafted on SO4 rootstock), trained to "tendone" trellis system. Three watering regimes were compared: V1, V2 and V3 (corresponding to 120, 80 and 40% of water lost by evapotranspiration (excluding effective rainfall)). Irrigation was scheduled using the "water balance" method starting after berry set. During the growing season, berry development and ripening kinetics were monitored; stem water potential and stomatal conductance were measured at different phenological stages in order to evaluate crop water status. At commercial harvest, the main quantitative and qualitative yield parameters were determined. Water stress was evident since fruit set, as shown by midday stem water potential and stomatal conductance, and has significantly affected berry growth, ripening kinetic and fruit yield. Compared to V1 treatment, a yield reduction of 12 and 32%, due to both bunch size and berry weight, was observed for V2 and V3 treatments respectively.

An experiment for evaluating the Nitrogen (N) dynamic following green manure has been performed in a 2 ha field sited in south Italy, submitted to semi-arid Mediterranean climate. The trial was carried out in the experimental farm of CRA-SCA, located in Rutigliano (40° 59' 25" N, 17° 1' 52" E, 122 m a.s.l.). The soil was classified as fine, mixed, superactive, thermic Typic Haploxeralfs, according to the Soil Taxonomy, overlying a calcareous bedrock and showing a variable rock fragment content (15% on average). Half-hourly ammonia (NH3) fluxes were measured following the incorporation of fava bean (Vicia faba minor L.), typically cultivated in Mediterranean region few months before the seeding of durum wheat. The NH3 fluxes were monitored by: (i) eddy covariance technique, using a tri-axial ultrasonic anemometer coupled to a QC-TILDAS (Aerodyne, Billerica, USA); (ii) the Aerodynamic Gradient Method (AGM), using the ROSAA analyser; (iii) the inverse dispersion models Windtrax and FIDES, while the concentration was also measured with ALPHA diffusion samplers. Hourly fluxes of nitrous oxide were measured by a static chamber system (SASSFLUX, Ecometrics, IT), employing an infrared gas analyzer. Measurements of gaseous fluxes started just after the incorporation of the green biomass on 22 May 2014 and stopped after 19 days. In order to identify the amount and evolution of the N added to the soil, destructive samples of soil, root and above-ground biomass were collected, following a stratified sampling design. In particular, soil samples were collected before the seeding of the crop, before the green manure and four times thereafter at 0 - 0.2 and 0.2 -0.4 m depths for quantifying the soil water content, mineral N (NO3- and NH4+) and pH. Specifically, NO3- and NH4+ were determined on KCl extracts (2 M), through spectrophotometric quantification. On crop biomass samples, total N (by dry combustion) and NH4+ were measured. Ancillary climatic variables were also measured.

Holm oak is an important evergreen tree species in the Mediterranean environment and plays a crucial role in reforestation and ornamental plant production. However, few data are available on nitrogen nutrition of containerised nursery plants. Two greenhouse experiments were carried out to investigate the effect of i) different fertilizer sources and ii) increasing N levels on N uptake, N use efficiency and N partitioning in Holm oak plants. Seven commercial fertilizers were chosen among traditional, organic, organic-mineral, coated and stabilized categories and were supplied at the rate of 1 g N plant-1 which was found to give optimal results in other species under similar growing conditions. Four increasing N levels were compared: 0, 0.5, 1 and 2 g N plant-1. Experiments were carried out simultaneously and lasted 177 days. Relative recovery and agronomic efficiency significantly decreased from 41.5% to 16.1% and from 22.9 to 8 g g-1, respectively, with the increase in N rate. Optimal N demand was met with a total supply of 1 g plant-1. A lower rate (0.5 g) reduced mainly leaf biomass and leaf area development; a further increase (2 g) gave higher N uptakes (+17%) but not significantly higher biomass. Among fertilizer sources, the best results were achieved with the coated products while the traditional (ammonium sulfate), the organic and the organic-mineral fertilizers were less efficient. Plant growth was more affected by different fertilizer sources compared to N uptake, and this caused a wide variation of physiological efficiency values (from 20.7 to 85.8 g g-1). Biomass partitioning was highly responsive to N availability. N fertilization significantly reduced root/shoot ratio. Moderate N stress conditions influenced more leaf growth than leaf N concentration. Under the same N supply, different release times affected mainly biomass partitioning between stem and root tissues.

Three-year observations about the canopy restraining of 15 olive cultivars trained according to the high-density system were made in order to supply up-to-date information about the varietal behavior foradult orchards of this new cropping system. The mechanical pruning started at the end of the 6th year from planting and it was repeated for the following two years. Cultivar vigour affected pruning biomassand olive yield. Canonical discriminant analysis was performed to identify differences among cultivars. Medium-low vigour cultivars (Spanish and Greek) can be successfully controlled by mechanical and manual prunings without compromising their yield; instead, medium-high vigour cultivars (traditional and new Italian) require mechanical prunings to control canopy size, but this operation can hardly compromise their yield level and constancy. Further investigations are required to understand the right width ofhedging to reach the correct equilibrium between vegetative and reproductive activity in adult orchards. At the moment, the correct varietal choice remains the only way to ensure the agronomical and economic sustainability of the high-density cropping systems, waiting for new results from breeding programs.

Faba bean (Vicia faba L.) is an important source of plant protein for humans and animals; however, nutritional value of seeds is notoriously deficient in sulphur (S)-containing amino acids. In this article, the effect of S fertilization on faba bean's capability of N2 fixation, grain yield and chemical characteristics in terms of protein fractions, fatty acids and minerals composition is reported. A randomized, complete block design with three replicates was used, and three S applications (0, 30 and 60 kg ha−1, respectively) for faba bean were performed. The S fertilization was split into two applications: 50% before sowing and 50% in the beginning of March as K2SO4. At the same time, both the legume and oat crops were fertilized uniformly with 10 kg N ha−1 as 15N NH415NO3 (10% 15N atomic excess) in solution form. In a Mediterranean climate under optimal spring rainfall situations, faba bean produced high yield of grain and protein. Sulphur application resulted in an increase in overall plant yield and N2 fixation. In addition, S fertilization enhanced the protein quality, increasing its degradable fraction. Fertilizing faba bean with 30 kg ha−1 of S resulted in a more appropriate dose in order to obtain a quantitative and qualitative crop improvement. From our findings, it can be concluded that S fertilization to faba bean should be recommended to soils with suboptimal S levels to obtain maximum seed and protein yields. Quality, yield and nitrogen fixation of faba bean seeds as affected by sulphur fertilization (PDF Download Available). Available from: https://www.researchgate.net/publication/232282045_Quality_yield_and_nitrogen_fixation_of_faba_bean_seeds_as_affected_by_sulphur_fertilization [accessed Jan 21, 2016].

La non lavorazione dei terreni (NT) è considerata una pratica agricola utile al fine di preservare il carbonio organico (C) nel suolo, tuttavia c’è ancora una grande incertezza sulle misure agronomiche più idonee a ridurre le perdite di anidride carbonica (CO2) dai suoli agricoli. In questo studio, misure sia di emissioni di CO2 in campo che di attività di mineralizzazione microbica sono state connesse alle proprietà chimiche e fisiche del suolo in un sistema colturale a grano duro soggetto a clima semi-arido in cui la NT, praticata da soli 4 anni, è stata confrontata con la lavorazione convenzionale (CT). I risultati non hanno evidenziato differenze significative tra CT e NT, confermando tempi simili nel turnover del C organico nei due trattamenti, probabilmente dovuti al fatto che il sistema NT era giovane (4 anni) e le misure sono avvenute lontano dalla lavorazione del terreno. Parole chiave: Sequestro del C, agricoltura conservativa, emissioni di CO2, respirazione basale eterotrofa, mineralizzazione del C.

Alfalfa is a highly productive and fertility-building forage crop; itsperformance, can be highly variable as influenced by within-field soilspatial variability. Characterising the relations between soil and for-age-variation is important for optimal management. The aim of thiswork was to model the relationship between soil electrical resistivity(ER) and plant productivity in an alfalfa (Medicago sativaL.) field inSouthern Italy. ER mapping was accomplished by a multi-depth auto-matic resistivity profiler. Plant productivity was assessed through nor-malised difference vegetation index (NDVI) at 2 dates. A non-linearrelationship between NDVI and deep soil ER was modelled within theframework of generalised additive models. The best model explained70% of the total variability. Soil profiles at six locations selected alonga gradient of ER showed differences related to texture (ranging fromclay to sandy-clay loam), gravel content (0 to 55%) and to the presenceof a petrocalcic horizon. Our results prove that multi-depth ER can beused to localise permanent soil features that drive plant productivity.

The potential effect of climate change on the optimal allocation of irrigation water was investigated for a Southern Italy district. The study was carried out on 5 representative crops (grapevine, olive, sugar beet, processing tomato, asparagus), considering six simulated climate change conditions, corresponding to three 30-year periods (2011-2040; 2041-2070; 2071-2100) for two greenhouse gas emission schemes proposed by IPCC (A2 and B1), plus the current climatic condition. The framework adopted was based on: i) the modeling of crop yield response for increasing levels of water supply, under current and future climatic conditions, through a non-linear regression equation and ii) the definition of the best water allocation by means of a mathematical optimization model written in the General Algebraic Modeling System (GAMS). Total irrigation water (TIW) volume was allowed to vary from a low total supply 10,000 m3 to 7,000,000 m3, whilst a fixed surface, corresponding to that currently occupied in the studied district, was assigned to each crop. The economic return was studied in terms of Value of Production less the fixed and variable irrigation costs (VPlic). The TIW volume that maximized the VPlic of the whole district surface under the current climatic condition was 5,697,861 m3. The total volume was partitioned among the five crops as a function of the surface occupied: grapevine>olive>processing tomato>asparagus>sugar beet. Nevertheless, grapevine and olive received seasonal volumes corresponding only to 59% and 50% of total irrigation water requirements. On the contrary, processing tomato and asparagus received seasonal water volumes close to those fully satisfying irrigation water requirements (100% and 85% ETc). Future climatic conditions slightly differed from the current one for the expected optimal allocation. Under water shortage conditions (160,000 m3) the whole irrigation water was allocated to the horticultural crops. Forecasted growing season features varied to a different extent in relation to crop and scenario considered with the more intense changes observed for A2 and olive.