Giancarlo Roccuzzo

Nutritional response of Zea mays L. seedlings to “on plant demand” fertilizer: A vector analysis approach

ABSTRACT Glass matrix based fertilizers (GMF) are new mineral fertilizers, able to release nutrients on the basis of plant demand: they are soluble only in metal complexing solutions, such as those exuded by plant roots. Moreover, nutrient release could be increased by mixing the glass-matrix fertilizer to different organic biomasses, such as leather meal, digested vine vinasse, etc. A greenhouse pot experiment was conducted for assessing the effect of an organo-mineral fertilizer, obtained by mixing GMF with increasing percentages of digested vine vinasse [DVV, at 5% (GMF95), 20% (GMF80) and 50% (GMF50) w/w], on the root and shoot biomass and nutritional status of Zea mays L. seedlings. Among tested fertilizers, the formulations GMF80 and GMF50 gave the best results as shoot/root ratio. The treatments with GMF, GMF95 and GMF80 gave rise to a significant increase of both shoot and root biomass and a tendency to increase the macro and micronutrients availability.

Non-destructive Proximal Sensing for Early Detection of Citrus Nutrient and Water Stress

This chapter reports the application of non-destructive optical-based technologies for the rapid and efficient assessment of the nutritional status and water stress detection improving their use efficiency. In the proximal sensing section, it was presented the use of spectral and hyperspectral imaging to evaluate the plant nutritional status. Proximal sensing offers the opportunity to rapidly collect a huge amount of crop canopy information. In the infrared thermography and thermometry section, results about their use to assess plant water stress analysing canopy and soil temperature variation were reported. Finally, the use of spectrophotometry and of the chlorophyll meter for the citrus nutrient detection is presented. The analyses of data were carried out by linear regressions and by multivariate statistics.

Organic Citrus: Soil Fertility and Plant Nutrition Management

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 scientific literature. Moreover, two case studies carried out in Southern Italy and aimed at comparing conventional 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.

DEFICIT IRRIGATION STRATEGIES: PRELIMINARY ASSESSMENT ON A SICILIAN YOUNG ORANGE ORCHARD

In Mediterranean regions the economical sustainability of fruit tree crops strictly depends on the limited availability of water resources. Deficit irrigation (DI) strategies are particularly suitable to optimize water resource, improve water use efficiency by reducing crop water requirements. In the study, DI strategies were adopted on a young orange orchard in Sicily (Southern Italy) and crop physiological features were monitored and analysed for possible negative effects. The orchard includes 300, 4-years old, trees, irrigated with drip and sub-drip irrigation systems. Four irrigation strategies (replicated 3 times), based on DI concepts, were adopted, each supplying different percentages (50, 75, 100%) of the irrigation requirement (IR). IR values were calculated via the Penman-Monteith model, by assuming a crop coefficient (Kc) of 0.45 typical for immature orchard, and correction coefficients accounting for the localized irrigation. Several physiological indices were measured during the trial, including Leaf Area Index, stem water potential, canopy temperature, and trunk diameter, among others. Preliminary observations, obtained during the two irrigation periods (2011-2012), evidenced slight variations of xylematic potential and stomata conductance among the monitored treatments. LAI, canopy volume and trunk circumference increases were quite similar among treatments. Accordingly, trees growth seems to sustain the imposed water restrictions, without significant stress symptoms on the analyzed physiological features.