Giacomo Tosti

Nitrogen Concentration Estimation in Tomato Leaves by VIS-NIR Non-Destructive Spectroscopy

Nitrogen concentration in plants is normally determined by expensive and time consuming chemical analyses. As an alternative, chlorophyll meter readings and N-NO3 concentration determination in petiole sap were proposed, but these assays are not always satisfactory. Spectral reflectance values of tomato leaves obtained by visible-near infrared spectrophotometry are reported to be a powerful tool for the diagnosis of plant nutritional status. The aim of the study was to evaluate the possibility and the accuracy of the estimation of tomato leaf nitrogen concentration performed through a rapid, portable and non-destructive system, in comparison with chemical standard analyses, chlorophyll meter readings and N-NO3 concentration in petiole sap. Mean reflectance leaf values were compared to each reference chemical value by partial least squares chemometric multivariate methods. The correlation between predicted values from spectral reflectance analysis and the observed chemical values showed in the independent test highly significant correlation coefficient (r = 0.94). The utilization of the proposed system, increasing efficiency, allows better knowledge of nutritional status of tomato plants, with more detailed and sharp information and on wider areas. More detailed information both in space and time is an essential tool to increase and stabilize crop quality levels and to optimize the nutrient use efficiency.

Actual N availability from winter catch crops used for green manuring in maize cultivation.

Field experiments were carried out in Central Italy on several green manure species (pure or mixed) and on succeeding grain maize to find practical relationships for predicting the N effect (N absorbed by maize that derives from the actual gain in soil available N due to green manure). Actually, little information is available for Mediterranean environments, where green manure species and strategies may be other than those of northern-temperate and tropical regions. Relationships were found for maize shooting (Neff = −3.61DW + 29.75N%; R2 = 0.67), flowering (Neff = −1.32DW + 27.47N%; R2 = 0.66) and physiological maturity (Neff = −4.84DW + 50.43N%; R2 = 0.74) (DW = incorporated biomass, N% = N concentration).

Tensile Behavior of Thermoplastic Films from Wheat Flours as Function of Raw Material Baking Properties

AbstractThe production of bioplastics directly from wheat flour has been demonstrated to be reliable, but scarce knowledge is available on how flour characteristics may affect the performance of thermoplastic films. In this work, we first established the most suitable recipe and process for the production of extruded films and then we used eight single-cultivar wheat flours with different baking technological properties to assess how they affect the mechanical properties of thermoplastic films. The results have shown that flours from soft grain cultivars offered more rigid and deformable films than flours from hard grain cultivars. For similar hardness, the alveographic P/L ratio of the dough was inversely related to rigidity and directly related to deformability of plastic films, while the deformation energy of the dough (W) played a role only for great differences of it. The subsequent fabrication of blends between each of the flours that yielded the best film properties and polycaprolactone (PCL) at different proportions indicated that a wheat flour/PCL ratio (TWF/PCL) of 75/25 offered the most suitable films for further application. Our results are likely to be useful for improving the plasticization of flour, in that selection of wheat flours could be tailored on the properties desired for the bioplastic films.

Crop Rotation as a System Approach for Soil Fertility Management in Vegetables

This paper reviews the recent literature on crop rotation as a tool to manage soil fertility specifically for vegetable production. All of the aspects dealing with soil fertility management, i.e. mineral and organic fertilisation, crop residue s management, cover cropping and green manuring, and intercrop ping, are examined in the frame of crop rotations in conventional and organic systems for both specialised and non-specialised vegetable production. A focus is given on conservation tillage practices to manage green manures and vegetable crop residues. The design and modelling of vegetable rotations are described under the viewpoint of increasing the nutrient use efficiency and the self-sufficiency of the system. Some long-term experiments including vegetables are described which evaluate cumulated effects of rotations on soil fertility and vegetable production. It is concluded that only integrating all the available techniques of soil fertility management at a whole rotation scale it is possible to contribute to the productive, economic and environmental sustainability of the system. For example, little supplementation of mineral or fast-release organic fertilisers delivered with rational fertilisation techniques (e.g. starter, split, and localised fertilisation; fertigation) may help compensate the temporal and spatial lack of matching between nitrogen release from slow-release organic sources and crop nitrogen demand. This would help modulate nutrient supply in a more flexible way and improve crop nutrient uptake, so allowing more constant yields across years and limited risks of nutrient loss to the environment.