Gestione delle infestanti del colza (<i>Brassica napus</i> var. <i>oleifera</i>) in ambiente mediterraneo: risultati preliminari

La coltura del colza è caratterizzata da un lento accrescimento nelle prime fasi di sviluppo, fasi in cui la rapida crescita delle infestanti risulta potenzialmente limitante. Una efficace competizione della coltura verso le infestanti si verifica solo dopo che la copertura vegetale ricopre completamente le interfile. Inoltre, le infestanti dotate di ramificazioni e di apparato radicale vigoroso esercitano una severa competizione per gli elementi nutritivi disponibili (Bishnoi et al., 2007). In Brassica sp.pl., Bishnoi et al. (2007) hanno riportato perdite comprese tra il 30 e il 50%, a seconda dell’accrescimento e della persistenza delle infestanti nel campo. Le difficoltà nella gestione delle infestanti del colza, oltre che derivare dalla possibile inadeguata preparazione del letto di semina e da un eventuale insufficiente grado di umidità del suolo, risiede nelle ridotte dimensioni dei semi e nel loro breve tempo di germinazione, che rendono la coltura molto sensibile alle avversità ambientali nelle sue fasi iniziali (Paudel et al., 2008). In mancanza di validi prodotti ad ampio spettro dicotiledonicida applicabili nella post-emergenza della coltura, il diserbo del colza si basa prevalentemente sull’impiego del metazachlor, che può essere applicato anche nei primi stadi di sviluppo. Rimane quasi insoluto il problema del controllo delle crucifere quali Sinapis, Rapistrum, Raphanus, e Brassica, specie tardive generalmente presenti in autunno e durante gli inverni miti. Obiettivo dello studio è stato quello di valutare l’effetto di diversi trattamenti di controllo delle infestanti, basati sull’impiego di metazachlor, sulla resa e sue componenti in colza var. Kabel

LCA study of oleaginous bioenergy chains in a Mediterranean environment

This paper reports outcomes of life cycle assessments (LCAs) of three different oleaginous bioenergy chains (oilseed rape, Ethiopian mustard and cardoon) under Southern Europe conditions. Accurate data on field practices previously collected during a three-year study at two sites were used. The vegetable oil produced by oleaginous seeds was used for power generation in medium-speed diesel engines while the crop residues were used in steam power plants. For each bioenergy chain, the environmental impact related to cultivation, transportation of agricultural products and industrial conversion for power generation was evaluated by calculating cumulative energy demand, acidification potential and global warming potential. For all three bioenergy chains, the results of the LCA study show a considerable saving of primary energy (from 70 to 86 GJ·ha−1) and greenhouse gas emissions (from 4.1 to 5.2 t CO2·ha−1) in comparison to power generation from fossil fuels, although the acidification potential of these bioenergy chains may be twice that of conventional power generation. In addition, the study highlights that land use changes due to the cultivation of the abovementioned crops reduce soil organic content and therefore worsen and increase greenhouse gas emissions for all three bioenergy chains. The study also demonstrates that the exploitation of crop residues for energy production greatly contributes to managing environmental impact of the three bioenergy chains

Integration of oil-seed crops in Mediterranean agro-pastoral systems to supply bio-fuels to local power industry

The growing of rape seed (Brassica napus var. oleifera D.C.) and Ethiopian mustard (Brassica carinata A. Braun) as oilseed crop for biodiesel production in southern Europe has gained new interest, following the implementation of policies aimed at increasing the production of locally produced biofuels. The study reported in this paper is part of a feasibility study designed to provide a scientific assessment on the introduction of oil seed crops in the context of the Mediterranean agro-pastoral systems of central Sardinia. Locally, the oil seed demand is from a 34 MW electric power station recently installed by Biopower Sardegna Spa, who funded the study, to supply the local industrial site. The overall objective of the experiments is also to build a dataset to adapt CROPGRO model of DSSAT (Jones et al., 2003) to rapeseed. In this paper, we will provide preliminary data from the field experiments on rapeseed and an overview of the research design

Adaptation of the CROPGRO model to simulate growth and yield of rapeseed (<i>Brassica napus</i> L. var. <i>oleifera</i> DC)

In Mediterranean area where its cycle lasts nearly seven months, the growth of winter oilseed rape Brassica napus L.is subjected to climatic hazards that may exert an important influence on yield, notwithstanding damage by pets. In the context of the European Common Agricoltural Policy, which promoted in Europe the growing of rape as bio-fuel crop, it seemed relevant to study the effects of soil and climate variability on both the final yield and the environmental impacts of this crop. As a consequence of their dynamic nature, these effecs may only be studied by means of a model simulating the relevant crop processes as related to managment and weather conditions. Here we tried to adapt the CROPGRO Soybean module to rapreseed by modifying species and cultivar file parameters. The resulting model, is discribed and tested against experimental data in this thesis. All parameters mentioned have been calibrated on a data set from a one-year experiment conducted on the experimental farm of the University of Sassari (Northwestern Sardinia) and on a private farm, located in the Central Sardinia. In both sites, cv Kabel was studied. Weather data were recorded with automatic weather stations, while phenological stages were weekly monitored. In the order to analyze the crop growth, destructive measurements were carried out every four weeks. Specific crop parameters including specific leaf area, the leaf stem partitioning parameter, and photothermal time requirements fro crop development were generated from field sampling. The modified soybean version of CROPGRO performs realistically but should be tested under different latidude

Biomass supply for energetic purposes from some <i>Cardueae</i> species grown in Mediterranean farming systems

In order to explore complementary biomass sources, field studies were conducted on Cynara cardunculus botanical varieties (globe artichoke and cultivated cardoon) for energy purposes. In addition, the potential of milk thistle (Silybum marianum L. Gaertn.) as a suitable energy crop for Southern Europe countries was investigated. The three different crops were compared over three years (2007–2010) in a Mediterranean environment (Sardinia, Southern Italy) for quantitative and qualitative (calorific value, ultimate and proximate analyses, ash composition) biomass characteristics. Annual biomass production across years averaged about 10, 4, and 16 Mg ha−1 in cardoon, globe artichoke and milk thistle, respectively. The chemical analysis of biomass showed a similar composition among crops with a mean ash content of 14% and a higher calorific value of about 17 MJ kg−1. Annual energy yield ranged between 64 GJ ha−1 reached by globe artichoke and 275 GJ ha−1 reached in milk thistle. The exploitation of globe artichoke crop residues for energetic purpose can represent a complementary income for farmers. The present study confirms the good biomass yield of cardoon in cultivation systems characterized by limited water input and indicate milk thistle as a promising crop for biomass production. Future work is necessary in order to investigate different genotypes of the three crops for potential biomass and grain yield and their chemical composition, to detect agronomic practices suitable to optimize qualitative crops performances and to set up specific cropping systems.</br

Predicting growth and yield of winter rapeseed in a Mediterranean environment: model adaptation at a field scale

The DSSAT Cropping System Model (CSM-CROPGRO) was used to adapt a new model for rapeseed (Brassica napus L. var. oleifera D.C.) and to evaluate it at a field scale under Mediterranean conditions. Model coefficients used to describe growth and development of soybean [Glycine max (L.) Merr.] were chosen as initial reference values. Information on rapeseed from the literature was then used to replace the parameters of the model. Phenology, growth, and partitioning were evaluated using experimental data from two locations of Sardinia (Italy) that were collected in 2007 and 2008. The simulated crop cycle (flowering, first pod, first seed and maturity date), leaf area index (LAI), specific leaf area (SLA), aboveground biomass and pod mass production, yield components, and grain yield and composition (oil and nitrogen content) of rapeseed were compared with specific observations for the early maturity cultivar Kabel, chosen among the most promising under Mediterranean conditions. Base temperatures for processes of this species are typically between 0 and 5 °C for photosynthetic, vegetative, and reproductive processes while corresponding optimum temperatures vary from 21 to 25 °C. Crop cycle was simulated with a RMSE of 0.8 days (d-index = 0.96). Mean predicted aboveground biomass at final harvest was 3825 kg ha−1, with a RMSE of 1582 kg ha−1 (d-index = 0.92). The model estimated SLA with a RMSE of 42.3 cm2 g−1 (d-index = 0.78). Predicted grain yield of rapeseed was 2791 kg ha−1 and was in agreement with the observed data. The results obtained from this model adaptation for rapeseed revealed satisfactory predictions of phenology, growth, and yield of rapeseed and hence suggested that the CSM-CROPGRO model can be used for simulation of rapeseed production in Mediterranean environments although further evaluation for water and nitrogen limiting environments is needed

Effect of input management on yield and energy balance of cardoon crop systems in Mediterranean environment

Sustainable cardoon (Cynara cardunculus L. var. altilis DC.) production system need to be developed to become a large-scale dedicated energy crop. Two field experiments were carried out in Italy to investigate the effects of management intensities and crop age on yield (biomass and seed), thermochemical traits, and energy efficiency of cardoon crops. The first experiment (Exp. 1) was based on the comparison of two crop management intensities (conventional chemical inputs and tillage, CT; reduced chemical inputs and tillage, LI), and it lasted five years. The second experiment (Exp. 2) lasted three years and evaluated two crop densities (standard density, SD; high density, HD). In Exp. 1, CT system performed better than LI for all analyzed agronomic traits. The average net energy yield of CT (157.7 GJ ha−1) was significantly higher compared with LI (103.1 GJ ha−1). The different crop densities in Exp. 2 did not influence seed yield and plant survival in the first and third year. Higher energy surpluses were found for HD than SD, due to the relatively high energy output. Our results also indicate that in less favorable soils at the Exp. 1, conventional management ensures better crop growth and energy budget, whereas in deep soils (Exp. 2), promising results could be obtained combining no N input with adjusted crop density

Solar radiation distribution inside a greenhouse with south-oriented photovoltaic roofs and effects on crop productivity

This study assessed the climate conditions inside a greenhouse in which 50% of the roof area was replaced with photovoltaic (PV) modules, describing the solar radiation distribution and the variability of temperature and humidity. The effects of shading from the PV array on crop productivity were described on tomato, also integrating the natural radiation with supplementary lighting powered by PV energy. Experiments were performed inside an east–west oriented greenhouse (total area of 960 m2), where the south-oriented roofs were completely covered with multi-crystalline silicon PV modules, with a total rated power of 68 kWp. The PV system reduced the availability of solar radiation inside the greenhouse by 64%, compared to the situation without PV system (2684 MJ m−2 on yearly basis). The solar radiation distribution followed a north–south gradient, with more solar energy on the sidewalls and decreasing towards the center of the span, except in winter, where it was similar in all plant rows. The reduction under the plastic and PV covers was respectively 46% and 82% on yearly basis. Only a 18% reduction was observed on the plant rows farthest from the PV cover of the span. The supplementary lighting, powered without exceeding the energy produced by the PV array, was not enough to affect the crop production, whose revenue was lower than the cost for heating and lighting. The distribution of the solar radiation observed is useful for choosing the most suitable crops and for designing PV greenhouses with the attitude for both energy and crop production

Effects of the photovoltaic roofs on the greenhouse microclimate

The installation of photovoltaic (PV) arrays on the greenhouse roof allows the farms to increase their competitiveness, by producing income from both crops and renewable electricity generation. This led to the spread of PV greenhouses in Southern Europe, often aiming at maximise the income deriving from energy production. In this study we investigated the solar radiation and temperature inside an east-west oriented greenhouse with 50% PV coverage, located in Sardinia, Italy (39°19’59”N, 8°59’19”E). The south-oriented roof was completely covered with multi- crystalline silicon PV panels, amounting to 68 kWp rated power. A high-light demanding crop (cherry tomato, Solanum lycopersicon L. ‘Shiren’) was chosen for comparing the environmental data with the achieved yield. The PV array decreased the yearly sunlight availability inside the greenhouse by 64%, compared to the situation without PV panels, while the temperature was averagely 2.8°C higher than outside. The temperature remained uniform over the greenhouse area, while the solar radiation was distributed following a north-south gradient, characterised by higher values on the sidewalls, and decreasing towards the centre of the span. The solar radiation under the conventional plastic roof was 305% higher than under the PV roof, causing a high variability of total production between the plant rows, which ranged from 1.9 kg m-2 in some rows under the PV cover, where plants showed a negative photosynthetic rate (up to -3.72 mmol CO2 m-2 s-1), to 5.1 kg m-2. The results suggested new design criteria for PV greenhouses, concerning the decrease of the PV array coverage and different installation patterns of the PV panels on the roof. Furthermore, the crop management in terms of irrigation should be adjusted for every plant row, according to the observed yield variability and the actual incident solar radiation. These measures can contribute to increase the agronomic sustainability of PV greenhouses