Efficient tree methods for option pricing

The aim of this dissertation is the study of efficient algorithms based on lattice procedures for dealing with two relevant issues arising in the recent literature on option pricing: the pricing of complex barrier-type options and the pricing of options when the equity model takes into account a stochastic interest rate. This research is developed with a twofold perspective: first, we propose a good solution from a numerical point of view through the introduction of efficient lattice procedures and secondly, we study the theoretical aspects related to the tackled problems (such as the convergence and the rate of convergence of the scheme proposed)

Supplemental LED Lighting Effectively Enhances the Yield and Quality of Greenhouse Truss Tomato Production: Results of a Meta-Analysis

Intensive growing systems used for greenhouse tomato production, together with light interception by cladding materials or other devices, may induce intracanopy mutual shading and create suboptimal environmental conditions for plant growth. There are a large number of published peer-reviewed studies assessing the effects of supplemental light-emitting diode (LED) lighting on improving light distribution in plant canopies, increasing crop yields and producing qualitative traits. However, the research results are often contradictory, as the lighting parameters (e.g., photoperiod, intensity, and quality) and environmental conditions vary among conducted experiments. This research presents a global overview of supplemental LED lighting applications for greenhouse tomato production deepened by a meta-analysis aimed at answering the following research question: does supplemental LED lighting enhance the yield and qualitative traits of greenhouse truss tomato production? The meta-analysis was based on the differences among independent groups by comparing a control value (featuring either background solar light or solar + HPS light) with a treatment value (solar + supplemental LED light or solar + HPS + supplemental LED light, respectively) and included 31 published papers and 100 total observations. The meta-analysis results revealed the statistically significant positive effects (p-value < 0.001) of supplemental LED lighting on enhancing the yield (+40%), soluble solid (+6%) and ascorbic acid (+11%) contents, leaf chlorophyll content (+31%), photosynthetic capacity (+50%), and leaf area (+9%) compared to the control conditions. In contrast, supplemental LED lighting did not show a statistically significant effect on the leaf stomatal conductance (p-value = 0.171). In conclusion, in addition to some partial inconsistencies among the considered studies, the present research enables us to assert that supplemental LED lighting ameliorates the quantitative and qualitative aspects of greenhouse tomato production

Supplemental LED lighting improves fruit growth and yield of tomato grown under the sub-optimal lighting condition of a building integrated rooftop greenhouse (i-RTG)

Unidad de excelencia María de Maeztu CEX2019-000940-MThe metabolism of a building can be connected to a rooftop greenhouse, exchanging energy, water and CO2 flows, therefore reducing emissions and recycling cultivation inputs. However, integrating a rooftop greenhouse onto a building requires the application of stringent safety codes (e.g., fire, seismic codes), to strengthen and secure the structure with safety elements such as thick steel pillars or fireproof covering materials. These elements can shade the vegetation or reduce solar radiation entering the rooftop greenhouse. Nevertheless, application of additional LED light can help to overcome this constraint. The present study evaluated supplemental LED light application in an integrated rooftop greenhouse (i-RTG) at the ICTA-UAB research institute, located in Barcelona (Spain), for tomato cultivation (Solanum lycopersicum cv. Siranzo). The experiment explored the effects of three LED lighting treatments and a control cultivated under natural light only (CK). Applied treatments, added to natural sunlight, were: red and blue (RB), red and blue + far-red (FR) for the whole day, and red and blue + far-red at the end-of-day (EOD), each for 16 h d−1 (8 a.m.-12 a.m.) with an intensity of 170 µmol m−2 s−1. The results indicate that LED light increased the overall yield by 17% compared with CK plants. In particular, CK tomatoes were 9.3% lighter and 7.2% fewer as compared with tomatoes grown under LED treatments. Fruit ripening was also affected, with an increase of 35% red proximal fruit in LED-treated plants. In conclusion, LED light seems to positively affect the development and growth of tomatoes in building integrated agriculture in the Mediterranean area

Winter Greenhouse Tomato Cultivation: Matching Leaf Pruning and Supplementary Lighting for Improved Yield and Precocity

Solar radiation entering a high-wire tomato greenhouse is mostly intercepted by the top of the crop canopy, while the role of lower leaves diminishes with age, turning them into sink organs rather than sources. Accordingly, the defoliation of basal leaves is a widely applied agronomic practice in high-wire greenhouse cultivation management. However, the recent increase in the application of supplemental light emitting diode (LED) lighting for high-density tomato production may affect the role of basal leaves, promoting their source role for fruit development and growth. The present research aims to explore the application of supplementary LED lighting on Solanum lycopersicum cv. Siranzo in the Mediterranean area during the cold season in combination with two regimes of basal defoliation. The defoliation factors consisted of the early removal of the leaves (R) right under the developing truss before the fruit turning stage and a non-removal (NR) during the entire cultivation cycle. The lighting factors consisted of an artificial LED lighting treatment with red and blue diodes for 16 h d−1 (h 8-00) with an intensity of 180 µmol s−1 m−2 (RB) and a control cultivated under natural light only (CK). The results demonstrated a great effect of the supplemental LED light, which increased the total yield (+118%), favoring fruit setting (+46%) and faster ripening (+60%) regardless of defoliation regimes, although the increased energy prices hinder the economic viability of the technology. Concerning fruit quality, defoliation significantly reduced the soluble solid content, while it increased the acidity when combined with natural light

Potential application of pre-harvest LED interlighting to improve tomato quality and storability

Unidad de excelencia María de Maeztu CEX2019-000940-MGrowing conditions and agronomical inputs play a key role in determining fruit qualitative and nutraceutical traits at harvest and post-harvest. The hereby presented research investigated the effects of pre-harvest supplemental LED interlighting on post-harvest quality of hydroponically grown tomatoes (Solanum lycopersicum "Siranzo"). Three LED treatments, applied for 16 h d-1 (h 8.00-00.00), were added to natural sunlight and consisted of Red and Blue (RB), Red and Blue + Far-Red (FR), and Red and Blue + Far-Red at the end-of-day for 30 min (EOD), with an intensity of 180 µmol m-2 s-1 for Red and Blue, plus 44 µmol m-2 s-1 for Far-Red. A control treatment (CK), where plants were grown only with sunlight, was also considered. Fruits at red stage were selected and placed in a storage room at 13 °C in darkness. Fruit quality assessment was performed at harvest time and after one week of storage. RB and FR increased fruit firmness compared to CK, opening possible benefits toward reducing fruit losses during post-harvest handling. RB treated fruits also maintained a higher content of lycopene and β-carotene after the first week of storage. The study demonstrates that supplementary LED interlighting during greenhouse tomato cultivation may enhance storability and help preserve fruit nutritional properties during post-harvest

Winter Greenhouse Tomato Cultivation : Matching Leaf Pruning and Supplementary Lighting for Improved Yield and Precocity

Unidad de excelencia María de Maeztu CEX2019-000940-MSolar radiation entering a high-wire tomato greenhouse is mostly intercepted by the top of the crop canopy, while the role of lower leaves diminishes with age, turning them into sink organs rather than sources. Accordingly, the defoliation of basal leaves is a widely applied agronomic practice in high-wire greenhouse cultivation management. However, the recent increase in the application of supplemental light emitting diode (LED) lighting for high-density tomato production may affect the role of basal leaves, promoting their source role for fruit development and growth. The present research aims to explore the application of supplementary LED lighting on Solanum lycopersicum cv. Siranzo in the Mediterranean area during the cold season in combination with two regimes of basal defoliation. The defoliation factors consisted of the early removal of the leaves (R) right under the developing truss before the fruit turning stage and a non-removal (NR) during the entire cultivation cycle. The lighting factors consisted of an artificial LED lighting treatment with red and blue diodes for 16 h d−1 (h 8-00) with an intensity of 180 µmol s−1 m−2 (RB) and a control cultivated under natural light only (CK). The results demonstrated a great effect of the supplemental LED light, which increased the total yield (+118%), favoring fruit setting (+46%) and faster ripening (+60%) regardless of defoliation regimes, although the increased energy prices hinder the economic viability of the technology. Concerning fruit quality, defoliation significantly reduced the soluble solid content, while it increased the acidity when combined with natural light

Closing the cycle: leverage agroindustrial compost leachate to cultivate sea fennel (Crithmum maritimum L.) in a floating system

[SPA] El objetivo de este estudio fue producir hinojo marino reduciendo la descarga de nutrientes mediante sistemas de cultivo en cascada (SCC). Los SCC consistían en un cultivo primario de rúcula [Diplotaxis tenuifolia (L.) DC] cultivada en dos sustratos de cultivo: compost y turba. El drenaje recogido se utilizó para cultivar hinojo marino (Crithmum maritimum L.) en un sistema flotante con los siguientes tratamientos: T1-100% drenaje de turba; T2-100% drenaje de compost; T3-mezcla de drenaje de turba y SN (50%/50%); T4- mezcla de drenaje de compost y SN (50%/50%); T5-100% SN. La reutilización del drenaje de compost como SN produjo un mayor rendimiento, uso eficiente de agua (WUE) y uso eficiente de nitrógeno (NUE) que la reutilización del drenaje de turba. Se necesita más investigación para optimizar el porcentaje de drenaje reutilizado para maximizar el rendimiento y la calidad del hinojo marino en un sistema flotante. [ENG] The objective of this study was to produce sea fennel reducing the nutrients unload by closing the cascade cropping systems (CCS). The CCS consisted of a primary crop of rocket salad [Diplotaxis tenuifolia (L.) DC] cultivated in two different growing media: agro-industrial compost and peat. The collected drainage was used to cultivate sea fennel (Crithmum maritimum L.) in a floating system with the following treatments: T1 – 100% peat leachate; T2 – 100% compost leachate; T3 - mixture of peat leachate and fresh nutrient solution (NS) (50/50 v/v); T4 - mixture of compost leachate and fresh NS (50/50 v/v); T5- 100%fresh NS. Reusing compost drainage at 100% as a NS produced higher yield, water use efficiency (WUE) and nitrogen use efficiency (NUE) than reusing peat drainage. However, further research is needed to optimize the percentage of reused drainage to maximize yield and quality of sea fennel in a floating system.Esta investigación se enmarca en el proyecto Agricultura urbana innovadora para una producción sostenible (Proyecto PID2020-114410RB-I00) financiado por MCIN /AEI /10.13039 /501100011033. Esta investigación ha recibido financiación externa a través de una ayuda posdoctoral Margarita Salas del Ministerio de Universidades y de la Unión Europea