STUDIES OF QUALITY AND NUTRIENT USE EFFICIENCY IN VEGETABLE CROPS GROWN UNDER DIFFERENT SUSTAINABLE CROPPING SYSTEM

Lo scopo del progetto di dottorato \ue8 stato quello di valutare gli effetti a livello fisiologico, biochimico e molecolare di prodotti biostimolanti su ortaggi da foglia (lattuga e rucola) e di approfondire la conoscenza sulla loro modalit\ue0 di azione. La prima parte del lavoro ha riguardato lo studio degli effetti di estratti acquosi di foglie (LE) e fiori (FE) di Borago officinalis L. su piante di lattuga, attraverso l\u2019utilizzo di tecniche di fenomica, agronomia, fisiologia e biochimica. I risultati ottenuti hanno mostrato come gli estratti di borragine siano in grado di aumentare il metabolismo primario e secondario nelle piante trattate. La concentrazione di flavonoidi totali, fenoli e proteine totali, come anche l\u2019attivit\ue0 in vitro della PAL e dei relativi livelli di proteine hanno mostrato un aumento a seguito dei trattamenti, in particolare dopo l\u2019applicazione dell\u2019estratto a base di fiori di borraggine. L\u2019estratto di fiori si \ue8 dimostrato efficace anche nel prevenire la degradazione dei pigmenti fotosintetici durante la conservazione post raccolta di foglie di lattuga. Si pu\uf2 quindi affermare che gli estratti a base di borragine, in particolare l\u2019estratto a base di fiori, sembrano possedere attivit\ue0 biostimolante su piante di lattuga. Gli stessi estratti sono stati applicati anche su piante di rucola, per verificare l\u2019influenza dei trattamenti sul metabolismo del nitrato e osservare le risposte indotte a livello molecolare. \uc8 stata effettuata l\u2019analisi dell\u2019espressione genica dei principali geni che codificano per gli enzimi coinvolti nel metabolismo del nitrato (nitrato reduttasi DtNR, nitrito reduttasi DtNiR, glutammato sintasi DtGLU, glutammina sintetasi DtGS1, trasportatore del nitrato DtNTR). Il risultato pi\uf9 interessante \ue8 stato, a livello biochimico, la marcata riduzione della concentrazione di nitrato nelle foglie di rucola a seguito dei trattamenti, influenza confermata anche dall\u2019incremento dell\u2019attivit\ue0 della nitrato reduttasi in vivo. I trattamenti hanno influenzato anche l\u2019espressione dei geni studiati, confermando che gli estratti testati hanno un ruolo nei processi fisiologici in cui tali geni sono coinvolti. Sono state anche svolte analisi mirate ad una migliore caratterizzazione gli estratti. \uc8 stata valutata l\u2019attivit\ue0 ormono-simile degli estratti su mutanti di mais e, considerando le numerose propriet\ue0 attribuite alla borragine, \ue8 stata anche testata la possibile attivit\ue0 allelopatica degli estratti sulla germinazione di differenti specie erbacee. L\u2019estratto a base di foglie ha mostrato un moderato effetto auxino-simile. Entrambi gli estratti di borragine sembrano possedere un effetto di inibizione sulla germinazione delle specie testate. \uc8 stata inoltre condotta un\u2019attivit\ue0 in collaborazione con un\u2019azienda multinazionale per valutare l\u2019efficacia di alcuni biostimolanti commerciali e prototipi sulla qualit\ue0 di ortaggi da foglia e sulla protezione contro stress di tipo abiotico (in particolare stress salino).The purpose of the Ph. D. research project was to investigate the effects of biostimulant products on leafy vegetables (lettuce and rocket) and deepen the knowledge on their mode of action. The first part of the work regarded the further deepening of the effects of aqueous extracts obtained from leaves (LE) and flowers (FE) of Borago officinalis L. on lettuce, involving phenomic, agronomic, physiological, and biochemical aspects. Results showed that borage extracts enhanced the primary metabolism. Total flavonoids and phenols, as well as the total protein levels, the in vitro PAL specific activity, and the levels of PAL-like polypeptides increased by all borage extracts, with particular regards to FEs. FEs also proved efficient in preventing degradation and inducing an increase in photosynthetic pigments during storage. In conclusion, borage extracts, with particular regard to the flower ones, appear indeed to exert biostimulant effects on lettuce. The borage extracts were also applied on rocket plants, to investigate the influence of treatments on nitrate assimilation pathway and on the molecular responses. Gene expression analysis of the main enzymes involved in the nitrate metabolism (DtNR, DtNiR, DtGLU, DtGS1, DtNTR) was evaluated. From the biochemical point of view, the most interesting result was surely the substantial reduction of nitrate level caused by both extracts, confirmed also by the increment of the NR in vivo activity. Borage treatments influenced also the gene expression, confirming that extracts have a role in the physiological processes in which the considered genes are involved. In addition, work regarding borage extracts characterization was carried out. The auxin- and gibberellin-like activity of extracts on maize mutants was explored and, due to the multitude properties attributed to borage, the allelopathic effects of borage extracts on seeds germination of different plant species was investigated. LE treatment seems to possess a slight auxin-like activity. The bioassay on allelopathic properties of borage LE and FE demonstrated that they exert an effect on seeds germination (inhibition effect). The work included also an activity carried out in collaboration with a private company to study the effectiveness of commercial biostimulants and prototypes on leafy vegetables quality and protection against abiotic stresses (salt stress)

Antioxidant and Mineral Composition of Three Wild Leafy Species : A Comparison Between Microgreens and Baby Greens

Wild plants may play an important role in human nutrition and health and, among them, many are the leafy species. We hypothesized that the wild greens could be profitably grown as microgreens and baby greens, specialty products whose market is increasing. We compared three wild leafy species (Sanguisorba minor Scop., Sinapis arvensis L., and Taraxacum officinale Weber ex F. H. Wigg.) harvested at the microgreen and baby green stages. Seedlings were grown hydroponically in a half-strength Hoagland nutrient solution under controlled climatic conditions. At harvest, the yield was assessed, and chlorophylls, carotenoids, anthocyanins, phenolic index, nitrate, and mineral elements were measured in the two types of product. The potential contribution to human mineral intake was calculated, and the possible risk due to the presence of metals potentially detrimental for health was estimated. Results showed that micro/baby greens of the studied wild plants achieved competitive yields and could contribute to the dietary intake of macroelements, microelements, and non-nutrient bioactive compounds. On the other hand, the wild greens showed high amounts of nitrate and traces of some metals potentially detrimental for health, suggesting the need for caution in the use of wild species for producing microgreens and baby leaves

The Mixing Ratio and Filling-Amount Affect the Tissue Browning and Antioxidant Properties of Fresh-Cut Baby Leaf Lettuce (Lactuca sativa L.) and Rocket (Eruca sativa Mill.) Grown in Floating Growing Systems

Different types of baby leaf vegetables (BLV) are often mixed and packaged as salad mixes. This work has evaluated the effects of BLV mixing ratios (100% lettuce ‘Lollo Bionda’, 100 LB; 75% lettuce + 25% rocket, 75 LB; 50% lettuce + 50% rocket, 50 LB) and the weight filling amount (125 g filling amount, 125F; 250 g, 250F) on the antioxidant properties and browning potential (BP) of lettuce and rocket baby leaves during storage for 9 days at 4 °C in the dark. The samples were packaged in thermos-sealed bags previously prepared using polypropylene film. The results showed that the 50 LB mix had preserved high amounts of chlorophylls and internal nutrients on d9, regardless of the filling amount. No visible browning symptoms were detected in the 50 LB samples. The 50 LB × 125F mix was found to be the most efficient strategy to maintain the antioxidant property of BLV. Thus, the optimisation of the mixing ratio and its combination with an appropriate filling amount could represent an effective postharvest practice

Variation of Vitamin D in cow’s milk and interaction with β-lactoglobulin

Vitamin D is the collective name for a group of closely related lipids, whose main biological function is to maintain serum calcium and phosphorus concentrations within the normal range by enhancing the efficiency of the small intestine to absorb these minerals from the diet. We used a commercially available ELISA method for the determination of vitamin D in bovine milk. Individual milk samples from two different Italian Friesian herds were analysed. The enzyme immunoassay method used was confirmed as a useful tool to measure the vitamin D in the milk as it greatly reduces the time required to perform the conventional HPLC analysis. An interesting variation was found among individual animals that may be associated with management factors and specific genetic effects. A relationship was highlighted between vitamin D and the genetic polymorphism of β-lactoglobulin, the main bovine whey protein which is involved in the transport of small hydrophobic molecules such as retinol and vitamin D. The relatively high content of vitamin D in most milk samples suggests an opportunity to improve the natural content of vitamin D in milk either by acting on the herd management or selecting individuals genetically predisposed to produce milk with a higher vitamin D content

Evaluation of postharvest storage and treatments in cut ruscus foliage

Danae racemosa (L.) Moench is an important cut foliage in the ornamental market. During postharvest, leaf senescence symptoms are leaf yellowing, weight loss and/or abscission of leaves. The aim of this work was to evaluate the effect of pre-treatments for 24 h with glycerol and Thidiazuron (TDZ) on Danae vase life before and after storage. Treatments were applied in vase water containing glycerol 0.1, 1 or 10 mM, 10 \u3bcM TDZ and a combined treatment of 10 \u3bcM TDZ plus 10 mM glycerol. The effect of treatments was evaluated through the determination of vase life, chlorophyll content, chlorophyll a fluorescence parameters, sucrose and total sugars content. The cut foliage were stored in sealed plastic bags and placed in a dark room at 4\ub0C for two months. The vase life, before and after storage, was determined in a controlled chamber set to 20\ub0C and RH 50-60% with a light intensity of 20 \u3bcmol m-2 s-1. Results demonstrated that 10 \u3bcM TDZ plus 10 mM glycerol was the most effective treatment in maintaining quality during vase life of stored and not stored cut foliage

Effect of Preharvest Abiotic Stresses on the Accumulation of Bioactive Compounds in Horticultural Produce

The quality of horticultural products is the result of the interaction of different factors, including grower\u2019s crop management ability, genotype, and environment. Sub-optimal environmental conditions during plant growth can induce abiotic stresses and reduce the crop performance with yield reduction and quality losses. However, abiotic stresses can induce several physiological, biochemical, and molecular responses in plants, aiming to cope with the stressful conditions. It is well known that these abiotic stresses are also elicitors of the biosynthesis of many metabolites in plants, including a wide range of bioactive compounds, which firstly serve as functional molecules for crop adaptation, but they have also a great interest for their beneficial effects on human health. Nowadays, the consumer is oriented to low-energy foods with low fat content, but at the same time, growing attention is paid to the presence of bioactive molecules, which are recognized as health-related compounds and concur to the nutraceutical value of plant-derived foods. In this context, fruit and vegetables play an important role as sources of bioactive ingredients in the diet. At the cultivation level, the understanding of crop responses to abiotic stresses and how they act in the biosynthesis/accumulation of these bioactive compounds is crucial. In fact, controlled abiotic stresses can be used as tools for improving the nutraceutical value of fruit and vegetables. This review focuses on the quality of vegetables and fruits as affected by preharvest abiotic stressors, with particular attention to the effect on the nutraceutical aspects

Variation of vitamin D in Cow's milk and interaction with β-Lactoglobulin

Vitamin D is the collective name for a group of closely related lipids, whose main biological function is to maintain serum calcium and phosphorus concentrations within the normal range by enhancing the efficiency of the small intestine to absorb these minerals from the diet. We used a commercially available ELISA method for the determination of vitamin D in bovine milk. Individual milk samples from two different Italian Friesian herds were analysed. The enzyme immunoassay method used was confirmed as a useful tool to measure the vitamin D in the milk as it greatly reduces the time required to perform the conventional HPLC analysis. An interesting variation was found among individual animals that may be associated with management factors and specific genetic effects. A relationship was highlighted between vitamin D and the genetic polymorphism of \u3b2-lactoglobulin, the main bovine whey protein which is involved in the transport of small hydrophobic molecules such as retinol and vitamin D. The relatively high content of vitamin D in most milk samples suggests an opportunity to improve the natural content of vitamin D in milk either by acting on the herd management or selecting individuals genetically predisposed to produce milk with a higher vitamin D content

The effect of a complete fertilizer for leafy vegetables production in family and urban gardens

The home vegetables cultivation in family or urban gardens for self -consumption is mainly performed as a hobby but without following the good agricultural practices. Home gardening is often carried out by inexperienced people, which may lead to wrong fertilization. In this work, a fertilizer was evaluated for providing the mineral nutrients required from vegetables and stimulate the nutrient use efficiency in the plant. The commercial product ONE\uae, commercialized by Valagro S.p.A., was tested on two different leafy vegetables, Lactucasativa L. and Cichoriumendivia L. In order to discriminate the nutritional effect from the biostimulant effects, ONE\uae treatments were compared to a control added with the minimum crops requirements and to solutions containing the same concentrations of macro-nutrients as in ONE\uae. Results showed that ONE\uae treatments were able to speed up the growing rate of plants that reached the commercial maturity earlier. The chlorophyll content was higher in ONE\uae treatments, showing a positive effect on the visual appearance of the vegetables. Nitrate content in lettuce was below 500 mg/kg fresh weight, a value much lower than the commercialization law limits. Treatment caused a higher increase of reducing sugars in lettuce respect to endive. In lettuce the sucrose content was higher in outer leaves compared to the inner leaves, while opposite results were found for total sugars. In endive sucrose and total sugar were lower in ONE\uae treatments compared to control. In conclusion, considering yield and quality parameters, ONE\uae was effective in improving the quality of the leafy vegetables tested