Maurizio Mulas

Improving storability of 'Tarocco' oranges by postharvest hot-dip fungicide treatments

Abstract The effectiveness of postharvest water dip, with or without thiabendazole (TBZ) or Kilol DF-100 (DF) fungicide treatments, at 52 °C on the keeping quality of ‘Tarocco’ oranges during two months storage at 8 °C and subsequent one week of simulated shelf-life at 20 °C was investigated in comparison to water dip with or without TBZ and DF at 25 °C. Considerable control of chilling injury and decay occurred both during storage and simulated shelf-life with 52 °C water dipping. TBZ fungicide was also effective in disease and disorders control, its efficacy being greatly enhanced when used in hot solution. Beneficial effects were also produced by DF applied alone or in combination with TBZ, but to a lesser extent at 25 °C. Respiration rate and ethanol amount in the juice were significantly affected by dip temperature and by treatments, while endogenous ethylene did not. Mean values of electrolyte leakage of flavedo peel discs from fruit dipped at 52 °C during storage were significantly lower than those dipped at 25 °C. After simulated shelf-life, values tended to level out. No detrimental effects on quality characteristics of fruits occurred as a consequence of prestorage dip treatment in water alone at 52 °C or with fungicide solutions.

Essential Oil Composition of Myrtle (Myrtus communis) Leaves

Nine cultivars of myrtle (Myrtus communis) were analyzed for their leaf essential oil yield and composition during two seasons. The oil yield composition on leaf dry weight basis varied with the year of collection and the season ranging from 0.6 to 10.7 g·kg−1 in the different cultivars. The oils were analyzed by GC–MS for compound identification and by GC for quantitative determinations by comparison with authentic standards. The main components of the essential oils were α-pinene (366.8 to 816.8 g·kg−1); limonene (42.8 to 468.8 g·kg−1), 1,8-cineole (32.0 to 230.6 g·kg−1), linalool (0.8 to 110.3 g·kg−1), geranyl-acetate (12.4 to 99.2 g·kg−1). Other minor components were α-terpineol (1.6 to 44.4 g·kg−1), terpinolene isomer 1 (0.0 to 42.6 g·kg−1), linalyl-acetate (0.0 to 36.3 g·kg−1), α-humulene (0.0 to 19.6 g·kg−1), terpinolene-isomer 2 (0.0 to 14.9 g·kg−1), p-cymene (0.0 to 13.0 g·kg−1) and geraniol (0.0 to 12.4 g·kg−1). The total content of the other minor components was less than 10 g·kg−1. All cultivars were suitable for hydro-alcoholic infusion production and, in spite of the minor oil yield, the leaves harvested in winter showed an essential oil composition quite similar to those from spring.

Myrtle (Myrtus communis L.) as a New Aromatic Crop: Cultivar Selection

SUMMARY Myrtus communis L. (Myrtaceae) is a typical shrub of the Mediterranean maquis which grows spontaneously in Sardinia. It is used in the drug, perfume and food industries. Intensive myrtle cultivation systems should be developed, in order to assure both a constant supply of good quality material for the liqueur industry and the preservation of natural myrtle populations. Cultivar selection is essential for the successful cultivation of this new aromatic crop and has been the main goal of our research. The main morphological and phenological characters of 16 cultivars selected for fruit and biomass production are presented here.

Lignin and gum deposition in wounded ‘Oroval’ clementines as affected by chilling and peel water content

Abstract Induction of lignin synthesis and gum deposition by wounding in the albedo and flavedo of ‘Oroval’ clementines exposed to low temperature has been studied. Wounded and non-wounded fruit were kept for 24 h at 20 °C (initial separate experiment), six and 18 days at 2.5 °C (cold storage), and 18 days at 2.5 °C plus two additional days at 20 °C (shelf-life). At 2.5 °C, fruit were kept under two different conditions: saturated humidity or at 85–90% relative humidity (RH). During the separate initial control and shelf-life periods RH was 60%. The greatest weight loss (WL) was found in wounded fruit stored at 85–90% RH. Chilling injury (CI) was enhanced by wounding in all treatments. The most severe water loss occurred in flavedo of wounded fruit kept at 85–90% RH but, not surprisingly, at saturated humidity, no difference was found. Albedo water content was lower than that of flavedo and decreased again after shelf-life. Cell wall residue (CWR) progressively increased during cold storage in both albedo and flavedo of wounded fruit kept at 85–90% RH. Lignin-thioglycolic compounds increased in flavedo and albedo of wounded fruit kept at 20 °C during the 24-h period of the separate initial control. Under cold storage, however, these compounds did not increase together with CI development and fruit senescence. Wounding, CI and senescence considerably increased the deposition of ethanol-extractable phloroglucinol/HCl- (pg/HCl) positive compounds in flavedo, indicating (specific test) that wound gum deposition was more likely related than lignin biosynthesis to healing process and to pitting development under chilling conditions.

Effect of water stress on growth, water use efficiency and gas exchange as related to osmotic adjustment of two halophytes Atriplex spp.

Atriplex halimus L. is known in the Mediterranean basin and along the coastal areas of Sardinia for its adaptability to salinity, although less information is available on the resistance of this species to water stress in absence of salinity. The effect of water stress on growth and water utilisation was investigated in two Atriplex species: A. halimus originating of south Sardinian island and the exotic species Atriplex nummularia Lindl., originating in Australia and widely used in land restoration of arid areas. Water stress was applied to young plants growing in 20L pots with a sufficient water reserve to store a potentially sufficient water reserve to maintain substrate near to field capacity (30%) between irrigations. Watering was at 70% (control) or 40% (stress) of field capacity. In order to simulate the grazing by livestock, four plant biomass cuttings were conducted at times T0, T1, T2 and T3, corresponding to one cutting at the end of well watered phase (T0) before water stress induction, two cuttings after cycles of 5 weeks each during full summer (T1) and late summer (T2) and one cutting during autumn (T3). All plants remained alive until the end of treatment although growth was strongly reduced. Leaf dry weight (DW) and water use efficiency (WUE) were determined for all cuttings; relative water content (RWC), turgid weight:dry weight ratio (TW:DW), water potential (Ψw), osmotic potential (Ψs), CO2 assimilation, osmotic adjustment (OA), abscisic acid (ABA) and sugar accumulation were determined for the late summer cutting at T2. Water stress induced a decrease in DW, RWC, Ψw, Ψs, TW:DW and CO2 assimilation for both species, but an increase in WUE expressed in terms of dry matter production and a high accumulation of ABA and total sugars mainly for A. halimus. This suggests a more developed adaptive mechanism in this selection. Indeed, the clone was selected from the southern part of the island, where natural populations of saltbush are more exposed to abiotic stresses, mainly the water stress generated not by salinity. A. nummularia showed a greater OA and a positive net solute accumulation as than A. halimus, suggesting that water stress resistance in A. halimus is linked to a higher WUE rather than a greater osmotic adjustment.

Effect of maturation and cold storage on the organic acid composition of myrtle fruits

BACKGROUND The effect of maturation and senescence on the chemical composition of two myrtle cultivars was studied in mature, overripe and cold-stored fruits in order to find the most appropriate harvesting period and best storage technology for industrial purposes. RESULTS After cold storage at 10 °C for 15 days, berry weight loss ranged from 12.5 to 18.4%, with the highest losses in less mature fruits. Titratable acidity decreased during maturation and cold storage in both cultivars. Reducing and total sugars increased during maturation. Anthocyanin concentration increased during maturation but decreased in overripe berries. The major organic acids in myrtle fruits were quinic, malic and gluconic acids. In fresh and cold-stored fruits, malic acid rose to 3 g kg(-1) and decreased thereafter. Quinic acid peaked at 90 or 120 days after bloom and decreased thereafter to reach low concentrations in mature fruits. CONCLUSION Cold storage for 15 days at 10 °C does not affect myrtle fruit quality for liqueur production. Anthocyanin concentration is the best indicator of harvest time for industrial purposes. Gluconic acid concentration is high in mature, overripe and cold-stored berries. This parameter can be used as a marker of the onset of fruit senescence.

Selection of Rosemary (Rosmarinus officinalis L.) Cultivars to Optimize Biomass Yield

SUMMARY Rosmarinus officinalis L. (Labiatae) is a typical shrub of the Mediterranean maquis. In spite of its multiple ornamental and aromatic uses, and the great interest in its cultivation, only a few cultivars or clones have been well characterized. Our breeding program has focused on optimizing biomass yield and improving the quality of cultivated rosemary. In a preliminary phase (1996–1997), 31 mother plants were identified and described in situ throughout Sardinia; spring-shoot samples were then evaluated in laboratory. In a second phase (1996–2000), cuttings of selected clones were planted in a repository at the Experimental Station of the University of Sassari, in central-western Sardinia. In this paper, morphological, biometric, qualitative and phenological characters of fifteen rosemary selections of the repository are reported. Selections tended to produce flowers, fruit and new shoots in various periods of the year. Selections showed a high variability for spring-shoot length, leaf length and width, essential oil content of leaves, and percentage of leaf weight in relation to total shoot fresh weight. Clones with higher leaf/wood ratio and higher essential oil content were considered more suitable for the optimization of biomass yield.

Water potential in soil and Atriplex nummularia (phytoremediator halophyte) under drought and salt stresses

ABSTRACT Atriplex nummularia is a halophyte widely employed to recover saline soils and was used as a model to evaluate the water potentials in the soil-plant system under drought and salt stresses. Potted plants grown under 70 and 37% of field capacity irrigated with solutions of NaCl and of a mixture of NaCl, KCl, MgCl2 and CaCl2 reproducing six electrical conductivity (EC): 0, 5, 10, 20, 30, and 40 dS m−1. After 100 days, total water (Ψw, plant) and osmotic (Ψo, plant) potentials at predawn and midday and Ψo, soil, matric potential (Ψm, soil) and Ψw, soil were determined. The type of ion in the irrigation water did not influence the soil potential, but was altered by EC. The soil Ψo component was the largest contributor to Ψw, soil. Atriplex is surviving ECs close to 40 dS m−1 due to the decrease in the Ψw. The plants reached a Ψw of approximately −8 MPa. The water potentials determined for different moisture levels, EC levels and salt types showed huge importance for the management of this species in semiarid regions and can be used to recover salt affected soils.

Microsprinkler irrigation influences clementine fruit quality, leaf temperature and physiology

Abstract The effect on leaf physiology and fruit quality, of two irrigation schedules, daily and twice a week irrigation (control), were tested on ‘SRA 63’ Clementine (Citrus reticulata Blanco) during 2002 and 2003. Micrometeorological data revealed a higher impact of everyday irrigation on air and leaf temperature compared with the control. While in 2002 daily irrigation treatment reduced air temperature up to 3.4°C with respect to the control, in 2003 the cooling effect was greater, with reductions of air temperature up to 9°C as compared with the control. In 2002, gas-exchange related parameters were influenced little by daily undertree microsprinkler irrigation, on the contrary, in 2003 net photosynthetic rates were significantly increased by daily irrigation with respect to the control.

Evaluation of Spontaneous Oleander (Nerium oleander L.) as a Medicinal Plant

SUMMARY Nerium oleander L. (Apocynaceae) is a spontaneous plant widely diffused throughout the Mediterranean region. In Sardinia, it grows mainly near water flows, preferring humid and sunny environments. Oleander is used mainly as an ornamental. Since ancient times, both the toxicity and the medicinal properties of this species were well known. In fact, all plant parts are toxic if ingested and they can cause death by heart paralysis. This paper consists of a review on the medicinal characteristics of Nerium oleander and on its possible applications. In addition, a survey conducted on oleander types growing in Sardinia, aiming at evaluating their aptitude for medicinal uses, is discussed.