Adalgisa Belligno

Modification of secondary metabolism and flavonoid biosynthesis under phosphate deficiency in bean roots

ABSTRACT The objective of this study was to evaluate the influence of phosphate deficiency on enzymatic activities and on compounds of the secondary metabolism linked with the production of root exudates in bean (Phaseolus vulgaris L.) plants cv. ‘Bianco di Bagnasco.’ Phosphate deficiency induced a decrease in root total soluble phenolic content, but also caused an increase in total soluble phenolic content of exudates. Alteration of phenolic production was paralleled by increased activity of L-phenylalanine ammonia-lyase (PAL) and decreased activity of chalcone isomerase (CHI) in roots. Two isoflavonoids daidzein and naringenin, have been detected in roots; they are considered signal molecules in the chemical trafficking with soil microorganisms. Naringenin content was reduced by phosphorus (P) deficiency, due to lower activity of CHI, the enzyme responsible for its biosynthesis. On the other hand, daidzein content was higher in –P plants than in the control. The results are discussed, considering the possible roles of phenolics and flavonoids in plant-soil microbe interactions and rizosphere modification.

Influence of NaCl treatment on Ca, K and Na interrelations in maize shoots

The growth, water status and the uptake of the major ions (K+, Ca2+, Na+ and Cl−) were investigated during a 9-day-stress period in seedlings of maize (Zea mays L. cv. Summer Il) grown in a half strength Hoagland’s 2 solution containing 0.24 M NaCl. NaCl induced a reduction in maize growth and significantly reduced the chlorophyll a, chlorophyll b, and total chlorophyll, the leaf water potential (Ψw) and leaf solute potential (Ψπ), but leaf turgor potential (Ψp) remained constant. In treated seedlings relative leakage ratio (RLR) was greater than in the control. At each sampling date the ion contents in the stressed seedlings were substantially higher than in the control, with the exception of Ca2+ after nine days of treatment. At the end of the experiment K+ reached the maximum uptake, accompanied by the lowest level of Na+. At the same date in the stressed seedlings the Ca2+/K+ ratio was more than twice higher than in the control, indicating that the increase of K+ might oppose to the uptake of Na+.

Chemical and Microbiological Aspects of Soil Amended with Citrus Pulp

ABSTRACT Citrus pulp is the pulp and peel waste generated by citrus fruit processing. It can be a pollutant when it is disposed of by burning or dumping, but it is rich in organic carbon (monosaccharides, polysaccharides, pectins, and organic acids), suggesting that it could also be a valuable soil amendment. For the purpose of studying the effects of citrus pulp amendant on soil fertility, a study was carried out using lysimeters where the soil was amended with different quantities of dried citrus pulp. Soil samples were taken periodically over a period of 2 years to evaluate the evolution of the organic matter and the activity of the microbial biomass. The former was evaluated by calculating the TOC and by extracting and characterizing the humified component, while the latter was evaluated through the calculation of the basal respiration, the C microbial content and some enzymatic activities (alkaline phosphatases, β-glucosidase, and arylsulphatase). The introduction of citrus pulp brought about an improvement in soil quality which continued for 20 months after the application of the amendant. In particular, there was an increase in the soil organic matter, despite the notable mineralization process which took place in the short-term due to the citrus fruit industry residues. In the medium term, the chemical-spectroscopic characterization of the organic compounds of the soil highlighted a great similarity to the natural humic substances. The improvement in soil quality was also demonstrated by the activity of the microbial biomass, with a large and long-lasting increase in microbial and respired C and the stimulation of enzymatic activity.

Seawater effects on antioxidant production in berries of three cultivars of tomato (Lycopersicon esculentum mill.)

Tomato is moderately tolerant to salt. However, under stress conditions, antioxidative defense mechanisms in tomato are activated. The effects of diluted seawater on the antioxidant capacity, namely ascorbate, tocopherols and cellular redox status, have been evaluated in three tomato cultivars. Two salad tomato cultivars, Jama and Gimar and a cherry tomato cv. Naomi were used. Our results indicate that the three cultivars had different salt tolerance. Naomi showed the best adaptive response due to its increased antioxidant pool after salinization.

Shelf Life Study of Fresh Celery (Apium graveolens L.) Grown under Different Nitrogen Fertilization Treatments

Nitrogen fertilization is useful for obtaining higher growth and quality of productions, and the use of nitrogen fertilization is widespread. To evaluate the influence of nitrogen-rich fertilizers on quality characteristics of celery, shelf life tests of celery grown with 2 levels of nitrogen and 2 different nitrogen fertilizers were performed. The treatments of the celery samples were identified as follows: T1, mineral nitrogen (80 kg ha(-1)); T2, mineral nitrogen (120 kg ha(-1)); T3, organic nitrogen (80 kg ha(-1)); T4, organic nitrogen (120 kg ha(-1)); R4, residual organic nitrogen (120 kg ha(-1)); and C, untreated control. Celery plants were selected and packaged in either of the following 2 plastic films: antifog polyolefin (AFP) film or microperforated polypropylene (MPP) film. The nitrate contents, weight loss, hardness, changes in color parameters, and total phenols were studied for both packaging types during storage. The results demonstrated that celery fertilized with organic nitrogen and packaged in AFP film reached a shelf life of 37 d. The control sample packaged in MPP film was not marketable after 20 d, but the same untreated sample packaged in AFP film reached a shelf life of 30 d.

Salinity influence on soil microbial population metabolism and enzymatic activities in lysimeter-grown Olea europaea and Nicotiana glauca

Since soil microorganisms are quite sensitive to changes in their habitat, their response in terms of selected metabolic and enzymatic activities was investigated as a possible indicator of the effects of saline irrigation in lysimeter-grown plants of Olea europea and Nicotiana glauca. Water electrical conductivity ranged from 0.8 dS/m in the control to 8.9,17.5, and 26.2 dS/m in treatments with 20%, 40% and 60% diluted seawater, respectively. While some results were non-significant, the following main conclusions could be drawn: Microbial biomass carbon, soluble soil carbon and respiration activity were not significantly correlated to salinity. In addition, the microbial biomass nitrogen was not correlated to salinity. Contrary to this, enzyme activities as shown by hydrolysis rate of fluorescein diacetate (FDA), acid and alkaline phosphatase, and β-glucosidase decreased consistently with salinity without any significant difference between the two plant species. FDA gave the most sensitive and consistent response.

Quality decay and shelf-life study of fresh celery (Apium graveolens L.) grown under different nitrogen fertilization

QUALITY DECAY AND SHELF-LIFE STUDY OF FRESH CELERY (Apium graveolens L.) GROWN UNDER DIFFERENT NITROGEN FERTILIZATION Valeria Rizzo, Giuseppe Muratore, Marco Antonio Russo, Riccardo Iacona, and Adalgisa Belligno Dipartimento Orto-Floro-Arboricoltura e Tecnologie Agroalimentari (DOFATA), Sezione Tecnologie Agroalimentari, Via Santa Sofia, 98 – 95123, Catania, Italy; Dipartimento di Scienze Agronomiche, Agrochimiche e delle Produzioni Animali (DACPA), Sezione Scienze Agrochimiche, Via Santa Sofia, 98 – 95123, Catania, Italy