Efficiency of Methodologies Used in the Evaluation of the Weed Seed Bank under Mediterranean Conditions

The objective of this study was to compare the efficiency of two methodologies, seed germination (SG) and seed physical extraction SPE), to assess the weed community from two locations with different soil and climatic conditions: M, with dry and low soil fertility, and S with high soil humidity and fertility. Over three years of study, the analysis of both methodologies confirmed differences in seed bank composition. In M, fewer seeds were recorded by SG than SPE (13.5% and 86.5% respectively), while in S, the difference between percentages was less (31.58% by SG and 68.41% by SPE). Our findings confirmed that Portulaca oleracea L., Amaranthus blitoides S. Watson and Chenopodium album L. were abundantly found in M. Anacyclus clavatus (Def.) Res. seeds were also found, mainly detected by SG. In S, Stellaria media (L.) Vill. was widely found. All species found in S were similarly detected by SG and SPE. The results confirmed that climatic and soil conditions influenced the efficiency of the methodology used to assess the seed bank. M conditions led to an increased seed reservoir, and both methodologies were necessary to obtain the seed bank composition. In S conditions, the seed bank was continuously renewed, and either one of methodologies defined the seed bank composition equally well.

Genotype and Seasonal Variation Affect Yield and Oil Quality of Safflower (Carthamus tinctorius L.) under Mediterranean Conditions

The adoption of climate-resilient and resource-use efficient crop species and varieties is a key adaptation action for farmers in the face of climate change. Safflower, an emerging oilseed crop, has been recognized for its high oil quality and its favorable agronomic traits such as drought and cold tolerance, making it particularly suitable to Mediterranean conditions. A 2-year field study was carried out to evaluate the effects of the genotype and growing season on the crop phenology, seed and oil production, macronutrient accumulation and partitioning, and fatty acid composition of spring-sown safflower grown under rainfed conditions. The experiment was conducted during the 2012 and 2013 growing seasons on an alluvial deep loam soil (Typic Xerofluvent) at the Centre for Agri-environmental Research “E. Avanzi” of the University of Pisa (Pisa, Central Italy). Higher seed yield and yield components (plant density, plant height, branching, number of capitula per plant and seeds per capitulum) were found in almost all genotypes when the seeds were sown in mid-March 2012 compared to in late April 2013. More favorable conditions in 2012, i.e., early sowing date, higher precipitation, and quite mild temperatures, led to a better seed and oil yield and greater aboveground biomass and nitrogen uptake, with the highest amounts being removed by straw. Greater seed yield was found to be associated with a greater plant height and a higher number of capitula per plant. Oil content was negatively affected by the higher temperatures and the lower amounts of precipitation that occurred during the 2012 growing season. Seasonal variation in fatty acid composition depended on the genotype. Lower precipitation and higher temperatures during 2013 favored oleic acid content in high linoleic acid genotypes and linoleic acid in medium to high oleic acid genotypes. Among the genotypes, the linoleic-type Sabina and the oleic-type Montola 2000 performed the best in both seasons. The results, besides identifying promising safflower genotypes for spring sowing in the Mediterranean region and for future breeding programs, pointed out the importance of early sowing to contrast unfavorable environmental conditions during seed-filling, thus ensuring higher yields.

FERTILISATION SOURCE AND DOSE OPTIMISATION BOOST YIELD OF DURUM WHEAT IN MEDITERRANEAN CLIMATIC CONDITIONS

Climate change, global warming, environmental pollution, greenhouse gas emissions from agricultural fields, stagnant wheat yields and reduced farm economic returns require optimisation of sources and doses of plant nutrients. A field study was conducted to evaluate wheat response to different forms of fertilisers and nitrogen (N) doses under Mediterranean conditions. The field trial was comprised of fertiliser sources, including chemical fertilisers, compost and leonardite, while different nitrogen levels (0, 80, 160, 240 kg ha-1) were also tested. The experimental variables included yield attributes (height of the, length of the spike, spikelets number per spike, thousand-grain weight and grain yield). In addition, nutritional quality attributes like protein and starch contents were studied along with NDVI values of wheat under different fertilisation regimes. The trial was executed using a randomised complete block (factorial) design using four replications. The results revealed that fertiliser forms and N doses remained ineffective for boosting yield attributes of wheat. For nutritional characteristics of wheat grains, a higher N dose remained instrumental in boosting protein, starch and wet gluten contents. Thus, 240 kg ha-1 of N dose might be recommended for general adoption under Mediterranean conditions; however, study findings are limited in scope and further in-depth studies are needed by testing organic manures from plant and animal origins.

Use of X-ray Mutagenesis to Increase Genetic Diversity of Zantedeschia aethiopica for Early Flowering, Improved Tolerance to Bacterial Soft Rot, and Higher Yield

The development of new cultivars is important for the profitability of the floriculture industry. There is a limited number of cultivars of Zantedeschia aethiopica, an iconic ornamental cut flower, garden plant, and potted plant, because of the incompatibility of interspecific crossings within the genus. Most present-day varieties are the result of spontaneous mutations or classical breeding within the species, followed by a long selection process. Here, Z. aethiopica mutants were generated by treating seeds with 100 Gy of X-ray radiation. The resulting putative mutants were selected based on particular flowering parameters and compared to nonirradiated, control plants. Over two growing seasons, characteristics such as early flowering, flower size and shape, yield, and response to soft-rot disease were monitored, and considerable variation was observed among the mutated lines. Out of 319 mutants, 20 lines were selected based on their phenotypes and then propagated and further analyzed. Within this group, only two phenotypes displayed at least five improved flowering properties under natural Mediterranean conditions. The rest displayed two to four desired combinations of flowering traits, some with great commercial potential.

Phytoextraction of Cr(VI)-Contaminated Soil by Phyllostachys pubescens: A Case Study

This work presents the results of experimental tests to evaluate the effects of prolonged contamination by Cr on Moso Bamboo (MB) (Phyllostachys pubescens) and the adaptability of the MB to the Mediterranean climate. A preliminary test on the MB was developed in the laboratory, simulating irrigation under Mediterranean conditions (600 mm per year) and tropical conditions (1800 mm per year), to evaluate the rate of growth and the MB’s capability for Cr phytoextraction from contaminated soil. The tolerance of MB to Cr was also performed showing a good response of the plant to 100 mg Cr/L solution, utilized for irrigation of the pots. The results show that the rate of MB’s removal of Cr from soil ranged from 49.2% to 61.7% as a function of the soil degree of contamination, which varied from approx. 100 mg/kg to 300 mg/kg. The distribution of Cr in the various sections of the bamboo revealed that the greater percentage was present in rhizomes: 42%, equal to 114 mg Cr for 600 mm per year, and 50%, equal to 412 mg Cr for 1800 mm per year. A noteworthy diffusion of the metal towards the outermost parts of the plant was shown. The values of Cr retained in the stems and leaves of MB tissues were quite high and varied from 1100 mg/kg to 1700 mg/kg dry weight.

Long-Term Assessment of Reference Baselines for the Determination of the Crop Water Stress Index in Maize under Mediterranean Conditions

Canopy temperature has been proposed as a relevant variable for crop water stress monitoring. Since crop temperature is highly influenced by the prevailing climatic conditions, it is usually normalized with indices such as the crop water stress index (CWSI). The index requires the use of two baselines that relate canopy temperature under maximum stress and non-water stress conditions with vapor pressure deficit (VPD). These reference baselines are specific to each crop and climatic region. In maize, they have been extensively studied for certain climatic regions but very little is known on their suitability to be used under Mediterranean-type conditions nor their temporal stability, both diurnally and between seasons. Thus, the objective of this work was to determine the reference baselines for maize grown under Mediterranean conditions, as well as its diurnal and long-term stability. An experiment was conducted for 3 years in a maize breeding field, under well-watered and water-stressed irrigation treatments. The determined reference baselines for computing CWSI in maize have shown to be stable in the long term but markedly influenced by the meteorological variations between 10–17 h UTC (Coordinated Universal Time). These results indicate that several reference baselines should be used for CWSI computing throughout the abovementioned time interval. The CWSI values calculated for well-watered and water-stressed maize breeding plots using the reference baselines derived in this study were successfully correlated with other physiological indicators of plant water stress.