Giovanni Avola

Weed control strategies for grain legumes

There has been increasing interest in sustainable weed management in low-input farming systems. In an integrated approach, the development of cropping systems such as appropriate spatial arrangement and efficient tillage will help crops themselves to compete with weeds. With this aim, we investigated the strategic use of plant lodging combined with mechanical weed treatment to improve crop competitiveness and reduce the use of herbicides. We studied weed infestation and grain yield of three grain legumes, field bean, chickpea and field pea, grown according to different plant lodgings (narrow, wide and twin rows) and weed suppression methods: untreated, chemical and mechanical control. In the two years of the trial, two different weed infestation levels were observed due to different meteorological conditions. Our results show that the different crops showed different competitive behaviours, especially in weedy conditions. Indeed, in the bean plots, weed infestation was decreased from 70% in wide rows to 30% in narrow rows. Mechanical treatment produced weed levels similar to those in narrow rows (27%). Mechanical treatment gave grain yields of 2.3 t ha−1, that are comparable with chemically treated plots (2.7 t ha−1). For chickpea, mechanical treatment combined with wide rows proved effective in fighting weeds at a similar level to chemical treatment. Moreover, the yield using mechanical treatment, of 1.6 t ha−1, was only slightly lower than the yield using chemical treatment (2.3 t ha−1). For field peas, mechanical and cropping weed control can limit herbicides, but they are unable to control weed infestation on their own.

Agronomic, chemical and genetic variability of saffron (Crocus sativus L.) of different origin by LC-UV–vis-DAD and AFLP analyses

The identification of a bi-univocal correspondence between geographical origin of saffron (Crocus sativus L.) and the composition of its stigmas has recently been the subject of many research papers, which have focused on the analysis of the differences among the so called “minor components”, such as flavonoids and volatiles, in the secondary metabolic pattern of this spice. Saffron pigments (crocetin esters), on the other hand, constitute the majority of the metabolites found in its stigmas, and their spectrophotometric measurement is still used as an official method to determine the quality of the spice in terms of coloring power. To our knowledge, no attempts have been made to find a correspondence between the geographical origin of different saffron samples and their morphological traits and pigments pattern. In this paper, we have demonstrated that saffron corms of different origins, grown in the same experimental field, produce daughter corms with different dimensions and still produce stigma samples with different pigment profiles. Furthermore, daughter corm dimensions and pigment profile even more so, may be related to the origin of the sample, and therefore pigments can be used as chemotaxonomic markers. Compositional analyses results were corroborated by genetic data obtained using AFLP molecular markers.

Physiological responses of Arundo donax ecotypes to drought: a common garden study

Genetic analyses have suggested that the clonal reproduction of Arundo donax has resulted in low genetic diversity. However, an earlier common garden phenotyping experiment identified specimens of A. donax with contrasting biomass yields (ecotypes 6 and 20). We utilized the same well‐established stands to investigate the photosynthetic and stress physiology of the A. donax ecotypes under irrigated and drought conditions. Ecotype 6 produced the largest yields in both treatments. The A. donax ecotypes exhibited identical high leaf‐level rates of photosynthesis (PN) and stomatal conductance (Gs) in the well‐watered treatment. Soil drying induced reductions in PN and Gs, decreased use of light energy for photochemistry, impaired function of photosystem II and increased heat dissipation similarly in the two ecotypes. Levels of biologically active free‐abscisic acid (ABA) and fixed glycosylated‐ABA increased earlier in response to the onset of water deficit in ecotype 6; however, as drought progressed, the ecotypes showed similar increases in both forms of ABA. This may suggest that because of the low genetic variability in A. donax the genes responding to drought might have been activated similarly in the two ecotypes, resulting in identical physiological responses to water deficit. Despite the lack of physiological ecotypic differences that could be associated with yield, A. donax retained a high degree of PN and biomass gain under water deficit stress conditions. This may enable utilization of A. donax as a fast growing biomass crop in rain‐fed marginal lands in hot drought prone climates.

Industrial orange waste as organic fertilizer in durum wheat

Nowadays agro-industrial waste induces increasing problems due to the high economic cost and heavy environmental impact of disposal. By contrast, its potential re-use as organic fertilizer could represent a sustainable approach to recycling nutrients and reintegrating organic matter into soil. Such recycling should be particularly beneficial in Mediterranean areas because there is a progressive loss of soil fertility. To assess the possible re-use of industrial citrus waste as organic fertilizer, a two-year research project was carried out to study the effects of dried orange waste on the growth and production of durum wheat (Triticum durum Desf.). Two dried orange waste doses of 4 and 8 kg/m2 were compared with conventional mineral fertilization, of 80 kg/ha2 of nitrogen, and with a control without fertilization in the first year. During the second year, the residual effects of the past year’s fertilization and two-year application of the orange waste doses and mineral fertilization on duration of biological cycle, grain yield, leaf area index, above-ground biomass and crop growth rate were studied. Our results show that organic fertilization gave similar wheat yields to the mineral fertilization, averaging at 3.63 t/ha. Organic fertilization promoted crop growth much more than mineral fertilization, by up to +400%. However, at the highest dose repeated organic fertilization induced a severe depressive effect on crop establishment. It indeed gave the lowest values for leaf area index of 0.6, biomass of 222 g/m2 dry weight and crop growth rate of 2.5 g m−2 d−1 at the heading stage, and a 50% decrease in wheat grain yield. In both years, the lowest dose of orange waste produced maximum agronomic efficiency. We conclude that an appropriate use of dried orange waste as fertilizer can partially solve environmental problems related to the citrus fruit processing industry, and represents a low cost organic matter source for Mediterranean soil with poor fertility.

Moderate Drought Stress Induces Increased Foliar Dimethylsulphoniopropionate (DMSP) Concentration and Isoprene Emission in Two Contrasting Ecotypes of Arundo donax

The function of dimethylsulphoniopropionate (DMSP) in plants is unclear. It has been proposed as an antioxidant, osmolyte and overflow for excess energy under stress conditions. The formation of DMSP is part of the methionine (MET) pathway that is involved in plant stress responses. We used a new analytical approach to accurately quantify the changes in DMSP concentration that occurred in two ecotypes of the biomass crop Arundo donax subject to moderate drought stress under field conditions. The ecotypes of A. donax were from a hot semi-arid habitat in Morocco and a warm-humid environment in Central Italy. The Moroccan ecotype showed more pronounced reductions in photosynthesis, stomatal conductance and photochemical electron transport than the Italian ecotype. An increase in isoprene emission occurred in both ecotypes alongside enhanced foliar concentrations of DMSP, indicative of a protective function of these two metabolites in the amelioration of the deleterious effects of excess energy and oxidative stress. This is consistent with the modification of carbon within the methyl-erythritol and MET pathways responsible for increased synthesis of isoprene and DMSP under moderate drought. The results of this study indicate that DMSP is an important adaptive component of the stress response regulated via the MET pathway in A. donax. DMSP is likely a multifunctional molecule playing a number of roles in the response of A. donax to reduced water availability.

Agronomic Characterization of Some Spontaneous Genotypes of Milk Thistle (Silybum marianum L. Gaertn.) in Mediterranean Environment

ABSTRACT Spontaneous populations of Silybum marianum L. of three environments were evaluated for their biological and productive traits. Despite the different environmental conditions of the studied sites (hill and plane), there was a general uniformity in the main observed plant traits. Hilly environments produced a higher number of secondary flower heads compared with the plane site. Seeds in the secondary flower heads had a conspicuously lower weight (−56%) when compared to the primary ones. Plant height and height of the first branch insertion was positively related, directly or indirectly, to the seed yield. A first approach for the definition of an ideotype is proposed.

Agronomic Characterization and α- and β‑ODAP Determination through the Adoption of New Analytical Strategies (HPLC-ELSD and NMR) of Ten Sicilian Accessions of Grass Pea

Ten accessions of grass pea (Lathyrus sativus L.) from different Sicilian sites, cultivated in the same environmental conditions, were analyzed for their morphological and productive parameters and for the content of two non-protein amino acids: α- and β-ODAP (α- and β-N-oxalyl-l-α,β-diaminopropionic acid). The β-isomer is the neurotoxin responsible for the neuron disease known as lathyrism. This analysis was carried out using two common analytical methodologies never applied in their determination, an HPLC separation with evaporative light scattering (ELS) as detector, and nuclear magnetic resonance (NMR). The content of the two isomers falls in the range reported for these compounds: 0.42-0.74 and 2.69-4.59 g/kg for α- and β-ODAP, respectively; and the two methods yield comparable results. High productivity and a high protein content were detected in three Sicilian accessions. Low β-ODAP content was found to be linked to accessions with heavier seeds and those originating at lower altitudes.