Sergio Miele

Responses in chemical traits and biomass allocation of Arundo donax L. to deficit resources in the establishment year

A large expansion in renewable energy production is underway with an increasing focus on sustainable second-generation biofuels. Fast growing rhizomatous perennial grasses are leading candidates for lignocellulosic feedstock thanks to their positive energy balance, and low ecological/agro-management demands. Biomass accumulation is favored by the efficient use of available resources. The aim of this study was to identify which accumulation processes were most affected in the establishment year of a giant reed (Arundo donax L.) field crop grown under water and N deficiencies. The relative plasticity of growth of A. donax in response to various levels of resource availability was evaluated. A field scale experiment was carried out, and treatments were arranged as a randomized complete block, strip-plot design with irrigation treatments as the main plot factor and pre-planting N rate as the sub-plot factor. Biometric relationships between variables were assessed to understand how agro-management factors influence the above ground biomass of giant reed, as well as yield over time. Evidence is presented indicating that growth is strongly enhanced by water availability (+97% dry weight biomass). Changes in composition were not significant within or among fixed treatments, rather changes were observed over time. A high content of glucans and xylans were detected from early stage, and as the mobilization of minerals increased, lignin content significantly increased as well (from 12% to 36% w/w). These results suggest that an increase in the growth of A. donax in the establishment year is accomplished by a limited use of the water input

Effects of Application of Municipal Solid Waste Compost on Horticultural Species Yield

Composting as a means of waste recycling in order to produce organic fertilizer has long been practised by farmers. Agronomic interest in compost is due to its elevated nutrient and organic matter content. However compost could have an adverse impact on account of its salinity or the presence of pathogens or toxic metals. Numerous studies on this last aspect have shown that heavy metal content in compost treated plant does not differ significantly from the control (Massantini et al., 1988; Stilwell, 1993). The agronomic trials carried out on compost have shown conflicting results for marked variability in composition, type of species grown and pedoclimatic characteristics of the trial area (Del Zan, 1989; Edwards et al., 1993; Paris et al., 1986). The purpose of the present research was to study the direct and residual agronomic effects of compost from treated municipal solid waste on horticultural species.

Growth and physiological response of Arundo donax L. to controlled drought stress and recovery

Abstract Soil water deficit constrains crop growth more than any other abiotic stress, both per se and in combination with other factors, making drought resistance a key element for the successful exploitation of marginal areas. Arundo donax (Poaceae), is a mesophyte that can adapt to a wide variety of ecological conditions, although its growth can be retarded by a shortage of water. The objective of the present research is to draw a comprehensive picture of the integrated response mechanisms of A. donax to controlled drought conditions, and characterize its ability to recover upon rewatering in terms of photochemical efficiency. Plants were subjected to a gradually applied drought stress for a period of three weeks, after which they were returned to fully hydrated soil conditions for one week. Overall, plant dry weight and key growth parameters were not significantly affected. However, detrimental effects were visible in the form of impaired leaf gas exchange, which influences the performance of photosynthesis, and pre-dawn leaf water potential (pdΨW), −92.1% of net CO2 assimilation rate and −0.36 MPa, respectively at the cessation of stress. Nonetheless, a rapid restoration of A. donax physiological functions was observed upon rewatering, testifying to the environmental plasticity of this species.