Sara Lazzereschi’s scientific contributions

Massa D., Prisa D., Lazzereschi S., Cacini S., Burchi G. (2018): Heterogeneous response of two bedding plants to peat substitution by two green composts. Hort. Sci. (Prague), 45: 164-172. The promotion, at local level, of resource recycling chains, with low environmental impact and costs, appears of great interest for the production of green composts to replace peat in ornamental crops. In this work, two green composts, diff ering for the criterion of raw material selection for composting, were tested for the cultivation of two bedding plants in comparison with 100% peat based substrate. Leaf chlorophyll (SPAD index), biometric and growth parameters, and tissue mineral composition were measured to assess growing media-plant system performances. Both growing media and plants gave heterogeneous responses depending on substrate characteristics and plant requirements and/or tolerance to abiotic stress. Plant biomass was reduced by 63% (on average) in the most sensitive species due to the high Cl concentration detected in one of the two green composts; a similar trend was observed for SPAD index. Th e results support the shared idea that the selection of raw material is a strategy of primary importance in the composting process to obtain high quality green compost.

Peat is the most representative component in the preparation of growing media used in horticulture. However, environmental issues and increased production costs, related to peat extraction and commercialization, are stimulating the use of new materials and technologies as alternatives to peat-based growing media. Among other locally-produced materials, green compost is one of the most promising alternatives for peat substitution although its variability in terms of physico-chemical characteristics represents the main constraint. In the present work, two composts, differing in terms of the initial composting raw materials, were evaluated for peat substitution and their influence on plant growth and quality, nutrient and water uptake, and gaseous exchange activity. A bedding plant (geranium), cultivated in an intensive growing system, was chosen as the test plant and 100% peat as the control. During the greenhouse experiment, plants were grown in five different growing media, i.e. only peat, 30% and 50% peat volume replaced by the two composts. Growing medium characteristics, plant growth and biometric parameters, water and nutrient uptake, and gaseous exchange activity were evaluated as crop performance indicators. The green compost derived from mixed raw material negatively influenced plant nutrition and photosynthesis, thus significantly reducing plant biomass accumulation and quality. The green compost derived from selected material was found to be a valuable growing medium for peat substitution. This thus supports the widespread opinion that high-quality compost can be produced through the selection of composting material.