Individuazione di substrati e di fertilizzanti nella produzione di piantine da trapianto da destinare alla coltivazione in biologico
Author(s)
Possanzini, Gabriella
Date Issued
May 8, 2006
Type
Doctoral Thesis
Abstract
The vegetable transplant industry in Italy relies entirely on soilless media, predominantly peat moss and vermiculite as a substrate for plant production. Coconut pith or coir is a waste product of the coconut industry and has been promoted or considered as a substitute for natural peat in growth media due to its suitable physical and chemical properties. Coir has been tested as an horticultural medium for several ornamental crops while little work has been done with coir as a medium component in vegetable transplant production, especially lettuce.
Moreover in Italy, citrus processing industry transforms, every year, 1,000,000 tons of citrus fruits, with a production of 600,000 tons of pastazzo, a mixture of pulp and peel, which is the main residue of citrus squeezing treatment. Citrus waste management represents an environmental and economic problem, which can be overcome through compost production and its utilization as soilless substrates, in substitution of peat.
The aim of this study was to set up organic substrates and the optimal rate of fertilization with guano based organic fertilizer for the nursery production of transplant seedlings.
Four greenhouse trials were conducted at the experimental farm of Tuscia University (Italy) using media prepared from peat and coir (v/v), the last trial was carried out with a substratum prepared by mixing peat and coir (v/v) and a compost from citrus processing industry.
In the first trial styro-foam transplant trays were sown in three type of medias (100% pith, 100%coir or a blend composed by 50% pith + 50% coir (v/v), combined with three levels of guano based organic fertilization (2.5, 5, 7.5 g/l) with Malidor‘ lettuce (Lactuca sativa L.) seeds. In the second year the trial was conducted using mixtures containing different percentages of coir and peat with the aim of individuate the optimal composition of the blend. The third trial was conducted using some organic fertilizers (Supernat 93 and Azomin) as cover fertilizers. In the fourth trial the mixture resulted the optimal, 50% peat and 50% coir (v/v), was used in combination with different percentages of the compost deriving from the residues of citrus processing industry. Plant growth measurements of the 3-week-old lettuce plants were recorded including fresh and dry weight yield, leaf area, shoot:root ratio and chlorophyll concentration.
The results showed that the rate of 2.5 g/l was the optimal for the guano based organic fertilization, the optimal percentage composition of the media containing around 50% coir and 50% peat. Compost gave the better results mixing 25% compost and 75% of the blend (50% peat + 50% coir).
These results showed that it is possible to use a media containing 50% coir and 50% peat as an alternative medium to peat in organic transplant production, with guano based organic fertlization (2.5 g/l), moreover it is possible to use a media obtained mixing this mixture (75%) and 25% of compost from citrus industry.
Additional information
Dottorato di ricerca in Ortoflorofrutticoltura
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