Author(s):
Gomes, Teresa 
; Pereira, J.A. ; Ramalhosa, Elsa ; Casal, Susana ; Baptista, Paula
Date: 2013
Persistent ID: http://hdl.handle.net/10198/8719
Origin: Biblioteca Digital do IPB
Subject(s): Lactuca sativa; Leaf-macronutrient content; Chlorophyll a and b; Carotenoids
Description
The coffee industry has experienced a constant growth and, as a consequence, large amounts of residues are generated worldwide. One of the main coffee residues are spent coffee grounds (SCG), which are the solid residues obtained after preparation of the coffee beverages. References to its use as organic fertilizer in domestic cultures, especially in gardens, are common. However, scientific evidence of its effectiveness or even safety remains largely unknown.
The main objective of this work was to assess the effect of SCG, both composted and uncomposted, on Lactuca sativa L. growth and mineral composition under greenhouse conditions. It is also expected to find the optimum dose of SCG that would give maximum lettuce growth. With this purpose, lettuce plants cv. “Four seasons” were grown on topsoil (control) or in topsoil mixed with different concentrations of fresh (2.5; 5; 10; 15; 20%, v/v) or composted (5; 10; 15; 20; 30%, v/v) SCG. After 39 days of transplantation, the plants were collected and used to evaluate several growth parameters, as well as photosynthetic pigments and mineral contents on leaves.
The application of both fresh and composted SCG, as well as their concentrations, had significant influence on all the parameters measured. Fresh SCG stimulated the plant growth at low concentrations (2.5-5%) but without significant differences when compared to control. A similar effect was observed for composted SCG, but only when applied at high concentrations (≥10%). By contrast, the foliar-N, -P and K- contents were, in general, reduced by fresh and composted SCG. When comparing to fresh SCG, the composted SCG resulted, in average, in higher carotenoids content, foliar-N and -K contents, and plant growth. Both treatments could be used to recycle coffee grounds with demonstrated horticultural benefits.
