Effectiveness of aqueous vegetal extracts in nutrition management of pear trees

In this study, two experiments were performed in order to test the hypothesis that vegetal extracts obtained from wild plants may improve and/or stimulate growth as well as nutritional status of pear trees. A 2-year experiment was performed on 1-year-old micropropagated pear trees (Pyrus communis ‘Abbé Fétel’) grown in 33-L pots on a sandy-loamy soil. Plant vegetal extracts were obtained by harvesting, drying and grinding the canopy of wild: a) Amaranthus retroflexus, b) Urtica dioica and c) Equisetum arvense. Each extract was tested at 2 concentrations (15 and 30 g L-1) both soil and foliar applied. Plants received weekly 10 and 6 applications throughout the season in the first and second year, respectively. The rate of a single application was 200 ml plant-1 and until run off for soil and foliar application, respectively. In addition, a 2-year field experiment was carried out in a mature pear orchard of ‘Abbé Fétel’ grafted on quince ‘Sydo’ where the following treatments were compared: a) Amaranthus retroflexus; b) Urtica dioica; c) fresh ground leaves of Melia azedarach; d) fresh ground fruits of Melia azedarach. The vegetal extracts were applied 5 times per year at a rate of 18 g plant-1 treatment-1 by fertigation, whereas the meliacee ground tissues were incorporated into the soil. Results from the potted trees indicated that, independetely of the rate, only soilapplied extracts of Amaranthus retroflexus and Urtica dioica increased trunk diameter and total plant dry weight while no effects were observed in the nutritional status of the plants. In field conditions treatments did not affect growth, yield, fruit quality and nutritional status of the trees. Nevertheless, Melia azedarach ground leaves and Urtica dioica extract stimulated soil microbial biomass