Alterações das características químicas de três substratos comerciais na produção de mudas cítricas

Abstract

The dynamics of nutrients in three commercial substrates were evaluated, from the transplanting until final nursery. The rootstocks were cultivated in 4L containers under greenhouse conditions. The experiment was developed at Estação Experimental Agronômica of UFRGS from June/2003 to November/2004, with the experimental design of completely randomized blocks, in factorial 3 x 3 x 2, where 3 commercial substrates were tested (Commercial 1, 2 and 3 - composed of black turf; processed and enriched barks, perlite, vermiculite expanded and turf; and, composted pine bark and vermiculite, respectively), 3 citrus rootstocks (Trifoliate orange – Poncirus trifoliata [L.] Raf.; 'C13' citrange – Citrus sinensis [L.] Osbeck x P. trifoliata [L.] Raf.; and 'Rangpur' lime – C. limonia Osbeck) and 2 citrus varieties ('Valencia' – C. sinensis [L.] Osbeck and the 'Montenegrina' mandarin – C. deliciosa Tenore). One evaluated the substrate chemical characterization and foliar nutritional content and dry mass content of the rootstock. The substrates showed significant reductions in the concentration of nutrients, specially phosphorus and potassium. However, one observed that the Commercial 2 substrate presents greater port of nutrients when compared to the other substrates, providing larger accumulation of dry mass in the rootstocks at grafting time and final nursery production.