Influence of fertilization on the growth of radicchio "Rosso di Chioggia" cultivated in two different environments
This study evaluated the influence of fertilization on some growth indexes in radicchio "Rosso di Chioggia". The trial was conducted in Rovigo (Italy) for two years and in Mendoza (Argentina) for one year. Increasing doses of macronutrients were considered, identified as N0P0K0, N1P1K1, N2P2K2 and, only in Rovigo, N3P2K2. Some indexes related to growth analysis: relative growth rate (RGR), net assimilation rate (NAR), leaf area ratio (LAR), specific leaf area (SLA), leaf weigh ratio (LWR), crop growth ratio (CGR), leaf area index (LAI) and leaf area duration (LAD) were calculated during the growing cycle. At Mendoza CGR was strongly influenced by NAR from transplant until 776 growth degree days (GDD). After that moment, CGR was affected by LAI that increased markedly due to favourable environmental conditions. From 1052 to 1653 GDD the high increase of LAI determined a reduction in photosynthetic efficiency. At Rovigo the trends in index values showed differences between the two years considered, especially in LAR and SLA. In the second year CGR had always higher values; mainly due to higher LAI values, since NAR did not differ significantly during the years. In the second half of the growing cycle, CGR was instead strongly linked to a contraction of photosynthetic effectiveness, due to head formation. High LAI values showed a growing cycle extension to the detriment of early head formation. It was also observed that when LWR is around 0.35 - 0.40 g g-1, the plant reaches marketable maturation and is ready to be harvested. In both environments, no clear effects of fertilization were observed on the growth indexes. In any case highly fertilized plants showed higher growing activity especially at the beginning of the growing cycle.