Investigation of Tuberose's Quantitative Characteristics and Identification of Its Associated Pathogens under Different Levels of Nitrogen and Potassium in Khuzestan Province

This study aimed to assess the effect of different levels of nitrogen and potassium on tuberose's quantitative characteristics and identification of its associated pathogens in the Khuzestan province of Iran. The experiment was carried out at Safiabad Agricultural Research and Education and Natural Resources Center as a completely randomized factorial design with 3 replications.  Factors included four levels of nitrogen (0, 100, 200 and 300 kg N ha-1) as Urea, three levels of potassium (0, 150 and 300 kg K2O ha-1) as potassium sulfate and a constant level of phosphorous (100 kg p 2O5 ha-1) as super phosphate.  In current study, leaf nitrogen, spike length, leaf length, SPAD readings, leaf area index (LAI), optical depreciation coefficient, disease percentage and absorbed photosynthetically active radiation parameters were measured. The results showed that the effect of nitrogen on leaf length, SPAD readings, optical depreciation coefficient, absorbed photosynthetically active radiation, and disease percentage was significant at 0.05 probability level while on leaf nitrogen, spike length, and LAI was significant at 0.01 probability level. Potassium had no any significant effect on corresponding parameters in this experiment. In addition, the causal agents of necrotic spots on the tips and edges of the leaves and petals were identified as Botrytis sp., Curvularia sp., and Fusarium sp. while the main cause of necrotic spots on the petals was a thrips, which is probably either F.intonsa or F.schultzei species. Overall, the application of 100 kg ha-1 of nitrogen and no application of K2O are the best treatments and recommended for florists (in planting large bulbs).