Effect of seedling age and NPK fertilizer on qualitative of Kohlrabi (Brassica oleracea var.gongylodes) grown under drip irrigation system

Abstract

Field experiment was conducted on Kohlrabi (Brassica oleracea var. gongylodes) ‘White Vienna cv.’ at the Experimental Station of the Department of Horticulture and Landscape, College of Agriculture, Tikrit University, Salah al-Din, Iraq, during the winter season of 2021-2022 under drip irrigation system. This study aimed to investigate the effect of seedling age (45, 60 and 75 days) and different combination of NPK (60:40:0, 70:50:20, 80:60:30, 90:70:40, 100:80:50 and 120:90:50 kg ha-1) on qualitative of kohlrabi plants. The experiment was carried ou according to Randomized Complete Block Design (RCBD) with three replications. The comparison of means was performed by Duncan at a P≤ 0.05 probability level. Results showed that seedling age 45 days increased significantly in the percentages of nitrogen in the leaves, phosphorus and potassium, total dissolved solids (TSS) in knob, content of vitamin C in knob and carbohydrates in the knob which were 3.045%, 0.425%, 3.868%, 6.333%, 0.389 mg ml-1 and 6.204% respectively. On the other hand, using combination fertilizer of NPK at level 120:90:50 kg ha-1, gave significant increment in all studied characteristics. Interaction treatment between seedling age 45 days and combination fertilizer of NPK at 120:90:50 kg ha-1 recorded highest values in all studied characteristics of qualitative for kohlrabi plant except the percentage of nitrogen in leaves. Whereas, seedling age 60 days and combination fertilizer of NPK at 120:90:50 kg ha-1 showed significant superiority in the percentage of nitrogen in leaves 5.533%.