The effects of nitrogen fertilization after hail damage simulated by leaf cutting on the yield and sugar ratio of sugar beet

The aim of this study was to determine the effects of different leaf loss rates simulating hail damage and nitrogen doses on plant growth and yield of sugar beet. The research was carried out as pot and field trials at Eskişehir Osmangazi University Faculty of Agriculture in 2022. In the field experiment, which was established in four replications according to the randomized complete block design, nitrogen doses of 0, 3, 6, and 9 kg N/da were applied at four-leaf stages in sugar beet plants whose leaves were clipped at different rates (control, removal of 50%, and 100% of the leaves). In the pot experiments, the same nitrogen doses were applied after the leaves of the plants were completely removed. After one month incubation, plant height, leaf number, plant fresh and dry weight, leaf area, leaf temperature, and chlorophyll ratio were examined. According to the results of the research, except for plant height of sugar beet plants whose leaves were completely removed from the increasing nitrogen doses; the effects on leaf number, plant fresh weight, dry weight, leaf area, leaf temperature, and chlorophyll ratio were found to be significant. Increasing nitrogen doses decreased the chlorophyll ratio from 45.6 SPAD to 51.3 SPAD, while the leaf number from 7.16 to 8.60, plant fresh weight from 8.66 g to 13.00 g, and leaf area increased from 168 cm2 to 240 cm2. Leaf temperature decreased from 26.1°C to 24.7°C with increasing nitrogen doses. The highest chlorophyll rate, number of leaves, fresh weight, dry weight, and leaf area were obtained from 9 kg N/da application. In the field experiment, as leaf loss rate increased, a significant decrease in root length was detected. Root weight was insignificantly reduced by leaf loss but root diameter and digestion were not affected. While increasing nitrogen doses caused increased root weight and yield per decare in control plants, no significant effect was determined in the plants with leaf damage. It was concluded that leaf loss in sugar beet during early development stage did not cause a significant reduction in yield. Beside, the nitrogen application of 6-9 kg N/da promoted plant growth, but it does not give effective results on beet yield and sugar content.