Effect of Different Nitrogen Concentration on Plant Growth, Yield and Quality of Sweet Potato (Ipomea Batatas [L.] Lam) Cultivated in Soilless Culture System

The soilless culture system effectively promotes plant growth by facilitating water and nutrient uptake by plant roots. To increase sweet potato production (Ipomoea batatas), we developed containerized planting in which tuberous roots were grown in solid substrates in the polybags supplied with a nutrient solution through an irrigation system. This study was conducted to investigate the effect of different nitrogen concentrations on sweet potato plant growth performance, yield, and tuber quality cultivated using a soilless culture system. The experimental setup included five treatments (T1-T5) with different levels of N (0-50-150-200-250 mg L-1), which were mixed in the nutrient solution, while P and K levels were held constant at 150 and 200 mg L-1 respectively. After three months of cultivation, there were significant differences between treatments in terms of plant growth performance, yield and tuber quality. Plants cultivated in the 250 mg L-1 of N showed the highest growth rate including plant height, shoot and leaves fresh weight, number of tillers, SPAD values, number of leaves, and diameter of tillers compared to other treatments. Data also revealed that the highest tuber yield was obtained from plants treated with 200 mg L-1 of N. Tuber harvested from the treatment of 200 mg L-1 of N showed the best quality in terms of Brix value, moisture content and tuber shape and length. Therefore, planting sweet potatoes using a soilless culture system is recommended with the application of 200 mg L-1 of N to obtain the optimum plant performance in terms of growth, yields, and tuber quality.