Optimizing transplanting and harvesting dates for 'Hopungmi' sweet potato (Ipomoea batatas L.) in Yeoju under climate change

Abstract

This study aimed to determine the optimal transplanting period for the sweet potato cultivar 'Hopungmi' in response to climate change. Field trials were conducted over two years (2023 and 2024) in Yeoju, South Korea. Transplanting dates were set at five intervals: April 15 (T1), April 20 (T2), April 25 (T3), April 30 (T4), and May 5 (T5), and harvests were conducted at 110, 120, and 130 days after transplanting. In terms of the number of marketable storage roots per plant, T5 and T3 recorded the highest values in 2023 and 2024, respectively, while the lowest were observed at T3 (2023) and T4 (2024). Marketable storage root yields (kg 10a(-)(1)) in 2023 were highest for T1 (2967.2), T4 (2952.5), and T5 (3270.2). In 2024, T3 produced the highest yield (2783.9), whereas T4 had the lowest (2216.0), with statistically significant differences (p < 0.05). Principal component analysis (PCA) incorporating shoot growth, root development, and environmental variables indicated that, in 2023, early-season soil moisture tension and air temperature were negatively correlated with average root weight. T3 was located opposite these environmental factors in the PCA loading plot, suggesting that lower temperatures and higher soil moisture tension reduced both the number of marketable roots per plant and overall yield. In 2024, T4 associated with the lowest yield was not significantly affected by air temperature but showed an inverse relationship with soil moisture tension, indicating that drought stress contributed to reduced productivity.