Chaiwimol, W., Songnuan, W., Ohara, H., Juprasong, Y., & Pichakum, A. 2025. The Influence of Bud Positions on the Changes in Carbohydrates and Nitrogen in Response to Hydrogen Cyanamide During Budbreak in Low-Chill Kiwifruit. Horticulturae, 11(7), 847. https://doi.org/10.3390/horticulturae11070847
Climate change has reduced the amount of winter cold that many temperate fruits need to grow and flower properly. This lack of winter chilling has lowered fruit production. Farmers often use a chemical called hydrogen cyanamide (HC) to help buds break when there is not enough cold weather, but its effects are not always fully understood.
In this study, we examined how HC helps low-chill kiwifruit break dormancy under warm conditions. We focused on different bud positions along the cane (top, middle, and bottom) and measured changes in sugars and nitrogen in the bark to understand how the HC works.
In this study, we examined how HC helps low-chill kiwifruit break dormancy under warm conditions. We focused on different bud positions along the cane (top, middle, and bottom) and measured changes in sugars and nitrogen in the bark to understand how the HC works.
We found that buds at the top (apical position) had the highest natural budbreak and number of flower buds. When HC was applied, budbreak increased greatly – by about 59% at the top and 375% in the middle. The number of opened flower buds also increased substantially. In addition, shoots from HC plants grew more evenly, while untreated plants showed uneven shoot growth.
HC treatment caused sugars in the bark to decrease earlier and more strongly, especially near the top buds. This suggests that sugars were being used to support bud growth. The top buds had the highest nitrogen levels, but HC did not change nitrogen content.
Overall, the results suggest that hydrogen cyanamide helps buds open by increasing the use of stored sugars for growth. This leads to better budbreak, more flower buds, and more uniform shoot development in low-chill kiwifruit grown under warm conditions.
