Publications

Climate change has contributed to a decline in winter chilling accumulation, a critical requirement for budbreak in temperate fruit crops. Its consequence has been a reduction in fruit production. To compensate for insufficient chilling, hydrogen cyanamide (HC) is widely applied, though its effectiveness remains limited. This study investigated the effect of HC application on budbreak in low-chill kiwifruit under warm conditions by correlating phenological responses with changes in carbohydrate and nitrogen concentrations in bark tissues across bud positions. Phenological observations revealed the highest budbreak percentage and total flower buds at the apical position. HC significantly increased budbreak by 58.82% at the apical position and by 375% at the middle position, with corresponding increases in total flower buds by 148.78% and 1066.67%, respectively. Additionally, shoot lengths were uniform among bud positions in HC-treated canes, whereas non-treated canes showed shoot length heterogeneity. Moreover, HC treatment triggered an earlier and more pronounced reduction in soluble sugars (sucrose and hexoses) concentrations along the gradient from apical to basal bud positions, where the response was strongest at the apical position, which was strongly associated with enhanced budbreak percentages and total flower bud formation. While total nitrogen content was highest in the apical position, it was unaffected by HC application. These findings indicate that HC may promote budbreak by enhancing the mobilization and consumption of soluble sugars for bud growth, thereby improving budbreak performance, flower bud production, and uniform shoot development in low-chill kiwifruit under warm conditions.

Rainy season is an obstruction for efficient off-season longan production in Thailand. In this experiment, the bloom performances of off-season 'Phuang Thong' longan as affected by microclimate in a private longan orchard at Ban Phaeo district, Samut Sakhon province was evaluated during the rainy season of 2020. This study focused on the reproductive development at four different times (plots) of potassium chlorate application: May, June, July, and August. Air temperature, relative humidity and light intensity at the canopy level were recorded. Rainfall data was obtained from the Meteorological Department of Thailand. The results showed that inflorescence length, female flower number, and sex ratio of female to male of the May plot were the highest compared to other plots, and it was associated with early rainfall occurrence during flower development and blooming time. The August plot had a low growing degree day and a short flowering period, which coincided with frequent rainfall during the flower development period. However, the pollen viability and female flower characters were unaffected by environment. In conclusion, flower induction in the early rainy season, especially in May, was an effective time for the production of off-season ‘Phuang Thong’ longan in Ban Phaeo district, Samut Sakhon province, Thailand. Keywords: Floral biology, Flower, Pollen, Microclimate, Heat unit