Comparative response of 'Early Gold' and 'Le-Conte' pear cultivars to dormancy-breaking agents under mild winter...

Insufficient winter chilling in warm regions such as Egypt's New Valley limits budbreak, flowering, and productivity of European pear cultivars. Dormancy‑breaking agents (DBAs), particularly hydrogen cyanamide (HC) and mineral oil (MO), are widely used to overcome these constraints, yet comparative responses among cultivars under arid conditions remain poorly understood. This study evaluated the effects of HC and MO, applied individually or in combination, on the bud behavior, vegetative growth, yield, and fruit quality of two low‑chilling pear cultivars, 'Early Gold' and 'Le‑Conte', grown under mild winter conditions.

Compared with the untreated control treatment, the dormancy‑breaking treatment significantly improved all the measured traits. Among the tested treatments under the conditions of this study, the combined application of HC 2%+ MO 2% produced the earliest and highest bud break (up to 90.69%), increased the floral bud proportion, and enhanced vegetative growth. HC 2% + MO 2% also resulted in the greatest fruit set (up to 24.14%) and yield (53.62 kg tree⁻¹), followed closely by HC at 3% and the combined HC 1.5% + MO 1.5%. Fruit physical and chemical attributes, including weight, firmness, TSS, and sugar fractions, were markedly improved by these treatments, with HC 2% + MO 2% producing the highest values across seasons. 'Early Gold' generally outperformed 'Le‑Conte' in terms of fruit set, yield, and quality. Correlation analysis revealed that earlier bud break was strongly associated with greater fruit set, increased yield, and increased sugar accumulation.

Hydrogen cyanamide combined with mineral oil, particularly at 2% each, is highly effective for promoting budbreak, improving yield, and enhancing the fruit quality of pears under inadequate winter chilling. The 'Early Gold' cultivar demonstrated superior adaptability to warm conditions, making it a promising cultivar for arid and semiarid production zones. These findings provide practical guidance for optimizing pear management in regions with mild winters.