Potato (Solanum tuberosum L.) is a vital staple crop globally, ranking fourth after rice, wheat, and maize in terms of human caloric intake. Its popularity stems from its adaptability across climates, high productivity, nutritional content, and diverse uses in both fresh and processed forms1. Vegetative propagation through seed tubers remains the principal method of potato cultivation worldwide2. Currently, potatoes represent the third most consumed vegetable and the fourth most cultivated food crop globally. In Pakistan, potatoes are grown on approximately 0.19 million hectares, producing about 4.6 million tons annually, with an average national yield of 24.2 tons per hectare. The country holds the 19th position globally in potato production and ranks 12th in exports3.
Potato cultivation in Pakistan follows a multiseasonal calendar: the main crop is planted in autumn (September–January), contributing 80–85% of the total production, with additional harvests in spring (10–15%) and summer (1–2%)4. However, potato production is frequently challenged by both abiotic and biotic stressors. Abiotic constraints include temperature extremes, drought, salinity, nutrient imbalances, poor irrigation, and soil degradation, all of which directly affect tuber initiation and development. Biotic pressures such as late blight (Phytophthora infestans), early blight (Alternaria solani), Fusarium wilt, and viral infections (e.g., Potato virus Y and X) further exacerbate yield losses5.
An additional constraint arises from postharvest physiological processes, particularly the dormancy phase, which significantly affects the timing and uniformity of sprouting. Dormancy in potato tubers is a genetically and environmentally regulated phase characterized by a temporary suspension of sprout initiation, even under optimal growing conditions. This dormancy begins post-harvest and continues until the apical buds initiate visible sprouting (usually at 2 mm length)6. Although dormancy has adaptive significance—allowing tubers to withstand unfavorable storage or overwintering conditions—it presents practical challenges, especially in commercial seed tuber production, where controlled and timely sprouting is essential for uniform crop establishment7.
The dormancy period is influenced by several factors, including cultivar genetics, plant maturity at harvest, tuber size and physiological age, and storage conditions (temperature and relative humidity)8. Inappropriate dormancy duration can either delay planting or lead to pre-harvest sprouting, both of which reduce seed viability and crop performance. Premature sprouting is associated with increased respiration, carbohydrate depletion, tissue desiccation, and ultimately loss of commercial quality9.
To regulate dormancy, both chemical and environmental approaches have been explored. Among chemical treatments, gibberellic acid (GA₃), a naturally occurring plant growth regulator, has emerged as a promising agent for breaking dormancy and promoting sprouting in seed tubers. GA₃ influences physiological and biochemical pathways associated with sprout emergence by enhancing the activity of hydrolytic enzymes, stimulating hormonal signaling, and promoting cell elongation at the tuber eyes10.
The application of GA₃ initiates key molecular mechanisms, including the upregulation of GA-responsive genes and activation of enzymes such as terpene cyclases and cytochrome P450 monooxygenases, which are involved in endogenous gibberellin biosynthesis and action. These effects collectively contribute to enhanced meristematic activity and earlier sprout initiation. However, GA₃ uptake and efficacy depend significantly on the permeability of the periderm (tuber skin). Since intact skin can impede hormone absorption, higher efficacy is often observed when tubers are freshly harvested, slightly abraded, or have undergone curing11. Environmental factors such as storage temperature and humidity also modulate the tuber’s hormonal responsiveness12. Moreover, the effectiveness of GA₃ varies across cultivars, and the optimal concentration and immersion time remain inconsistent among studies. For example, while some studies report effective dormancy break at high concentrations (e.g., 1500 ppm GA₃ combined with thiourea), such treatments may not be economically viable or scalable for resource-limited farming systems13. Lower concentrations, when properly timed and combined with effective soaking durations, may offer a practical alternative for breaking dormancy without compromising tuber quality or causing hormonal overstimulation.
In Pakistan, the postharvest handling of potato seed tubers remains suboptimal due to limited access to cold storage, poor seed certification systems, and inadequate agronomic support. These issues, coupled with the natural dormancy of locally preferred cultivars such as ‘Ratta,’ often result in delayed or uneven sprouting during planting seasons.
Given this context, optimizing the concentration and exposure duration of GA₃ treatments offers a promising avenue to enhance seed tuber performance. While previous research has established the dormancy-breaking potential of GA₃, there remains a need for cultivar-specific, locally validated recommendations tailored to Pakistan’s agricultural conditions.
The present study was designed to evaluate the effect of different GA₃ concentrations (0, 50, 100, and 150 ppm) and dipping durations (6, 12, 18, and 24 hours) on dormancy break and sprouting behavior of ‘Ratta’ potato tubers. The study aimed to measure key physiological parameters such as sprouting percentage, days to first sprout emergence, number of sprouts per tuber, sprout length and diameter, sprout fresh and dry weights, weight loss during storage, and relative water content of sprouts. These metrics collectively provide a comprehensive understanding of GA₃-induced dormancy release and the quality of subsequent sprouting, offering practical recommendations for seed tuber management.
The outcomes of this research will contribute to developing effective and affordable dormancy-breaking protocols suitable for small- to medium-scale farmers, ultimately supporting improved crop establishment, higher productivity, and enhanced profitability in Pakistan’s potato sector.