Assessment of the Influence of Phosphorus and Nitrogen Fertilization Regimes on Tuber Dormancy Characteristics of Six Potato Genotypes Grown Under Agroecological Conditions of Pakistan

In Pakistan, growers use excessive levels of fertilizers to obtain maximum tuber yields, which ultimately increases the cost of production as well as loss of resources, and may also affect the length of tuber dormancy. Tuber dormancy delays sprout growth, preventing the use of harvested potatoes as seed for the next planting season. This is particularly critical in multiple‐year cropping systems, where seed tubers must sprout soon after harvest to ensure timely replanting and sustain crop cycles. Therefore, a 2‐year (2022−23 and 2023−24) field trial was conducted on a sandy loam soil irrigated with a furrow system in the Horticulture Experimental Area, The Islamia University of Bahawalpur, Punjab, Pakistan. The trial was aimed to investigate the influence of five different phosphorus (P) and nitrogen (N) application rates on tuber dormancy‐related attributes of six genotypes, including Sante, Riviera, SL28‐51, Lebella, Alouette, and Sutlej, in order to to establish the optimal rate of P:N that does not directly or indirectly prolong tuber dormancy, hence enhance multiple cropping, without affecting the tuber yield. The results showed significant variations ( p ≤ 0.05) between the genotypes (G), fertilization regimes (F), and/or storage period and their interactions: G × F , and/or G × SP for dormancy period (DP), sprout length (SL), dry matter (DM), specific gravity (SG), tuber yield (TY), the enzyme activities of catalase (CAT), superoxide dismutase (SOD), peroxidase (POD), and ascorbate peroxidase (APX), as well as hydrogen peroxide (H 2 O 2 ), glucose (Glu), fructose (Fruc), sucrose (Suc), abscisic acid (ABA), zeatin (ZT), and gibberellin A 1 (GA 1 ). A very strong positive correlation ( r ≥ 0.8) ( p < 0.05) of DP was found with DM, H 2 O 2 , and ABA, while an inverse correlation ( r ≤ −0.8) ( p < 0.05) was found with SL, Glu, Fru, Suc, ZT, and GA 1 . Thus, the genotypes with relatively lower DM, H 2 O 2 , and ABA production were found to have shorter tuber dormancy, and those with quite high DM, H 2 O 2 , and ABA production were found to have longer tuber dormancy. A cluster dendrogram constructed from 16 different physicochemical traits divided genotypes into two main groups of short‐/moderate‐term dormancy genotypes, including Sante, Sutlej, SL28‐51, and Alouette, and long‐term dormancy genotypes, including Labella and Riviera. Among different fertility rates, low level resulted in decreased yield and DP, while high fertility led to prolonged DP with reduced SL, pointing out the need for balanced nutrient management. Overall, the findings of this study indicated that genotypes had substantial genetic variations for dormancy period and associated traits, and P:N 75:100 kg acre –1 (recommended fertilization) produced highest yield (26.5 ton ha –1 ) in Alouette with minimal effect on tuber dormancy, hence recommended for potato growers in Pakistan.