Assessment of Heterosis and Inbreeding Depression on Agronomic Traits in TPS-derived Potato Hybrids Under Northern Pakistan Climatic Conditions

True Potato Seed (TPS) breeding offers a promising pathway to develop high-yielding, disease-resistant, and climate-resilient potato hybrids, contributing to food security and sustainable agriculture in regions such as Pakistan. This study evaluated heterosis and inbreeding depression in eight potato hybrids derived from true potato seed under climatic conditions of Northern Pakistan. A randomized complete block design was employed with three replications at Battakundi and Abbottabad during 2022–2024. Analysis of variance revealed that all the genotypes had showed highly significant differences (P < 0.01, 0.05), reflecting substantial genetic variability. High estimates of relative heterosis (64.10%), heterobeltiosis (54.58%) for the number of marketable tubers per plot, and standard heterosis (48.64%) for their weight revealed strong hybrid vigor. Negative inbreeding depression ranging from –0.81% to –349.7% suggested superior hybrid performance over parental cultivars. Positive correlations among yield and yield attributed traits provided greater opportunities for selection in potato breeding. Results concluded that among the tested combinations, Sarpomira × Roko and Kuroda × Burna demonstrated significant positive heterotic effects for yield traits and desirable negative heterosis for late blight incidence, identifying them as promising candidates for future hybrid release. Overall, the findings highlight TPS breeding as a viable approach for enhancing productivity and resilience of potato crops in high-altitude and similar agro-ecological regions.