Influence of Pollen Genotype on Fruit Morphology and Ripening Dynamics in Date Palm ( Phoenix dactylifera L.)

This study evaluated the metaxenic effects of seven pollen genotypes (M1–M7) on fruit morphology, ripening dynamics and pollen vigour in three date palm cultivars: Ghars, Deglet Noor and Mech Degla, grown in southeastern Algeria in 2022. Controlled pollinations revealed significant differences in pollen germination (75.0% for M3 to 95.8% for M6) and tube length (760 µm for M7 to 1711 µm for M6). Ghars produced the largest fruits (length: 36.2–44.5 mm; weight: 6.7–9.2 g), Deglet Noor was intermediate (length: 36.2–38.5 mm; weight: 6.1–6.9 g) and Mech Degla had the smallest (length: 31.6–35.6 mm; weight: 4.6–6.3 g). Using a linear mixed‐effects model accounting for the nested experimental design (fruit within spadix within tree), cultivar identity significantly affected 12 of 13 biometric traits, while pollen source and the cultivar × pollen–source interaction significantly affected ten of these traits, including fruit weight, pulp moisture and mineral content and shape‐related indices, but not fruit length, fruit width or pit length. Principal component analysis explained 82.7% of total variance (PC1: 51.9%, PC2: 18.2% and PC3: 12.6%). Hierarchical clustering identified three phenotypic clusters corresponding exactly to the three maternal cultivars (cophenetic correlation = 0.76), with 67.4% of total variance attributable to cultivar identity. Strong positive correlations among fruit developmental stages ( r  = 0. 79–0.98) reflected their sequential measurement rather than a pollen‐driven pattern, cultivar‐dependent trait correlations indicated that estimates pooled across cultivars may partly reflect cultivar identity rather than pollen effects. Pollen germination rate was strongly correlated with fruit retention across all ripening stages ( r  = 0.88–0.96, p  < 0.01), whereas pollen tube length was not ( r  = 0.35–0.48). While maternal genotype was the dominant determinant of fruit traits, pollen source exerted specific, measurable effects on a defined subset of traits, suggesting a modulating role that may inform pollen selection pending further validation of yield and fruit set.