The role of indole acetic acid in modifying morphological features of three Prunus domestica L. cultivars.

Indole-3-acetic acid (IAA) is a key auxin involved in bud activation and early vegetative growth, but its effects in plum propagation may vary with cultivar and concentration. This study evaluated the influence of pre-budding IAA application on sprouting behaviour and selected morphological traits of three plum (Prunus domestica L.) cultivars, namely 'Fazle Manani', 'Santa Rosa', and 'Red Beauty', grafted onto Mariana rootstock. Bud sticks were soaked for 12 h in four IAA concentrations (300, 600, 900, and 1200 mg/L) and a control prior to T-budding. The experiment was arranged in a two-factor factorial randomized complete block design with three replications. Data were collected on days to sprouting, sprouting percentage, plant height, number of branches per budding, number of leaves per budding, budding diameter, and internode length, and were analysed using two-way ANOVA followed by Tukey's HSD test at the 5% level. Days to sprouting were significantly affected by IAA concentration, cultivar, and their interaction, demonstrating cultivar-dependent responses to IAA treatment. Earlier sprouting was observed in 'Fazle Manani' at 300 mg/L, in 'Santa Rosa' at 600 mg/L, and in 'Red Beauty' at 600-900 mg/L. Plant height and number of branches per budding were also significantly influenced by the interaction between IAA concentration and cultivar. In contrast, sprouting percentage was affected by cultivar only, whereas number of leaves per budding, budding diameter, and internode length were not significantly affected by IAA concentration, cultivar, or their interaction. These results indicate that pre-budding IAA treatment can improve certain propagation and early growth traits in plum, but the response is both cultivar-specific and trait-dependent. Therefore, the use of IAA in plum propagation should be optimized for individual cultivars rather than applied uniformly.