Interactive effects of plantlet height and hydroponic medium characteristics on growth of acclimatised pineapple (Ananas comosus (L.) Merr.) plantlets

The successful establishment of hydroponically acclimatised plantlets produced from pineapple axillary buds requires optimal substrate with water-related properties which regulate moisture availability, aeration, shoot growth and canopy formation. A hydroponic study was conducted to examine the synergistic effect of different levels of plantlet height and inert hydroponic substrates on physical and water-related characteristics of substrate and subsequent plant shoot growth responses and canopy formation. High water-holding capacity (100 %), high porosity (94.93 %), low bulk density (0.120 g/cm3) and substantial expansion volume (99.79 %) was shown by cocopeat, whereas pebbles exhibited a high bulk density (5.373 g/cm3) alongside an enhanced coarse particle distribution (3.556 mm) and pebbles exhibited the highest air capacity (30.30 %). Increased height, leaf production, leaf area and shoot biomass were consistently greater produced by taller pineapple plantlets. Among the hydroponic medium tested, superior growth occurred in cocopeat, which favoured biomass accumulation, whereas pebble medium supported the shoot elongation response due to aeration. Sufficient initial plantlet vigour and properties of substrates such as balanced water retention and aeration indicated significant difference in interaction effects. Principal component analysis (PCA) yielded ten independent components which accounted for 99.8 % of the total variance. Among the first three principal components, PC1 had the highest variability (85.7 %). The correlation analysis revealed a strong and statistically significant positive relationship among most traits whereas leaf area on 60th day exhibited significant negative correlations with almost all traits. Overall, the findings reveal that taller plantlets grown in cocopeat as hydroponic medium are optimum for production of good quality pineapple plantlets.