Interactive Effects of Plant Growth Regulators and Varieties on Morpho-florimetric Traits and Flower Yield of China Aster (Callistephus chinensis L. Nees)

Abstract

The combined effects of plant growth regulators (PGRs) and varietal selection are important for improving ornamental crop productivity; however, variety-specific responses to PGRs have been less systematically examined in China aster. This study evaluated seven exogenous PGR treatments (T1–T7) and three varieties (V1–V3) using a two-factor experimental design to determine their effects on growth, flowering and flower yield. Eleven morpho-florimetric traits were recorded and analysed using two-way ANOVA, Pearson correlation, principal component analysis (PCA) and scree plots. PGR treatments and varieties significantly affected (p < 0.001) most traits, including plant height, leaf dimensions, branches per plant, flowering duration, flower diameter, flower weight, flowers per plant and total yield. Significant treatment × variety interactions (p < 0.05) were observed for plant height, branches per plant and flowers per plant, indicating differential varietal responses to PGR application. The T3V3 combination produced the highest flower yield (13.43 t ha⁻¹), whereas T1V1 recorded the lowest yield (8.01 t ha⁻¹). Flower yield was strongly and positively associated with flowers per plant (r = 0.91), flower weight (r = 0.85), branches per plant (r = 0.69) and flowering duration (r = 0.68). PCA indicated that the first two principal components explained more than 75% of the variance, with branches per plant, flower weight and flowers per plant contributing prominently to yield. These findings suggest that PGR recommendations for China aster should consider varietal responsiveness.