Optimization of irrigation and fertigation interactions for enhanced growth dynamics and floral quality in chrysanthemum (Chrysanthemum morifolium Ramat.) cultivars

Floral pigmentation stability, supported by balanced soil water and nutrient availability, plays a crucial role in enhancing inflorescence traits and determining growth, yield and profitability in chrysanthemum cultivation. Therefore, field experiments were conducted during the rabi seasons of 2023–24 and 2024–25 at the Precision Farming Development Centre (PFDC), Water Technology Centre, ICAR-IARI, New Delhi, to evaluate the effects of various irrigation and fertigation regimes on the performance of chrysanthemum (Chrysanthemum morifolium Ramat.) cultivars. The study employed a split-split plot design comprising two cultivars (Autumn Pink and Autumn White), three irrigation levels (0.5, 0.75, and 1.0 Epan), and three fertigation regimes (50%, 75%, and 100% RDF). The study was conducted in a semi-arid, sub-tropical climate characterized by hot, dry summers and cold winters. The experimental soil was classified as sandy loam, consisting of 71% sand, 14% silt, and 15% clay. It had a pH of 7.65, an electrical conductivity of 0.29 dS/m, and an organic carbon content of 0.43%. The soil moisture analysis revealed that the experimental site had a field capacity of 24.3% and a permanent wilting point of 7.3%. The available nutrient levels of nitrogen (N), phosphorus (P), and potassium (K) were recorded as 125.66, 26.55, and 281.41 kg/ha respectively indicated that optimal nutrient supplementation is essential for sustaining soil fertility and crop performance. The final results revealed that among the cultivars autumn white performed superior results than autumn pink with respective of plant height (81.92 cm), internodal length (4.22 cm), stem diameter (15.39 mm), dry matter (71.50 g/plant), number of buds per plant (14.47), flower diameter (9.71 cm), weight of flower (9.59 g), cut flowers per plant (6.16) and flower yield (14.62 t/ha). Among different irrigation regimes irrigation scheduled at 0.75 Epan produced the maximum vegetative growth and flower yield, indicating that it is a more water-efficient strategy without sacrificing productivity. Notably, irrigation at 1.0 Epan exhibited performance comparable to the 0.75 Epan treatment, highlighting its similarly effective influence on crop growth and yield. Similarly, among different fertigation levels 100% RDF provided better results with respective of all flowering and yield attributes, confirming that adequate irrigation coupled with higher fertigation not only enhanced nutrient status in soil but also helped in maintaining better residual soil fertility across both chrysanthemum varieties. Similarly, PCA (Principal Component Analysis) technique successfully reduced the dimensionality of the dataset and effectively identified the dominant growth and flowering parameters contributing to yield variability, highlighting the importance of biomass and floral traits in overall productivity of chrysanthemum. The study concluded that optimized irrigation and fertigation (particularly 0.75 Epan irrigation with 100% RDF) coupled with Autumn white cultivars significantly improved growth, flowering attributes, yield and overall profitability and also served as a sustainable strategy for commercial chrysanthemum production, especially in water-limited environments.