Optimizing plant density and spacing for morphological traits, floral characteristics, yield and economic returns in Lisianthus (Eustoma grandiflorum)

Abstract

An experiment was conducted during 2024-25 at the Department of Horticulture, College of Agriculture, Navile, Shivamogga, to evaluate the influence of different planting densities on growth, flowering, flower quality, yield and economics of Lisianthus (Eustoma grandiflorum Shinn.). The experiment was laid out in a Randomized Complete Block Design (RCBD) with six treatments and four replications. The treatments comprised T₁-10 cm × 10 cm (100 plants/m²), T₂-10 cm × 15 cm (66 plants/m²), T₃-10 cm × 20 cm (50 plants/m²), T₄-15 cm × 15 cm (44 plants/m²), T₅-15 cm × 20 cm (33 plants/m²) and T₆-20 cm × 20 cm (25 plants/m²). The results revealed significant differences among the treatments. Closer spacing (T₁) produced the tallest plants (107.13 cm), maximum number of leaves (47.67), maximum branching (2.00) and longer internodes (12.03 cm), while wider spacing (T₆) promoted maximum leaf area (3217.99 cm²/plant) and plant spread (17.62 cm). Earliness in flowering was observed in T₁ with bud initiation, flower opening and stalk harvest at 64.30, 75.60 and 81.55 days, respectively, whereas T₆ recorded delayed flowering (67.75, 78.60 and 85.80 days). Flower quality traits were superior in T₁, which recorded higher stalk length (73.20 cm), stalk girth (1.15 mm), bud size, flower diameter (5.21 cm) and flower weight (4.76 g). Yield parameters were also highest in T₁ with 11.58 buds/plant, 1.64 spikes/plant and 161.42 spikes/m², compared to minimum values in T₆ (9.00 buds/plant, 1.01 spikes/plant, 30.19 spikes/m²). Economic analysis indicated maximum gross returns (₹ 98,65,200), net returns (₹ 85,50,200) and benefit-cost ratio (7.50) in T₁, whereas T₆ recorded the lowest values. Overall, the study concludes that closer spacing at 10 cm × 10 cm (100 plants/m²) is optimal for achieving higher growth, superior flower quality, enhanced yield and greater profitability in Lisianthus cultivation under naturally ventilated polyhouse conditions.