Microclimate modification through green shade nets enhances growth, yield, and water productivity of Chrysanthemum indicum L. under semi-tropical conditions

The adoption of sustainable horticulture techniques has been shown to intensify ornamental flower production within a limited area, particularly under adverse climatic conditions. The primary objective of this research was to evaluate the potential of 50% green shade nets in comparison to the open field to enhance the agronomic traits and water use efficiency (WUE) of Chrysanthemum indicum L. During the period from October 2024 to February 2025, a well-controlled experiment was conducted in Bengaluru city of India (semi-tropical climate). The study design involved a randomized block with six replications. The findings indicated that plants grown under green shade nets exhibited a 23.6% increase in plant height, reaching 60.2 cm, as opposed to 48.7 cm in the open field. In addition, the green shade nets treatment resulted in a 47.1% increase in the number of branches per plant. The leaf area index (LAI) was 50.7% higher under green shade nets, at 3.24 compared to 2.15 in the open field. Flower yield parameters such as number of flowers per plant were higher by 45.3 flowers per plant under green shade nets (45.3) than open condition (29.7), indicating an increase of 52.5%. The green shade nets treatment also improved flower quality, with flower diameter being 5.8 cm and the fresh flower weight (single flower) of 10.2 g, compared to 4.9 cm and 8.4 g, respectively, in the open field. Cumulatively, these advantages led to a significant increase in total yield by 50.6%, with green shade nets achieving 12.95 t ha⁻¹ compared to the 8.60 t ha⁻¹ in open field. Microclimate data showed that the maximum temperatures were 2.4 °C lower and relative humidity 6-8% higher during the hottest part of the day under shade nets than in the open field. Photosynthetically active radiation (PAR) was reduced by about 50% under the green shade nets. Water use efficiency (WUE) was recorded to be 3.37 kg m⁻³ in green shade net as against 1.92 kg m⁻³ in open field, signifying a 75.5% enhancement. Statistical analysis indicated that there were strong positive associations between flower yield and LAI (r = 0.82) and number of branches (r = 0.79), and a strong negative correlation between flower yield and the mean maximum temperature (r = -0.71). In conclusion, the application of 50% green shade nets emerges as an effective and promising technique for the sustainable intensification of chrysanthemum cultivation in semi-tropical regions, offering concurrent advantages in terms of growth, yield, quality, and water productivity.