Influence of Effective Irrigation Water Usage on Carrot Root Productivity and Quality Properties in Soilless Culture

The availability of irrigation water is becoming an increasingly significant concern for crop production in urban areas of Southeast Asia, particularly in Bangladesh. To ensure optimal plant growth and development, it is essential to establish precise irrigation scheduling. Therefore, this study examines the effects of limited irrigation usage on the root quality, production, and morphophysiological features of carrots grown under soilless conditions. Irrigation treatments were in intervals of 200 mL 3-day, 250 mL 2-day, 300 mL 3-day, and 350 mL 4-day. Plants were grown on biodegradable substrates, including cocopeat, sawdust, rice husk, and a mixture of all three with 10% wood ash and 40% cow dung following a randomized complete block design (RCBD). Significant differences in root yield and quality of carrots were observed by irrigation water levels and media types. The yield and quality attributes decreased most when they were subjected to reduced watering, accompanied by a decline in morphological traits (plant height, leaf number, root mass, root length, and diameter) and physiological aspects (relative water content, membrane stability index, and chlorophyll content of leaves). Root quality metrics, i.e., brix, vitamin C, sugar content, beta-carotene, and phenolic content, were also influenced by the frequency of irrigation water used. Root yield and irrigation water usage efficiency were highest with the 2-day interval of 250 mL treatment. The growing media, cocopeat, was found to have acceptable levels of water-holding capacity (87.73%), porosity (69.80%), bulk density (0.10 g cm⁻³), pH (6.73), and EC (0.14 dSm⁻¹), allowing for optimal carrot growth and development. Watering the plants with 250 mL every 2 days was the best irrigation schedule for growing carrots under a cocopeat-based growth medium, ensuring effective carrot root production considering quality and water use efficiency.