Irrigation Levels and Fertilization Rates as Pre-Harvest Factors Affecting the Growth and Quality of Hippeastrum

Growing Hippeastrum in an open field or a greenhouse requires precision irrigation and fertilizer to promote plant growth and development. Therefore, this research aimed to study the effect of irrigation level combined with fertilization rate on the growth and development of Hippeastrum. Two experiments were carried out to determine the influence of irrigation and fertilizer on the growth, flowering, and bulb quality of Hippeastrum. In the first experiment, bulbs of Hippeastrum ‘Red Lion’ with circumferences of 25 cm were grown in plastic plots using mixed soil as growing media under a 50% shading net. Plants were irrigated daily until drainage and water contained in macropores by gravity action (Field capacity: FC) for 90 days after planting (DAP) and supplied with three different 15N-15P₂O₅-15K₂O fertilization rates, i.e., 0, 2.5, and 5 g per pot. Plant growth and water use efficiency were measured at 45, 60, and 90 DAP. The results showed that plants supplied with 0 g of fertilizer had the lowest plant height and number of leaves per plant at 90 DAP, whereas there was no significant effect of fertilizer rate treatments on flower quality. The water use efficiency, evapotranspiration rate (ET), crop evapotranspiration under standard condition (ETc), crop coefficient (Kc), photosynthetic rate, and stomatal conductance were decreased when plants were supplied with fertilizer at a rate of 0 g per pot at 90 DAP. In the second experiment, plants were irrigated with four levels, i.e., 100, 75, 50, and 25% ETc combined with three fertilization rates, i.e., 0, 2.5, and 5 g per pot. At 180 DAP, the results showed that water deficit treatment (50 and 25% ETc) decreased plant growth and bulb quality. Irrigation with 100% ETc combined with 2.5 or 5 g per pot and irrigation with 75% ETc combined with 5 g per pot were the optimum levels to promote plant growth and bulb quality in Hippeastrum.