Subirrigation of Container-Grown Tomato I: Decreased Concentration of the Nutrient Solution Sustains Growth and Yield

Abstract

Subirrigation of containerized vegetable crops is a promising strategy to increase water and fertilizer use efficiency. However, the nutrient solution may cause salts accumulation in the substrate top layer. The objective of this study was to determine the effect of nutrient solution concentration in container-grown tomato under surface drip-irrigation and subirrigation. The plants were irrigated with solutions at concentrations of ‒0.072, ‒0.058 and ‒0.043 MPa (100%, 80% and 60% of Steiner’s nutrient solution, respectively). Except at the highest concentration, the greatest yields occurred in subirrigated (10.6 kg plant−1) compared to drip-irrigated plants (9.5 kg plant−1). In drip-irrigated plants, yield was higher with the highest solution concentration. The increased yield in subirrigated plants at low solution concentrations was related with increased fruit N and Ca content. The higher accumulation of N, P, K and Ca demonstrates that subirrigation allows for increased nutrient use efficiency, particularly when using nutrient solutions of low concentration. Water use efficiency was markedly increased in subirrigated tomato, as 300 to 460 g of fruit L‒1 were produced, compared to 50 g L‒1 in drip-irrigated plants. Our results indicate that subirrigation is a feasible system for soilless-cultivated tomato provided the nutrient solution is reduced to a 60% of the total concentration.

Subirrigation of Container-Grown Tomato II: Physical and Chemical Properties of the Growing Medium

“…Considering previously reported data [1] and the physical and chemical properties averaged across substrate layers, fruit yield increased as easily available water and substrate pH increased in subirrigated plants ( Figure 6), in contrast, in drip-irrigated plants, the yield decreased as easily available water and pH increased. The remaining physical properties exhibited similar tendencies on fruit yield.…”

“…Salt buildup in the upper layer of the medium negatively affects root and shoot growth, quality, and yield, especially in sensitive plants [7].The longer growing season of some vegetable species, compared to the shorter growing cycle of containerized ornamental plants, may more markedly affect the physical and chemical properties of the substrate; however, there is limited information on the effect of subirrigation on properties of the growing medium in containerized systems for vegetable plants production. The objectives of the present study were to determine the effects of the irrigation system (subirrigation vs. drip-irrigation) and the concentration of the nutrient solution on: i) the physical and chemical properties of the growing media; and ii) root development in containerized tomato (Solanum lycopersicum L.) plants in order to understand how subirrigation with reuse of the nutrient solution allows a significant increase in water use efficiency in tomato, as previously reported by Garcia-Santiago et al [1].…”

“…Planted containers were placed 40 cm apart within the row and rows were kept 120 cm apart. Additional information on the experimental set up and growing conditions are as described previously by Garcia-Santiago et al [1].…”

“…In conclusion, subirrigation with reuse of the nutrient solution is a promising strategy to reduce water waste through runoff and leaching as water use efficiency increases due to greater water retention properties in the substrate, the maintenance of an EC within a range the plants can tolerate, and a lower acidification of substrate pH.2 of 13 60% [1]. In a previous paper, we are reporting that 1 L of water was required to produce 300 to 460 g of fruit, compared to 50 g in drip-irrigated plants, demonstrating that subirrigation increases water use efficiency by 6× to 9× [1].The movement of nutrients and water within growing media, and the subsequent chemical and physical properties, is dependent on the type of irrigation system used [2][3][4][5]. In surface irrigation, gravitational forces move water and nutrients downwards from the top of the container [6], affecting air and water retention capacities [2] and resulting in salt buildup in the lower portion of the growing media profile [6].…”

“…2 of 13 60% [1]. In a previous paper, we are reporting that 1 L of water was required to produce 300 to 460 g of fruit, compared to 50 g in drip-irrigated plants, demonstrating that subirrigation increases water use efficiency by 6× to 9× [1].…”