Vegetable Crops Grown under High Soil Water Availability in Mediterranean Greenhouses

Abstract

The soil water availability of six vegetable crop cycles, irrigated with water of 0.4 dS m−1 electrical conductivity, was modified by varying the irrigation frequency in typical Mediterranean greenhouses at SE Spain. The soil matric water potential (SMP) in the middle of the loamy soil layer where most roots usually grow was maintained between −10 and −20 kPa (H), −20 and −30 kPa (C), and −30 and −50 kPa (L) for the crops grown under high, conventional and low soil water availability, respectively, while the total irrigation water applied was similar for the three treatments. The high soil water availability (H) did not improve the fresh weight of total, marketable and first class fruits, or the shoot biomass and partitioning. The irrigation frequency did not affect the total root biomass at the end of the autumn–winter cucumber, but the crop under L distributed its root biomass more homogenously throughout the soil profile than the crop under H. Regulating the soil water availability (maintaining the SMP higher than or close to the level at which crop water stress may occur) over the cycle as a function of crop conditions or farmers’ requirements appears to be a useful management practice for controlling soil root distribution or shoot partitioning.

Effect of Distribution Uniformity and Fertigation Volume on the Bio-Productivity of the Greenhouse Zucchini Crop

“…Létourneau et al [36] improved yields of strawberry crops (6.2%) with a soil matric potential of −15 kPa to −20 kPa. However, the results obtained in this study are in disagreement with the results obtained by Bonachela et al [38] who affirm that fruit-vegetable greenhouse crops can be irrigated under a relatively wide range of SMP values without significantly affecting their yields. This statement would be valid in the context that these authors study (experiments are not fully comparable), since they apply the same volume of irrigation water in all treatments (in the treatment of high availability of water in the soil and in the treatment of low availability of water in the soil) considering that the high or low availability of water in the soil is associated with the SMP before irrigation.…”

Can Organic Amendments Improve Soil Physical Characteristics and Increase Maize Performances in Contrasting Soil Water Regimes?

“…Consequently, the results of experiments based on Θ in a particular soil type are difficult to generalize to different soil types. To circumvent this problem, an increasing number of recent experiments have controlled the level of plant water stress by controlling and monitoring the soil Ψm [40][41][42]. However, the water-stress threshold values of Ψm varies depending on soil properties and the plant type.…”

“…Valença et al [43] indicated that Ψm ranging from −40 to −120 hPa caused water stress for papaya, but not for lettuce. For vegetable crops growing in a loamy sand, Bonachela et al [40] considered −100 to −200 hPa, −200 to −300 hPa and −300 to −500 hPa as high, conventional and low soil water availability, respectively. For an experiment in which maize plants were grown on a sandy material for a short time, Ahmed et al [44] set the Ψm (during 16 days) to −20 to −30 hPa to get non-stressing conditions, when Dowd et al [41] set the Ψm (during 9 days) to −1,000 hPa and −3,000 hPa for non-stressing and mildly stressing conditions, respectively.…”