Alterations in the Chemical Composition of Spinach (Spinacia oleracea L.) as Provoked by Season and Moderately Limited Water Supply in Open Field Cultivation

Abstract

The current use and distribution of agricultural water resources is highly prone to effects of global climate change due to shifting precipitation patterns. The production of vegetable crops in open field cultivation often requires demanding water applications, being impaired in regions where climate change will increasingly evoke water scarcity. To date, increasingly occurring precipitation-free periods are already leading to moderate water deficits during plant growth, e.g., in southern Europe. Among all vegetable crops, leafy vegetables such as spinach (Spinacia oleracea L.) are particularly vulnerable to limited water supply, because leaf expansion is highly dependent on water availability. Besides biomass production, water limitation might also affect the valuable nutritional composition of the produce. Therefore, we investigated the impact of moderately reduced water supply on the chemical composition of spinach, cultivated in the open field in three consecutive years. Two different water supply treatments, full and reduced irrigation, were used in a randomized block design consisting of three sets of six plots each. In the reduced water supply treatment, the total amount of supplied water, including both irrigation and natural precipitation, amounted to 90%, 94% and 96% in 2015, 2016 and 2017, respectively, of the full, optimal water supply treatment. Spinach grown under limited water supply showed significantly higher fresh biomass-based contents of polyols (e.g., inositol, glycerol), ascorbic acid, potassium, nitrogen, phosphorous, zinc and manganese, as well as total flavonoids and carotenoids. Increased dry biomass-based levels were found for total inositol, zinc and manganese, as well as decreased levels for malic acid, fumaric acid, phosphate and chloride. Furthermore, we report a high seasonal variation of several minor phytochemicals, such as single flavonoids. Spinacetin derivatives, spinatoside-glucoside as well as a rather unusual hexuronylated methylenedioxy flavonoid showed highest amounts when grown under relatively low irradiation in autumn. Levels of patuletin derivatives tended to increase under high irradiation conditions during spring. In summary, the chemical composition of spinach was shown to be highly sensitive to moderately reduced water supply and seasonal variation, but the overall nutritional quality of fresh marketable spinach was only marginally affected when considering health-related constituents such as minerals, trace elements, flavonoids and carotenoids.

Effects of Coir-Based Growing Medium with Municipal Solid Waste Compost or Biochar on Plant Growth, Mineral Nutrition, and Accumulation of Phytochemicals in Spinach

“…This may be owing to genotype and/or growing conditions [ 31 ]. In spinach, carotenoid content is affected by water [ 35 ], nutrient uptake [ 36 ], etc. The Chl a/Chl b ratio was lower in plants grown in mixes than those grown in coir.…”

Impact of Plasma-Activated Water Treatment on Quality and Shelf-Life of Fresh Spinach Leaves Evaluated by Comprehensive Metabolomic Analysis

“…Consequently, the flavonoid level in vegetables is a decisive factor for the evaluation of food quality. Spinach has a substantial total flavonoid content of about 1000 mg/kg green mass, which normally remains relatively stable, although individual derivatives can vary considerably depending on the environmental conditions in the growth period and the post-harvest storage conditions [ 58 , 59 ]. Important flavonoid derivatives in spinach include spinacetins, patuletins, jaceidins, glucuronides and acylated di- and triglycosides of methylated and methylenedioxy derivatives of 6-oxygenated flavonols [ 60 ].…”

Horticultural Crop Response to Different Environmental and Nutritional Stress

“…The study shows the relationship of the irrigation water supply with that of the chemical composition of the Spinach (Spinacia oleracea L.) [8]. Trials of the study recorded a slight effect on the chemical composition of the plant from providing a moderate water supply which ultimately influenced the product quality of field-grown spinach plants.…”

“…The effect of environment conditions (temperature, rainfall, altitude, soil types, hail) [5][6][7][8][9], nutritional strategies [5,6,[10][11][12][13][14], water (stress, salinity) [5,8,12,15], container substrate of cultivation [16] on yield, yield traits and quality were analyzed in different crops in an open field [8,9,13,14,17] and greenhouses [5][6][7][10][11][12]15,16].…”

“…Different innovative strategies were presented that included protected structures, container type, cultivation techniques [5,10,16], symbiotic relationships [6,7], fertigation strategies [10] new agricultural management technologies (remote sensing, smartphone) [11] novel hybrids for breeding [12] spraying of Gibberellic acid [17], water supplies [8,15] and substrate [16] cover crops management [13] and stand reduction [9].…”