Abstract
As climate change evokes changing precipitation patterns, the cultivation of vegetable crops in open fields might become more difficult in the future. Nowadays, many vegetable growers are already facing relatively long unprecedented precipitation-free periods. In many growing regions, irrigation is only available to a limited extent or not at all, and the cultivated plants will suffer from moderate water stress more often. Therefore, we examined the effects of moderately-reduced water supply on the chemical composition of pickling cucumber, cultivated in an open field and in a separate greenhouse trial. In the field trial, the reduced water supply treatment (RWS) provided 85–90% of the total water amount of the well-watered control treatment (CTR), applying a randomized block design with six replications comprising two consecutive weekly harvest periods. In fruits obtained by cultivation with reduced irrigation, levels of malic acid, calcium, and magnesium significantly increased, while those of phosphate, phosphorous, nitrogen, and iron decreased based on dry matter. Fresh matter-related results additionally revealed a decrease of myo-inositol and zinc, while sugars and total phenols remained unchanged. In the greenhouse experiment, the RWS obtained 60% of the irrigation amount of the CTR. Here, single cucumber compartments (exocarp, mesocarp, and endocarp) were examined. Chemical compositions changed in a similar, but more pronounced, manner as compared to the open field trial. The levels of individual, nutritionally relevant carotenoids in the peel of pickling cucumber, like lutein and β-carotene, were affected by RWS. Regarding the nutritional quality of fresh marketable cucumber fruits, malic acid, certain minerals and trace elements, as well as the carotenoids were shown to be sensitive to moderate water reduction.
Highlights
The nutritional composition of vegetables grown in open fields depends highly on the water supply and local climate conditions
The univariate results clarified that sugars and polyols, as well as most of trace elements and polyphenols, had been little affected by mildly-reduced water supply. These findings are partly contrary to our results observed for vegetables, such as spinach and radish grown within the same field experiment under similar conditions, where we observed a significant increase of polyols, such as inositol in both vegetables upon moderate water supply reduction [4,5]
Elements and polyphenols, had been little affected by mildly-reduced water supply
Summary
The nutritional composition of vegetables grown in open fields depends highly on the water supply and local climate conditions. Growers worldwide already struggle with the consequences of rising temperatures and fluctuating precipitation patterns, which might be temporarily absent during the cultivation period These climate change-driven uncertainties are very likely to affect vegetable production in certain regions. Future projections indicate a decrease in the potential water availability during summer in the Mediterranean regions [1] that will affect the complex interactions in the plants’ metabolism in any case, especially under highly heterogenic conditions in open field production. Such variable growing conditions in open field cultivation severely complicate the derivation of suitable crop management strategies for farmers. In addition to those climate-related effects, the picking time in relation to the plants’ growth stages has been reported to have an effect on the chemical composition of fruity vegetables such as cucumber [2], which are being harvested over a certain period during the plants’
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