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With depleting sources of fresh water, approaches must be taken to reduce the use of water in agricultural systems. Along with reduced usage, research should focus on using resources more efficiently. Hydroponic production systems offer higher resource use efficiency, such as water and fertilizer, compared to traditional agriculture systems. Notably, water usage can be reduced by more than 90% and fertilizer by 60% depending upon the system and crop. This review focuses on water and nutrient use efficiency of different crops in greenhouse production systems to further elucidate the current accomplishments and future needs in this research area. This is important because water and nutrient use efficiency is highly dependent upon multiple factors like type of crop, cultivars, environment, type of system used, nutrient concentration and form, flow rate of water, water depth, location, etc. Herein, nutrient film technique (NFT), deep-water culture, aeroponics, drip, and other systems were compared for different water and nutrient use efficiencies. Because different crops were used in these studies, direct comparison was limited, but we found that crop type and cultivars, NFT channel depth, and fertilization rate were among the most influential factors affecting nutrient use efficiency in hydroponic systems. Surprisingly, water use efficiency in aeroponic systems was greater when more nozzles were used. Aeroponic systems also showed greater water use efficiency when compared to NFT systems. Overall, this review highlights the resource use efficiency of different vegetable crops in hydroponic production systems and highlights opportunities for future research.
Regmi et al. (Mon,) studied this question.