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High-pressure sodium (HPS) lighting is increasingly replaced by LED lighting in lettuce greenhouse cultivation. In contrast to HPS lighting, LEDs do not heat radiation. Therefore, the leaf temperature is significantly lower under LEDs. This raises the question of whether LED lighting has a positive impact on the reduction in water consumption during lettuce production. In this paper, we investigated this question and found that the water consumption of lettuce produced under LEDs was significantly lower (−15%) than under HPS without loss of yield. We also found that supplementary lighting increases the concentrations of caffeoylquinic acid, dicaffeoyltartaric acid, dicaffeoylquinic acid and that of the total phenolic compounds in lettuce leaves by 61%, 39%, 163% and 38%, respectively. Only the LED fixture was also efficient enough to increase the concentration of caffeoyltartaric acid (+24%). Most of the phenolic compounds showed a very strong positive correlation with the chlorophyll concentration in lettuce, which predominated in the leaves exposed to the LED lighting. Based on these facts, we conclude that by optimizing the light composition, more sustainable plant production, higher concentrations of chlorophyll and some phenolic compounds are possible.
Dennis Dannehl; Thomas Schwend; Daniel Veit; Uwe Schmidt. LED versus HPS Lighting: Effects on Water and Energy Consumption and Yield Quality in Lettuce Greenhouse Production. Sustainability 2021, 13, 8651 .
AMA StyleDennis Dannehl, Thomas Schwend, Daniel Veit, Uwe Schmidt. LED versus HPS Lighting: Effects on Water and Energy Consumption and Yield Quality in Lettuce Greenhouse Production. Sustainability. 2021; 13 (15):8651.
Chicago/Turabian StyleDennis Dannehl; Thomas Schwend; Daniel Veit; Uwe Schmidt. 2021. "LED versus HPS Lighting: Effects on Water and Energy Consumption and Yield Quality in Lettuce Greenhouse Production." Sustainability 13, no. 15: 8651.
In agriculture, the increasing scarcity of arable land and the increase in extreme weather conditions has led to a large proportion of crops, especially vegetables, being cultivated in protected soilless cultivation methods to provide people with sufficient and high-quality food. Rockwool has been used for decades as a soil substitute in soilless cultivation. Since rockwool is not biodegradable, it is disposed in landfills after its use, which nowadays leads to ecological concerns and drives the search for alternative substrates, especially organic materials. The objectives of this study were to investigate the effects of organic materials (wood chips, sphagnum moss, and hemp fibers) in relation to rockwool substrate on plant growth and quality of lettuce as a result of physical and chemical properties of the mentioned substrates. We were able to show that sphagnum moss is a suitable substitute substrate for lettuce cultivation, contrary to hemp. All investigated substrates presented good physical properties, but differed in their decomposition stability. Within 8 weeks, 30% of the hemp and about 10% of both sphagnum and wood materials were degraded. It was concluded that the increased microbiological activity immobilized nitrogen and led to oxygen deficiency in the rhizosphere and resulted in increased phenolic acid contents in lettuce but poor yield on hemp. Sphagnum caused a pH decrease and accumulation of ammonium in the nutrient solution and allowed the highest yield for lettuce at moderate phenolic acid contents. Low yields were obtained on wood, which could possibly be increased by optimized nutrient solution, so that wood as an alternative to rockwool was not excluded. By applying used organic substrates as soil additives on arable land, the nutrients accumulated in it might fertilize the open field crops, thus saving mineral fertilizers. This, together with the avoidance of waste, would contribute to a greater sustainability.
Annika Nerlich; Dennis Dannehl. Soilless Cultivation: Dynamically Changing Chemical Properties and Physical Conditions of Organic Substrates Influence the Plant Phenotype of Lettuce. Frontiers in Plant Science 2021, 11, 1 .
AMA StyleAnnika Nerlich, Dennis Dannehl. Soilless Cultivation: Dynamically Changing Chemical Properties and Physical Conditions of Organic Substrates Influence the Plant Phenotype of Lettuce. Frontiers in Plant Science. 2021; 11 ():1.
Chicago/Turabian StyleAnnika Nerlich; Dennis Dannehl. 2021. "Soilless Cultivation: Dynamically Changing Chemical Properties and Physical Conditions of Organic Substrates Influence the Plant Phenotype of Lettuce." Frontiers in Plant Science 11, no. : 1.