Establishment of a cultivation method for leaf lettuce (Lactuca sativa var. crispa) and komatsuna (Brassica rapa var. perviridis) with high zinc content for patients with zinc deficiency and evaluation of its effectiveness.

BACKGROUND: Insufficient intake of zinc is associated with various diseases worldwide. To overcome this problem, we aimed to establish a method for cultivating leafy vegetables with high zinc content in hydroponics without inhibiting their growth. Furthermore, we evaluated the effectiveness of the cultivated leafy vegetables with high zinc content in zinc-deficient mice. RESULTS: By adjusting the zinc concentration in the hydroponic solution to 5 mg L-1 starting from 7 days before harvesting, the zinc content in leaf lettuce increased eight times of that in the control, without any inhibition of the growth. Furthermore, when oxidized glutathione (GSSG) was added simultaneously with zinc to the hydroponic solution, the zinc content further doubled (16 times of that in the control). Similar results were obtained with komatsuna and red leaf lettuce, although there was a difference in the effect of GSSG treatment. The effectiveness of leafy vegetables with high zinc content in ameliorating zinc deficiency was evaluated by feeding lettuce with high zinc content to zinc-deficient mice. High zinc content lettuce significantly increased the zinc content in the liver, kidneys, gastrocnemius, and tibia of these mice. CONCLUSION: We established a cultivation method for lettuce and komatsuna with high zinc content without inhibiting growth by adjusting the zinc concentration in the hydroponic solution at an appropriate concentration for an appropriate period. The result of feeding test indicates that the intake of leafy vegetables with high zinc content can ameliorate zinc deficiency and might be useful in protection from several diseases associated with this deficiency. © 2020 Society of Chemical Industry.

Controlled comparisons between soil and hydroponic systems reveal increased water use efficiency and higher lycopene and ß-carotene contents in hydroponically grown tomatoes.

There are many different types of systems used to grow food that are distinguished by ideology or the technology used. It is often difficult to directly compare yield and quality in different growth systems due to the complicated interactions between genotype, physiology and environment. Many published comparisons do not identify and acknowledge confounding factors. However, there is urgency to undertake controlled comparisons to identify the most efficient and effective food production systems, because the world faces considerable challenges to food supply with population rise, ongoing environmental degradation and the threat of climatic change. Here we compared soil with two hydroponic growth systems, drip irrigation and deep-water culture (DWC). It is often claimed that such systems differ in water use, yield and crop quality; however, such comparisons are often confounded by assessing plant and system parameters in different growth environments or where factors that are difficult to standardise between systems, such as nutrient status, are not controlled. We grew tomato (Solanum lycopersicum L.) in the three growth systems in two replicated experiments, in either a polytunnel or glasshouse. We controlled and monitored water use and nutrient levels across all systems as different fertilizer applications can influence the nutritional values of produce. Plants in the two hydroponic systems transpired less water and were more water-efficient with a lower product water use than plants grown in soil. Fruit yield was similar and total soluble solids and sugar levels were not significantly different between the three growing systems. However, levels of lycopene and ß-carotene were either similar or significantly higher in DWC compared to growth systems using soil or drip irrigation. Our results identify hydroponic systems as more water use efficient with DWC also capable of producing higher quality produce.

Effects of Photoperiod on Survival, Growth, Physiological, and Biochemical Indices of Redclaw Crayfish (Cherax quadricarinatus) Juveniles.

Through a 30-day experiment, this study investigated the effects of five photoperiods (0L:24D, 6L:18D, 12L:12D, 18L:6D, and 24L:0D) on the survival, enzyme activity, body color, and growth-related gene expression of redclaw crayfish (Cherax quadricarinatus) juveniles. The results showed that C. quadricarinatus juveniles under 18L:6D and 24L:0D photoperiods exhibited the highest survival rate, which was significantly higher than the survival rates of juveniles under the other three photoperiods (p < 0.05). However, the 0L:24D group had the highest final body weight and weight gain rate, significantly surpassing those of the 12L:12D, 18L:6D, and 24L:0D groups (p < 0.05). Regarding enzyme activity and hormone levels, juveniles under the 18L:6D photoperiod exhibited relatively higher activity of superoxide dismutase (SOD), acid phosphatase (ACP), and lysozyme (LZM) enzymes than those under other photoperiods, but their levels of melatonin and cortisol were relatively low. In addition, the 24L:0D group showed the highest malondialdehyde (MDA) content. Analysis of gene expression levels revealed that retinoid X receptor (RXR) and α-amylase (α-AMY) genes in C. quadricarinatus juveniles exhibited significantly higher expression levels under the 18L:6D photoperiod than those under the other four photoperiods (p < 0.05). With increasing daylight exposure, the body color of C. quadricarinatus changed from pale blue to yellow-brown. In summary, C. quadricarinatus juveniles achieved high survival rates, good growth performance, strong antioxidant stress response, and immune defense capabilities under an 18 h photoperiod. Therefore, in the industrial seedling cultivation of redclaw crayfish, it is recommended to provide 18 h of daily light. Further, the study demonstrated the ability to manipulate the body color of C. quadricarinatus through controlled artificial photoperiods. These findings provide essential technical parameters needed for the industrial cultivation of C. quadricarinatus juveniles.

Analysis of the evolution of water culture and water security in the Weihe River Basin over a 100 year-period.

The significance of water culture in addressing water crises and ensuring water security has garnered considerable attention, emerging as a focal point in global change and water science research. Water culture is a societal adaptation to changes in hydrological systems. However, this needs to be acknowledged within contemporary discourse on water security governance. This study utilized historical policy document data from many sources, including local municipal records from Shaanxi and Gansu, and water conservancy records. It aimed to identify the significant nodes and stages of policy transformation in the Weihe River Basin (WRB) during the last century (1949-2020). This study employed a content analysis method to elucidate the evolutionary patterns of water culture in the study region during the previous century. Drawing on the co-evolution framework, our investigation delved into the reciprocal relationship between changes in water culture and the evolution of water security in the WRB. Our findings indicated that water culture transformation in the WRB has undergone four significant stages: the Disaster-Resistant Hydraulic (1949-1966), Irrigation Hydraulic (1967-1998), Resources Hydraulic (1999-2010), and Ecological Hydraulic (2011-2020) phases. Water security assessment showed that policy attention varied across the different stages. The disaster-resistant hydraulic phase primarily addressed water-related disaster concerns, whereas the irrigation hydraulic phase emphasized the scarcity of water resources. The resource hydraulic phase focused on ensuring the security of the water environment, while the ecological hydraulic phase placed emphasis on safeguarding water sustainability. Moreover, we found that prevailing water policies prioritize resolving isolated issues; however, water security is a multifaceted systemic matter that requires a comprehensive approach. This study has the potential to offer policy makers a more comprehensive and systematic perspective, enabling them to enhance their understanding of the underlying nature of the problems. Additionally, this study can assist in developing future water security policies.

Effect of aquaponic water and substratum material on biofilm formation by Aeromonas hydrophila.

Aeromonas hydrophila is a zoonotic pathogen causing illness in fish and susceptible humans. This emerging pathogen has been isolated within aquaponic systems and could cause disease in fish and a hazard to humans consuming aquaponic produce. This study determined whether A. hydrophila from an aquaponic farm could form biofilms in aquaponic water and on materials used in these systems. A. hydrophila biofilm biomass and cell density in aquaponic water were evaluated by crystal violet staining and culture-based enumeration. Biofilm biomass and biofilm cell density were affected by the water source and A. hydrophila isolate (P < 0.05). A. hydrophila formed the most biomass from the beginning of deep-water culture (BDWC) water (OD570 0.202 ± 0.066) and the least from the end of deep-water culture (EDWC) water (OD570 0.140 ± 0.036; P < 0.05). Enumerated A. hydrophila from the biofilm varied among water sources; the fish tank water supported the greatest cell density (7.04 ± 0.71 log CFU/mL) while the EDWC supported the lowest cell density (6.76 ± 0.83 log CFU/mL). Biofilm formation was also evaluated on aquaponic materials such as nylon, polyvinyl chloride, polyethylene liner, bead filter, and foam. Biofilm formation on the liner had the greatest population (2.39 ± 0.022 log CFU/cm2), and the bead had the least (0.64 ± 0.039 log CFU/cm2; P < 0.05). Pathogenic organisms, such as A. hydrophila, may pose a greater risk to produce harvested from the BDWC and MDWC due to greater biofilm formation.

Symbiotic association of microalgae and plants in a deep water culture system.

In this study, microalgae culture (Chlorella vulgaris) and mint seedlings (Mentha spp.) were combined in a hydroponic system to improve plant growth. Mint seedlings were grown both in microalgae-containing and in microalgae-free trial groups, and both groups were subjected to aerated and non-aerated conditions to show the effect of aeration and microalgae co-cultivation on the mint weight and height. The plant quality was also determined with color measurements of the mint leaves. The increase in the weight of the plants was the highest in microalgae-containing and aerated group (0.47 g) and the lowest in microalgae-free and non-aerated group (0.22 g). On the other hand, the variation in the plant height was not significant between the groups, the growth was lateral. The best quality mint leaves were also produced in microalgae-containing and aerated group. Our results have revealed the symbiotic life of the mint plant placed in the hydroponic system with microalgae and demonstrated improved mint growth and quality. This co-cultivation system is also potentially more environmentally friendly compared to growing microalgae and mint independently because of lower cost of aeration and mixing for microalgae cultivation, higher nutrient consumption efficiency, and reduced nutrient outflow.

Aquaponics: a sustainable alternative to conventional agriculture in Egypt - a pilot scale investigation.

Conventional agriculture has been widely used to overcome food scarcity in Egypt, but in turn created new environmental, social, and economic problems. Aquaponics has a huge potential as a sustainable solution since it demonstrates promising results for urban food development while providing new entrepreneurship and start-up opportunities. Although it presents a big opportunity especially for developing countries like Egypt, it still requires further studies and researches to fully overcome foreseen challenges. This study discusses the possibility of implementing aquaponics as an alternative to conventional agriculture in Egypt through a comparison between aquaponics and conventional agriculture. The first section of this investigation analyzes the economic feasibility of aquaponics in terms of capital and operational expenditure costs. Then, an experimental comparative study is carried out examining two pilot-scale aquaponics systems (Deep water Culture system and Integrated Aqua-Vegaculture system), where crop quality (vitamins, heavy metals, and pesticides residues) of the two systems has been compared among each other, as well as to that of the commercially available organic food available in supermarkets. Results indicated that both systems produce high-quality safe organic food. The economic feasibility analysis indicated that Integrated Aqua-Vegaculture System is producing more crops with a wider variety of almost 20% less capital expenditure and operational expenditure costs. Fish production for both systems was close, yet slightly higher in Deep Water Culture. Although, on the short term, aquaponics entails relatively high capital and operational expenditure costs compared with conventional agriculture; yet, on the long term, it is more profitable, while saving up to 85% of the water wasted by conventional farming techniques. Finally, the study discusses the main limitations, drawbacks, and future of aquaponics in Egypt where public awareness and a new mindset are needed to highlight the link between agriculture and sustainability.

Maximum Plant Uptakes for Water, Nutrients, and Oxygen Are Not Always Met by Irrigation Rate and Distribution in Water-based Cultivation Systems.

Growing on rooting media other than soils in situ -i.e., substrate-based growing- allows for higher yields than soil-based growing as transport rates of water, nutrients, and oxygen in substrate surpass those in soil. Possibly water-based growing allows for even higher yields as transport rates of water and nutrients in water surpass those in substrate, even though the transport of oxygen may be more complex. Transport rates can only limit growth when they are below a rate corresponding to maximum plant uptake. Our first objective was to compare Chrysanthemum growth performance for three water-based growing systems with different irrigation. We compared; multi-point irrigation into a pond (DeepFlow); one-point irrigation resulting in a thin film of running water (NutrientFlow) and multi-point irrigation as droplets through air (Aeroponic). Second objective was to compare press pots as propagation medium with nutrient solution as propagation medium. The comparison included DeepFlow water-rooted cuttings with either the stem 1 cm into the nutrient solution or with the stem 1 cm above the nutrient solution. Measurements included fresh weight, dry weight, length, water supply, nutrient supply, and oxygen levels. To account for differences in radiation sum received, crop performance was evaluated with Radiation Use Efficiency (RUE) expressed as dry weight over sum of Photosynthetically Active Radiation. The reference, DeepFlow with substrate-based propagation, showed the highest RUE, even while the oxygen supply provided by irrigation was potentially growth limiting. DeepFlow with water-based propagation showed 15-17% lower RUEs than the reference. NutrientFlow showed 8% lower RUE than the reference, in combination with potentially limiting irrigation supply of nutrients and oxygen. Aeroponic showed RUE levels similar to the reference and Aeroponic had non-limiting irrigation supply of water, nutrients, and oxygen. Water-based propagation affected the subsequent cultivation in the DeepFlow negatively compared to substrate-based propagation. Water-based propagation resulted in frequent transient discolorations after transplanting in all cultivation systems, indicating a factor, other than irrigation supply of water, nutrients, and oxygen, influencing plant uptake. Plant uptake rates for water, nutrients, and oxygen are offered as a more fundamental way to compare and improve growing systems.

A novel plant-based-sea water culture media for in vitro cultivation and in situ recovery of the halophyte microbiome.

The plant-based-sea water culture medium is introduced to in vitro cultivation and in situ recovery of the microbiome of halophytes. The ice plant (Mesembryanthemum crystallinum) was used, in the form of juice and/or dehydrated plant powder packed in teabags, to supplement the natural sea water. The resulting culture medium enjoys the combinations of plant materials as rich source of nutrients and sea water exercising the required salt stress. As such without any supplements, the culture medium was sufficient and efficient to support very good in vitro growth of halotolerant bacteria. It was also capable to recover their in situ culturable populations in the phyllosphere, ecto-rhizosphere and endo-rhizosphere of halophytes prevailing in Lake Mariout, Egypt. When related to the total bacterial numbers measured for Suaeda pruinosa roots by quantitative-PCR, the proposed culture medium increased culturability (15.3-19.5%) compared to the conventional chemically-synthetic culture medium supplemented with (11.2%) or without (3.8%) NaCl. Based on 16S rRNA gene sequencing, representative isolates of halotolerant bacteria prevailed on such culture medium were closely related to Bacillus spp., Halomonas spp., and Kocuria spp. Seed germination tests on 25-50% sea water agar indicated positive interaction of such bacterial isolates with the germination and seedlings' growth of barley seeds.

Occurrence of cluster roots on Myrica cerifera L. (Myricaceae) in water culture in relation to phosphorus nutrition.

When Myrica cerifera was grown in a number of 1/1-strength Hoagland's solutions, each lacking one mineral nutrient, cluster roots formed only in solutions lacking phosphorus (P). In seedlings initially fertilized with various P concentrations, cluster root formation decreased with increasing P supply and was totally suppressed in solutions containing ≥ 1 mg P l-1 . As total root weight did not vary significantly between P treatments, the proportion of the root system expressed as cluster roots or non-cluster roots varied with phosphorus supply. A similar response to increasing levels of foliar-applied P suggests that it may be internal P concentration in the plant that determines the initiation of cluster roots and not external P levels in the soil. Nitrogen, supplied as fixed dinitrogen or nitrate, did not have any effect on development of cluster roots and it appears that the capacity of actinorhizal plants to fix nitrogen by symbiotic association with a soil micro-organism is of no significance to cluster root formation. While abundant root hair development and extensive mycorrhizal mycelium distribution in the rhizosphere may represent more efficient morphological forms of improving plant P uptake, the significance of cluster roots in relation to P nutrition and the mechanisms involved in their development warrant further investigation.