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The single-truss production system for tomatoes (Solanum lycopersicum L.) is a relatively new developed cultivation technology that guarantees high yields and high-quality fruit throughout the annual cycle. In this study, we examined the impact of electrical conductivity (EC) of nutrient solutions on the growth, yield, and fruit quality of tomatoes grown in a single-truss system in a hydroponic culture. Plants were supplied with nutrient solution at the following EC values: 0.8, 1.0, 1.2, and 1.4 mS·cm−1 in the spring and summer cycles, and at 1.0, 1.2, 1.4, and 1.6 mS·cm−1 in the winter cycle. In the spring cycle, the EC of the nutrient solution increased in all treatments, particularly after pinching the main stem. Increased EC values of nutrient solutions were also recorded at the 1.2 and 1.4 EC in the summer cycle and the 1.4 and 1.6 EC in the winter cycle. The leaf number per plant did not differ between treatments in all production cycles. The largest leaf area was found at the 1.2 and 1.4 EC in the spring cycle and the 1.0 and 1.2 EC during the summer. During the winter cycle, no differences in leaf area between treatments were observed. In spring, plants at the 1.2 and 1.4 EC had the highest yields and largest fruits, while during the summer, plants at the 1.0 and 1.2 EC produced the most fruit. In winter, the highest yield was found at the 1.4 EC. The soluble solids concentration (SSC) of fruit was increased at the 1.4 EC both in the spring and summer cycles, while in the winter cycle, there was no difference between the treatments. Only fruit at the 1.4 EC in the summer cycle had an increased acidity. The findings indicate that under greenhouse conditions, tomato cultivation in a single-truss system can be successful if the plants are supplied with a nutrient solution at an EC value of 1.2–1.4 mS·cm−1.

Floating seedling technology was used to propagate banana seedlings. The effects of different substrates, such as wood bran, vermiculite, and Murashige and Skoog (MS) nutrient solution, at different concentrations on the survival rate of banana floating seedlings and the growth of seedling stem, leaf, and root systems were compared. The results showed that banana seedlings treated with MS nutrient solution at one-half or one-third concentration or hydroponically with controlled slow-release fertilizer (0.5–0.6 g/plant) directly added to the wood bran substrate grew the fastest and had the largest number of roots. At 50 days after transplanting, these banana seedlings reached the standard of first-grade packaged seedlings, with the number of expanded leaves reaching 6.6 to 7.6, the width of leaves reaching 6.5 cm to 7.3 cm, and the root system relatively developed. The comprehensive characteristics of the seedlings were all better than those of other treatments. The results of this study have certain reference significance for accelerating seedling growth in greenhouses and large-scale production of disease-free banana seedlings. The banana floating seedling system we developed did not need watering every day and may be simpler than other seedling raising methods.

The floating raft constitutes a valuable system for growing herbs as it effectuates high yield and prime functional quality. However, the pressing need for advancing sustainability in food production dictates the reduction of chemical fertilizer inputs in such intensive production schemes through innovative cultivation practices. In this perspective, our work appraised the productive and qualitative responses of two "Genovese" basil genotypes (Eleonora and Italiano Classico) grown in a floating raft system with nutrient solutions of varied electrical conductivity (EC; 2 and 1 dS m−1) combined with root application of protein hydrolysate biostimulant at two dosages (0.15 and 0.3 0 ml L−1 of Trainer®). The phenolic composition, aromatic profile, and antioxidant activities (ABTS, DPPH, and FRAP) of basil were determined by UHPLC/HRMS, GC/MS, and spectrophotometry, respectively. "Eleonora" demonstrated higher number of leaves (37.04 leaves per plant), higher fresh yield (6576.81 g m−2), but lower polyphenol concentration (1440.81 μg g−1 dry weight) compared to "Italiano Classico." The lower EC solution (1 dS m−1) increased total phenols (+32.5%), ABTS, DPPH, and FRAP antioxidant activities by 33.2, 17.1, and 15.8%, respectively, and decreased linalool relative abundance by 5.5%. Biostimulant application improved crop performance and increased total phenolic concentration in both genotypes, with the highest phenolic concentration (1767.96 μg g−1 dry weight) registered at the lowest dose. Significant response in terms of aromatic profile was detected only in "Eleonora." Our results demonstrate that the application of protein hydrolysate may compensate for reduced strength nutrient solution by enhancing yield and functional quality attributes of "Genovese" basil for pesto. [ABSTRACT FROM AUTHOR]

Hydroponics is a viable alternative to open field cultivation for year-round vegetable production in urban areas. However, the total dependence on external chemical inputs (fertilizers) makes these systems often less environmentally sustainable. In this perspective, the use of biostimulants could represent a valuable and eco-friendly tool to limit the excessive use of fertilizers without a negative impact on the yield. To this end, our work aimed to evaluate the productive and physiological response of two cultivars of 'Genovese' basil (Eleonora and Italiano Classico) for the industrial production of "pesto" grown for 22 days in two nutrient solutions with different electrical conductivity (1 and 2 dS m−1) and the application of two doses of protein hydrolysates (0.15- and 0.30-mL L−1 of Trainer® in the nutrient solution). The mineral profile was evaluated by ion chromatography coupled with a conductivity detector, while pigments were evaluated by UV-Vis spectrophotometry. Generally, the nutrient solution concentration did not significantly affect the fresh yield of the two cultivars tested. On the contrary, the use of the maximum dose of biostimulant (BT2 = 0.30 mL L−1 of nutrient solution) increased fresh yield, leaf area, and ACO2 by 20.7, 27.5, and 17.6%, respectively, compared with the control. Using the lowest dose of biostimulant (BT1 = 0.15 mL L−1 of the nutrient solution) reduced nitrate by 6.6% compared with the control. The results obtained showed that basil cultivation in a floating raft system combined with biostimulant in the nutrient solution could be an excellent solution to improve productivity, reduce nitrate, and cut fertilizer costs. [ABSTRACT FROM AUTHOR]

Soilless cultivation is an important alternative to traditional agriculture and facilitates harvest by allowing for the precise control of plant nutrients to maximize the vegetable production of uniform fruits. Nutrient solution concentration is a critical factor affecting nutrient supply in soilless cultivation. Although some nutrient solution concentrations throughout the growth cycle for tomatoes have been developed, there are limited studies on nutrient solution concentrations at different phenological stages. Hence, we studied the effects of nutrient solution concentrations in different growth stages on the physiology, yield and fruit quality of cherry tomatoes with a previously developed nutrient solution formulation. The whole growth cycle of the tomato was divided into three stages which were irrigated with a nutrient solution with different electrical conductivities (ECs). A total of five treatments were set: CK (EC was 3.0 ms·cm−1 for the 1st–3rd stage), T1 (EC was 1.5 ms·cm−1 for the 1st stage, 3.0 ms·cm−1 for the 2nd–3rd stage), T2 (EC was 1.5 ms·cm−1 for the 1st stage, 3.0 ms·cm−1 for the 2nd stage, 4.5 ms·cm−1 for the 3rd stage), T3 (EC was 1.5 ms·cm−1 for the 1st–2nd stage, 3.0 ms·cm−1 for the 3rd stage), and T4 (EC was 1.5 ms·cm−1 for the 1st stage, 4.5 ms·cm−1 for the 2nd–3rd stage). The results showed that the tomato plants treated with T2 and T4 had the strongest growth (with the highest plant height and leaf formation) as well as the best leaf photosynthetic performance (the chlorophyll content and the net photosynthetic rate were significantly increased). Additionally, the use of T2 and T4 significantly improved cherry tomato fruit quality as reflected by the significant promotion of total soluble solids by 9.1% and 9.8%, respectively, as well as by the improvement of maturity by 12.9% and 13.7%, respectively. Additionally, the yields for treatments T2 and T4 were increased by 7.3% and 13.4%, respectively, which was mainly due to the increase in single fruit weight. More importantly, nutrient solution EC management improved fertilizer use efficiency: the partial fertilizer productivity of T1, T2, and T4 was increased by 2%, 7% and 14%, respectively, while that of T3 was reduced by 7%. A comprehensive comparison showed that the ranking of the effect on production was T4 > T2 > T1 > CK > T3. Our results suggest that the regulation of EC in different growth stages affects the growth and yield characteristics of cherry tomatoes. This study may provide some references for further research to adjust the concentration of nutrient solutions to improve the utilization rate of fertilizer and fruit quality. [ABSTRACT FROM AUTHOR]

The floating raft constitutes a valuable system for growing herbs as it effectuates high yield and prime functional quality. However, the pressing need for advancing sustainability in food production dictates the reduction of chemical fertilizer inputs in such intensive production schemes through innovative cultivation practices. In this perspective, our work appraised the productive and qualitative responses of two “Genovese” basil genotypes (Eleonora and Italiano Classico) grown in a floating raft system with nutrient solutions of varied electrical conductivity (EC; 2 and 1 dS m−1) combined with root application of protein hydrolysate biostimulant at two dosages (0.15 and 0.3 0 ml L−1 of Trainer®). The phenolic composition, aromatic profile, and antioxidant activities (ABTS, DPPH, and FRAP) of basil were determined by UHPLC/HRMS, GC/MS, and spectrophotometry, respectively. “Eleonora” demonstrated higher number of leaves (37.04 leaves per plant), higher fresh yield (6576.81 g m−2), but lower polyphenol concentration (1440.81 μg g−1 dry weight) compared to “Italiano Classico.” The lower EC solution (1 dS m−1) increased total phenols (+32.5%), ABTS, DPPH, and FRAP antioxidant activities by 33.2, 17.1, and 15.8%, respectively, and decreased linalool relative abundance by 5.5%. Biostimulant application improved crop performance and increased total phenolic concentration in both genotypes, with the highest phenolic concentration (1767.96 μg g−1 dry weight) registered at the lowest dose. Significant response in terms of aromatic profile was detected only in “Eleonora.” Our results demonstrate that the application of protein hydrolysate may compensate for reduced strength nutrient solution by enhancing yield and functional quality attributes of “Genovese” basil for pesto.

During the past few decades, vertical farming has attracted a lot of interest as an alternative food production method. Vertical farms use engineered growth environments and hydroponic cultivation techniques for growing plants indoors. One of the important factors in vertical farming for the cultivation of different plants is the amount of nutrients, which can be measured as electrical conductivity (EC). Studying the optimal EC is important for avoiding nutrient loss and deficiency in vertical farms. In this study, we investigated the effect of five EC levels (2, 1.2, 0.9, 0.7, and 0.5 dS m-1) of Hoagland nutrient solution on the growth and development of basil cultivar ‘Emily’ and lettuce cultivar ‘Batavia-Caipira’. During the study, the environmental parameters were kept fixed using an automatic dosing machine. The experiment was done in automatic vertical farms using the hydroponic ebb–flow cultivation technique with a temperature of 20 ± 1 °C, relative humidity of 50–60%, CO2 concentration of 450 ppm, pH = 6, the PPFD (photosynthetic photon flux density) of 215 ± 5.5 -mol m-2 s-1, and the photoperiod of 16:8 h (day/night). Each treatment was replicated four times. We studied the effects on several growth parameters (including the dry and fresh weight of leaves and roots, number of leaves, and leaf area) as well as the chlorophyll and nitrogen concentration of the leaves. According to the results, the basil and lettuce growth parameters among the five treatments have been significantly higher in the treatment with EC of 1.2 and 0.9 dS m-1. These EC values are lower than the recommended EC value given as the optimum in the previous studies. However, the concentration of chlorophyll and nitrogen show different trends and were higher in full strength of nutrient solution with EC = 2 dS m-1. [ABSTRACT FROM AUTHOR]

Phytoremediation technology using aquatic plants combined with microorganisms in constructed ecological floating bed (EFB) is increasingly applied to remediate eutrophic water. Utilizing the hydroponic Chlorophytum comosum, in combination with biofilm developed in polymeric fibrous carriers from sequencing batch reactor (SBR), to fabricate EFB, was implemented to reduce pollution and improve water quality for eutrophic water. The results indicated that the hydroponic C. comosum with long root and leaf, rich Chlorophyll, low cell membrane permeability and strong antioxidant activity enzymes was obtained through different nutrient concentration test. The combination of the hydroponic C. comosum and the biofilm developed in polymeric fibrous carriers could remove 75% chemical oxygen demand (CODCr), 61% permanganate index (PI), 50% total nitrogen (TN) and 57% total phosphorus (TP). Specially, the combination group exhibited higher removal efficiency of CODCr, PI and TN, compared with the sole biofilm group or the sole hydroponic C. comosum group. The result demonstrated that the combination of hydroponic C. comosum and the biofilm to construct the EFB was capacity to repair the eutrophic Huajin River. [ABSTRACT FROM AUTHOR]

Hydroponics is a viable alternative to open field cultivation for year-round vegetable production in urban areas. However, the total dependence on external chemical inputs (fertilizers) makes these systems often less environmentally sustainable. In this perspective, the use of biostimulants could represent a valuable and eco-friendly tool to limit the excessive use of fertilizers without a negative impact on the yield. To this end, our work aimed to evaluate the productive and physiological response of two cultivars of ‘Genovese’ basil (Eleonora and Italiano Classico) for the industrial production of “pesto” grown for 22 days in two nutrient solutions with different electrical conductivity (1 and 2 dS m−1) and the application of two doses of protein hydrolysates (0.15- and 0.30-mL L−1 of Trainer® in the nutrient solution). The mineral profile was evaluated by ion chromatography coupled with a conductivity detector, while pigments were evaluated by UV-Vis spectrophotometry. Generally, the nutrient solution concentration did not significantly affect the fresh yield of the two cultivars tested. On the contrary, the use of the maximum dose of biostimulant (BT2 = 0.30 mL L−1 of nutrient solution) increased fresh yield, leaf area, and ACO2 by 20.7, 27.5, and 17.6%, respectively, compared with the control. Using the lowest dose of biostimulant (BT1 = 0.15 mL L−1 of the nutrient solution) reduced nitrate by 6.6% compared with the control. The results obtained showed that basil cultivation in a floating raft system combined with biostimulant in the nutrient solution could be an excellent solution to improve productivity, reduce nitrate, and cut fertilizer costs.

Soilless cultivation is an important alternative to traditional agriculture and facilitates harvest by allowing for the precise control of plant nutrients to maximize the vegetable production of uniform fruits. Nutrient solution concentration is a critical factor affecting nutrient supply in soilless cultivation. Although some nutrient solution concentrations throughout the growth cycle for tomatoes have been developed, there are limited studies on nutrient solution concentrations at different phenological stages. Hence, we studied the effects of nutrient solution concentrations in different growth stages on the physiology, yield and fruit quality of cherry tomatoes with a previously developed nutrient solution formulation. The whole growth cycle of the tomato was divided into three stages which were irrigated with a nutrient solution with different electrical conductivities (ECs). A total of five treatments were set: CK (EC was 3.0 ms·cm−1 for the 1st–3rd stage), T1 (EC was 1.5 ms·cm−1 for the 1st stage, 3.0 ms·cm−1 for the 2nd–3rd stage), T2 (EC was 1.5 ms·cm−1 for the 1st stage, 3.0 ms·cm−1 for the 2nd stage, 4.5 ms·cm−1 for the 3rd stage ), T3 (EC was 1.5 ms·cm−1 for the 1st–2nd stage, 3.0 ms·cm−1 for the 3rd stage), and T4 (EC was 1.5 ms·cm−1 for the 1st stage, 4.5 ms·cm−1 for the 2nd–3rd stage). The results showed that the tomato plants treated with T2 and T4 had the strongest growth (with the highest plant height and leaf formation) as well as the best leaf photosynthetic performance (the chlorophyll content and the net photosynthetic rate were significantly increased). Additionally, the use of T2 and T4 significantly improved cherry tomato fruit quality as reflected by the significant promotion of total soluble solids by 9.1% and 9.8%, respectively, as well as by the improvement of maturity by 12.9% and 13.7%, respectively. Additionally, the yields for treatments T2 and T4 were increased by 7.3% and 13.4%, respectively, which was mainly due to the increase in single fruit weight. More importantly, nutrient solution EC management improved fertilizer use efficiency: the partial fertilizer productivity of T1, T2, and T4 was increased by 2%, 7% and 14%, respectively, while that of T3 was reduced by 7%. A comprehensive comparison showed that the ranking of the effect on production was T4 > T2 > T1 > CK > T3. Our results suggest that the regulation of EC in different growth stages affects the growth and yield characteristics of cherry tomatoes. This study may provide some references for further research to adjust the concentration of nutrient solutions to improve the utilization rate of fertilizer and fruit quality.

BACKGROUND: Through precise control of the nutrient solution (NS), closed soilless systems enable targeted manipulation of plant secondary metabolites, which constitute health‐promoting components of the human daily diet. A nutrient film technique (NFT) system was employed to assess the effect of NS macronutrient‐based concentration (full, half‐, and quarter‐strength corresponding to electrical conductivity (EC) of 1.5, 0.75, and 0.5 dS m−1) on the bioactive profile of red and green‐pigmented Salanova® butterhead lettuce. RESULTS: Half‐strength NS reduced fresh biomass of both cultivars by 14%, whereas quarter‐strength NS reduced the fresh biomass of green and red Salanova by 24% and 38%, respectively. However, moderate nutrient stress (half‐strength NS) boosted red Salanova total ascorbic acid, chlorogenic, chicoric, caffeoyl‐meso‐tartaric, total phenolic acids, and anthocyanins concentrations by 266%, 199%, 124%, 251%, 162%, and 380%, respectively compared with the control, full‐strength NS. CONCLUSIONS: Nutritional eustress and appropriate cultivar selection are effective means to increase phytochemical content and optimize year‐round production of lettuce in closed soilless systems. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

During the past few decades, vertical farming has attracted a lot of interest as an alternative food production method. Vertical farms use engineered growth environments and hydroponic cultivation techniques for growing plants indoors. One of the important factors in vertical farming for the cultivation of different plants is the amount of nutrients, which can be measured as electrical conductivity (EC). Studying the optimal EC is important for avoiding nutrient loss and deficiency in vertical farms. In this study, we investigated the effect of five EC levels (2, 1.2, 0.9, 0.7, and 0.5 dS m−1) of Hoagland nutrient solution on the growth and development of basil cultivar ‘Emily’ and lettuce cultivar ‘Batavia-Caipira’. During the study, the environmental parameters were kept fixed using an automatic dosing machine. The experiment was done in automatic vertical farms using the hydroponic ebb–flow cultivation technique with a temperature of 20 ± 1 °C, relative humidity of 50–60%, CO2 concentration of 450 ppm, pH = 6, the PPFD (photosynthetic photon flux density) of 215 ± 5.5 μmol m−2 s−1, and the photoperiod of 16:8 h (day/night). Each treatment was replicated four times. We studied the effects on several growth parameters (including the dry and fresh weight of leaves and roots, number of leaves, and leaf area) as well as the chlorophyll and nitrogen concentration of the leaves. According to the results, the basil and lettuce growth parameters among the five treatments have been significantly higher in the treatment with EC of 1.2 and 0.9 dS m−1. These EC values are lower than the recommended EC value given as the optimum in the previous studies. However, the concentration of chlorophyll and nitrogen show different trends and were higher in full strength of nutrient solution with EC = 2 dS m−1.

The effect of different nitrogen (N) concentrations on growth changes, leaf N concentration and accumulation patterns, N nutrition index (NNI), fresh weight yield, and N use efficiency (NUE) was determined for lettuce grown over three consecutive seasons (fall, winter, and spring) in a recirculating hydroponic system, under unheated and naturally lit hoop house in Uvalde, TX. The lettuce cultivars Buttercrunch, Dragoon, and Sparx were grown at six N concentrations, initially 100, 150, 200, 250, 300, and 400 mg·L-1 using a nutrient film technique (NFT). Leaf number, accumulated dry weight (DW) and N, and leaf area index (LAI) followed a logistic trend over time, characterized by a slow increase during early growth followed by a linear increase to a maximum. By contrast, plant total N concentrations were the highest at early stage and decreased slightly over time. Effect of season and cultivar on these growth traits was more pronounced than that of the N concentrations. Averaged across cultivar and N concentrations, DW in spring was 73% and 34% greater than that in fall and winter, respectively. At each sampling date, there were linear, quadratic, or cubic effects of N concentrations on each of these variables. The cultivar Sparx was the most productive, with 63% and 32% higher fresh weight yield in fall, 145% and 114% in spring, than 'Buttercrunch' and 'Dragoon', respectively. Increasing nutrient solution N concentrations from 100 to 400 mg·L-1 increased the yield from 5.9 to 6.7 kg·m-2 in fall, 8.1 to 10.7 kg·m-2 in winter, and 10.3 to 12.6 kg·m-2 in spring. The NUE was the highest at the lowest N concentration (100 mg·L-1) and decreased with increasing N concentrations. The NNI during mid- to late-growth stages was near or greater than one, even at the lowest N. These results demonstrated that N concentrations of 100-150 mg·L-1 maximized the growth and yield of hydroponically grown lettuce. [ABSTRACT FROM AUTHOR]

Hydroponically grown long-mat rice seedlings (HLMS) is a novel seedling cultivation method that improves work efficiency with lower labor costs, increases flexibility of seedling age, enables high-yield and high-efficiency rice production. Seedbed nutrient management is very important for the cultivation of vigorous rice seedlings under mechanical transplanting. Thus, it is of great importance for high yield formation to understand rice seedling quality, mechanical transplanting quality, field growth characteristics and yield formation affected by different nutrient solution concentrations. In this paper, field experiment was conducted in 2014 by using two different cultivars japonica rice (Wuyunjing 24) and indica hybrid rice (6 Liangyou 9368) under different nutrient solution concentrations S1, S2, S4 and S8 for HLMS. Those treatments mean 1, 2, 4, 8 times as much as original nutrient solution concentration, respectively, and the composition of original nutrients in the solution were 0.643 g/kg N, 0.615 g/kg P2O5, 0.359 g/kg K2O, 127.2 mg/kg Mg, 26.34 mg/kg Fe, 8.26 mg/kg Mn, 0.11 mg/kg Mo, 0.66 mg/kg B, 0.99 mg/kg Zn, 1.405 mg/kg Cu, 49 mg/kg SiO2, 709.1 mg/kg Ca. The results showed that there were increases in shoot dry biomass, seedling base stem diameter, root-developing ability, plant nitrogen content, leaf area index and photosynthetic rate along with the increase of nutrient solution concentrations for both cultivars before transplantation. However, under the high nutrient solution concentration (S8), the root growth (dry matter accumulation, root activity) was inhibited, seedling emergence rate and antioxidant enzymes activities (superoxide dismutase (SOD), peroxidase (POD)), malonaldehyde (MDA) contents in leaves and roots were decreased. Further, the missing hill rate was increased along with the increase of nutrient solution concentrations in both Wuyunjing 24 and 6 Liangyou 9368 cultivars, and it was significantly higher in S8 than that of S1, S2 and S4. The floating seedling rate was increased firstly and then decreased with the increase of nutrient solution concentrations. The differences of seedlings per hill among all treatments were not obvious for Wuyunjing 24, but the seedlings per hill of S1, S2, S4 treatments were respectively significantly higher than that of S8(P<0.05) for 6 Liangyou 9368. There was no significant difference in dry matter accumulation among treatments S2, S4 and S8 at maturity stage of Wuyunjing 24.; but for 6 Liangyou 9368, the dry matter accumulation at maturity of treatment S2 and S4 were significantly higher than that of treatment S1 and S8 , respectively. The period dry matter accumulation ratio from heading to maturity stage was increased firstly and then decreased with the increase of nutrient solution concentrations. The reduction of grain yield under treatment S1 (10.74 t/hm2 for Wuyunjing 24 and 10.96 t/hm2 for 6 Liangyou 9368) resulted from weaker seedling quality, slower seedling reviving in the paddy field, delayed tiller emergence, lower dry matter accumulation in the paddy field and less panicles. Under the treatment S2 and S4, the grain yield of Wuyunjing 24 was 12.09 and 11.64 t/hm2 respectively, and 6 Liangyou 9368 were 12.16 and 12.47 t/hm2. The grain yield increased with the increase of nutrient solution concentrations when the concentration of nutrient solution was equal or less than 4 times of the original solution. However, the grain yield did not continue to increase with the increase of nutrient solution concentration due to the non-increased panicles and the decreased spikelets number per panicle. The grain yield of Wuyunjing 24 and 6 Liangyou 9368 were 11.59 and 11.48 t/hm2 under S8 treatment). Therefore, the suitable nutrient solution concentration of HLMS was S2 for Wuyunjing 24 and S2-S4 for 6 Liangyou 9368. [ABSTRACT FROM AUTHOR]

Closed-cycle management of soilless cultivation is one of the promising strategies to prevent pollution, while increasing the efficiency of water and fertilizer use. However, in order to encourage the adoption of closed-cycle cultivation even in countries characterized by a low-tech greenhouse industry, effective easy-management systems need to be developed. A greenhouse experiment was carried out to determine the influence of two irrigation methods (drip irrigation open-cycle and subirrigation closed-cycle) and two nutrient solution (NS) concentrations (100 and 80% of the macro-element concentration normally used for soilless cultivation) on substrate electrical conductivity (EC), plant growth, gas exchange, yield, fruit quality, and water-use efficiency of green bean ( Phaseolus vulgaris L., cv. Saporro). Subirrigated plants showed higher substrate EC and higher Na + and Cl − concentrations, especially in the upper layer of the growing medium, while moisture distribution throughout the substrate profile showed an opposite trend and was more uniform in drip irrigation. The total fresh and dry biomass of the drip-irrigated plants were higher than in those grown in subirrigation, while whole plant dry matter percentage was lower. Differences in terms of plant height, number of leaves, leaf area, root growth, chlorophyll content, net photosynthesis, stomatal conductance and transpiration rate were recorded, with higher values in drip-irrigated plants. With closed-cycle subirrigation, green bean total and marketable yield (598 and 574 g plant −1 , respectively) were, on average, 33% lower than for drip irrigation, but fruit quality was higher in terms of “extra class” number of pods (93.6 vs 88.3%) and dry matter percentages. On average, both total and marketable yield were 9% higher with NS 80%, with a 13% higher water consumption, while slight or no effects were observed on net photosynthesis, stomatal conductance and shoot growth. The highest WUE (11.2 kg m −3 ) was obtained with subirrigation, where recirculating NS was never discharged, compared to drip irrigation (8.5 kg m −3 ). The green bean response to closed-cycle subirrigation showed a general decrease in productive performance. Detrimental effects were reduced by reducing the NS concentration. Lower yield could be compensated by savings of water and fertilizers and lower environmental impact. [ABSTRACT FROM AUTHOR]

Highlights: [•] We studied perlite substrate and nutrient solution for growing carrot hydroponically. [•] Carrot yield increased greatly in 0.6mm perlite with 100% ‘Enshi’ nutrient solution. [•] Shorter, wider and whitish carrots with reduced carotenoids found in 0.3mm perlite. [•] We recommended 0.6mm perlite and 100% ʻEnshiʼ nutrient solution for first culture. [•] Properly cleaned and disinfected perlites can be reused for growing carrot. [Copyright &y& Elsevier]

Nutrient solution concentration (NSC) is a critical factor affecting plant growth in hydroponics. Here, we investigated the effects of hydroponic NSC on the growth and yield of sweetpotato (Ipomoea batatas (L.) Lam.) plants. First, sweetpotato cuttings were cultivated hydroponically in three different NSCs with low, medium, or high electrical conductivity (EC; 0.8, 1.4, and 2.6 dS m−1, respectively). Shoot growth and storage root yield increased at 143 days after plantation (DAP), depending on the NSC. Next, we examined the effect of NSC changes at half of the cultivation period on the growth and yield, using high and low NSC conditions. In plants transferred from high to low EC (HL plants), the number of attached leaves increased toward the end of the first half of the cultivation period (73 DAP), compared with plants transferred from low to high EC (LH plants). Additionally, the number of attached leaves decreased in HL plants from 73 DAP to the end of the cultivation period (155 DAP), whereas this value increased in LH plants. These changes occurred due to a high leaf abscission ratio in HL plants. The storage root yield showed no significant difference between HL and LH plants. Our results suggest that the regulation of hydroponic NSC during the cultivation period affects the growth characteristics of sweetpotato. [ABSTRACT FROM AUTHOR]