We investigated the effects of fermented nori ( <i> Pyropia yezoensis </i> ) liquid fertilizers on plant growth, soil plant analysis development (SPAD) values, and nutrient uptake of komatsuna ( <i> Brassica rapa </i> L. var. wakana komatsuna) plants. The four types of fermented nori seaweed liquid fertilizers (SLFs) evaluated in this study were prepared by anaerobic fermentation of unwashed nori (SLF1), aerobic fermentation of unwashed nori (SLF2), anaerobic fermentation of washed nori (SLF3), and aerobic fermentation of washed nori (SLF4). In Experiment 1, the highest plant growth, SPAD, and nutrient uptake values were obtained from treatment with SLF2 and SLF4. There were no significant differences between the effects of basal and foliar application of SLFs, except for iodine (I) content; plants treated with SLF1 had the highest I content. In Experiment 2, plant growth and nutrient uptake decreased with higher concentrations of SLFs. Plants treated with 25% SLF2 + 75% chemical fertilizer (CF) or 25% SLF4 + 75% CF exhibited significantly higher plant growth and nutrient uptake. The highest I content resulted from treatment with 75% SLF1 + 25% CF or 100% SLF1. Taken together, our results showed that 25% SLF + 75% CF produced the best plant growth characteristics, nutrient uptake, and I content relative to the controls. Therefore, basal application of these liquid organic fertilizers can be used to increase productivity, nutrient uptake, and I content and to reduce nitrate-nitrogen content in komatsuna production.
Excessive use of inorganic fertilizers has detrimental effects on the physicochemical properties of soil. In contrast, organic fertilizers contribute to the deposition of crop residues and physicochemical properties of soil [
Nori (Pyropia yezoensis) is cultivated on the coast of the Ariake Sea in Fukuoka Prefecture, which has become a leading area of nori production in Japan (Ministry of Agriculture, Forestry, and Fishery, 2015) through use of the pole system cultivation method [
Nori is rich in protein, iodine (I), dietary fiber, and several vitamins including folic acid and vitamins B12 and K (Japan Food Standard Ingredient
A vegetable-rich diet provides many health-promoting substances such as minerals, vitamins (A, C, B1, B6, B9, and E), dietary fiber, and phytochemicals. Despite the nutritional benefits of eating vegetables, they also contain substances that adversely affect human health, such as nitrates and nitrites [
In recent years, liquid fertilizers based on seaweed extracts have been commercialized [
Experimental materials included faded waste nori, molasses (SPOON SUGAR Co. Ltd., Hyogo, Japan), well water, and the microbial material BASE EIGHT (Sunpowers Co. Ltd., Nagasaki, Japan). Thirty-three liters of well water, 7 kg of nori (unwashed or washed with well water), 2.5 L of molasses, and 2.5 L of BASE EIGHT (total volume 45 L) were added to a 50-L fermentation tank (MH-50; Suico Co. Ltd., Hyogo, Japan) and mixed well. The nori was fermented aerobically and anaerobically. Fermentation was carried out for 3 months from April to July of 2016. Four types of SLF were produced: anaerobically fermented unwashed nori (SLF1), aerobically fermented unwashed nori (SLF2), anaerobically fermented washed nori (SLF3), and aerobically fermented washed nori (SLF4).
Soil pot Experiment 1 was conducted in a greenhouse at Kyushu University from October 10 to November 14, 2017. A randomized complete block (RCB) design was used with three replications and 12 treatments. Treatments were basal and foliar application of chemical fertilizer (CF), 0.4 g of NPK (in distilled water, foliar); 0.3 g of NPK per pot + 0.1 g of N derived from each of the four SLFs, SLF1 (all N content from seaweed), SLF2 (all N content from seaweed), SLF3 (all N content from seaweed), and SLF4 (all N content from seaweed); and a control (NPK)0. Foliar spray applications of 10 mL of 10-fold dilutions of original solutions of SLF1, SLF2, SLF3, and SLF4; CF in distilled H2O; and distilled H2O as a control were performed at 5-day intervals beginning 14 days after sowing.
For pot preparation, a/5000 Wagner pot was filled with 3.5 kg (oven-dried basis) of Futsukaichi soil. The physiochemical properties of Futsukaichi soil were analyzed by Myint et al. (2011) [
Physicochemical property | Value | Physicochemical property | Value |
---|---|---|---|
Soil pH (Soil:H2O; 1:2.5) | 6.11 | Available P (mg 100 g−1) | 5.42 |
EC (Soil:H2O; 1:5) (mS/m) | 1.77 | CEC (molc・kg−1) | 12.55 |
Total N (g・ka−1) | 0.68 | Exc. Ca (molc・kg−1) | 10.76 |
Mineralizable N (mg 100 g−1) | 0.06 | Exc. Mg (molc・kg−1) | 0.89 |
Total P2O5 (g・kg−1) | 0.37 | Exc. K (molc・kg−1) | 0.37 |
Abbreviation: CEC, cation exchangeable capacity: Exc., exchangeable.
KH2PO4 + K2HPO4). The water holding capacity of the soil was maintained at 60% at the time of sowing.
To study the effects of application of the SLFs in various ratios with CF, soil pot Experiment 2 was conducted in a greenhouse at Kyushu University from April 7 to May 5, 2018. An RCB design was used with three replications and 18 treatments. Basal application treatments included 0.5 g of NPK (100% CF), 0.5 g of N derived from each of the four SLFs (100% SLF, 25% of each SLF + 75% CF, 50% of each SLF + 50% CF, and 75% of each SLF + 25% CF), and a control (NPK)0. All SLF treatments in Experiment 2 were calculated based on the total N content. The pots were prepared as in Experiment 1. The CF contained 0.5 g of N from (NH4)2SO4, 0.5 g of P2O5, and 0.5 g of K2O (from KH2PO4 + K2HPO4). The water holding capacity of the soil was maintained at 60% at the time of sowing.
Komatsuna seeds were sown at 15 seeds per pot and the germinated seedlings were thinned 10 days after sowing to five plants per pot. The pots were watered weekly with tap water according to the water holding capacity of each pot when the pot weight decreased to 200 - 300 g.
Plant growth characteristics (leaf number and leaf length) were measured and the Soil Plant Analysis Development (SPAD) values were recorded at 3-day intervals beginning 10 days after sowing using a chlorophyll meter (SPAD-502, Konica Minolta Sensing Inc., Osaka, Japan). The final data collection was performed 1 day before harvest. After 35 days, the plants were harvested by cutting at the cotyledonary node and the plants were washed three times with deionized water to remove the nutrients contained in the foliar spray. Plants were freeze-dried for 72 h for I extraction and oven dried at 70˚C for 72 h for nutrient analysis and measurement of shoot dry weight (DW; g).
Oven-dried shoot samples were ground to fine powder using a Cyclotec 1093 sample mill (100 - 120 mesh, Tecator AB, Hoedanaes, Sweden). The fine powders were digested using the salicylic acid-H2SO4-hydrogen peroxide (H2O2) digestion method [
To determine the I content of plants, samples were extracted with tetramethylammonium hydroxide [(CH3)4NOH, TMAH] according to the extraction method of Fecher et al. [
The NO3-N content of plant samples was determined using a rapid colorimetric method by nitration of salicylic acid according to the method of Cataldo et al. [
Data were statistically analyzed using STATISTIX 8 (Analytical Software, Tallahassee, FL, USA) software and the mean values were compared using Tukey’s HSD test at P < 0.05.
The nutrient contents of the four SLFs evaluated in this study are shown in
SLFs | N | P | K | Ca | Mg | Na |
---|---|---|---|---|---|---|
Concentration (mM) | ||||||
SLF1 | 49.64 ± 0.10 | 4.13 ± 0.08 | 55.12 ± 0.13 | 13.10 ± 0.25 | 24.48 ± 0.21 | 59.37 ± 0.87 |
SLF2 | 107.68 ± 0.93 | 3.93 ± 0.11 | 59.34 ± 1.53 | 11.52 ± 0.36 | 23.04 ± 0.41 | 61.88 ± 0.33 |
SLF3 | 42.18 ± 0.52 | 3.71 ± 0.11 | 40.03 ± 0.13 | 10.09 ± 0.39 | 15.22 ± 0.41 | 14.35 ± 0.87 |
SLF4 | 76.90 ± 0.83 | 4.17 ± 0.00 | 38.36 ± 1.28 | 12.71 ± 0.04 | 18.10 ± 0.00 | 22.51 ± 0.76 |
Data show mean values ± standard deviation (SD).
SLFs | NH4+ | NO3− | H2PO4− | CL− | SO42− | pH | EC |
---|---|---|---|---|---|---|---|
Concentration (mM) | (s/m) | ||||||
SLF1 | 0.12 ± 0.04 | 2.68 ± 0.00 | 0.84 ± 0.00 | 2.09 ± 0.00 | 0.26 ± 0.00 | 3.48 ± 0.01 | 1.51 ± 0.01 |
SLF2 | 63.56 ± 0.56 | 3.03 ± 0.10 | 1.65 ± 0.03 | 2.15 ± 0.00 | 0.17 ± 0.00 | 7.16 ± 0.01 | 2.06 ± 0.01 |
SLF3 | 0.40 ± 0.00 | 1.94 ± 0.02 | 0.85 ± 0.01 | 1.43 ± 0.00 | 0.23 ± 0.00 | 3.85 ± 0.01 | 1.01 ± 0.00 |
SLF4 | 50.22 ± 0.60 | 2.08 ± 0.06 | 2.13 ± 0.02 | 2.01 ± 0.00 | 0.26 ± 0.00 | 6.38 ± 0.01 | 1.51 ± 0.00 |
Data show mean values ± standard deviation (SD).
Plant growth characteristics and SPAD values differed significantly among plants treated with basal and basal-plus-foliar applications of SLFs or CF and control (NPK)0 plants (
Uptake of N, P, K, Ca, Mg, and Na by plants treated with basal and basal-plus-foliar applications of the four SLFs or CF differed significantly from that of the control plants (
Basal and basal-plus-foliar applications of SLF1 resulted in significantly higher I content (38.30 and 39.30 µg・g−1, respectively) than the control treatment (
Basal and basal-plus-foliar application of CF produced significantly higher NO3-N (1.3 and 1.1 mg・g−1, respectively) content than all basal and basal-plus-foliar applications of SLF treatments (
Treatments | Application (AVG) | Leaf no plant−1 | Leaf length (cm) | Shoot dry weight g∙pot−1 | SPAD |
---|---|---|---|---|---|
Control | B | 5.10 ± 0.03 d | 12.07 ± 0.60 c | 2.71 ± 0.14 e | 32.50 ± 0.9 e |
B + F | |||||
CF | B | 8.45 ± 0.24 ab | 23.34 ± 1.22 ab | 10.85 ± 1.10 ab | 50.65 ± 1.3 a |
B + F | |||||
SLF1 | B | 7.51 ± 0.24 c | 22.31 ± 0.71 b | 8.02 ± 0.83 d | 45.22 ± 0.9 d |
B + F | |||||
SLF2 | B | 8.39 ± 0.26 ab | 24.14 ± 0.53 a | 10.27 ± 0.97 bc | 47.22 ± 1.1 bc |
B + F | |||||
SLF3 | B | 8.04 ± 0.35 b | 22.82 ± 0.71 ab | 9.49 ± 0.44 c | 46.18 ± 1.0 cd |
B + F | |||||
SLF4 | B | 8.77 ± 0.24 a | 22.87 ± 0.77 ab | 11.65 ± 0.48 a | 48.92 ± 1.1 b |
B + F | |||||
Source of variance | |||||
Treatments | 0.49** | 1.43** | 1.53** | 1.89** | |
Application method | ns | ns | ns | 0.73** | |
Interaction (T × A) | ns | ns | ns | ns | |
CV% | 3.57 | 3.75 | 9.17 | 2.34 |
Data show mean values ± standard deviation (SD) in each column followed by the same letters are not significantly different at P < 0.05 (Tukey’s test). T: treatment; A: application; CF: chemical fertilizer; B: basal, B + F: basal plus foliar. *P < 0.05; **P < 0.01.
Treatments | Application (AVG) | N | P | K | Ca | Mg | Na |
---|---|---|---|---|---|---|---|
Control | B | 30.89 ± 1.89 c | 24.71 ± 1.99 c | 46.50 ± 6.77 e | 51.79 ± 3.54 d | 4.45 ± 0.46 d | 5.90 ± 0.86 e |
B + F | |||||||
CF | B | 325.52 ± 12.42 a | 138.58 ± 11.73 a | 321.02 ± 15.61 d | 227.00 ± 27.20 b | 14.56 ± 1.38 ab | 74.51 ± 10.35 a |
B + F | |||||||
SLF1 | B | 248.85 ± 13.35 b | 108.82 ± 8.99 b | 394.52 ± 28.72 c | 180.83 ± 15.55 c | 10.87 ± 1.36 c | 23.68 ± 4.66 d |
B + F | |||||||
SLF2 | B | 317.84 ± 12.25 a | 123.11 ± 7.83 ab | 425.96 ± 10.13 ab | 233.93 ± 23.79 ab | 15.73 ± 2.31 a | 59.03 ± 7.95 b |
B + F | |||||||
SLF3 | B | 279.14 ± 28.31 b | 126.99 ± 8.80 a | 437.28 ± 9.21 a | 207.98 ± 13.52 bc | 12.40 ± 0.66 bc | 20.20 ± 5.98 d |
B + F | |||||||
SLF4 | B | 325.78 ± 22.03 a | 132.83 ± 9.44 a | 401.55 ± 14.49 bc | 265.45 ± 17.47 a | 17.17 ± 1.01 a | 39.97 ± 7.67 c |
B + F | |||||||
Source of variance | |||||||
Treatments | 26.66** | 17.53** | 33.24** | 35.85** | 2.46** | 12.88** | |
Application method | ns | ns | ns | ns | 0.95* | ns | |
Interaction (T × A) | ns | ns | ns | ns | ns | ns | |
CV% | 7.3 | 8.93 | 5.47 | 10.25 | 10.92 | 19.64 |
Data show mean values ± standard deviation (SD) in each column followed by the same letters are not significantly different at P < 0.05 (Tukey’s test). T: treatment; CF: chemical fertilizer; A: application; B: basal, B + F: basal plus foliar. *P < 0.05; **P < 0.01.
Plant growth and SPAD values of plants treated with combinations of SLFs and CF in various proportions differed significantly from those of control plants (
N, P, K, Ca, Mg, and Na uptake differed significantly between the plants treated with various proportions of SLFs and the control plants (
The I content of plants treated with 25% SLF4 + 75% CF or 75% SLF4 + 25% CF and the control plants differed significantly from those of plants treated with any of the other proportions of SLFs and CF (
Basal and basal-plus-foliar applications of CF, 100% SLF1, and 75% SLF4 + 25% CF produced significantly higher NO3-N contents of 0.43, 0.38, and 0.38 mg・g−1, respectively, than all of the other SLF treatments (
Treatments | Leaf no plant−1 | Leaf length (cm) | Shoot DW g・pot−1 | SPAD |
---|---|---|---|---|
Control | 6.19 ± 0.11 j | 12.20 ± 0.65 h | 4.09 ± 0.13 g | 34.87 ± 0.25 i |
CF 100% | 10.83 ± 0.03 a | 24.05 ± 0.54 a | 17.19 ± 0.32 ab | 49.30 ± 0.16 ab |
SLF1 25% + CF 75% | 9.99 ± 0.06 de | 22.97 ± 0.40 ab | 14.81 ± 0.79 cde | 46.27 ± 0.61 ef |
SLF1 50% + CF 50% | 8.89 ± 0.25 g | 19.39 ± 0.37 ef | 9.74 ± 0.27 f | 45.50 ± 0.41f |
SLF1 75% + CF 25% | 6.91 ± 0.14 i | 15.82 ± 0.43 g | 3.83 ± 0.29 g | 40.77 ± 0.19 i |
SLF1 100% | 5.11 ± 0.84 k | 10.68 ± 0.62 i | 1.33 ± 0.35 h | 39.57 ± 0.37 hi |
SLF2 25% + CF 75% | 10.47 ± 0.22 ab | 24.03 ± 0.12 a | 18.08 ± 0.74 a | 48.80 ± 0.28 abc |
SLF2 50% + CF 50% | 10.00 ± 0.04 cde | 21.37 ± 0.09 bcd | 15.55 ± 0.70 bcd | 47.07 ± 0.24 de |
SLF2 75% + CF 25% | 9.96 ± 0.06 de | 20.37 ± 0.27 def | 14.13 ± 0.64 de | 47.80 ± 0.14 bcd |
SLF2 100% | 9.28 ± 0.20 fg | 19.62 ± 0.10 ef | 12.92 ± 0.99 de | 46.07 ± 0.12 ef |
SLF3 25% + CF 75% | 9.92 ± 0.10 de | 22.62 ± 0.27 b | 15.86 ± 0.23 bcd | 49.57 ± 0.33 abcd |
SLF3 50% + CF 50% | 9.65 ± 0.09 ef | 20.71 ± 0.51 de | 12.85 ± 0.29 e | 43.97 ± 0.17 g |
SLF3 75% + CF 25% | 8.99 ± 0.02 g | 18.98 ± 0.10 f | 10.27 ± 1.45 f | 43.53 ± 0.50 g |
SLF3 100% | 7.67 ± 0.55 h | 16.51 ± 0.45 g | 5.47 ± 0.78 g | 42.67 ± 0.48 gh |
SLF4 25% + CF 75% | 10.57 ± 0.38 ab | 24.09 ± 0.05 a | 18.37 ± 0.38 a | 48.97 ± 0.95 ab |
SLF4 50% + CF 50% | 10.51 ± 0.34 abc | 22.46 ± 0.41 bc | 17.01 ± 0.56 abc | 47.43 ± 0.42 cde |
SLF4 75% + CF 25% | 10.23 ± 0.29 bcd | 21.07 ± 0.11 cd | 16.74 ± 0.61 abc | 47.90 ± 0.16 abcd |
SLF4 100% | 10.31 ± 0.35 bcd | 21.11 ± 0.13 cd | 15.37 ± 0.28 bcd | 49.63 ± 0.40 abcd |
Data show mean values ± standard deviation (SD) in each column followed by the same letters are not significantly different at P < 0.05 (Tukey’s test).
Treatments | N | P | K | Ca | Mg | Na |
---|---|---|---|---|---|---|
Control | 46.43 ± 1.65 i | 42.62 ± 0.09 ij | 44.92 ± 1.51 i | 113.6 ± 8.27 g | 8.90 ± 0.53 h | 11.84 ± 3.02 f |
CF | 356.14 ± 14.44 a | 219.57 ± 0.30 a | 362.13 ± 1.95 a | 464 ± 19.36 ab | 37.22 ± 1.32 bc | 127.08 ± 3.77 a |
SLF1 25% + CF 75% | 252.76 ± 14.30 cde | 150.41 ± 0.19 cd | 252.76 ± 0.80 cde | 337.20 ± 10.46 de | 21.60 ± 0.40 ef | 64.22 ± 5.83 bcd |
SLF1 50% + CF 50% | 191.27 ± 4.28 fg | 112.23 ± 0.38 fg | 191.27 ± 0.34fg | 243.56 ± 17.94 f | 17.61 ± 0.92 fg | 51.89 ± 3.92 d |
SLF1 75% + CF 25% | 161.06 ± 7.23 gh | 57.46 ± 0.01 hi | 161.06 ± 0.69 gh | 107.96 ± 14.62 gh | 10.26 ± 0.46 h | 50.98 ± 3.33 d |
SLF1 100% | 59.35 ± 15.32 i | 20.36 ± 0.01 j | 59.35 ± 0.11 i | 32.53 ± 8.49 h | 3.15 ± 0.55 i | 18.14 ± 4.49 f |
SLF2 25% + CF 75% | 361.73 ± 13.81 a | 199.49 ± 0.39 ab | 361.73 ± 2.36 a | 474.55 ± 48.69 ab | 39.61 ± 2.01 ab | 84.35 ± 10.60 b |
SLF2 50% + CF 50% | 279.46 ± 12.46 | 146.07 ± 0.19 cde | 279.46 ± 0.82 cd | 417.83 ± 21.53 bc | 32.80 ± 0.23 c | 76.76 ± 5.80 bc |
SLF2 75% + CF 25% | 246.10 ± 9.79de | 131.34 ± 0.18 def | 246.10 ± 0.86 de | 370.93 ± 6.53 cde | 27.82 ± 0.47 d | 69.07 ± 3.08 bcd |
SLF2 100% | 238.90 ± 17.16 def | 144.45 ± 0.16 ef | 238.90 ± 1.11 def | 327.83 ± 2.44 e | 24.93 ± 2.99 de | 67.95 ± 4.83 bcd |
SLF3 25% + CF 75% | 274.42 ± 3.81 cd | 154.57 ± 0.20 cd | 274.42 ± 0.69 cd | 368.07 ± 6.20 cde | 27.72 ± 0.40 d | 54.54 ± 3.97 cd |
SLF3 50% + CF 50% | 245.66 ± 6.47 de | 150.01 ± 0.48 cd | 245.66 ± 2.15 de | 327.22 ± 11.67 e | 25.66 ± 0.75 de | 52.02 ± 2.33 d |
SLF3 75% + CF 25% | 221.03 ± 30.56 ef | 107.62 ± 0.00 fg | 221.03 ± 1.07 ef | 242.58 ± 25.31 f | 16.38 ± 0.81 g | 46.49 ± 6.49 de |
SLF3 100% | 135.26 ± 19.35 h | 79.20 ± 0.08 gh | 135.26 ± 0.30 h | 114.32 ± 19.81 g | 10.73 ± 2.71 h | 25.57 ± 5.73 ef |
SLF4 25% + CF 75% | 365.49 ± 11.49 a | 199.88 ± 0.01 ab | 365.49 ± 1.92 a | 497.41 ± 36.57 a | 44.00 ± 0.70 a | 76.27 ± 2.23 bc |
SLF4 50% + CF 50% | 339.82 ± 10.34 ab | 171.21 ± 2.33 bc | 339.82 ± 1.61 ab | 472.75 ± 25.21 ab | 43.64 ± 0.82 a | 60.47 ± 4.96 cd |
SLF4 75% + CF 25% | 300.45 ± 10.41 bc | 147.79 ± 2.06 cd | 300.45 ± 1.35 bc | 460.11 ± 5.93 ab | 25.45 ± 0.36 de | 58.16 ± 18.14 cd |
SLF4 100% | 269.00 ± 0.47 cde | 126.02 ± 1.41 def | 269.00 ± 0.95 cde | 414.82 ± 25.88 bcd | 24.56 ± 0.45 de | 55.27 ± 2.35 cd |
Data show mean value ± SD (n = 3). The same letters are not significantly different at P < 0.05 (Tukey’s test) in each column.
In our study, treatment with SLFs resulted in significant increases in yield. In Experiment 1, the growth characteristics of plants treated with SLFs or CF differed significantly from those of the control plants. Moreover, SLF2 and SLF4, which were produced from aerobic fermentation, caused significantly different increases in plant growth compared with SLF1 and SLF3, which were produced from anaerobic fermentation, but their effects did not differ significantly from those of CF treatment. In the aerobic fermentation process, sufficient oxygen is present and many low molecular weight organic substances are decomposed into carbon dioxide and inorganic matter. Therefore, SLF2 and SLF4 were easily decomposed into an available form in the soil and thus easily absorbed by the plants. Kannan et al. [
Application of SLFs and CF produced SPAD values that differed significantly from those of the control (NPK)0. Fan et al. [
In Experiment 1, treatment with SLFs and CF resulted in significantly different N, P, K, Ca, Mg, and Na uptake from that of the control treatment. Plants treated with SLF2, SLF3, or SLF4 exhibited increased K uptake compared with SLF1- and CF-treated plants and control plants. Kingman and Moore [
Experiment 2 showed that higher concentrations of SLFs resulted in decreased plant growth, shoot DW, and nutrient uptake. Plant growth and shoot DW were markedly depressed by increased concentrations of SLF1 and SLF3, but increased concentrations of SLF2 and SLF4 had no detrimental effects. The plants treated with 25% SLF + 75% CF exhibited better plant growth, shoot DW, and nutrient uptake than the plants subjected to higher concentration treatments (50% SLF + 50% CF, 75% SLF + 25% CF, and 100% SLF). Similar results were obtained in okra by Sasikumar et al. [
Experiment 2 also showed that plants treated with 100% CF, 25% SLF2 + 75% CF, or 25% SLF4 + 75% CF exhibited highly significantly differences in N, P, K, and Ca uptake relative to plants treated with SLF2, SLF4, SLF1, or SLF3 and the control plants. Mg uptake was significantly greater in plants treated with 25% SLF2 + 75% CF or 25% SLF4 + 75% CF, and Na uptake was significantly higher with 100% CF treatment than with the other treatments. These results confirm the findings previously reported by [
Linear regression analysis showed that the plants treated with CF or the SLFs exhibited decreased shoot DW, whereas the nutrient (N, P, K, Na, N/P, Mg/K) content of the plants increased. However, the shoot DW increased in plants treated with CF or the SLFs when the nutrient content of the plants decreased. These results suggest that treatment with higher concentration of nutrients depressed the shoot DW of komatsuna. Based on linear regression analysis, the plants treated with the higher concentrations of CF and SLFs exhibited decreased shoot DW (
Nutrients (%) | Regression analysis between DM and Nutrients content (%) |
---|---|
N | y = −0.1303x + 3.8944 |
R2 = 0.6653 | |
P | y = −0.0325x + 1.5259 |
R2 = 0.5241 | |
N/P | y = −0.0448x + 2.558 |
R2 = 0.3544 | |
K | y = −0.1576x + 5.1263 |
R2 = 0.7055 | |
Ca | y = 0.0132x + 2.3878 |
R2 = 0.0747 | |
Mg | y = −0.0019x + 0.2244 |
R2 = 0.0467 | |
Na | y = −0.0415x + 1.0671 |
R2 = 0.4762 | |
Ca/Mg | y = 0.1836x + 10.882 |
R2 = 0.1279 | |
Mg/K | y = 0.0024x + 0.0379 |
R2 = 0.385 |
Total samples numbers were n = 54.
In Experiment 1 of this study, both basal and basal-plus-foliar applications of SLF1 resulted in the highest I contents, 38.30 and 39.30 µg・g−1, respectively. In Experiment 2, the plants treated with 75% SLF1 + CF 25% and 100% SLF1 had the highest I contents, 118.18 and 120.83 µg・g−1, respectively. These results reflect that nori is rich in protein, I, dietary fiber, and several vitamins, including folic acid and vitamins B12 and K (Japan Food Standard Ingredient
The plants treated with basal and basal-plus-foliar applications of CF had significantly higher nitrate N (1.3 and 1.1 mg・g−1) content than plants treated with basal and basal-plus-foliar applications of the SLFs. In Experiment 2, the plants treated with 100% CF, 100% SLF1, or 75% SLF4 + 25% CF had higher nitrate N contents of 0.42, 0.38, and 0.37 mg・g−1, respectively. In our study, the nitrate contents of plants subjected to all of the SLF and CF treatments in Experiments 1 and 2 were lower than the level considered harmful for human health. Markiewicz et al. [
Our results show that fermented nori SLFs enhanced plant growth, SPAD values, and nutrient uptake of komatsuna compared with controls. Treatment of komatsuna with 25% SLF + 75% CF produced the best plant growth, shoot DW, nutrient uptake, highest I content, and lowest NO3-N content relative to control plants. Although basal application of SLFs was effective on komatsuna, foliar application was not effective, except for its effects on I content. The I content of komatsuna was increased by SLF treatment. Taken together, we conclude that basal application of fermented SLFs can enhance plant growth, nutrient uptake, and I content while decreasing NO3-N content in komatsuna. SLFs could be used as an organic fertilizer to reduce chemical fertilizer usage, leading to more sustainable agriculture.
We are grateful to Japan International Cooperation Agency (JICA) Scholarship Program (2016-2018) for financial support of this study.
The authors declare no conflicts of interest regarding the publication of this paper.
Moh, S.M., Moe, K., Obo, Y., Obo, S., Htwe, A.Z. and Yamakawa, T. (2018) Effects of Fermented Nori (Pyropia yezoensis) Seaweed Liquid Fertilizers on Growth Characteristics, Nutrient Uptake, and Iodine Content of Komatsuna (Brassica rapa L.) Cultivated in Soil. American Journal of Plant Sciences, 9, 2227-2243. https://doi.org/10.4236/ajps.2018.911161