The effect of three nutrient solutions including hydro greens, knop and bio-Life on some parameters related yield and quality of hydroponic vegetable mustard (brassica integrifolia)

153 HNUE JOURNAL OF SCIENCE DOI: 10.18173/2354-1059.2017-66 Chemical and Biological Science 2017, Vol. 62, Issue 10, pp. 153-160 This paper is available online at THE EFFECT OF THREE NUTRIENT SOLUTIONS INCLUDING HYDRO GREENS, KNOP AND BIO-LIFE ON SOME PARAMETERS RELATED YIELD AND QUALITY OF HYDROPONIC VEGETABLE MUSTARD (Brassica integrifolia) Le Thi Thuy and Nguyen Thi Thuy Van Faculty of Biology, Hanoi National University of Education Abstract. The nutrient solution is an important factor which directly effects on growth and development of hydroponic crops. Therefore, finding appropriate nutrient solution for each plant is necessary to ensure hydroponic crop yields. In this study, the effects of three common nutrient solution including Hydro Greens, Knop and Bio-life on vegetable mustard (Brasscia integrifolia) growth were evaluated. The study results indicated that Hydro Greens solution had the most positive influence on both groups of parameters, including productivity parameters (the height, fresh weight and leaf area) and parameters related quality (the reducing sugar content, vitamin C content, iron content). In addition, the nitrate content of the vegetable mustard grown in Hydro Greens solution remained within safe health limit. The experimental results have also shown that the vegetable mustard grown slowly in Knop solution and worst in Bio-life solution. Keywords: Hydroponics, nutrient solution, vegetable mustard (Brasscia integrifolia). 1. Introduction The scientific name of the vegetable mustard (sweet mustard) is Brassica integrifolia that belongs to the Brassicaceae family. This plant species originates from India, in Vietnam, it is one of the most popular leaf vegetables. It contains high levels of vitamins C, B1, B2, B3, K, proteins, minerals such as Ca, P, Fe. Regular using of vegetable mustard in diets is good for supporting the treatment of diseases related to digestion, cardiovascular disease, diabetes, etc. [1]. Hydroponic technology (also known as hydroponics) is a technique which grow crops in nutrient solution, or defined as grow plants without soil. Hydroponic technology has been researching from the seventeenth centuries. So far, this technology is a good solution, towards producing clean, green and non-polluting products. This technique can be applied on different scales from households to industrial production. In addition, the hydroponics can be used to grow many plant objects, for example: food crops, flowers especially the vegetable species, including vegetable mustard [2, 3]. Received June 16, 2017. Revised November 30, 2017. Accepted December 8, 2017. Contact Le Thi Thuy, e-mail address: hienthuy20@gmail.com Le Thi Thuy and Nguyen Thi Thuy Van 154 The nutrient solution has a great influence on the growth and development of hydroponic plants, including Brassicaceae family. The study results of Nguyen Quang Thach et al. shown that the vegetable mustards grown in two self-blending solutions NC1 and NC2 were of equivalent quality and as 70-90% as yield compared with vegetables grown in AVRDC solution (the nutrient solution providing by the Asian Vegetable Research and Development Center) [4]. In another study, Do Thi Truong tested green cabbage grown in six self-infused nutrient solutions. The results indicated that CT6 was a nutrient solution that increased biological productivity and productivity in comparison with the remaining five solutions [5]. When comparing the effects of three research nutrient solutions including the nutrient solution made by the Hanoi University of Agriculture, VRQ1 nutrient solution made by Fruit and Vegetable Research Institute and VRQ2 nutrient solution, Tran Khac Thi et al. realized that two former solutions were more appropriate for off-season production of green cabbage by hydroponic method [9]. In addition, in a recent study, when comparing the effect of three nutrient solutions HA, Hewit and Steiner, Nguyen Thuy Ha found that green cabbage cultivated in Hoagland-Amon grown well and had the highest net yield of 3 kg/m 2 , economic efficiency reached 15,000 VND/m 2 [6]. Therefore, the selection of suitable nutrient solutions will contribute to increase the yield and quality of the plants by hydroponic method. Currently, most of the nutrient solutions are recommended to use for variety of crops. However, there are not many studies evaluating the quality of these solutions on the vegetable mustard. This study was conducted to assess the effects of three nutrient solutions including Hydro Greens, Knop and Bio-life on some parameters related to the vegetable mustard yield and quality to find the appropriate nutrient solution for this plant in hydroponic method. 2. Content 2.1. Materials and methods 2.2.1. Materials * Plant: Vegetable mustard seeds (Brassica integrifolia) providing by Binh Minh Co., Ltd, Vietnam. * Nutrient solutions - Hydro Greens nutrient solution providing by Vinaxanh Co., Ltd, Vietnam comprises 2 parts: Part A including total nitrogen (N) 4.64% (nitrate nitrogen 4.32% and ammoniacal nitrogen 0.32%), calcium (Ca) 4.40%, soluble potassium (K2O) 3.06% and Part B including total nitrogen (N) 1.77% (nitrate nitrogen 1.17% and ammoniacal nitrogen 0.60%), soluble potassium (K2O) 3.94%, available phosphate (P2O5) 3.05%, magnesium as Mg 0.32%, chelax Fe 0.02% and other trace elements 0.03% (Mn, Cu, Zn, Mo, B). - Bio-life nutrient solution providing by Vi Dan Co., Ltd, Vietnam contains the cations (ppm) including potassium 275, calcium 80, magnesium 75, iron 110, manganese 110, zinc 130, boron 10, copper 140, sodium 5); The anions (ppm) including nitrate 495, dihydrophosphate 195, chlorine 880, molybdate 5, silicate 30, sulfates 40; Vitamin (B1, B2, B12, C); Glucose; NAA, cytokinin, interoperability NVP, EDDHA (red) and the admixtures. The effect of three nutrient solutions including hydro greens, knop and bio-life on some parameters 155 - Knop solution: In special 1000 mL Knop solution contains Ca(NO3)2 22.88g; KNO3 5.72g; KCl 2.84g; KH2PO4 5.72g; MgSO4 5.72g; FeCl3.6H2O (5%) 4 drops. - Nutrient solutions are mixed according to the manufacturer's instructions 2.2.2. Methods * Method of experimental arrangement The vegetable mustard plants were grown by the static hydroponic method. Seeds were sown in plastic cups containing coconut fiber, the bottom of which was punched through the roots. Each cup contained 5 plants, 3 days old plants were planted in nutrient solution. Each nutrient solution was placed in 5 boxes that was size of 60x40x34cm. Each box contains 30l of nutrient solution and 12 plastic cups (the 60 plants/box). The growth and physiological-biochemical parameters related to yield and quality of the vegetable mustard were evaluated in harvest periods (5 - 6 leaves). The experiment (each solution/treatment) was repeated three times. The experiments had been conducted at the Experimental Gardens of Faculty of Biology, Hanoi National University of Education. The experimental area was covered by transparent plastic sheet to protect from rain, in addition to other ecological factors such as temperature, humidity, light were ensured similar to natural conditions. Parameters were conducted at the Laboratory of Department of Plant Physiology and Application, Faculty of Biology, Hanoi National University of Education. The experiments were studied from August 2014 to February 2015. * Analytical methods of growth parameters Height of plant: use the measure with the accuracy of 1 mm to measure the height from the stem to the longest leaf tip. Fresh weight of plant: weighed in technical balance 2 x 10 -2 g precision. Leaf area: Determined based on the relationship between mass and area, as described by Nguyen Duy Minh et al. Root volume: Root volume: defined as the rise of water in a water-filled hose as described by Nguyen Duy Minh et al. * Analytical methods of quality parameters Total chlorophyll content in leaf: use UV spectrophotometer Visible Model SPECORD 200 Plus with equation of Wettstein 1957. Vitamin C content determined by the iodine titration method. Reducing sugar content determined by dinitrosalicylic acid method (DNS). Nitrate content determined by colorimetric method according to TCVN 8742: 2011 [7]. Iron content determined by AAS - Atomic Absorption Spectrophotometric NovAA 350 Analytik Jena. Destruction of plant sample use wet ash method at 550 o C. Each parameter analyzed 15 samples. * Data processing Using Microsoft Excel 2010 software and SPSS 16.0 software to process statistical data. The data were processed by statistical one -way ANOVA analysis (Turkey’s - b) at the significance level of α = 0.05. Le Thi Thuy and Nguyen Thi Thuy Van 156 2.2. Result and discussions 2.2.1. The effect of the nutrient solutions on some parameters related yield of vegetable mustard The vegetable mustard is a leaf vegetable, so the plant height, leaf area, and fresh weight are direct parameters decided the economic productivity of vegetable mustard. These are also important parameters to evaluate the growth of plants in various nutrient solutions. Table 1. Effect of three nutrient solutions on some parameters related yield (the height, fresh weight, leaf area and root volume) of the vegetable mustard in hydroponic method Note: Values in the same column followed by the same letter are not significantly different at 0.05 Comparing the effect of nutrient solutions on three parameters related to vegetable mustard productivity, the results in Table 1 show that the vegetable mustards were the best growth in Hydro Green solution and the least growth in Bio-life solution. Specifically, the plant's height was 18.72 cm when grown in Hydro Greens solution, about 1.5 times higher than that in Bio-life solution and 1.2 times higher than that in Knop solution. Similar to leaf area, the data obtained show that the vegetable mustard's leaf grown in Hydro Greens solution had the largest area, reaching 0.494 dm 2 , this result in Knop and Bio-life solutions were in turn 0.38 dm 2 and 0.267 dm 2 . Due to the difference in the height and the leaf area of the vegetable mustard grown in the three nutrient solutions, it is easy to see the difference in fresh weight of the plant (the parameter directly reflects the yield of the leaf vegetable) when grown in three various nutrient solutions. In details, the average fresh weight of the vegetable mustard grown in Hydro Green solution was 19.7 g, 4.13 g higher compared to the plant in the Knop and 9.74 g higher than that in Bio-life (9.96 g). That is to say, the fresh weight of the vegetable mustard cultivated in Bio-life solution was only half the fresh weight of the plant grown in HG solution (In other words, yield of the vegetable mustard collected in Hydro Greens solution was as twice as in Bio-life solution). This result can be explained by the difference in composition and mineral content between the three nutrient solutions. The full presence of macro- and micronutrient minerals in the Hydro Greens solution provided a favorable environment for the growth of the vegetable mustard. Although, the Bio-life solution has the same mineral content as Hydro Greens solution, while also supplementing with some vitamins and phytohormones, it may be due to the low composition of macronutrient minerals (including K, Ca and Mg Parameters Solutions Height (cm) Fresh weight (g) Leaf area (dm 2 ) Root volume (mL) Hydro Greens 18.720 a ±0.156 19.700 a ±0.318 0.494 a ±0.004 0.540 b ±0.040 Knop 15.590 a ±0.147 15.570 b ±0.394 0.380 b ±0.003 0.560 b ±0.070 Bio-life 12.600 b ±0,171 9.960 c ±0.089 0.267 c ±0.003 0.760 a ±0.110 The effect of three nutrient solutions including hydro greens, knop and bio-life on some parameters 157 content) was not satisfied with the growth of the vegetable mustard. So, a balanced nutrient supply is essential for the healthy growth of plants in hydroponic systems [3]. The study results on other leaf vegetable (the amaranth) also shown that Hydro Greens is more suitable than Bio-life solution for the plant's growth. However, that study indicated that the amaranths grown in the Knop had equivalent yield and quality with the amaranths in the Hydro Greens solution [8]. Besides the three parameters related to the yield of the vegetable mustard (including the height, the leaf area and the fresh weight) above, the results in Table 1 also shown a direct correlation between the vegetable mustard's root volume index and the composition along with mineral content in the nutrient solutions. With low content of some of the essential mineral elements, the Bio-life solution did not meet the needs of the plant's growth (especially at the time of the strong growth of the plant), resulting in the plant adapted to find the more nutrient resource by enhancing the growth of the root system. This could be the cause, the average root volume of the vegetable mustard in Bio-life solution was the largest (reaching 0.76 mL), 1.4 times larger compared to that in Knop and Hydro Greens solution. 2.2.2. The effect of the nutrient solutions on some parameters related quality of the vegetable mustard Many studies have shown that nutrient solutions not only affect productivity, but also significantly affect the quality of plants by hydroponic method. Because as we know, mineral elements participate in the structural component of cells and enzymes, besides they also play a regulating role in the metabolism of the cell. In this study, we conducted an assessment of some of the basic parameters related to the quality of the vegetable mustard including vitamin C, reducing sugars, iron and total chlorophyll content. The results are presented in Table 2. Table 2. Effect of three nutrient solutions on some of parameters related quality of the vegetable mustard in hydroponic method Parameters Solutions Vitamin C content (mg/g) Reducing sugar content (mg/g) Iron content (mg/g) Total chlorophyll content (mg/g) Hydro Greens 63.36 a ±0.964 0.328 a ±0.027 0.048 a ±0.001 14.76 a ±0.245 Knop 52.80 b ±1.245 0.319 a ±0.034 0.032 c ±0.001 14.00 b ±0.158 Bio-life 51.28 b ±0.787 0.269 b ±0.019 0.042 b ±0.003 12.71 c ±0.228 Note: Values in the same column followed by the same letter are not significantly different at 0.05 Unlike productivity-related parameters, according to the statistic data in Table 2, there is no significant difference in comparison between the parameter related to the productivity of the vegetable mustard grown in three nutrient solutions. On the other hand, the fluctuation of these parameters also does not follow the general rule. Le Thi Thuy and Nguyen Thi Thuy Van 158 Vitamin C content Vitamin C or ascorbic acid is an essential nutrient for many organisms. The presence of vitamin C is necessary for a variety of metabolic reactions in the body. Vitamin C is found in fresh fruits like oranges, lemons, tangerines, and with a high content in some vegetables including vegetable mustard [1]. Vitamin C content was highest in the vegetable mustard grown in Hydro Greens solution (63.36%). During, the results of this parameter were not different between the vegetable mustard grown in Knop and Bio-life solutions. This data also shown that the vitamin C content of the vegetable mustard is higher of the amaranth when they grown in the same nutrient solution [8]. Reducing sugar content The reducing sugar is the sugar that contains the aldehyde group (-CHO) or ketone (- CO) as glucose, fructose, arabinose. These sugars participate in the synthesis of organic substances in the plant body from lipids, proteins to nucleic acids. It is an important parameter to evaluate quality of agricultural products. The results in Table 2 shown that the reduction sugar content of the vegetable mustard cultivated in 3 solutions ranged from 0.269 mg/g to 0.328 mg/g. Specifically, the lowest reducing sugar content was obtained in the vegetables grown in the Bio-life solution, whereas the statistical results indicated that there was no difference of this index in comparison between the vegetable mustards grown in Hydro Greens and Knop solution. Iron content For humans, iron is one of three essential micronutrients (vitamin A, iron and iodine) but often lack in the diet of humans. Iron content is usually low in vegetables, but for its nutritional value, the iron content is also an important element contributing to the quality of vegetables. Unlike the two indicators presented above, the iron content of the vegetable mustard grown in Knop solution was the lowest in comparison with the plants in the other two solutions. Specifically, this index of the vegetable mustard grown in Knop was 0.032 mg/g, which was about 0.01 to 0.016 mg/g lower than that obtained of the vegetable mustard grown in Hydro Greens and Bio-life solution. This result is a very clear reflection of the effect of the iron content which presents in the nutrient solution on the Fe accumulation in the vegetable mustard. Total chlorophyll content Total chlorophyll content has a decisive role to photosynthetic capacity of the plants. Therefore, total chlorophyll content has an important role for the growth, development, yield formation and quality of products after harvest. Besides, the chlorophyll content is a parameter that affects the aesthetic value of the leaf vegetables. The studies have demonstrated that the process of chlorophyll synthesis is influenced by some mineral elements such as Mg, Fe, etc. From the results shown in Table 2, it was found that the chlorophyll content of vegetable mustard grown in HG solution was highest value (14.46 mg/g), followed by the chlorophyll contents of the plants grown in the Knop solution (14.40 mg/g) and finally the vegetable mustard in Bio-life (12.71 mg/g). This result is suitable in comparison with the The effect of three nutrient solutions including hydro greens, knop and bio-life on some parameters 159 results of the parameter related yield that presented in item 2.2.1, and is also consistent with the nutrient content of the three solutions. 2.2.3. The effect of the nutrient solution on the accumulation of nitrate content in the vegetable mustard Nitrate (NO3 - ) is the main nitrogen that the plants can absorb from the nutrient solution Providing a sufficient content of nitrate for the plant make it verdurous and colorful. However, the presence of nitrate in agricultural products can be affect human health and excess levels of nitrates in plant tissue can be seen as a poison [7]. So it has always been one of the criteria for assessing the quality of fruits and vegetables, especially for vegetables grown by hydroponics. A suitable nutrient solution not only makes the plants high yield and good quality but also brings safe products. So in this study, to evaluate the safe level of the nutrient solutions, we determined the accumulation of nitrate in the vegetable mustard grown in three nutrient treatments at the harvest stage and the results obtained as the Table 3. The results presented in Table 3 indicated that nitrate accumulation in the vegetable mustard ranged from 290.70 to 305.75 mg/kg. Although the vegetable mustard grown in Bio-life solution had the highest nitrate accumulation, this higher nitrate content is not big in comparison with that in the other two solutions including Hydro Greens and Knop. However, according to the criterion given in TCVN 5247:1990, the permitted limit of nitrate content in leaf vegetables should not exceed 600 mg/kg. Thus, in comparison with this standard, the vegetable mustards grown in all three nutrient solutions have a significantly lower nitrate value than the allowable limit. Based on the accumulation of nitrate the product, from the results of this study it can be said that Hydro Greens, Knop and Bio-life solutions are safe to cultivate the vegetable mustard. Table 3. The nitrate content in the vegetable mustard grown in three hydroponic solutions in the harvest stage (mg/kg) Note: Values in the same column followed by the same letter are not significantly different at 0.05 The study results are consistent with the publication by the some other authors when they carried out evaluating the food safety based on the study about the nitrate content of vegetables grown by hydroponics [4, 6, 9]. Nitrate contents Solutions In crops Allowable limit Hydro Greens 293.40 b ± 5.25 Knop 290.70 b ± 6.84 600 Bio-life 305.75 a ± 7.78 Le Thi Thuy and Nguyen Thi Thuy Van 160 3. Conclusions The experimental results indicated that: (1) The height, leaf area and fresh weight of vegetable mustards grown in Hydro Greens were 1.2 to 2 times higher than that in Knop and Bio-life solution; (2) The vegetable mustard's quality cultivated in Hydro Greens, that is expressed in the parameters including vitamin C, reducing sugar, iron and total chlorophyll content, was equivalent or better than that in other solutions; (3) The nitrate content of the vegetable mustard in Hydro Greens was as a half as the maximum safe limitation of TCVN 5247: 1990. Thus, based on the study results about the some parameters related yield and quality of the vegetable mustards that grown in three nutrient solutions, it maybe to see that Hydro Greens is the most appropriate solution to cultivate the vegetable mustard in comparison with Knop and Bio-life solution. REFERENCES [1] Nguyen Cong Khan, Ha Thi Anh Dao, Nguyen Thi Lam, Le Hong Dung, 2007. Vietnamese food ingredients table. 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