• Journal of Bio-Environment Control
• /
• v.10 no.2
• /
• pp.101-105
• /
• 2001

Plant roots are affected by the root zone environment rather than substrate material itself. It is important to provide a suitable environment for the roots by amending the substrate and adjusting supply of the nutrient solution. In an expanded rice hull substrates, 1.5 L nutrient solution was supplied on each day at different frequency. In rice hull substrate, plant growth and yield were the greatest in the treatment where a 1.5L nutrient solution was supplied as 24 equal aliquots, wheres in perlite substrate plant growth and yield were the greatest in the treatment with 16 aliquots. Nitrogen deficiency symptoms caused by early decomposition of rice hulls by microorganisms was recovered by increasing solution EC from 1.7 to EC 2.0 dS.m$^{-1}$ for 25 days after planting. Plant growth and yield increased in the treatment of Ec 3.0 dS.m$^{-1}$ , but the cause for this increase is not clear.

• Journal of Bio-Environment Control
• /
• v.4 no.1
• /
• pp.25-31
• /
• 1995

This study was carried out to investigate the effect of the concentration of nutrient solution on the growth of tomato(Lycopersicon esculentum Mill. cv. seokwang) in substrate culture. The substrates used in the experiment were perlite, vermiculite, and peatmoss. Tomato plants were treated with different concentrations of nutrient solution, viz. 0.5, 1.0, 2.0, 3.0, and 5.0mS/cm at seedling stage and transferred to different treatments, 1.0, 2.0, and 3.0mS/cm after transplanting in each substrate. As the concentrations of nutrient solution increased from 0.5 to 3.0mS/cm at seedling stage, the $CO_2$ assimilation rates of seedlings increased in all three substrate culture. Beyond this range, the $CO_2$ assimilation rates of seedlings decreased. By increasing the concentrations of nutrient solution, plant height, leaf length, leaf width, stem diameter, and top dry weight increased in perlite and were high at 2-5mS/cm in vermiculite. On the other hand, in peatmoss, the best result was shown at 3.0mS/cm. Therefore, the adequate concentration of nutrient solution on early growth of seedlings differed among substrates and was shown to be 3.0-5.0mS/cm in perlite, 2.0-5.0mS/cm in vermiculite, and 3.0mS/cm in peatmoss. Generally, as the concentrations of nutrient solution increased from 1.0 to 3.0mS/cm after transplanting, dry weight increased significantly in all three substrate culture. However, dry weights of tomato plants grown under high concentration of 5.0mS/cm slightly increased both at seedling stage and after transplanting.

• The Journal of Natural Sciences
• /
• v.13 no.1
• /
• pp.83-96
• /
• 2003

Effect of Nutrient Concentrations, fertigation frequency, and learching percentage on crop growth and nutrient concentrations in root media were evaluated. The treatment of each irrigation with $50 mg.L^{-1}$ of nitrogen in stage 2 and increase to $80 mg.L^{-1}$ nitrogen in stage 3 had the highest crop growth at 34 days after sowing among treatments tested. Feeding with low nutrient concentrations and elevated frequency decreased crop growth. In treatments of each leaching percentage, feeding with low nutrient concentrations and elevated frequency resulted in increased tissue nutrient contents. The less tissue potassium content and higher calcium and magnesium contents were observed in treatment of 50% leach than those in 0% leach. All treatment tested had soil solution pH higher than 6.8. Electrical conductivity in treatments of 50% leach were lower than those of 0% leach. Feeding with low nutrient concentrations and elevated feeding frequency in each leaching percentage resulted in increased electrical conductivity in soil solution of root media. Trends of medium nutrient concentrations were similar to those of electrical conductivity.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.9 no.5
• /
• pp.1059-1065
• /
• 2005

In this study, an nutrient solution control system have been designed and implemented, which controls the density of nutrient and the nutrient supply automatically using embedded real time operating system and fuzzy control algorithm. The factors which affect the growth of crop consist of solar radiation, external temperature, and external humidity. Also, nutrient temperature, electric conductivity(ED, and pH are monitored. According to the surveyed results, a fuzzy control algorithm for nutrient control is developed in order to control the density of nutrient and the nutrient supply. The exclusive embedded controller which consists of an embedded real time operating system, a korean LCD, and a graphic is developed for common users.

• Korean Journal of Medicinal Crop Science
• /
• v.24 no.3
• /
• pp.198-206
• /
• 2016

Background: Electrical conductivity (EC) and pH are important features of nutrient solution, affecting both growth and quality of crops by altering nutrient uptake. Methods and Results: The pH values of nutrient solutions were controlled at 5.0, 5.5, 6.0, 6.5 and EC values were controlled at 0.68, 0.84, 1.23, 1.41 dS/m. Gingesng root weights were higher during the initial growth period when the plants were treated with low pH and low EC nutrient solutions. However, the higher pH and EC levels, the greater the increase in the rate of root weight between the initial and middle growth periods. The highest ginsenoside amount changed during growth period. The total ginsenoside amount was highest in the root, and the lowest in leaves at 45 and 90 days after treatment, respectively, with solution at a pH of 6.0. After 135 days of treatment, the highest total ginsenoside amount was detected in root treated with soluton with EC values of 1.23 dS/m. Conclusions: For the cultivation of ginseng using a nutriculture system, the pH and EC values of nutrient solutions should to be controlled based on the stage of growth and targeted plant organ (root or leaves).

• Journal of Bio-Environment Control
• /
• v.28 no.4
• /
• pp.447-453
• /
• 2019

In this study, the effect of supplying volume and frequency of a nutrient solution consisted with $NO_3-N$ 4.6, $NH_4-N$ 3.4, $PO_4-P$ 3, K 3, Ca 4.6 and Mg $2.2mmol{\cdot}L^{-1}$ on growth and fruit quality of 'Duke' blueberry was investigated. Three years old 'Duke' blueberry bushes cultivated in containers ($60{\times}80{\times}40cm$) filled with 130L peat moss and 40L pearlite (v/v) were selected for the experiment. The growth containers were mulched with sawdust. Two different volumes (4L and 8L) of nutrient solution was tested at three different supplying frequencies (one time, two times, and three times) per week and the drainage quality of nutrient solution and fruit quality of 'Duke' blueberry was evaluated. The optimal drainage rate for the vegetable cultivation is known to be 20-30%. The results revealed that the average drainage rates of 27% and 29% for the nutrient solution supplied in 'Duke' blueberry growth medium at 4L, 2 times/7 days and 4L, 3 times/7days, respectively. The highest shoot diameter (4.2mm) and shoot length (31cm) of 'Duke' blueberry was recorded with the 8L of nutrient solution supplied at 3 times per 7 days. According to the analysis of inorganic components in the drainage of nutrient solution, there was a tendency of absorbing nitrogen at the early stage of growth. The supplying volume and frequency of nutrient solution was not significantly affected on 'Duke' blueberry fruit weight, soluble solids content, and titratable acidity. The highest yield per bush (2.7kg) was recorded for the nutrient solution supplied with 4L at three times per 7 days, while the 4L nutrient solution supplied at one time per 7 days resulted the lowest yield of 1.4kg per bush. Consequently, the tested nutrient solution can be applied for the 'Duke' blueberry bushes with the volume of 4L at three times per week for the better crop growth.

• Korean Journal of Environmental Agriculture
• /
• v.20 no.1
• /
• pp.28-33
• /
• 2001

Lettuces were grown hydroponically in three different nutrient solutions, normal and 30 or 50 mM $KNO_3-added$ nutrient solutions, and the electrical conductivities of the nutrient solutions were 1.0, 4.5, and 6.5 dS/m, respectively. Lettuces grown in the $KNO_3-added$ nutrient solutions showed a decrease in the germination ratio and the lower indices of growth, such as plant height, stem diameter, leaf length, and leaf width. Microsomes were prepared from the roots of lettuce and characteristics of microsomal ATPases were investigated. The activities of microsomal ATPases grown in the 30 mM and 50 mM $KNO_3-added$ nutrient solutions were higher than that grown in the normal nutrient solution. The highest activities of microsomal ATPases were observed at pH 7.0 in all culture conditions. The activities of microsomal ATPases were increased in a reaction buffer solution containing high concentration of $K^+$, whereas they were decreased in a reaction buffer containing $Na^+$. The stimulating effect of $K^+$ in the reaction buffer was greater on the microsomal ATPases of lettuces grown in the $KNO_3-added$ nutrient solutions than that grown in the normal nutrient solution. These results imply that the activities of microsomal ATPases in the root tissue are increased as increasing the $KNO_3$ concentration in the hydroponical nutrient solution.

• Korean Journal of Soil Science and Fertilizer
• /
• v.37 no.5
• /
• pp.329-335
• /
• 2004

Acid deposition in forest adjacent to the industrial complexes causes soil acidification resulting in the leaching of cations, decreases of buffering capacity and increases of toxic metal concentrations such as Al, Fe, Mn and Cu in soil solution. Changes of nutrient availability equilibria by acid deposition have been known to retard the growth of pine trees. Objective of this research was to assess the critical ratios of Ca/Al and Mg/Al limiting the growth of Pinus thunbergii in the hydroponic culture. The Ca concentration and Ca/Al ratio in stalks of pine tree were increased as increasing Ca/Al molar ratio in the nutrient solution, but were not changed when the Ca/Al molar ratio was adjusted to greater than 1. Growth of Pinus thunbergii was inhibited at the Ca/Al molar ratio lower than l due to the Ca deficiency. The molar ratios of Ca/Al in the needles of Pinus thunbergii showed the similar tendency with the stalks. This indicated that Ca/Al molar ratio of 1 in the growth media was the critical level limiting the growth of Pinus thunbergii. Concentration of Mg and Mg/Al molar ratios in the stalks of pine tree were increased as increasing Mg/Al molar ratio in nutrient solution. Molar ratios of Mg/Al in the needles were increased as increasing Mg/Al ratios in nutrient solution up to 0.83, which was the critical level limiting the growth of Pinus thunbergii.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.5 no.1
• /
• pp.7-12
• /
• 2004

The steps related to the nutrient solution management were divided into 4 categories. The resistance for water movement in every steps was proposed. The priorities among the steps were set according to the cultural situation, which were used as the basis for the management in perlite bag culture. The enhancement of historical root development is especially critical, as well as how to supply essential water efficiently by minimizing the water movement distance to the root, which is the narrowest neck of a bottle in solution management.

• Horticultural Science & Technology
• /
• v.32 no.6
• /
• pp.812-818
• /
• 2014

Raising seedlings is important for fruit crops and is especially significant for strawberries as it accounts for 80% of their cultivation. However, there are few studies on raising seedlings of strawberries by hydroponics. Since strawberries show clear differences in growth characteristics based on cultivar, it is necessary to develop suitable fertilizer formula, concentration and pH for each cultivar, and also to examine the amount of nutrient feeding appropriate for each medium type. A key to raising seedlings of strawberries by hydroponics is the development of strategies to manage the concentration of nutrient solution. The mother plants of 'Daewang' strawberries were planted on hydroponics benches filled with cocopeat on March 28, 2012. Three nutrient solution treatments were employed during the term of raising seedlings: a type that supplied EC $0.6dS{\cdot}m^{-1}$ nutrient solution for 30 days and only water for 20 days [0.6 (30) + 20]; a type that supplied EC $1.2dS{\cdot}m^{-1}$ nutrient solution for 30 days and only water for 20 days [1.2 (30) + 20]; and a type that supplied EC $1.2dS{\cdot}m^{-1}$ nutrient solution for 50 days [1.2 (50)]. The plants were then planted on hydroponics benches filled with cocopeat on September 20, and managed with EC $0.6-0.8dS{\cdot}m^{-1}$ strawberry nutrient solution developed by Yamazaki. After planting, shoot growth, flowering rate and fruit quality of the first cluster were investigated. The petiole length, leaf length, leaf width and crown diameter showed the highest grown in the [1.2 (50)] treatment, followed by [1.2 (30) + 20], and then [0.6 (30) + 20], indicating that the higher concentration of nutrient solution was preferable for raising seedlings. However, the growth differences among treatments gradually disappeared as growth continued, and the crown diameter especially grew to exhibit almost no difference at all among treatments. The point of flowering came first in [0.6 (30) + 20], followed by [1.2 (30) + 20] and then [1.2 (50)]. The [0.6 (30) + 20] treatment showed much earlier flowering than other treatments, which implies that low-concentration nutrient solution may be beneficial to the flowering of 'Daewang' strawberries while raising seedlings. There was no statistically significant difference among treatments in fruit length, fruit diameter and fruit firmness. Fruit weight in [1.2 (50)] treatment was significantly higher than other treatments. However, soluble solids of fruit was the lowest in [1.2 (50)] treatment. Together, the results of this experiment imply that it is better to supply EC $0.6dS{\cdot}m^{-1}$ solution for 30 days and then supply only water for 20 days to adequately manage concentration of nutrient solutions during the period of raising seedlings of strawberries by hydroponics.