Gyeong Lee Choi

Rapid monitoring of proline accumulation in paprika leaf sap relative to leaf position and water stress

The present study evaluated the pattern of proline accumulation in paprika leaf sap using a modified high-performance liquid chromatography (HPLC) method. Leaf sap samples were extracted using five different solvents and two extraction procedures, and were analyzed using modified HPLC analytical conditions. Enhanced extraction and HPLC analytical conditions were applied to analyze paprika leaf sap obtained from different plant parts (petiole and lamina sap) under different environmental conditions. The results showed that pure water extraction without heating or organic solvent performed best. This newly developed HPLC method was validated and confirmed suitable for analyzing proline content in leaf sap. The proline concentration in both the petiole and lamina sap showed a similar accumulation pattern, exhibiting the lowest proline concentration in the arbitrary node group I (1–5 nodes) and the highest concentration in the VI node group (21–30 nodes). In addition, sap from both the petiole and lamina of side stem leaves showed statistically higher proline content than the main stem leaves. The proline concentration also increased with increasing water stress during both the fruit enlargement and coloring stages, but primarily during the fruit coloring stage. The overall results suggest that the proline concentration in paprika leaves differentially accumulates throughout the plant and can be analyzed by water extraction using a modified HPLC method.

Effect of EC Level of Irrigation Solution on Tomato Growth and Inorganic Ions of Root Zone in Soilless Culture of Tomato Plant Using Coir Substrate

In hydroponics, the nutrient solution is supplied considering the water and nutrient uptake characteristics of crops. However, as the ionic uptake characteristics are changed as a result of the weather conditions or the growth response of the crops, the root zone can not be maintained in optimal condition. In addition, the coir substrate has been used mainly for the tomato cultivation in place of the inorganic substrate, there are few studies on long-term cultivation using coir substrate. Therefore, this study was conducted to investigate the effect of EC level of irrigation solution on tomato growth and inorganic ions of root zone in soilless culture using coir. Coir substrate mixed with 5 : 5 chip and dust was used. EC level of irrigation solution was 1.0, 1.5, 2.0, and 3.0 dS·m. At the initial stage, NO3N, P, Ca and Mg in the drainage were lower than the irrigation level at 1.0 and 1.5 dS·m. However, EC 2.0 dS·m or higher, all the ions except P were highly concentrated in the drainage. The average fruit weight was not significantly different between 1.0 and 1.5 dS·m until 3th cluster, but from the next cluster, the higher the EC level, the smaller the weight. The number of fruit and yield to 6th cluster was the highest at 1.5dS·m. From the next cluster, The yield was decreased with the higher EC level. At the early stage of growth, BER occurred only in EC 3.0 dS·m, but increased in all treatments with increasing irradiation. The incidence rate of EC 3.0 dS·m was higher than that of the lower EC level treatment. Additional key words : EC, drainage, blossom-end rot(BER), soluble solids content

Erratum to: Optimal levels of N, P, and K for the cultivation of single-stemmed roses in a closed hydroponic system

It is necessary to identify the optimum levels of mineral nutrients for the commercial production of single-stemmed roses in a closed hydroponic system to avoid the accumulation of undesirable ions in the root zone and to improve shoot growth and flower quality. We determined the optimal concentrations of nitrogen (N), phosphorous (P), and potassium (K) in a nutrient solution by analyzing the amount of mineral nutrients absorbed by the plant, plant growth, and photosynthesis characteristics. Rose plants (Rosa hybrid L. cv. Red Velvet) were subjected to different concentrations of macronutrients, including N (0, 10, 50, 100, 150, or 200 mg·L-1), P (0, 10, 20, 40, 80, or 100 mg·L-1), and K (0, 10, 50, 100, 150, 200, or 250 mg·L-1). The uptake of nitrate-N (NO3-) was inhibited by high P levels, and the NO3-N concentration in the nutrient solution was significantly higher in the 100 mg·L-1 P treatment than in the other P treatments, indicating reduced NO3- uptake by the plants. The concentration of phosphate (PO4-) decreased considerably in all N and K treatments during the entire growth period. To ensure a sufficient supply of P for single-stemmed roses, it is necessary to increase the PO4- concentration in the nutrient solution. Increasing the K+ level significantly increased the concentrations of calcium (Ca2+) and magnesium (Mg2+) in the nutrient solution. This may be the result of low Ca and Mg absorption from plants over the growth period. Although there was an increase in the fresh weight and stem length with higher levels of N [NO3- and ammonium (NH4+)], PO4-, and K+, growth did not significantly increase at levels higher than 150 mg·L-1 N, 40 mg·L-1 P, and 200 mg·L-1 K treatments. The photosynthetic rates (Pn) increased rapidly as the concentration in the nutrient solution increased to 100 mg·L-1 N, 40 mg·L-1 P, and 150 mg·L-1 K, followed by a reduction as the ion concentrations increased to the maximum ranges. A distinct reduction of the Pn was observed in the plants supplied with nutrient levels above 150 mg·L-1 N, 80 mg·L-1 P, and 200 mg·L-1 K. Considering the nutrient-water absorption patterns, growth, and photosynthesis characteristics of single-stemmed roses, the mineral nutrient levels of 100–150 mg·L-1 N, 30-50 mg·L-1 P, and 100–150 mg·L-1 K were found to be optimal for the production of single-stemmed roses in a closed hydroponic system.