• Korean Journal of Agricultural Science
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• v.44 no.3
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• pp.359-365
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• 2017

Biochar has the ability to mitigate climate change, improve crop productivity, and adsorb various contaminants. The aim of this work was to confirm the effect of biochar as a soil amendment on growth of Chinese cabbage (Brassica chinensis) using a pot experiment. Biochar was produced from residual-wood burnt at a pyrolytic temperature of $400^{\circ}C$ and consisted of 51.6 % carbon (C) by mass. The biochar was added to the soil at 0, 1, 3, and 5% by weight, which represent about 0, 18, 54, and $90t\;ha^{-1}$, respectively. The treatments were arranged in a randomized complete block design with 3 replications. The Chinese cabbage was grown for 49 days in a glasshouse in pots filled with sandy loam soil. Experimental results showed that the residual-wood biochar used for the experiment was slightly alkaline (pH 7.5). The fresh weights of Chinese cabbage were 86.22 g, 84.1 g, 63.23 g and 70.87 g, respectively, for biochar applications at 0, 18, 54, and $90t\;ha^{-1}$. Compared with the control (i.e., no biochar), biochar application increased soil pH and electrical conductivity (EC). Addition of biochar (54 and $90t\;ha^{-1}$) to sandy loam soil had no effect on growth of Chinese cabbage. This might be due to excessive increase of soil pH from the biochar application, leading to reduced availability of plant nutrients. Based on these results, the authors conclude that an excessive addition of biochar may have negative effects on the healthy growth of Chinese cabbage.

• Korean Journal of Weed Science
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• v.17 no.3
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• pp.310-313
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• 1997

The seedling of barley and weed would be generally inhibited by rice straw residues in the field. This experiment was carried out to investigate the allelopathic effects of rice straw and environmental conditions of germination such as osmotic potential, pH on the seedling of barley and water foxtail. The pH did not affect the germination of barley and water foxtail. Osmotic potential to -2.9bar, -0.6bar did not affect the germination of barley and water foxtail, respectively. Rice straw mixed with soil at the concentration of 4%(w/w) reduced the dry weight of shoot and root, and volume of barley root, as compared to the untreated control. Dry weight of water foxtail by rice straw mulching was decreased by 87.1%, 86.2%, respectively.

• Korean Journal of Soil Science and Fertilizer
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• v.24 no.1
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• pp.17-21
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• 1991

The experiment was conducted to investigate the origin of pH changes in a continuous cropping soil. The results obtained were as follows : 1. The concentration of phytotoxin increased and at the same time the soil pH decreased with the prolonged practice of continuous cropping. 2. The decrease of soil pH by the phytotoxin materials was higher in the distilled water and tap water than in the soil. 3. The effect of phytotoxin on plant germination was higher in benzoic acid than in p-hydroxybenzoic acid. 4. The treatment of acetone to the continuous cropping soil recovered the initial soil pH and sesame growth was normal in the soil.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.2
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• pp.103-107
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• 2003

Phosphorus (P) is a macronutrient playing important roles in many plant processes. Significant interest has been devoted to search and utilize genotypic variations in P use efficiency in rice but with little effort to understand its physiological and biochemical bases. In this study, we examined responses to P deprivation of some primary and secondary traits in 3-week-old seedlings of the three genotypes, Sobi-byeo (japonica), Dasan-byeo (japonica $\times$ indica) and Palawan (indica). In general, percent weight due to root was increased up to 26%, but amounts of root protein and proteins secreted from roots were decreased by 11 to 19% and 31 to 51 %, respectively, by 3 to 21 days of P deprivation in the three genotypes. Interestingly, however, responses of Palawan to short-term P deprivation were contrasting to those of Dasan-byeo and Sobi-byeo in seedling weight and contents of shoot protein, chlorophyll and anthocyanin. Seedling weight was not decreased, but shoot protein content was decreased in P-deprived seedlings of Palawan. Contents of chlorophyll in leaves and anthocynin in roots were increased in Dasan-byeo and Sobi-byeo, but decreased in Palawan. The results suggest that responses of protein and pigment synthesis to P deficiency are different in modem and traditional varieties and the difference may at least in part be due to the selection for high yield under highly fertilized conditions.

• Korean Journal of Medicinal Crop Science
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• v.4 no.4
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• pp.340-344
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• 1996

This experiment was conducted for the production of alismatis rhizoma (Alisma plan­tago-aquatica var. orientale Samuelsson) with high root tuber yield and alisol-B monoacetate content by treatment of different fertilizers levels. The results obtained were as follows: Shoot growth tended to in­crease as the fertilizers levels increased. Root tuber yield increased by 25% and 20% with 20-10-20 and 30-15-30 treatment, respectively. Alisol-B monoacetate contents increased as fertilizers levels increased, being the highest in 30-15-30 treatment.

• Journal of The Korean Society of Grassland and Forage Science
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• v.9 no.2
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• pp.82-87
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• 1989

A field experiment was carried out to determine the effects of 11 different application levels of nitrogen (N), phosphorous ($P_2O_5$) and potassium($K_2O$) fertilizer in late-autumn on the winter survival, early spring growth and dry matter(DM) yield, carbohydrate reserves (CHO-R) in stubble of grasses, and botanical composition in orchardgrass dominated existing pasture in Suwon from October, 1987 to May, 1988. Winter survival of grasses was high (ca. 90%) in all N-fertilized plots, regardless of $P_2O_5$ and $K_2O$ application, and those in zero-N and zero-NPK plots were low as 86.5% and 81.4%, respectively. Early spring growth was vigorous in N-fertilized plots. Heading rate at the fist harvest was 80-86% in all N plots, regardless of $P_2O_5$ and $K_2O$, while those in zero-N and zero-NPK plots were very low as 61% and 56%, respectively. The DM yield of first harvest was higher in the plots of N 35 kg(Site B) and N 70kg $ha^{-1}$ (Site A), regardless of $P_2O_5$ and $K_2O$ level, and those in zero-N and zero-NPK plots were very low (p < 0.05). But no significant difference of yield was observed between N 75 kg and N 105 kg. CHO-R in stubble and legumes were high in zero-N and zero-NPK plots, and low relationship was found between winter survival and CHO-R of grasses. Winter survival, early spring growth and DM yield were significantly influenced by N fertilizer. In this experiment, the optimum application level of N in late-autumn could be recommended in 35-70 kg $ha^{-1}$, and no beneficial effects were observed by $P_2O_5$ and $K_2O$ fertilizer.

• Korean Journal of Weed Science
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• v.32 no.2
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• pp.115-120
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• 2012

Weed control is of fundamental importance when planting cereal crops, particularly during the establishment phase. Weeds compete for nutrients, water and light, and can severely threaten the survival and early growth of newly planted crops. Field experiment was conducted to evaluate the effect of ethanol treatment on the weed control efficacy in cereal crops in protected vinylhouse. Five treatments like water, 25 L, 50 L, 75 L, and 100 L per $m^{-2}$ at 2% ethanol were applied and covered with vinyl on 10 days before foxtail millet seeding. After that, foxtail millet seeds were sown on June 20 at $60{\times}10cm$ planting distance and weed control efficacy was recorded at 30, and 50 days after seeding based on the dry weight. Soil oxidation-reduction potential was recorded -200~-400 mV after treatment 2 days. Weed control efficacy of at 75 L, and 100 L per $m^{-2}$ was observed 92%, 84% in 2% ETOH, respectively. Yields of foxtail millet at 75 L, and 100 L per $m^{-2}$ were 1,570 kg $ha^{-1}$, 1,230 kg $ha^{-1}$, respectively.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.4
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• pp.344-352
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• 2019

Drought stress caused by global climate change is a serious problem for rice cultivation. Increasingly frequent abnormal weather occurrences could include severe drought, which could cause water stress to rice during the seedling stage. This experiment was conducted to clarify the effects of drought during the seedling period on yield and quality of rice. Drought conditions were created in a rain shelter house facility. The drought treatment was conducted at 3, 10, and 20 days after transplanting. Soil water content was measured by a soil moisture sensor during the whole growth stage. In this study, we have chosen 3 rice cultivars which are widely cultivated in Korea: 'Haedamssal' (Early maturing), 'Samkwang' (Medium maturing), and 'Saenuri' (Mid-late maturing). The decrease in yield due to drought treatment was most severe 3 days after transplanting because of the decrease in the number of effective tillers. The decrease in grain quality due to drought treatment was also most severe 3 days after transplanting because of the increased protein content and hardness of the grains. The cultivar 'Haedamssal' was the most severely damaged by water stress, resulting in about a 30% yield loss. Drought conditions diminished the early vigorous growth period and days to heading in early-maturing cultivars. The results show that drought stress affects yield components immediately after transplanting, which is a decisive factor in reducing yield and grain quality. This study can be used as basic data to calculate damage compensation for drought damage on actual rice farms.

• The Journal of the Convergence on Culture Technology
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• v.9 no.3
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• pp.861-866
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• 2023

Unlike conventional smart farms that require chemical fertilizers and large spaces, aquaponics farming, which utilizes the symbiotic relationship between aquatic organisms and crops to grow crops even in abnormal environments such as environmental pollution and climate change, is being actively researched. Different crops require different environments and nutrients for growth, so it is necessary to configure the ratio of aquatic organisms optimized for crop growth. This study proposes a method to measure the degree of growth based on area and volume using image processing techniques in an aquaponics environment. Tilapia, carp, catfish, and lettuce crops, which are aquatic organisms that produce organic matter through excrement, were tested in an aquaponics environment. Through 2D and 3D image analysis of lettuce and real-time data analysis, the growth degree was evaluated using the area and volume information of lettuce. The results of the experiment proved that it is possible to manage cultivation by utilizing the area and volume information of lettuce. It is expected that it will be possible to provide production prediction services to farmers by utilizing aquatic life and growth information. It will also be a starting point for solving problems in the changing agricultural environment.

• Korean Journal of Medicinal Crop Science
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• v.4 no.2
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• pp.153-156
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• 1996

This study was carried out to know the proper method of stem cutting (defloration) to improve growth and yield of root in B. flacatum L. Dryed yield of two-year old roots was increased by cutting at 50cm height. Root yield was increased by 56% (1, 670kg/ha) than that of control in the case of twice stem cutting at 50cm height on both June 16 and July 16.