Development of an Expolinear Growth Model for Pak-choi Using the Radiation Integral and Planting Density

조영열,이정현,신종화,손정익 한국원예학회 2015 Horticulture, Environment, and Biotechnology Vol.56 No.3

The objectives of this study were to develop a growth model of pak-choi using an expolinear function and to estimate the effect of the radiation integral and planting density on the crop growth rate. The growth and yield of hydroponically grown pak-choi (Brassica campestris ssp. chinensis) were investigated at four different planting densities (27, 33, 44, and 67 plants/m2). The shoot dry and fresh weights per m2 increased with increasing planting density and could be expressed as expolinear functions based on the daily photosynthetically active radiation (PAR). A linear relationship was observed between the shoot dry weight and fresh weight, regardless of the planting density. The maximum crop growth rate and light use efficiency (LUE) increased with increasing planting density, but the lost daily PAR integral decreased. The maximum relative growth rate was not significantly different among the planting densities. Using the relative growth rate per the daily PAR integral and LUE, an expolinear growth model of pak-choi was developed. The measured and estimated shoot dry weights exhibited strong agreement with Y = 1.010·X (R2 = 0.982***) using the PAR and leaf area index as inputs. The expolinear growth model was determined to be useful for quantifying the growth and yield of pak-choi in controlled environments.

Effects of Electrical Conductivity on Growth and Yield of Hydroponically-Grown Pak-Choi (Brassica campestris ssp. chinensis)

조영열,손정익 한국원예학회 2007 Horticulture, Environment, and Biotechnology Vol.48 No.2

. Management of electrical conductivity (EC) is very important for crop growth in hydroponics. To determine the effect of EC on growth and yield of pak-choi (Brassica campestris ssp. chinensis) with growth stage, fresh and dry weights, number of leaves, yield, crop growth rate, and yield per area were evaluated in deep flow technique and nutrient film technique systems under different EC conditions. The growth stages were divided into two stages: stage 1, from seedling emergence to transplanting with 3 or 4 true leaves; stage 2, from transplanting to harvest at fresh weight ³60 g. The EC conditions were 0.5, 1.0, 1.5, 2.0, and 2.5 dSám1 for growth stage 1 and 1.0, 1.5, 2.0, and 2.5 dSám1 for growth stage 2. In growth stage 1, shoot fresh weight was highest at 1.5 dSám1, while shoot dry weight was highest at 2.0 dSám1. Both shoot fresh and dry weights were lowest at 1.0 dSám1. In growth stage 2, leaf length, leaf width and number of leaves were highest at 2.0 dSám1. Both shoot fresh and dry weights were highest at 2.5 dSám1. Yield per area was highest at 2.0 and 2.5 dSám1. Except for 1.0 dSám1, no significant differences in shoot fresh, dry weights and yield per area were observed. Cumulative water absorption per plant was highest at 2.0 dSám1. Adequate ECs for growth and yield of pak-choi were 1.52.0 dSám1 from seedling emergence to transplanting and 2.0 dSám1 from transplanting to harvest. Optimum conditions of EC could improve the growth and yield of hydroponically-grown pak-choi.

Application of Quadratic Models for Establishment of Adequate Temperature Ranges in Germination of Various Hot Pepper (Capsicum annuum L.) Cultivars

조영열,이용범,오명민,손정익 한국원예학회 2012 Horticulture, Environment, and Biotechnology Vol.53 No.3

Appropriate temperature control of seeds leads to uniform germination and efficient management of the production of seedling grafts, which are required for successful cultural practices. In this study, the base, optimum,and maximum temperatures of four hot pepper cultivars were used as scions as well as four hot pepper cultivars used as rootstocks were estimated using a quadratic model. Seeds of the cultivars were germinated in growth chambers at constant temperatures of 20℃, 25℃, 30℃, and 35℃. Cumulative germination was described using a logistic function. The base, optimum, and maximum temperatures were estimated by regressing the inverse of the time to 50% germination (1/GR50) against temperature. Although germination rates varied according to cultivar and temperature, the highest germination rates were observed at temperatures of 25℃ and 30℃. Wongang 1 was the most tolerant at low temperature,whereas Koregon PR-380 and Wongang 1 were the most tolerant at high temperature. Further, we suggest appropriate combinations of scion and rootstock cultivars based on our cardinal temperature results for the eight hot pepper cultivars.

Development of Models for Estimating Total Leaf Area and Shoot Fresh and Dry Weights of Tomato (Lycopersicon esculentum cv. Seokwang)

조영열,손정익 한국원예학회 2005 Horticulture, Environment, and Biotechnology Vol.46 No.2

Nondestructive and mathematical approaches by modeling are very convenient and useful for estimating plant growth even though their accuracy should be verified by all means. Models for predicting total leaf area and shoot fresh and dry weights of tomato (Lycopersicon esculentum cv. Seokwang) were developed using plant height, leaf length, leaf width of tomato, and some combinations of these variables. Eighteen regression equations commonly used in developing growth models were compared in terms of accuracy and adaptability. Three nonlinear models as follows were developed; total leaf area (LA)=44919.9H22.2W+1.55HW (R2=0.956), shoot fresh weight (SFW)=40.2+0.07HW (R2=0.939), and shoot dry weight (SDW)=0.430.09H+0.003H2 (R2= 0.857), where H=plant height, W=leaf width, and HW=HW. In model validation, estimated total leaf area and shoot fresh and dry weights showed good agreements with measured ones, respectively. Shoot fresh weight was highly correlated with shoot dry weight. It is concluded that these models can estimate the total leaf area and shoot fresh and dry weights of tomato accurately.

Growth Characteristics of Sowthistle (Ixeris dentata Nakai) under Different Levels of Light Intensity, Electrical Conductivity of Nutrient Solution, and Planting Density in a Plant Factory

조영열,최기영,이용범,손정익 한국원예학회 2012 Horticulture, Environment, and Biotechnology Vol.53 No.5

The objective of this study was to investigate the growth characteristics of sowthistle (Ixeris dentata Nakai)under different levels of light intensity (photosynthetic photon flux, PPF), electrical conductivity (EC) of nutrient solution,and planting density for efficient production in a closed-type plant factory system. Growth and yield of the plants were analyzed at EC 1.5 and 2.0 dS·m-1 with PPF 100 and 200 ㎛ol·m-2·s-1. Further, growth and yield were measured under four different planting densities: a 15-cm between-row distance with within-row distances of 10, 15, 20, and 25 cm. Shoot dry weight and leaf photosynthetic rate all increased with increasing EC and light intensity. Shoot fresh and dry weights, chlorophyll content, and leaf photosynthetic rate were maximal at EC 2.0 dS·m-1 with PPF 200 ㎛ol·m-2·s-1. For all planting densities, number of leaves and leaf width were not significantly different. Shoot fresh and dry weights per plant were not significantly different, however, shoot fresh and dry weights per area decreased with increasing plating densities. A linear relationship was observed between the number of leaves and days after transplantation. Based on the results, we suggest a nutrient solution of EC 2.0 d·sm-1, PPE 200 ㎛ol·m-2·s-1, and planting density 15×10 cm for maximal growth and yield of sowthistle in a closed-type plant factory.

Effect of Planting Density on Growth and Yield of Hydroponically-Grown Pak-choi (Brassica campestris ssp. chinensis)

조영열,Junk Eek Son 한국원예학회 2005 Horticulture, Environment, and Biotechnology Vol.46 No.5

Planting density is an important factor to determine crop productivity and spacing efficiency in vegetable production systems. In this study, the growth and yield of hydroponically-grown pak-choi (Brassica campestris ssp. chinensis) were investigated under five different planting densities (27, 33, 44, 67, and 133 plants/m2). Number of leaves and top fresh weight per plant were decreased with increasing the planting density, while yields per area were increased reaching the maximum value at 133 plants/m2. Maximum crop growth rate, light use efficiency yield, and yield index, which are closely related with planting density, were the highest at 67 plants/m2. Especially the yield index was 23-31% higher at 67 plants/m2 than that at 33 plants/m2. The marketable rate, which was 100% between 27 and 44 plants/m2, was sharply decreased with increasing the planting density and then became the lowest at 133 plants/m2 due to the poor light environment, while the marketable yields per area were the highest at 67 plants/m2. From a practical point of view, the marketable yield per area was an appropriate factor to evaluate the planting density in hydroponics, a 67 plants/m2 (1510 cm) was considered as an optimum planting density for hydroponically-grown pak-choi.

Soil Depth Affects the Growth of Lettuce and Chicory in Extensive Green Roofs

조영열 한국원예학회 2008 Horticulture, Environment, and Biotechnology Vol.49 No.6

The objective of this study was to examine the effect of soil depth on the growth of lettuce and chicory in a green roof environment. Three soil depths of 5, 10, and 20 cm were applied to the plants. Seedlings of lettuce and chicory were transplanted to the green roof systems. Soil water content was the highest at 20 cm deep and the lowest at a depth of 5 cm. Shoot fresh and dry weight of lettuce was the highest when planted at a depth of 10 cm and the lowest at a depth of 20 cm. Shoot fresh and dry weight of chicory was the highest when planted at a depth of 5 cm and the lowest at a depth of 20 cm. Dry matter (DM) of lettuce and chicory were the highest when planted at a depth of 20 cm and the lowest at a depth of 5 cm. Relative growth rate (RGR) of lettuce was the highest when planted at a depth of 10 cm and the lowest at a depth of 20 cm. RGR of chicory was the highest when planted at a depth of 5 cm and the lowest at a depth of 20 cm. Photosynthesis, stomatal conductance, and transpiration rate of lettuce were not significantly different among the three soil depths, but these were the highest when planted at a depth of 5 cm. In these leafy vegetables, the contents of T-N, P and K were not significantly different among the three soil depths. In lettuce leaves, the contents of T-N, Ca and Mg were the highest when planted at a depth of 5 cm. In chicory leaves, the contents of T-N and Ca were the highest when planted at a depth of 10 while the content of Mg was the highest at a depth of 5 cm. Based on the findings, it is recommended that the depth of planting lettuce and chicory must be over 5 cm for safe load, but a depth of 10 cm is best to reduce water consumption in extensive green roofs.

Modeling Approaches for Estimating Cardinal Temperatures by Bilinear, Parabolic, and Beta Distribution Functions

조영열,손정익,오영민 한국원예학회 2009 원예과학기술지 Vol.27 No.2

Estimation of the cardinal temperatures – the base, optimum and maximum temperatures – is indispensable because plant growth and development are affected by temperature. Although several models including linear and nonlinear functions are available to estimate the temperatures, a model suitable to the specific crop should be selected. The objectives of this study were to analyzed the estimated the cardinal temperatures for germination of spinach (Spinachia oleracea cv. Gwibin) by bilinear, parabolic and beta distribution models and to find a model reflecting the plant response to temperature adequately. Seeds of spinach were germinated in a growth chamber at constant temperatures of 2, 4, 8, 12, 16, 20, 24, 28, 32, and 36℃. Radicle emergence of 1 mm was scored as germination. The time course of germination was fitted using a logistic function. The base, optimum, and maximum temperatures were estimated by regression of the inverse time to 50% germination rate against temperature gradient. We obtained the base, optimum and maximum temperatures of -4.0, 17.1 and 33.2℃ in bilinear function; -0.9, 15.8 and 32.5℃ in parabolic function; and -2.6, 16.6 and 32.6℃ in beta distribution function, respectively. Among the three functions, a beta distribution function had a good agreement with the plant response to temperature showing the highest R2 (coefficient of determination) and the lowest RMSE.

Determination of Suitable Parameters for Developing Adequate Growth Model of Pak-choi Plants

조영열,손정익 한국원예학회 2009 Horticulture, Environment, and Biotechnology Vol.50 No.6

Since growth and development of plants is influenced by environmental factors such as temperature and radiation, selection of suitable parameters in developing models is very important. Purpose of this study was to determine suitable parameters of in growth model of pak-choi (Brassica campestris ssp. chinensis). Expolinear function was used for developing growth model. The growth parameters of maximum relative growth rate, maximum crop growth rate and lost time in themodel were described by growing degree-days (GDD) and daily photosynthetically active radiation (PAR) integral parameters. Therefore shoot dry weight per area (g・m-2) could be predicted using those parameters as described above. Daily PAR integral, compared with time and GDD, improved the accuracy of the model (Y=0.83・X, R2=0.998***). Also shoot dry weight showed closely linear relationship with shoot fresh weight of pak-choi. From the results, we concluded that daily PAR integral was a suitable parameter for predicting the growth of pak-choi plants. The expolinear growth model developed using daily PAR in this study worked satisfactorily and could be a useful tool for optimizing farm management andcontrolling crop growth.

日帝의 對宣敎師政策 : George Kennan의 활동을 중심으로

조영열 한국사학회 1987 史學硏究 Vol.- No.39