• Journal of Bio-Environment Control
• /
• v.29 no.4
• /
• pp.399-405
• /
• 2020

Recently, it is difficult to produce uniform scions and rootstocks with high quality in a greenhouse due to weather extremes. The closed transplant production system is useful for producing scions and rootstocks with desirable morphological characteristics by environment control regardless of weather outside. In this study, we investigated transpiration rates and growth of cucumber and tomato scions and rootstocks grown under different light intensity conditions for precise irrigation control in a closed transplant production system. Hanging system to measure continuously the weight of plug tray consisting of seedlings and substrate with load-cell was installed in each growing bed. Using this system, we confirmed initial wilting point of cucumber and tomato seedlings, and conducted subirrigation when moisture content of substrate was not below 50%. The irrigation time of cucumber scions and rootstocks were 7 and 6 days after sowing, respectively. In tomato scions and rootstocks grown under PPF (photosynthetic photon flux) 300 μmol·m^-2·s^-1, the irrigation time were 5, 8, 11, and 13 days after sowing. Increasing light intensity increased transpiration rates and differences of transpiration rates by light intensity was higher in tomato seedlings. The growth of cucumber and tomato seedlings was promoted by increasing light intensity, especially, hypocotyl elongation and stem thickening was affected by light intensity. Cumulative transpiration rate of plug tray in cucumber and tomato seedlings was increased by increasing light intensity, and daily transpiration rate per seedling was regressed by 1st-order linear equation with high correlation coefficient. Estimation of transpiration rates by weighing continuously plug tray of vegetable seedlings can be useful to control more accurately irrigation schedule in a closed transplant production system.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.53 no.1
• /
• pp.93-101
• /
• 2008

The effects of $CO_2$ enrichment on growth of maize (Zea mays L.) were examined. Parameters analyzed include growth characteristics, yields, photosynthetic rates, evaporation rates and photosynthesis-related characteristics under elevated $CO_2$. The plants were grown in growth chambers with a 12-h photoperiod and a day/night temperature of $28/21^{\circ}C$ at the seedling stage and $30/23^{\circ}C$ from the silking stage. The plants were exposed to two elevated $CO_2$ of 500, 700ppm and ambient levels (350 ppm). Chalok 1 and GCB 70 germinated three days after seeding, and germination rates were faster in the elevated $CO_2$ than the control. Germination rates displayed significant differences among the $CO_2$ treatments. At the seedling stage, leaf area, top dry weight, and photosynthetic rates, and plant height indicated positive relationship with elevated $CO_2$ concentrations. At the $5{\sim}6$ leaf stage, $CO_2$ concentration also indicated positive relationship with plant height, leaf area, top dry weight, and photosynthetic rates. At the silking stage, increased plant height of Chalok 1 was noted in the $CO_2$ treatments compared to the control. No significant differences were noted for GCB 70, in which leaf area decreased but photosynthetic rates increased progressively with $CO_2$ concentration. Stomatal aperture was a little bigger in the elevated $CO_2$ than the control. $CO_2$ concentration was negatively related to stomatal conductance and transpiration rates, resulting in high water use efficiency.

• Korean Journal of Medicinal Crop Science
• /
• v.28 no.6
• /
• pp.412-420
• /
• 2020

Background: Measurement of chlorophyll fluorescence (CF) is useful for detection the ability of plants to tolerate environmental stresses such as drought, and excessive sunlight. Cnidium officinale Makino is highly sensitive to water stress and excessive sunlight. In this study, we evaluated the effect of soil water and shade treatment on the photosynthesis and leaf temperature change of C. officinale. Methods and Results: C. officinale was cultivated under uniform irrigation for 1 week drought stress (no watering) for 6 days. A significant decrease in CF was observed on the 5th day of withholding water (approximately 6% of soil water content) regardless of shading. Notably, the Rfd_lss parameter (CF decrease rates) with and without shade treatment was reduced by 73.1% and 56.5% respectively, at 6 days compared with those at the initial stage (0 day). The patterns of the degree of CF parameters corresponded to those of the soil water content and difference between leaf temperature (Ts) and air temperature (Ta). Meanwhile, CF parameters recovered to the 3 - 4 days levels after re-watering, while the soil water potential was completely restored. The suitable soil water content for C. officinale optimal growth was between -5 kPa and -10 kPa in this experiment. Conclusions: Lack of soil water in the cultivation of C. officinale, even with shading, decreased latent heat cooling through transpiration. As a result, heat dissipation declined, and the plant was subjected to drought stress. Soil water content plays a major role in photosynthesis and leaf temperature in C. officinale.

• Journal of Bio-Environment Control
• /
• v.15 no.4
• /
• pp.296-305
• /
• 2006

The heterogeneity of crop transpiration is important to clearly understand the microclimate mechanisms and to efficiently handle the water resource in greenhouses. A computational fluid dynamic program (Fluent CFD version 6.2) was developed to study the internal climate and crop transpiration distributions of greenhouses. Additionally, the global solar radiation model and a crop heat exchange model were programmed together. Those models programmed using $C^{++}$ software were connected to the CFD main module using the user define function (UDF) technology. For the developed CFD validity, a field experiment was conducted at a $17{\times}6 m^2$ plastic-covered mechanically ventilated single-span greenhouse located at Pusan in Korea. The CFD internal distributions of air temperature, relative humidity, and air velocity at 1m height were validated against the experimental results. The CFD computed results were in close agreement with the measured distributions of the air temperature, relative humidity, and air velocity along the greenhouse. The averaged errors of their CFD computed results were 2.2%,2.1%, and 7.7%, respectively.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.27 no.2
• /
• pp.175-181
• /
• 1982

This experiment was carried out to study the influence of the various soil water regimes on photosynthesis and growth and development of ginseng plant (3 years). The results were as follows: optimum soil water content for root dry weight and diameter appeared to be 62% of field capacity (13.9% fresh weight basis). The 62% field capacity showed superiority in leaf area, leaf dry weight and also in number of flower, fruit, seed per plant. Net photosynthesis rates per unit area increased with increasing soil water content but net photosynthesis rates per plant were superior in 62% field capacity. Rates of transpiration increased linearly with increasing soil water content but density of stomata decreased with increasing soil water content.

• Korean Journal of Soil Science and Fertilizer
• /
• v.46 no.4
• /
• pp.245-252
• /
• 2013

Leaf area index (LAI) is important in explaining the ability of crops to intercept solar energy for biomass production, amount of plant transpiration, and in understanding the impact of crop management practices on crop growth. This paper describes a procedure for estimating LAI as a function of image-derived vegetation indices from temporal series of RapidEye imagery obtained from 2010 to 2012 using empirical models in a rice plain in Seosan, Chungcheongnam-do. Rice plants were sampled every two weeks to investigate LAI, fresh and dry biomass from late May to early October. RapidEye images were taken from June to September every year and corrected geometrically and atmospherically to calculate normalized difference vegetation index (NDVI). Linear, exponential, and expolinear models were developed to relate temporal satellite NDVIs to measured LAI. The expolinear model provided more accurate results to predict LAI than linear or exponential models based on root mean square error. The LAI distribution was in strong agreement with the field measurements in terms of geographical variation and relative numerical values when RapidEye imagery was applied to expolinear model. The spatial trend of LAI corresponded with the variation in the vegetation growth condition.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.28 no.2
• /
• pp.189-194
• /
• 1983

The experiment was carried out to know the ripeness effect of Gemgang when ABA and BA were sprayed at the heading stage. ABA promoted the stomatal movement, BA kept plant from senescence. Percent of filled grain, grain weight, photosynthesis, content of chlorophyll, transpiration and content of ATP were measured at 1-week interval from 2-weeks after heading.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2022.10a
• /
• pp.17-17
• /
• 2022

Leaves are an important organism for photosynthesis and transpiration. The shape of leaf is crucial factor affecting plant architecture. V-shape leaf rolling is enhancing canopy photosynthesis by increasing the CO₂ penetration and the light capture by reducing the shadow between the leaves. Therefore, moderate leaf rolling is thought to more high grain yield per area than flat leaf. We investigated 278 KRICE_CORE accession's Adaxial Leaf Rolling Index (LRI) in first heading using the following equation. For each accession, genomic DNA was used for sequencing. We sequenced the genomics with ~8 X coverage to detect SNPS. Raw reads were aligned against the rice reference (IRGSP 1.0) for SNP identification and genotype calling. To generate genotype data for GWAS, SNPs were filtered with minor allele frequency 0.05. Finally, 841,134 high-quality SNPs were used for our GWAS. The significant threshold was -log10(P)>7.23. From the results, 2 significance SNP were detected. Considering the LD block of 250kbp, 60 candidate gene were selected including Hypothetical gene and Conserved gene. In this poster, we analyzed candidate gene affecting adaxial Leaf Rolling through single-trait GWAS.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2022.10a
• /
• pp.243-243
• /
• 2022

Leaves are an important organism for photosynthesis and transpiration. The shape of leaf is crucial factor affecting plant architecture. V-shape leaf rolling is enhancing canopy photosynthesis by increasing the CO₂ penetration and the light capture by reducing the shadow between the leaves. Therefore, moderate leaf rolling is thought to more high grain yield per area than flat leaf. We investigated 278 KRICE CORE accession's Adaxial Leaf Rolling Index (LRI) in first heading using the following equation. For each accession, genomic DNA was used for sequencing. We sequenced the genomics with ~8 X coverage to detect SNPS. Raw reads were aligned against the rice reference (IRGSP 1.0) for SNP identification and genotype calling. To generate genotype data for GWAS, SNPs were filtered with minor allele frequency 0.05. Finally, 841,134 high-quality SNPs were used for our GWAS. The significant threshold was -log10(P) >7.23. From the results, 2 significance SNP were detected. Considering the LD block of 250kbp, 60 candidate gene were selected including Hypothetical gene and Conserved gene. In this poster, we analyzed candidate gene affecting adaxial Leaf Rolling through single-trait GWAS.

• Journal of Bio-Environment Control
• /
• v.13 no.2
• /
• pp.102-106
• /
• 2004

Objective of this research was to investigate the effect of fertigation setting point such as -5, -10, -20, and -30 ㎪ on the growth and fruit quality of sweet pepper (Capsicum annuum L.) in greenhouse culture. The net $CO_2$ assimilation and transpiration rate were the lowest in the treatment of -30㎪. The pH and EC in soil solution were not severly affected by irrigation setting point and no statistical differences were observed among treatments of irrigation setting point tested. The N content of above ground plant tissue was the lowest in the treatment of -30 ㎪ and those of K, Ca, and Mg were the highest in the treatment of -10 ㎪. But that of P did not show statistical differences among treatments tested. As the fertigation setting point was getting low, the growth decreased at 60th day after planting, while there were no differences among treatments at 210th day after planting. The fruit quality except sugar contents did not show differences among treatments, but sugar contents was the highest in the treatment of -30 ㎪ with $8.0^{\circ}$Brix. Above results indicated that fertigation setting point should be in the range from -10 ㎪ to -20 ㎪ to ensure good crop growth and fruit quality in sweet pepper production.