• The Plant Pathology Journal
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• 제34권4호
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• pp.316-326
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• 2018

The effect of simulated climate changes by applying different temperatures and $CO_2$ levels was investigated in the Blumeria graminis f. sp. tritici/wheat pathosystem. Healthy and inoculated plants were exposed in single phytotrons to six $CO_2$+temperature combinations: (1) 450 ppm $CO_2/18-22^{\circ}C$ (ambient $CO_2$ and low temperature), (2) 850 ppm $CO_2/18-22^{\circ}C$ (elevated $CO_2$ and low temperature), (3) 450 ppm $CO_2/22-26^{\circ}C$ (ambient $CO_2$ and medium temperature), (4) 850 ppm $CO_2/22-26^{\circ}C$ (elevated $CO_2$ and medium temperature), (5) 450 ppm $CO_2/26-30^{\circ}C$ (ambient $CO_2$ and high temperature), and (6) 850 ppm $CO_2/26-30^{\circ}C$ (elevated $CO_2$ and high temperature). Powdery mildew disease index, fungal DNA quantity, plant death incidence, plant expression of pathogenesis-related (PR) genes, plant growth parameters, carbohydrate and chlorophyll content were evaluated. Both $CO_2$ and temperature, and their interaction significantly influenced powdery mildew development. The most advantageous conditions for the progress of powdery mildew on wheat were low temperature and ambient $CO_2$. High temperatures inhibited pathogen growth independent of $CO_2$ conditions, and no typical powdery mildew symptoms were observed. Elevated $CO_2$ did not stimulate powdery mildew development, but was detrimental for plant vitality. Similar abundance of three PR transcripts was found, and the level of their expression was different between six phytotron conditions. Real time PCR quantification of Bgt was in line with the disease index results, but this technique succeeded to detect the pathogen also in asymptomatic plants. Overall, future global warming scenarios may limit the development of powdery mildew on wheat in Mediterranean area, unless the pathogen will adapt to higher temperatures.

• 한국작물학회지
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• 제63권2호
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• pp.86-97
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• 2018

The objective of this study was to determine the effects of low temperature on starch accumulation in rice grains. We used four major Japonica-type Korean rice cultivars as materials: Jinbu (JB), Junamjosaeng (JJ), Geumyoung (GY), and Hwawang (HW). Rice plants were moved into two phytotrons the day after heading. Temperatures in the two phytotrons were maintained at $19/29^{\circ}C$ (night/day) as the control, and $13/23^{\circ}C$ as the low temperature condition, both under natural daylight with a relative humidity of 65%. The ripening rates of JB and JJ showed no significant difference between the low temperature and control conditions at 45 days after heading (DAH). In contrast, the ripening rates of GY and HW were 86% and 57% lower than those of JB and JJ under the low temperature condition at 45 DAH, respectively. However, the ripening rates of these four varieties at 61 DAH (when accumulated temperature reached $1,100^{\circ}C$) under the low temperature condition were similar to those at 45 DAH under the control condition (JB, 94%; JJ, 97%; GY, 97%; HW, 88%). The total starch contents showed no significant difference between the control and low temperature conditions. However, the amylose contents in the cultivars were higher under the low temperature than under the control condition. The enzyme activities of starch biosynthesis were about 5-10 days slower in cultivars under the low temperature than under the control. The grain-filling rate showed significant correlations with the enzyme activities of SuSase ($r^2=0.70^{***}$), AGPase ($r^2=0.63^{***}$), UDPase ($r^2=0.36^{***}$), StSase ($r^2=0.51^{***}$), and SBE ($r^2=0.59^{***}$). In conclusion, although StSase activity was increased at $13/23^{\circ}C$ up to 20 DAH, there might not be enough time for SBE to synthesize amylopectin, thus affecting the amylose content of HW, which had the slowest grain filling rate. Notably, the decreased activity of SuSase and SBE and late increase in AGPase activity under the low temperature during the ripening stage are considered to be disadvantageous, as they delay ripening and increase the amylose content.

• 한국작물학회지
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• 제65권1호
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• pp.22-29
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• 2020

Rice is very sensitive to high temperatures during the reproductive stage, particularly during the flowering and anthesis periods. To determine how high temperatures result in sterility during the flowering period in Korean rice cultivars, groups of 11 cultivars were subjected to different temperature regimes (24, 28, 30, and 33℃) during the flowering stage using sunlit phytotrons. At an average of 33℃, all 11 rice cultivars reached anthesis earlier than at the other temperatures. Microscopy analyses revealed significant differences in pollen germination and pollen viability in cultivars grown at 33℃ compared to those cultured at lower temperatures. At 33℃, the cultivars had significantly lower fertility rates (47% reduction) than cultivars grown at 24℃. These findings are important as rice pollination and fertility depend on the pollen viability and germination. The present study shows that rice fertility is negatively affected by excessively high temperatures.

• Journal of Biosystems Engineering
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• 제17권1호
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• pp.55-64
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• 1992

The aim of this study was to develop a phytotron for studying the effects of environmental factors such as temperature and humidity on plant growth. This equipment consists of the growth chamber, and the measurement and control system including control algorithms required for optimum operation. As the first step of the study, a temperature and humidity control system was developed. The results of this study are summarized as follows ; 1. Pt-100 was selected to measure temperature and a linearized op-amp circuit was developed for signal conditioning. 2. Pt-100 wet bulb thermometer based on Asmann's principle was developed to measure relative humidity. 3. Temperature and relative humidity conditions were controlled by ON-OFF and PWM operation using a PID controller. And an autotuning algorithm using the characteristics of step response was developed to determine optimal PID constants which were independent of the size of apparatus and environmental factors. 4. Under the ambient temperature of $20^{\circ}C{\sim}25^{\circ}C$, the temperature was kept within the error of ${\pm}0.3^{\circ}C$ in the range of $10^{\circ}C{\sim}40^{\circ}C$, and the relative humidity was kept within the error of ${\pm}5%$ in the range of ${\pm}50%{\sim}90%$.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2022년도 추계학술대회
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• pp.172-172
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• 2022

The heading response of 40 genotypes, originated from South Korea, North Korea, and northern China, was tested under the temperature and day-length conditions of thirteen major rice production area in North Korea, with aims to select adaptable varieties to the given environment and crop period for each region. To simulate regional environment, seven-day mean temperature with 10℃ daily temperature range and day-length for each region were imposed at a weekly interval in the walk-in phytotrons. Olbyeo1, Olbyeo2 and Sonbong9 originated from North Korea, Kenjiandao3 and Nongdae3 from northern China, and Joun from South Korea demonstrated the earliest heading stage depending on the regional environment. Thirty-four varieties reached heading stage within the regional safe marginal heading date (SMHD) under Haeju and Sariwon conditions while 16-17 varieties reached the stage under Wonsan, Changjon, Supung, and Yongyon environment. Some of the middle and mid-late maturing varieties originated from South Korea could reach heading stage within SMHD under the temperature and day-length conditions of Kaesong, Haeju, Sariwon, Nampo, and Pyongyang located in west-southern plain. Majority of early maturing varieties, but not middle or mid-late ones, showed heading stage within SMHD under the conditions of Singye, Anju, Kusong and Sinuiju. Only some early maturing varieties demonstrated heading stage within SMHD under Yongyon, Changjon and Wonsan environment. These results provide basic information on the varieties able to complete their normal life cycle under the regional environment in North Korea. It it further suggested that yield performance of the selected varieties for each region in this study be tested to select high yielding rice varieties adaptable to North Korean environment.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.229-229
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• 2017

This research study was conducted to analyze the characteristics of different rice cultivars in abnormal temperature conditions (low temperature) for ripening period abnormalities, and to investigate the physiological causes behind the abnormalities. Four Korean high quality japonica-type rice cultivars, Jinbu (JB), Junamjosaeng (JJ), Geumyoung (GY), Hwawang (HW) were used in the experiment. The following day after flowering, they were then moved into two phytotrons under natural daylight with 65% RH but controlled at different temperatures - one at $19/29^{\circ}C$ (night/day) and the other at $13/23^{\circ}C$ as the low - temperature study on ripening. For the cultivars at $13/23^{\circ}C$ (low temperature study), JB and JJ had a ripening rate of 93% which is similar to the ripening rates of cultivars at $19/29^{\circ}C$ at 45 days after heading (DAH). In contrast, GY and HW recorded lower ripening rates of 86% and 57% respectively. However, when the cultivars at $13/23^{\circ}C$ were harvested at 61 DAH (when the accumulated temperature reached $1100^{\circ}C$), the difference in ripening rates compared to the 4 cultivars of $19/29^{\circ}C$ harvested at 45 DAH was not obvious (JB 94%, JJ 97%, GY 97%, HW 88%). Starch content showed little difference among the 4 cultivars at different temperature conditions while amylose content was higher for cultivars at $13/23^{\circ}C$ compared to those at $19/29^{\circ}C$. In addition, the enzyme activities of starch biosynthesis were about 5~10 days slower in cultivars at $13/23^{\circ}C$ compared to cultivars at $19/29^{\circ}C$. The grain-filling rate showed highly significant correlations with the enzyme activities of Sucrose synthase ($R^2=0.70^{***}$), ADP glucose pyrophosphorylase ($R^2=0.63^{***}$), UDP glucose pyrophosphorylase ($R^2=0.36^{***}$), Starch synthase ($R^2=0.51^{***}$), and Starch branching enzyme ($R^2=0.59^{***}$). Among the enzymes, Sucrose synthase activity had the highest correlation coefficient with grain-filling rate. In conclusion, the activity of enzymes such as Sucrose synthase, UDP glucose pyrophosphorylase, ADP glucose pyrophosphorylase, Starch synthase, Starch branching enzyme in starch biosynthesis is proven to be highly related to the grain filling process. Notably, the decrease in the activity of Sucrose synthase and Starch branching enzyme and the late increase in ADP glucose pyrophosphorylase activity at low temperature in the ripening stage are considered to be disadvantageous as they delay ripening and increased amylose content.