• Journal of Photoscience
• /
• v.9 no.2
• /
• pp.332-334
• /
• 2002

We examined the effects of supplementary ultraviolet-B (UV-B) radiation on the changes in synthesis and degradation of ribulose-I, 5-biphosphate carboxylase /oxygenase (Rubisco) and light-harvesting chlorophyll a/b binding protein of PSII (LHCII), as well as mRNA levels for small and large subunits of Rubisco (rbcS and rbcL, respectively) and LHCII (cab) with leaf age in UV-sensitive rice (Norin I) and UV-resistant rice (Sasanishiki). Both Rubisco and LHCII were actively synthesized until the leaf had fully expanded, and then decreased with leaf age. Synthesis of Rubisco, but not LHCII, was significantly suppressed by UV-B in Norin 1. The degradation of Rubisco was enhanced by UV-B around the time of the leaf maturation in the two cultivars. The levels of rbcS and rbcL were reduced by UV-B at the early leaf stages after emergence in both cultivars. The level of cab was first present at the highest level in the two cultivars, but drastically decreased due to UV-B treatment immediately after leaf emergence in Norin 1. It was proved that synthesis and degradation of Rubisco and LHCII greatly changed with leaf age: Rubisco synthesis was significantly suppressed by supplementary UV-B radiation at the transcription step during the early leaf stages. It was also suggested that the difference between the two rice cultivars in sensitivity to UV-B in the synthesis of Rubisco might be due to the specific suppression not only after transcription but also at transcription.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 1997.05a
• /
• pp.58-59
• /
• 1997

• Korean Journal of Weed Science
• /
• v.16 no.4
• /
• pp.354-361
• /
• 1996

This study was conducted to evaluate the susceptibility of rice(Oryza sativa L.) cultivars to herbicide thiobencarb through the determination of protein patterns using SDS-PAGE. In both greenhouse and laboratory screening tests, IR 10198-66-2 and IR 9660-50-3-1 showed relatively tolerant response to thiobencarb, while IR 22, IR 31802-48-2-2-2 and IR 20656-R-R-R-6-1 were susceptible to it. The total protein content of susceptible cultivars markedly decreased as the thiobencarb concentrations increased, but tolerant cultivars such as IR 10198-66-2 and IR 9660-50-3-1 showed very slight changes suggesting that protein synthesis of susceptible cultivars may be inhibited by thiobencarb. The protein profiles of the tolerant cultivars were not much affected by thiobencarb treatment. However, the protein spots with molecular weights of 14.4 kD and 55 kD in the susceptible cultivar of IR 22 disappeared with the treatment of 3 ppm thiobencarb, indicating that differential susceptibilities of rice cultivars against thiobencarb can be attributed to their difference in protein metabolism affected by thiobencarb.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.46 no.1
• /
• pp.40-46
• /
• 2001

Ozone ($O_3$)-induced changes in chlorophyll content and specific activities of antioxidant enzymes, such as superoxide dismutase (SOD), ascorbate peroxidase (APX), guaiacol peroxidase (GPX), dehydroascorbate reductase (DHAR) and glutathione reductase (GR) were investigated in two rice cultivars (Oryza sativa L.) grown under variable nutrient treatments. For this study, two rice cultivars of Ilpumbyeo (IL) and Keumobyeo#l (KM), which were known as resistant and susceptible to $O_3$, respectively, were exposed to $O_3$at 0.15ppm for 30 days and investigated with 10 days interval. The available nutrient regimes were varied by doubling the supply of nitrogen (N), phosphorus (P) and potassium (K) Within a basic fertilizer status (N, P, K; 15, 12, 12kg/l0a$^{-1}$ ). In both cultivars and at all nutrient status, chlorophyll content in $O_3$-treated plants decreased with prolonged treatment period, although higher N, P and K supply with $O_3$ treatment alleviated the decrease in chlorophyll content. The activities of almost all enzymes investigated for this study were decreased during initial stages of $O_3$- exposure except GPX which maintained higher activity throughout the exposure period than the non-treated plant. However, the antioxidant enzymes in $O_3$-treated plants showed almost the same or higher activities on 30 days after $O_3$ - exposure. The most significant changes in activities were observed in GR of the $O_3$-treated leaves. With the prolonged treatment period, the activity of GR at 30 days was increased by 3-8 times compared to those in 10 days. Most of the investigated enzymes showed very similar tendency to $O_3$ treatment in all fertilizer status. There was no observed evidence for enhanced detoxification of $O_3$-derived activated oxygen species in plants grown under higher fertilizer status compared with that in plants grown under basic fertilizer status. The increase in the activities of SOD, APX and GR in rice leaves by relatively long-term treatment with $O_3$ at low concentration is considered to indicate that the plant became adapted to the $O_3$ stress and the protection system increased its capacity to scavenge toxic oxygen species. Our results in two rice cultivars indicated that there was little difference in the activities of antioxidant enzymes between IL and KM, which were known as resistant and susceptible cultivar to $O_3$

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.47 no.1
• /
• pp.29-35
• /
• 2002

This study was carried out to investigate the characteristics of shattering habit and germination of offtype rice plants collected in Korea which were classified into seven groups based on grain characteristics. In the long-grain red rice group, the short-grain red rice group, the long-grain normal rice group, and the long-grain waxy rice group, the tensile strength of grain and primary rachis branch was relatively low and the fiber cell of the primary rachis branch was short. Characteristics of shattering-related traits and germination in relation to grain and esterase isozyme zymogram type of off-type rice plants. In most lines of the extremely late and sterile rice group, the tensile strength of grain was low, while that of primary rachis branch was high, and the fiber cell was long. However, in the type 1 esterase isozyme zymogram(EIZ) lines among the long-grain normal rice group and the type 6 and 5+6 EIZ plants among the extremely late and sterile rice group, the tensile strength of grain was relatively higher. The long-grain waxy rice group and the type 3 EIZ lines among the long-grain red rice group, showed higher germinability than did cultivars which are known to germinate well even in low-temperature. The other off-type rice group, except for the short-grain waxy rice group and type 1 and 7 EIZ lines among the long-grain normal rice group, had higher germination speed than that of the cultivars.

• Preventive Nutrition and Food Science
• /
• v.18 no.1
• /
• pp.67-75
• /
• 2013

Descriptive analysis and consumer acceptance tests were conducted with frozen (FCR), homemade (HCR), and aseptic-packaged (ACR) cooked rice products from two cultivars-IM and SD. FCR was prepared using a rapid freezing process, which may provide consumers with a quality similar to that of HCR. The intensity of the flavors of roasted, glutinous rice, rice cake, and rice starch and the textures of glutinousness, moistness, chunkiness, adhesiveness, and squishiness were all greater in the FCR as compared to the HCR and ACR (p<0.05) in IM and SD cultivars. The differences in sensory characteristics between the FCR and ACR were larger than the equivalent differences between the FCR and HCR. Overall consumer acceptance ratings for FCR in overall aspect, appearance, aroma, and texture were not significantly different compared to those for HCR (p>0.05); however, in most cases these factors showed significant differences when compared with ACR (p<0.05). From partial least square regression analysis, cooked rice was positively related to sweet, transparency, glossiness, roasted, glutinousness, chunkiness, moistness, glutinous rice, adhesiveness, rice shape, rice starch, and squishiness attributes but negatively related to raw rice, old rice, old rice aroma, a particle feeling, off-aroma, white color, scatteredness, slickness, size of cooked rice, and firmness attributes.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.49 no.4
• /
• pp.271-278
• /
• 2004

This study was conducted to obtain basic information of growth, chlorophyll, and $Na^+\;and\;K^+$ content of rice (Oryza sativa L.) seedlings after transplanting in different NaCl conditions. Plants grown in pots for 8 days after germination were grown for 10 days after transplanting in 50 and 100 mM NaCl concentrations. At higher NaCl concentration, plant height, root length, dry weight and chlorophyll content were reduced with NaCl stress. Among rice cultivars, the shoot dry weight of Gancheokbyeo, Janganbyeo and Hwasungbyeo, and the root dry weight of Janganbyeo, Gancheokbyeo and Juanbyeo showed relatively low reduction compared to the other rice cultivars at 100 mM NaCl stress. The $Na^+$ content in seedling rapidly increased with the increase of NaCl concentration but $K^+$ contents decreased. There was a significant relationship between $Na^+$ content and shoot and root dry weight after transplanting rice seedlings to saline conditions. The shoot and root dry weight showed highly negative relationship with the $Na^+/K^+$ ratio in saline conditions.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.44 no.1
• /
• pp.44-48
• /
• 1999

Uptake, assimilation and translocation of nitrogen and dry matter assimilation and translocation in ten rice cultivars were observed in no-till direct-sown rice-vetch cropping system. There was a large degree of variation in N-uptake, grain yield, nitrogen translocation efficiency and dry matter assimilation and translocation in tested rice cultivars. Forty kg N/ha base, as compound fertilizer (21-17-21% of N-P-K) three weeks after sowing and 30 kg N/ha top-dressed at panicle initiation stage as in the form of (NH$_4$)$_2$$CO_2$ was applied. ‘Newbounet’, ‘Daesanbyeo’, and ‘Hwayeongbyeo’ showed higher translocation efficiency. The contribution of pre-heading dry matter assimilates to grain ranged from 33% to 99% of dry grain weight. Dry matter of ‘Calrose 76’ was lower than Newbounet but N content was higher in Calrose 76 than Newbonnet. By maturity, N content in vegetative parts declined considerably more than dry matter, vegetative and reproductive parts, N translocation efficiency, and N harvest index. Nitrogen translocation efficiency was greater in ‘Nonganbyeo’, Daesanbyeo, and Newbounet. Grain N concentration was positively correlated with N concentration or N content of the vegetative parts at heading in Nonganbyeo, ‘Dasanbyeo’, ‘Dongjinbyeo’, and Newbonnet. These results indicated that the greater amount of dry matter and N accumulated before heading stage, the higher translocation rates of dry matter to grain and the greater net losses at maturity.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.45 no.6
• /
• pp.356-360
• /
• 2000

With isogenic waxy and non-waxy rice cultivars, growth responce as affected by leaf-removal treatment were examined in various fertilizer application. Vertical dry matter of culm was significantly decreased from ground upto 10cm. Culm dry matter of waxy rice was more steadily decreased than that of non-waxy rice. Starch content of culm in non-waxy rice was higher than waxy rice, and that in waxy and non-waxy rice were the lowest in three leaf-removal but no difference in single leaf-removal. Flag leaf in waxy rice and 2 nd leaf in non-waxy rice were dominantly affected yield by leaf-removal. The 1000-grain weight and rippend grain ratio of non-waxy rice were more higher than waxy rice and that in waxy and non-waxy rice were the lowest value in three leaf-removal but no difference in single leaf-removal treatments.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2000.11a
• /
• pp.12-27
• /
• 2000

During the recent decades, he problem of climate variability and change has been in the forefront of scientific problems. The objective of this study was to assess the impact of climate variability on crop growth and yield. The growth duration was the main impact of climate variability on crop yield. Phyllochronterval was shortened in the global worming situations. A simple model to describe developmental traits was provided from heading data of directly seeded rice cultivars and temperature data. Daily mean development rate could be explained by the average temperature during the growth stage. Simple regression equation between daily mean development rate(x) and the average temperature(y) during the growth period as y = ax + b. It can be simply modified as x = 1/a $\ast$ (y-b). The parameters of the model could depict the thermo sensitivity of the cultivars. On the base of this model, the three doubled CO2 GCM scenarios were assessed. The average of these would suggest a decline in rice production of about 11% if we maintained the current cultivars. Future cultivar's developmental traits could be suggested by the two model parameters.