Response of grain yield and milled-rice protein content to nitrogen topdress (N) timing at panicle initiation stage (PIS) is critical for quantifying real-time N requirement for target grain yield and milled-rice protein content. Two split-split-plot experiments with three replications, one in 2004 and the other in 2005, were conducted in Experimental Farm, Seoul National University, Suwon, Korea. The experiments included three N rates at tillering stage (TS), three N timing treatments at panicle initiation stage (PIS) and two rice cultivars. The N rates at TS, N timing at PIS, and rice cultivars were randomly assigned to main plot, sub plot, and sub-sub plot, respectively. Results showed that the delayed N application at PIS reduced grain yield in 2004 and increased milled-rice protein content in both years significantly at 0.05 probability level. The calculated optimum N timing at PIS from pooled data by N rates and rice cultivars in two years was at 28 days before heading (DBH). However, real-time of N timing at PIS was dependent on plant growth and N status around PIS that in turn was dependent on applied N rates at TS. The optimum N timing at PIS was at 30 DBH for no N treatments at TS while at 27 DBH for 3.6 and 7.2 kg N/10a treatments and at 27 and 29 DBH for Hwaseongbyeo and Daeanbyeo, respectively. In general, earlier applied N at PIS resulted in lower milled-rice protein content but the highest grain yield was expected to be obtained when N topdress at PIS was applied at the time when shoot N concentration started to drop below about 23 mg/g due to dilution effect after transplanting. In conclusion, the results of our experiments imply that the currently recommended N topdress time (24DBH) at PIS in Korea should be reconsidered for the higher grain yield and the better quality of rice.
Response of grain yield and milled-rice protein content to nitrogen (N) rates at various growth stages is critical for quantifying real-time and real-amount of applied N requirement for target grain yield and protein content. An experiment including 10 N rate treatments at transplanting, tillering and panicle initiation stages with four rice cultivars in 2003, 6 N treatments with two rice cultivars in 2004 and 2005 was conducted. Increase of N rates at PIS significantly increased both grain yield and milled-rice protein content but increase of N rates at tillering stage significantly increased grain yield but not milledrice protein content. Therefore, high grain yield and low milled-rice protein content would be difficult to obtain only by adjusting N rates at PIS. Internal N use efficiency (INUE) was 60.5 kg grain/kg N accumulation on an average over N treatments, cultivars, and experimental years, showing considerable reduction especially at high shoot N accumulation in the experimental year of low sunshine duration. Milled-rice protein content tended to increase almost linearly with increasing shoot N accumulation, but it revealed big variation even at the same shoot N accumulation at harvest. Milled-rice protein content decreased with increasing INUE. N accumulation in the milled rice increased at an almost constant proportion of 45.5 percent of the shoot N accumulated at harvest, showing slight decresing proportion with the increasing shoot N accumulation.
This study was conducted to determine the optimum number of inter-rows according to distance of drainage furrow (DF) for running-off excessive-water stress (EWS) in paddy field. The most soil water potential was shown in high ridge (distance of DF by 70 cm) cultivation and the soil water potential showed increasing tendency in over four inter-rows cultivation by DF. The growth of soybean reduced by extended inter-row and its reducing level was high, especially, over four inter-rows (DF distance by 2.8 m) because of EWS. The photosynthetic rate decreased in the more extensive field by distance of DF at V5 and R2 stages, especially, in over four interrows cultivation. Also, root activity decreased at wider DF. The yield was reduced with wider distance of DF more extensively, the highest yield of 270 g per m2 at the every row, but yield showed decreasing tendency at over the 4th row (2.8 m) cultivation. Soybean cultivation in paddy field could be founded with DF of every other or 4th row.
The nitrogen (N) absorption and partition of the rice plants are important indicators that can be used to improve the N use efficiency (NUE) of the plants. Improving the plant NUE can help to avoid nutrient waste that may cause environmental pollution. To investigate the N absorption and partition of the rice plants, Hwaseongbyeo (Japonica) and Dasanbyeo (indica/japonica) were applied with N fertilizers at the rates of 60, 120, and 180 kg N per ha in paddy field. Also micro plots of 0.81m2 were established inside each plot for application of 15N-labeled fertilizer. The differences in N utilization of the rice plants were associated with the total N absorption and partitioning after the heading stage. In the grain filling period, the increase of nitrogen content in the total and leaf blades of Dasanbyeo was higher than that of Hwaseongbyeo. Soil N was the main contributor for the increase of total N of Dasanbyeo during the grain filling period. The N fertilizer uptake rate of Hwaseongbyeo rapidly increased with the increment of N fertilization rate. In Dasanbyeo, N fertilizer uptakes were similar under all rates and times of N application. From heading stage to harvest, Dasanbyeo continued accumulating nitrogen, whereas Hwaseongbyeo had small changes. In conclusion, the difference in nitrogen absorption and partition after heading of the two cultivars was caused by the ability of Dasanbyeo to accumulate and remobilize soil nitrogen to the grains during the grain filling period.
To understand the heading habit of recently developed 20 Korean rice cultivars, rice plants in a phytotron were exposed to different temperature: 22.5~circC(day~;27~circC/night~;18~circC),~;27.5~circC(day~;32~circC/night~;23~circC) , and day-length conditions: 10, 12, 13, 14, 15 hours. Four rice cultivars (Sobibyeo, Juanbyeo, Ilpumbyeo and Shindongjinbyeo) showed relatively short Basic Vegetative Phase (BVP) of 17 to 18 days, while Dasanbyeo showed the longest (35 days) BVP, compared to other remaining 15 tested cultivars which exhibited 24 to 31 days of BVP. In this experiment, it was tried out to separate the eliminable vegetative phase into photosensitivity and thermo-sensitivity with two different pathways. Many tested cultivars, however, exhibited quite different responses under low temperature and / or long day-length conditions. Especially, Surabyeo and Juanbyeo were the most difficult cultivars to separate into photo- or thermo-sensitivity in that the eliminable vegetative phase of these two cultivars increased greatly only under low temperature (22.5~circC) and long day-length (15 hr.) conditions. Regarding the heading response to temperatures, tested cultivars could be categorized into 2 groups. In 1st group of rice cultivars, the eliminable vegetative phase decreased almost equally as the temperature changed from 20.0~circC~rightarrow22.5~circC~rightarrow25.0~circC~rightarrow27.5~circC . In contrast, the 2nd group of rice cultivars exhibited eliminable vegetative phase slowly decreasing when the temperature changed from 22.5~circC~rightarrow25.0~circC~rightarrow27.5~circC , but rapidly decreasing when the mean temperature changed from 20.0~circC~;to~;22.5~circC . All the cultivars belonged to 2nd group, the heading date would be very delayed if cool summer comes.
Naturally occurring soybean isoflavones are known to be influenced by various genetic and environmental conditions. Growth, yield, and isoflavone content were determined in four different cultivars of soybean grown under drained paddy and upland fields. Most of growth characteristics and yield components of four different soybean cultivars harvested in drained paddy field were greater than those in upland field, regardless of cultivar. By means of high performance liquid chromatography, total daidzein and genistein contents of soybean in drained paddy field were increased up to 40 and 35%, respectively, compared with those in drained paddy field. Besides isoflavone contents, the growth and yield of soybean were significantly affected by cultivar and field conditions, indicating the necessity of genetic program for soybean cultivars appropriate to drained paddy field conditions. In conclusion, converting paddy field into upland may effectively improve soybean cropping system, especially in terms of isoflavone increment under paddy field conditions.
This study was conducted to investigate the crossability, seed dormancy and overwintering ability of rice plant in GM (glufosinate ammonium-resistant lines. Iksan 483 and Milyang 204) and non-GM (their parents) or red rice (Andongaengmi). Seed-setting rate was not significantly different between GM and non-GM rice varieties. Iksan 483 and Milyang 204 showed the similar level of seed germination rate from 30 to 50 days after heading as compared to non-GM rice varieties. After overwintering in paddy field, seed germination rate of GM and non-GM rice varieties ranged from 14.3 % to 57.6 % in dry soil condition, but there was no germination in wet-soil except red rice. The result in wet-soil condition may help to set up a strategy for reducing the risk of gene flow of transgene via dispersal of seeds of GM plants. The crossability, seed dormancy and seed overwintering of Iksan 483 and Milyang 204, herbicide resistant GM rice varieties, were not significantly different compared to non-GM rice varieties. The results might be helpful to reduce the risk of transgene dispersal from GM crop via seeds and pollens.
The impermeable seed coat is valuable trait in soybean because impermeable seed retain viability for longer period than permeable seed under adverse conditions such as delayed harvest or prolonged storage. Soybean seeds of various size showing different seed hardness were examined for their water absorption and seed viability under adverse storage conditions. Of one hundred thirty nine genotypes, eight types of seeds having different seed hardness and seed size were used as material. Soybean genotypes showing high hard seed rate, GSI13125 (89%), GSI10715 (54%), and GSI10284 (42%), were slow in water absorption and low in the electroconductivity of seed leachate in distilled water. Germination of GSI10284 and GSI13125 that have higher hard seed rate was less affected by CSVT and artificial aging treatment indicating higher seed storability. The higher storing ability of both collections was confirmed by electroconductivity test for leachate. GSI10122 showed low seedling emergence when the seeds were artificially aged. This genotype was considered as to having a poor storing ability based on difference of electroconductivity before and after artificial aging. Among tests conducted in the experiment, CSVT could be used for determining storage life in legumes. In conclusion, water absorption property of seed was strongly related to the hardness that is directly related to the seed viability and storing ability in soybean seed.
Spikelet proteins expressed at the young microspore stage in rice were separated and analysed by two-dimensional polyacrylamide gel electrophoresis (2DE). The separated proteins were electro blotted onto a polyvinylidene difluoride (PVDF) membrane, and 50 proteins were analyzed by a gas-phase protein sequencer. The N-terminal amino acid sequences of 20 out of 50 proteins were determined. N-terminal regions of the remaining proteins could not be sequenced because of blocking. The internal amino acid sequences of proteins were determined by sequence analysis of peptides obtained by the Cleveland peptide mapping method. Results revealed the presence of the photosynthetic apparatus at rice young microspore stage. Major proteins identified in this study could be used as a marker for various studies on physiological stresses.
Sesame (Sesamum indicum L.) seeds contain abundant oil and antioxidative lignans related to the seed quality. To evaluate the potential effects of drought stress on the chemical composition of sesame seeds, eighteen cultivars were imposed water-deficit condition by withholding irrigation during 15 days at podding and maturing stage, compared with well-watered plants as control in seed yield and chemical composition. Drought treatments showed great decrease of seed yield with not affecting seed weight. The contents of sesamin and sesamolin decreased while lignan glycosides inversely increased in response to drought stress. Oil content was not significantly changed by drought treatment in spite of its slight decrease. In case of fatty acid composition, there were significant differences in increase of oleic acid while inverse decrease of linoleic acid under drought stress condition. These results demonstrate that the chemical composition of sesame seed may be modified with drought stress. In particular, the increase of sesaminol glucosides with strong antioxidative activity was observed.
The 117 soybean cultivars were collected from nine provinces in Korea, and various seed quality traits along with isoflavone contents were evaluated to elucidate their relationship. The 100-seed weight of the black soybean (31.2 g) was significantly higher (p<0.05) than yellow soybeans (28.6 g). The composition of genistein, daidzein, and glycitein accounted for 75.8, 22.8, and 1.4 % of total isoflavone in yellow soybean cultivars, while their compositions in black soybeans were 58.5, 39.7, and 1.8%, respectively. The mean contents of total isoflavone in yellow and black soybean were l,561.6~mug~;g-1~;and~;l,018.3~mug~;g-1 . The isofalvone content showed significant variation among cultivars when classified by the seed size. In the yellow soybeans, total isoflavone content was higher in small size soybean cultivars (1,776.0~mug~;g-1) and medium size soybean cultivars (1,714.3~mug~;g-1) compared to large size ones (1,518.5~mug~;g-1) . Genistein content was proved as the major factor determining the relationship between isoflavone content and 100-seed weights (r =-0.206*). Daidzein and glycitein, however, showed no significant relationship with the 100-seed weights. Isoflavone content was not significantly correlated with color parameters L (lightness) and a (redness) values, but color parameter b (yellowness) was positively correlated with glycitein (r=0.264*) in the yellow soybeans, while its negative correlation between daidzein (r=-0.245*) and total isoflavone (r=-0.256*) were observed in black soybeans. However, these findings suggested that the seed color value may not serve as an effective parameter for estimating the isoflavone intensity of the soybeans. Variation of protein and lipid contents between yellow soybeans (n=58) and black soybeans (n=59) was relatively stable, however, protein and lipid contents have no significant relationship with isoflavone content.
Traditionally fatty acid composition used to be analysed by a GC and the sample preparation process includes lipid extraction from sample and subsequent methyl esters preparation, which are time-consuming and cumbersome. As an alternative, simultaneous extraction/methylation methods are being developed for rapid and simplified sample preparation. To optimize one-step extraction/methylation method for analysis of fatty acid composition in brown rice, various reaction factors such as sample to reaction solution ratio, reaction time and temperature, shaking intensity were changed and resultant fatty acid composition data were evaluated in comparison with previous reports. The ratio of sample weight to reaction solution volume was the most critical factor in that higher sample to reaction solution ratio caused overestimation of palmitic acid and linoleic acid composition, resulting in underestimation of oleic acid. Lower reaction temperature also induced overestimation of linoleic acid and underestimation of oleic acid. Reaction duration and the intensity of shaking prior to and during the reaction, however, caused no significant changes in analysis results. In conclusion, the optimum condition was mixing 5 grains (about 0.2 g) of brown rice with 680~muL of extraction/methylation mixture and 400~muL of heptane, followed by reaction at 80~circC for 2 hours.
Sesamin and sesamolin, antioxidant lipidsoluble lignan compounds, are abundant in sesame (Sesamum indicum L.) seed oil and provide oxidative stability of oil related to sesame quality. The sesamin and sesamolin contents of 403 sesame land races of Korea were determined by HPLC analysis of methanol extract (HPLC value), and their total lignan content was compared with those by using UV-Vis spectrophotometric analysis (UV method) of methanol (UV-MeOH value) and hexane (UV-Hexane value) extracts. HPLC values of total lignan content were strongly associated with UV-Hexane (r=0.705**) and UV-MeOH (r=0.811**) values. The UV values from both the extracts were 3.8-4.7 times higher than those of HPLC values. Lignan content was overestimated by UV method because total compounds in the mixture solution were quantified by absorbing at the same ultraviolet wavelength as in HPLC method. UV method could more rapidly analyze small amount of sample with higher sensitivity of detection than HPLC method. Average contents of lignans in sesame germplasm evaluated in this study were 2.09~pm1.02mg/g of sesamin, and 1.65~pm0.61mg/g of sesamolin, respectively, showing significant variation for lignan components. The results showed that UV method for the determination of sesamin and sesamolin could be practically used as a faster and easier method than HPLC by using the regression equations developed in this study
Common thistle contains water-soluble substances that are phytotoxic to neighboring plant species. A series of aqueous extracts from leaves, stems, roots and flowers of common thistle (Cirsium pendulum Fisch.) were assayed against alfalfa (Medicago sativa) seedlings to determine their allelopathy, and the results showed highest inhibition in the extracts from flowers and leaves, and followed by stems, and roots. The extracts at 40 g dry tissue L-1(g~;L-1) applied on filter paper in a Petri-dish significantly inhibited root growth of test plant by 87%. Methanol extracts at 100 g L-1 from leaves inhibited root growth of alfalfa and barnyardgrass (Echinochloa crus-galli) by 89 and 98%, respectively. Hexane and ethylacetate fractions of common thistle reduced alfalfa root growth more than did butanol and water fractions. Incorporation into soil with the leaf residues at 100g~;kg-1 inhibited shoot fresh weights of barnyardgrass and eclipta (Eclipta prostrate) by 88 and 58%, respectively, showing higher sensitivity in grass species. These results suggest that common thistle plants had allelopathic potential for eco-friendly vegetation management, and that especially their activities were differently exhibited depending on plant part.
This study was to verity that the uptake inhibition and accumulation of nitrogen in different potassium levels. Lettuce was used as model plant in this study and grown in pot of 10cm's in diameter and depth with mixture media of vermiculite and perlite under supply of different culture solution for three weeks. Nitrogen absorption at root was inhibited by increased potassium concentration in nutrient solution, and nitrate accumulation of plant was depended on absorption of nitrogen because nitrate content of 0 K level was 4-5 times higher than that of 2 K level, Concentration of ascorbic acid was decreased by increasing the nitrogen absorption, since ascorbic acid (AsA) content of 2K level was higher than those of OK level in both of old leaf and flesh leaf