• Journal of Microbiology and Biotechnology
• /
• v.11 no.4
• /
• pp.644-648
• /
• 2001

The biological control potential of entomopathogenic nematodes (EPN) can be enhanced by improved culture efficiency. Optimization of the media is a key factor for improving in vitro mass production of entomopathogenic nematodes. This study reports the effect of medium concentration. The medium is a combination of carbohydrates, lipids, proteins, sats, and growth factors, on the growth of Heterorhabditis bacteriophora and its symbiotic bacterium Photorhabdus liminescens. The overall optimal medium concentration for nematode recovery, hermaphrodite size, bacterial mass, infective juveniles (IJs) yield, and doubling time was 84 g/l. At this concentration rate, the doubling time of IJs production and the biomass of symbiotic bacteria was 1.6 days and 12.8 g/l, respectively. The maximum yield of $2.4{\times}{10^5}IJs/ml$ was attained within a one-generation cycle (eight days). The yield coefficient was $2.8{\times}{10^6}$ IJs/g medium, and the maximum productivity was $3.1{\times}{10^7}$ IJs per day. Medium concentration affected two independent factors, recovery and hermaphrodite size, which in turn influenced the final yield.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.45 no.4
• /
• pp.237-240
• /
• 2000

This experiment was conducted to evaluate the effect of split application of nitrogen(N) on development of vascular bundle(VB) and yield components of rice. Two cultivars were used in this study; IR58, an indica type and Shinunbongbyeim a japonica type. The number and total cross sectional area of the VB in the peduncle and leaf blade were more and bigger in N split application than 100 percent basal fertilizer. Nitrogen split application at necknode differentiation stage increased the number and size of the VB. Nitrogen split application resulted in increased panicle number with application of N before transplanting and at tillering stage; increased spikelets number with N application at necknode differentiation stage; and increased spikelet fertility and 1000 grain weight with N application at necknode differentiation and heading stages. Grain yield increased 7-10% in N split as compared to all basal application. The total cross sectional area of VB in peduncle closely correlated with the number of spikelets per panicle. Nitrogen management can have an impact on spikelet differentiation through more and bigger VB and increase grain yield potential.

• Asian-Australasian Journal of Animal Sciences
• /
• v.12 no.2
• /
• pp.161-164
• /
• 1999

Dairy performances of Pabna cows and its crossbreds with Sahiwal (SL) and Friesian (F) in the Baghabarighat dairying area of Bangladesh were evaluated. Four SL and three F sires were used for the crossbreeding. The exotic sire effect of individuals on their daughters were also evaluated in this study. It showed that the genetic group had a significant (p<0.05) effect on birth weight, age at first heat, calving interval, lactation length and lactation yield. The lowest birth weight (17.9 kg), longest age at first heat (39.2 m) and calving interval (16.3 m) shortest lactation length (199 d) and lowest lactation yield (728 L) were found in Pabna cows. The highest birth weight (22.5 kg). shortest age at first heat (25.5 m) and calving interval (13.7 m), longest lactation length (253 d) and highest lactation yield (1936 L) were found in the F crossbreds. Within the same breed, the effect of individual sire was significant (p<0.05) on age at first heat, lactation length and lactation yield. Individual sire effects of SL bulls differed significantly (p<0.05) but F sires had a non-significant (p>0.05) effect on calving interval in their progeny. The fat % and SNF % in milk and number of services required for conception did not differ (p>0.05) among inter-and intra- breed sire groups.

• Korean Journal of Agricultural Science
• /
• v.47 no.2
• /
• pp.305-313
• /
• 2020

Root hair development has the potential to increase crop yields and at the same time to decrease fertilizer use, which will be required in the next 30 years to meet the demand for crop-derived commodities in a world with decreasing available natural resources. Root hair defective six (RHD6) encoding a basic helix-loop-helix transcription factor, is associated with root hair differentiation, and its roles are root hair initiation and elongation. Grass plants, rice and Brachypodium have been used as model plants to study the gene function of the root hair defective six like (RSL) subfamily which is orthologous to AtRHD6. The RSL subfamily has an identical gene function with AtRHD6 which is involved with root hair differentiation as well. Plants with longer root hairs within a species should have an improved Pi uptake efficiency; therefore, we would expect that a plant with a high Pi uptake could contribute to increasing the plant yield. We achieved increased root hair length by manipulating the RSL subfamily genes. It is expected that in these transgenic plants, the long root hairs would be sufficient to improve the Pi uptake and hence improve biomass and yield component (tiller, spikelet number, and spikelet weight) of the plant. Here, we demonstrate that Brachypodium transgenic plants overexpressing the BdRSL subfamily genes have an improved biomass and grain yield. The result of this study could be applied to important crop plants like rice.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.36 no.2
• /
• pp.112-126
• /
• 1991

The atmospheric carbon dioxide concentration is ever-increasing and expected to reach about 600 ppmv some time during next century. Such an increase of $CO_2$ may cause a warming of the earth's surface of 1.5 to 4.5$^{\circ}C$, resulting in great changes in natural and agricultural ecosystems. The climatic scenario under doubled $CO_2$ projected by general circulation model of Goddard Institute for Space Studies(GISS) was adopted to evaluate the potential impact of climate change on agroclimatic resources, net primary productivity and rice productivity in Korea. The annual mean temperature was expected to rise by 3.5 to 4.$0^{\circ}C$ and the annual precipitation to vary by -5 to 20% as compared to current normal climate (1951 to 1980), resulting in the increase of possible duration of crop growth(days above 15$^{\circ}C$ in daily mean temperature) by 30 to 50 days and of effective accumulated temperature(EAT=∑Ti, Ti$\geq$1$0^{\circ}C$) by 1200 to 150$0^{\circ}C$. day which roughly corresponds to the shift of its isopleth northward by 300 to 400 km and by 600 to 700 m in altitude. The hydrological condition evaluated by radiative dryness index (RDI =Rn/ $\ell$P) is presumed to change slightly. The net primary productivity under the 2$\times$$CO_2$ climate was estimated to decrease by 3 to 4% when calculated without considering the photosynthesis stimulation due to $CO_2$ enrichment. Empirical crop-weather model was constructed for national rice yield prediction. The rice yields predicted by this model under 2 $\times$ $CO_2$ climatic scenario at the technological level of 1987 were lower by 34-43% than those under current normal climate. The parameters of MACROS, a dynamic simulation model from IRRI, were modified to simulate the growth and development of Korean rice cultivars under current and doubled $CO_2$ climatic condition. When simulated starting seedling emergence of May 10, the rice yield of Hwaseongbyeo(medium maturity) under 2 $\times$ $CO_2$ climate in Suwon showed 37% reduction compared to that under current normal climate. The yield reduction was ascribable mainly to the shortening of vegetative and ripening period due to accelerated development by higher temperature. Any simulated yields when shifted emergence date from April 10 to July 10 with Hwaseongbyeo (medium maturity) and Palgeum (late maturity) under 2 $\times$ $CO_2$ climate did not exceed the yield of Hwaseongbyeo simulated at seedling emergence on May 10 under current climate. The imaginary variety, having the same characteristics as those of Hwaseongbyeo except growth duration of 100 days from seedling emergence to heading, showed 4% increase in yield when simulated at seedling emergence on May 25 producing the highest yield. The simulation revealed that grain yields of rice increase to a greater extent under 2$\times$ $CO_2$-doubled condition than under current atmospheric $CO_2$ concentration as the plant type becomes more erect.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2017.06a
• /
• pp.339-339
• /
• 2017

The long grain rice varieties adaptable to South-east Asia tropical regions were tried to develop in Cambodian Agriculture Research and Development Institute (CARDI), Cambodia. The final goal is to develop rice varieties which can culture in diverse environmental conditions of tropical regions of South-east Asia under climate change. We collected and evaluated for agronomic traits of 131 rice germplasm from Cambodia, China, India, Indonesia, Myanmar, Philippines and Vietnam in CARDI. We selected core germplasm including leading varieties of target countries and made 813 F1 cross combinations between leading varieties of each country and promising germplasm of high yield potential, resistance to biotic/abiotic stresses, aromatic rice, and so on. Out of 607 F1s evaluated to heading date, plant type, agronomic traits, and grain type, 106 F1s selected and advanced to F2 populations. 106 F2 populations were evaluated to major agronomic traits, grain type and yield-component traits, and selected 2,560 plants in 62 F2 populations. During six seasons in 2014~2016, the lines of F3 subsequent-generation were cultured a total of 6,256 lines. In yield trial for promising lines in F5 generation, the growth duration from sowing to harvesting was 97~114 days. These lines were 88~129 in number of grain per panicle, an average of 84.6% in the range of 79.3~91.9% in the percentage of ripened grain and 17.5~22.8g in 1000-brown rice weight. The rough rice yields were in the range of 4.33~6.06 ton/ha with an average of 5.23 ton/ha. The yield was increased to 5~47% than Chulsa and 12~41% than IR66. Five lines, KR54-28-1, KR55-14-2, KR57-5-2, KR67-57-2 and KR128-19-1 were 5.33~6.06 ton/ha in rough rice yield. These high yield potential lines would be evaluated to adaptability in Cambodia, Laos, Myanmar and Vietnam during 2017.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2017.06a
• /
• pp.155-155
• /
• 2017

The long grain rice varieties adaptable to South-east Asia tropical regions were tried to develop in Cambodian Agriculture Research and Development Institute (CARDI), Cambodia. The final goal is to develop rice varieties which can culture in diverse environmental conditions of tropical regions of South-east Asia under climate change. We collected and evaluated for agronomic traits of 131 rice germplasm from Cambodia, China, India, Indonesia, Myanmar, Philippines and Vietnam in CARDI. We selected core germplasm including leading varieties of target countries and made 813 F1 cross combinations between leading varieties of each country and promising germplasm of high yield potential, resistance to biotic/abiotic stresses, aromatic rice, and so on. Out of 607 F1s evaluated to heading date, plant type, agronomic traits, and grain type, 106 F1s selected and advanced to F2 populations. 106 F2 populations were evaluated to major agronomic traits, grain type and yield-component traits, and selected 2,560 plants in 62 F2 populations. During six seasons in 2014~2016, the lines of F3 subsequent-generation were cultured a total of 6,256 lines. In yield trial for promising lines in F5 generation, the growth duration from sowing to harvesting was 97~114 days. These lines were 88~129 in number of grain per panicle, an average of 84.6% in the range of 79.3~91.9% in the percentage of ripened grain and 17.5~22.8g in 1000-brown rice weight. The rough rice yields were in the range of 4.33~6.06 ton/ha with an average of 5.23 ton/ha. The yield was increased to 5~47% than Chulsa and 12~41% than IR66. Five lines, KR54-28-1, KR55-14-2, KR57-5-2, KR67-57-2 and KR128-19-1 were 5.33~6.06 ton/ha in rough rice yield. These high yield potential lines would be evaluated to adaptability in Cambodia, Laos, Myanmar and Vietnam during 2017.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.44 no.2
• /
• pp.106-111
• /
• 1999

To investigate the effects of planting density and nitrogen level on growth and yield potential of newly bred heavy panicle japonica rice with large grain (Iksan 435 and Iksan 438) or many spikelets per panicle(HR14022-21-8-4 and HR14022-21-8-6), four heavy panicle type rices and two many panicle type rices(Dongjinbyeo and Donganbyeo) as the checks were planted under standard planting density (30$\times$15 cm) and dense planting density (15$\times$15 cm) with two nitrogen levels of standard nitrogen level(110 kg h $a^{-1}$) and heavy nitrogen level(165 kg h $a^{-1}$). Effective tiller rate decreased in dense planting or heavy nitrogen, when compared to standard nitrogen and planting, while leaf area index and to dry weight increased in dense planting or heavy nitrogen. Tiller numbers and panicle numbers were more increased by dense planting than heavy nitrogen, whereas spikelet numbers were more increased by heavy nitrogen than dense planting. Ripened grain ratio was slightly lower only in dense planting. 1,000 grain weight in brown rice was not significantly different in dense planting or heavy nitrogen. Milled rice yield was highest in heavy nitrogen with standard planting for heavy panicle type rice, while yield for many panicle type rice was highest in heavy nitrogen with dense planting, suggesting that many panicle type rice possesses higher adapt-ability for dense planting than heavy panicle type rice. Path coefficient analysis revealed that top dry weight, spikelet number and grain weight were the greatest positive contributors to yield, whereas tiller number was negative to yield.d.

• Journal of Animal Science and Technology
• /
• v.63 no.5
• /
• pp.1098-1113
• /
• 2021

Maturation process of alfalfa (Medicago sativa L.) could be prevented by the reduction of lignin content in terms of conventional breeding or transgenic technology. Alfalfa could exhibit higher leaf/stem ratio, with a concern of yield loss. The objective of this study was to compare forage yield and nutritive value of low lignin alfalfa and two reference varieties subjecting to two harvest intervals and three seeding rates. The experimental design was a randomized complete block in a split-split plot arrangement with four replicates, where harvest intervals (28-day and 35-day) were assigned to whole plots, seeding rates were subplots, and varieties were sub-subplots. The weighted mean nutritive value was applied to two production years of 2016 and 2017. Hi-Gest 360 (low lignin alfalfa) provided similar yield potential and increased nutritive value compared to two reference varieties. Over a two-year production period, alfalfa harvested at every 28-day interval provided more economic returns than those at 35-day interval. For the seeding year and first production year, five cuts made by the 28-day interval produced more yield than four cuts by the 35-day interval. Due to limited rainfall in May 2017, a sharp drop of the first cutting overturned the advantage of the five-cut system. Shorter intervals between harvests generally increased crude protein (CP) concentrations. The differences of relative feed value (RFV) between two harvest intervals tended to be great during the first and second cuttings. Overall, harvest interval had a large effect on nutritive value and a more significant effect on alfalfa dry matter yield than variety selection. Seeding rate did not affect alfalfa yield and nutritive value.

• Advances in Computational Design
• /
• v.5 no.3
• /
• pp.323-347
• /
• 2020

The enhancements of bioenergy production effectiveness require the comprehensively experimental study of several parameters affecting these bioprocesses. The interpretation of the obtained experimental results and the estimation of optimum yield are extremely complicated such as misinterpreting the results of an experiment. The use of mathematical modeling and statistical experimental designs can consistently supply the predictions of the potential yield and the identification of defining parameters and also the understanding of key relationships between factors and responses. This paper summarizes several mathematical models used to achieve an adequate overall and maximal production yield and rate, to screen, to optimize, to identify, to describe and to provide useful information for the effect of several factors on bioenergy production processes. The usefulness, the validity and, the feasibility of each strategy for studying and optimizing the bioenergy-producing processes were discussed and confirmed by the good correlation between predicted and measured values.