• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.8
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• pp.467-473
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• 2014

In the direct sequence spread spectrum system, the correct synchronization is very important; hence, several acquisition schemes based on the sequential estimation have been developed. Typically, the rapid acquisition sequential estimation (RASE) scheme, the seed accumulating sequential estimation (SASE) scheme, the recursive soft sequential estimation (RSSE) scheme have been developed for the correct acquisition. However, the objective performance comparison and analysis between former estimation schemes have not been performed so far. In this paper, we compare and analyze the performance of the above sequential estimation schemes by simulating the correct chip probability and the mean acquisition time (MAT).

• Journal of Ecology and Environment
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• v.32 no.3
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• pp.137-143
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• 2009

Pre-dispersal seed predation by a granivorous bird, the masked grosbeak (Eophona personata, Fringillidae), was investigated in two bird-dispersed trees, Celtis sinensis and Aphananthe aspera (Ulmaceae). The objectives of this study were to 1) measure direct damage of predation by grosbeaks on plant crops, 2) reveal the temporal pattern of predation within each tree species and its causal factors, and 3) test whether foraging grosbeaks hinder foraging of frugivorous birds, thereby indirectly impacting the reproduction of both tree species. A substantial amount of fruit and seed crop was consumed by grosbeaks (24.3% in Celtis; 55.5% in Aphananthe), and only 17.7% (Celtis) and 16.7% (Aphananthe) were removed by frugivorous birds. At the study site, the grosbeak population size fluctuated greatly during the fruiting seasons of both plant species. As for Celtis, predated seed density also fluctuated temporally, and the local population size of grosbeaks was responsible for predated seed density. In Aphananthe, predation was not fully explained by grosbeak populations or plant phenology, but its peak coincided with that of grosbeak population. These results suggest that predispersal seed predation by granivorous birds can have large negative impacts on the bird-dispersed plants. Changes in local population size of granivorous birds can influence predatation and can affect reproductive success of the bird-dispersed plants available to the birds.

• Food Science and Preservation
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• v.16 no.4
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• pp.490-498
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• 2009

This study attempted to examine the profitability and marketing costs of seed potato under contract farming system of BADC (Bangladesh Agricultural Development Corporation) with the help of primary and secondary data. Total 45 contract farmers were randomly selected. Attempts were made to calculate costs, returns and profitability of seed potato production under contract farming system, and to identify marketing channels of seed potato. The field level data were collected by a farm survey during the months of April 2005 through direct interviews with contract farmers and registered dealers using a structure survey questionnaire. The results showed that the gross return per hectare was Tk. 252,464 for all categories of farms. Cost of seeds, fertilizers, pesticides, irrigation and human labor were critical inputs for profitability of seed potato. Cobb-Douglas production function analysis was used to determine the effects of the key variables to seed potato production under contract farming system. The elasticity of seed potato production was at 0.727 for all categories of farms. The findings exhibited that the summation of elasticity of different inputs for seed potato production was less than one, implying that the production function exhibited decreasing returns to scale. Registered dealers and Upazila Sales Centers were involved in seed potato marketing formed a straightforward marketing channel. The total marketing costs of registered dealers were Tk. 759.49 per ton of seed potato. The net marketing margin of registered dealers was estimated at Tk. 465.51 per ton of seed potato. The selected contract farmers and registered dealers faced a number of problems and some of recommendations were suggested.

• Korean Journal of Plant Resources
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• v.18 no.1
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• pp.8-14
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• 2005

This study was carried out to investigate the possibility of double cropping of safflower(Carthamus tinctotious L.) in vinyl house for rainshield culture. Planting methods, i.e., direct seeding as the first crop and direct seeding and transplanting as the second crop, were investigated. Growth characters and establishment were better in the first crop than in the second crop. Between direct seeding and transplanting of the second crop, growth was not significantly different, but establishment was much higher in direct seeding than in transplanting. Seed yield of the second crop was lower $30\~74\%$ than that of the first crop. In planting methods of the second crop, seed yield was higher in direct seeding than in transplanting. Therefore, optimum method of the second crop for double cropping of safflower in the middle parts of Korea was estimated as direct seeding.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.8 no.1
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• pp.121-127
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• 1970

In order to find out the suitable periods and methods of seeding and the suitable seed bed location of fall grown potatoes in Seoul, this experiment was conducted at College of Agriculture, Korea University from 2nd July to 30th September in 1970. Experimental results using Irish cobbler, our leading variety, were as follows; 1. The suitable seeding period of fall grown potatoes seems about 21st July. 2. The direct seeding method is available where the upland farm is well drainage. 3. The sprouting in the field conditions forcing makes healthy stands of seed potatoes.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.62 no.1
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• pp.9-15
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• 2017

Germination characteristics, seedling emergence, and early seedling growth of iron-coated rice seeds, cultivars Daebo and Samdeokbyeo, under different water depths were compared with those of non-coated seeds (control) and the results evaluated to obtain basic information for establishing stable seedlings in direct water seeding. The total germination percentage of the two seed treatments was similar, but iron-coated seeds had slightly faster germination and shorter mean germination time than non-coated seeds. Water absorption rates of iron-coated seeds were lower than that of non-coated seeds during seed germination. The germination percentage of the two iron-coated rice seed cultivars showed a significant decline of 15-22% after one year of storage under natural conditions. The seedling emergence percentage and uniformity of the two rice cultivars were significantly higher in the iron-coated seeds at 1-13 cm water depths but the percentage of floating seedlings was lower in iron-coated seeds than in non-coated seeds. The iron-coated seeds had a high seedling emergence percentage of 91.3-93.3% at all flooding depths whereas the non-coated seeds had a significantly low seedling emergence percentage of 57.7-71.7% at a water depth of 13 cm. Moreover, the shoot dry weight and seedling health score of iron-coated seeds were significantly higher than those of non-coated seeds, while root dry weights were similar in iron-coated and non-coated seeds, regardless of water depth. These results suggest that iron-coated seeds are more appropriate for stable seedling establishment in direct water seeding than are non-coated seeds.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.66 no.4
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• pp.419-427
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• 2021

In South Korea, direct seeding of rapeseed (Brassica napus L.) is difficult during spring cultivation in early March because of the low yield production associated with late flowering and poor seed quality. To compare the period of direct sowing, the present study investigated the growth characteristics of rapeseed according to planting dates. Specifically, 35 day-old seedlings were transplanted or directly sown on four different dates (late February, early March, late March, and early April) in 2020 and 2021. As the planting date was delayed, the days to flowering of rapeseed decreased. Similarly, the plant height, seed set percentage, and seed yield of rapeseed were reduced upon delay in planting. The seed yield of rapeseed through direct seeding in late February was the highest, 2.76 ton·ha^-1. On all seeding dates, except for late February, the transplanted rapeseed produced a higher yields than the directly seeded rapeseed. The crude oil and oleic acid content, which is related to the quality of rapeseed, decreased with the delay in planting dates, and this decrease was greater, with the direct seeding of rapeseed depending on the sowing time. In the correlation analysis, the planting date was significantly and negatively correlated with the yield, crude oil content, and oleic acid content of the transplanted rapeseed, while the sowing date was negatively correlated with the plant height, silique size, yield, and seed quality of the directly seeded rapeseed. Finally, the effect of planting date on rapeseed growth was stronger in direct seeding than in transplanting. Therefore, during spring cultivation after late February to early March, transplanting, rather than direct seeding, in more advantageous in terms of seed quality and yield.

• Journal of Biosystems Engineering
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• v.21 no.3
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• pp.306-314
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• 1996

A seeder monitoring system was developed to solve the problems of mis-sowing and tube clogging in direct seeding machines, which have been one of the factors that reduce the performance of sowing operations. The system consisted of photo sensors, air nozzles, an air compressor, and a one-chip micro-computer based controller. The system was also equipped with the devices that perform the functions of self-checking and intermittent air injection for cleaning seed tubes. The performance of the system was tested in the laboratory and field. Using the well-cleaned rice seed, the average time for checking the mis-sowing was 1.37 seconds in the field and 1.2 seconds in the laboratory without any malfunction. Overall evaluation of the system indicated that the system can be utilized for seeding machines not only for paddies but beans and corns.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.443-452
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• 1993

Direct freezing tests of soybean seed by liquid nitrogen were carried out at various moisture contents and the following important conclusions were drawn from the results of temperature measurements of soybean seed and photographs of bubbles generated on its surface : 1) Assuming that the temperature gradient in a soybean seed is negligible because of its small seed size and the freezing ratio is followed the Heiss's formula, and a differential equation based on the heat energy balance was introduced . The equation was easily solved by the Runge-Kutta-Gill method and the predicted values of the temperature were in good agreement with the observed data. 2) The photographs of bubble generation during freezing showed the boiling mode was nucleate, and then the most suitable formula on the nucleate boiling heat transfer was introduced from many formulate proposed up to now by fitting the calculated values based on the formula to the observed data. The formula used for the predict on of the seed temperature was as follows: $\frac{{\partial}T_s}{\partial\theta}\;=\;-\frac{{\alpha}(T_s\;-\;T_L)^{3.3}}{W(C_s\;-\;\frac{{\delta}m(CT_s\;+\;{\sigma})}{T_s^2})}$ where C = difference of the specific heat between pure ice and water m=moisture content of soybean seed $T_s$ = seed temperature $T_L$ = Temperature of liquid nitrogen W = mass of soybean seed $\alpha$ = proportional constant $\delta$ = constant depends on variety or the type of seed $\theta$ = time $\sigma$ = latent heat of melting of pure ice This study will give important information in the hydro-freezing technique by liquid nitrogen, available as a new technique of processing agricultural products in the near future.

• Molecules and Cells
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• v.41 no.12
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• pp.1072-1080
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• 2018

A plant-specific B3 domain and AP2 domain-containing transcription factor, RAV1 acts as a negative regulator of growth in many plant species and its transcription was down-regulated by BR and ABA. In this study, we found that RAV1-overexpressing transgenic plants showed abnormally developed ovules, resulting in reduced seed size, weight, and number in a silique. Interestingly, the endogenous expression of RAV1 fluctuated during seed development; it remained low during the early stage of seed development and sharply increased in the seed maturation stage. In plants, seed development is a complex process that requires coordinated growth of the embryo, endosperm, and maternal integuments. Among many genes that are associated with endosperm proliferation and embryo development, three genes consisting of SHB1, MINI3, and IKU2 form a small unit positively regulating this process, and their expression was regulated by BR and ABA. Using the floral stage-specific RNAs, we found that the expression of MINI3 and IKU2, the two downstream genes of the SHB1-MINI3-IKU2 cascade in the seed development pathway, were particularly reduced in the RAV1-overexpressing transgenic plants. We further determined that RAV1 directly binds to the promoter of MINI3 and IKU2, resulting in their repression. Direct treatment with brassinolide (BL) improved seed development of RAV1-overexpressing plants, but treatment with ABA severely worsened it. Overall, these results suggest that RAV1 is an additional negative player in the early stages of seed development, during which ABA and BR signaling are coordinated.