• Journal of Ecology and Environment
• /
• v.35 no.2
• /
• pp.73-78
• /
• 2012

$Calotropis$ $procera$ L. is a perennial shrub distributed in saline areas of deserts of South Asia. Salt stress is a very challenging subject in arid and semi-arid areas. Germination stage is very sensitive and many plants do not germinate in saline soil. The objective of this study was identifying the salinity effect on seed germination of $Calotropis$ $procera$ L. The experimental design was a complete randomized block design with NaCl and $CaCl_2$ at five levels of isobar concentrations: 0.0, -0.01, -0.05, -0.1, and -0.15 MPa. Osmotic potential had significant effects ($P$ < 0.01) on germination percentage, germination rate, shoot length, root length, and seedling dry weight. All seedling characteristics decreased with decrease in osmotic potential. Shoot length and root length decreased more than the seedling characteristics. Germination was completely inhibited in -0.1 Mpa. Priming with NaCl and $CaCl_2$ (-0.1 MPa) for four days had significant effects ($P$ < 0.01) on the germination percentages. Priming improved the seedling characteristics in all samples, especially in -0.05 Mpa, but a decrease with decrease in osmotic potential.

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 1993.10a
• /
• pp.850-858
• /
• 1993

Germinatin and early growth of tobacco seedlings in trays containing many cells is increasing in popularity . Since 100 % germination is not likely , a major problem is to locate and replace the content of those cells which contain either no seedling or a stunted seedling with a plug containing a viable seedling. Empty cells and seedlings of poor quality take up valuable space in a greenhouse. They may also cause difficulty when transplanting seedlings into the field. Robotic technology, including the implementation of computer vision, appears to be an attractive alternative to the use of manual labor for accomplishing this task. Operating AGBOT, short for Agricultural ROBOT, involved four steps : (1) capturing the image, (2) processing the image, (3) moving the manipulator, (4) working the gripper. This research seedlings within a cell-grown environment. the configuration of the cell-grown seedling environment dictated the design of a Cartesian robot suitable for working ov r a flat plane. Experiments of AGBOT performance in transferring large seedlings produced trays which were more than 98% survived one week after transfer. In general , the system generated much better than expected.

• Journal of Practical Agriculture & Fisheries Research
• /
• v.21 no.2
• /
• pp.77-86
• /
• 2019

To determine none top soil covering in rice seedling nursery method for the sparse machine transplanting, four different sowing methods were tested. Shoot and root length, fresh weight, leaf number and color using leaf color chart(LCC) and SPAD were collected as the data comparison of methods. The seedling height showed the highest growth according to the conventional (230g seed rate of pre-emerged seeds and top-soil covering) > high sowing density 1 (290g seed rate of pre-emerged seeds and top-soil covering) ≥ high sowing density 2(290g seed rate of pre-emerged seeds and none top-soil covering) > high sowing density 3(290g seed rate of iron-coated seeds and none top-soil covering). There was any statistical difference between groups in root length, leaf number, LCC, and SPAD values. Thus, a high sowing density of 290g for rice nursery seedling box was recommended to the sparse machine transplanting in rice cultivation with the none top-soil covering method, enabling convenient handling in transportation and machine transplanting work.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.44 no.3
• /
• pp.236-242
• /
• 1999

To examine the seedling stand and growth as affected by early seeding dates of dry direct seeded rice in the Honam plain area of Korea, Dongjinbyeo was seeded at six seeding dates from early March to late April in rice fields of silty loam soil(Jeonbuk series) at the National Honam Agricultural Experiment Station (NHAES) for two years, 1996 and 1998. Seedling stand decreased slightly. with an early seeding date, but it produced more than the optimum seedling number except for the seeding of 25 March in 1996. Days to emergence was significantly longer, as seeding date was earlier, and days to emergence by early seeding was shortened only by 8 days because the mean air temperature was lower in 1996 than average, while in 1998, the reduction effect was nine to twenty five days because the mean air temperature was higher than average. In early seeding, various weeds occurred at the emergence date of rice and dominant weeds were Alopecurus aequailis, Ludwigia prostata and Rorippa islandica. NH$_4$$^{+}$ -N content in the soil at the 5th leaf stage and maximum tillering stage were lower, as the seeding date was earlier when nitrogen was split applied as basal and top dressed in 1996, while it was not significantly different among seeding dates when nitrogen was intensively applied as a top dressing in 1998. Tiller number at the maximum tillering stage and panicle number/m$^2$ were more, as seeding date was earlier in 1996, while it was not different in 1998. Filled grain rate and 1,000 grain weight was not different among the seeding dates. Milled rice yield was significantly decreased in the seeding before the middle of March, but in the seeding after late March, it was not varied when compared with the normal seeding date in 1996, while in 1998, there was no difference among seeding dates. From the above results, in consideration of seedling stand, weed occurance, rice growth and milled rice yield, the critical optimum early seeding time in the southern plain area may lie in early April. But it was suggested that when soil moisture is proper for seeding practices, seeding amount is increased and nitrogen is applied after plumule emergence of rice, milled rice yield may not be reduced in the seeding of middle or late March, compared with the seeding in April.l.

• Korean Journal of Plant Resources
• /
• v.14 no.1
• /
• pp.15-23
• /
• 2001

Effects of growth regulators, scion length and scion diameter on shooting and seedling characteristics were investigated to increase seedling products by root cuttings of lacquer tree. Shoots developed and emerged above-ground from the root scion at 3∼5 weeks after cut plating, most of that was a shoot but some of that were 2∼3 shoots. Otherwise, non-shooting was the reason that cortical layer was decayed. Soaking in zeatin was the most effective on shooting of root cuttings and high concentration was effective. Also soaking on high contents of BA or kinetin was effective on shooting but was lower totally than soaking on zeatin. Seedling characteristics among 3 growth regulators and 3 concentrations were not any difference in statistical significant, but were move excellent than control. As root scion was tall, shoots were developed at early. 15cm length scion was the most excellent to use seedlings but 3cm length scion was wickedness. 10cm scion, however, was highest to product of seedlings than any others. 0.3∼0.5 cm length scion was showed 76% shooting rate at 10 weeks after cut planting, but seedling characteristics were not any difference among the kind of 3 diameters.

• Journal of Ginseng Research
• /
• v.32 no.3
• /
• pp.257-263
• /
• 2008

This study was carried out to obtained the basic information for seed coat dehiscence and seedling performance according to seed size of eight ginseng cultivars. Seed size was separated into four grade(upper 5.0, 5.0-4.7, 4.7-4.0, and under 4.0mm in diameter). Seed coat dehiscence and survival ratio of seedling were not affected by seed size. Aerial parts growth of seedling such as stem length, stem diameter, and leaf area of seedling were larger seed(upper 5.0 mm) better than those of small seeds(4.7-4.0, and under 4.0 mm in diameter). Also root part growths such as root diameter, and fresh weight were larger seed(upper 5.0 mm) higher than those of small seeds(4.7-4.0, and under 4.0 mm in diameter). However, root length was not affected by seed size. Growth status of aerial and root parts of 'unpoong' 'umpoong' and 'opoong' were better than those of other cultivars in each grade of seed sizes. The growth of characteristics of 'hunpoong' and 'hungsun' were less than those of other cultivars.

• Journal of Korean Society of Forest Science
• /
• v.108 no.2
• /
• pp.189-199
• /
• 2019

The forest management paradigm has recently shifted from focusing on commercial production to focusing on ecosystem management. Accordingly, a natural seedling regeneration method that has a naturally high affinity has attracted much attention in recent years. The aim of this study was to determine the relationship among various environmental factors, lower stratum vegetation, and seedling regeneration in Pinus densiflora forests. The survey site comprised 50 sectors divided using the line transect method, and the survey data were divided into those from wet habitat (19 sites) and dry habitat (31 sites), depending on the soil humidity, and were analyzed separately to show the close relationship between soil humidity and natural seedling regeneration. As a result, the dry habitat exhibited high seedling density (157,419 trees/ha), with the main species being Quercus serrata, Zanthoxylum piperitum, Smilax china, and Pueraria lobata, while wet habitat exhibited low seedling density (57,895 trees/ha), with the main species being Stephanandra incisa, Castanea crenata, Lespedeza maximowiczii, Lysimachia barystachys, Aralia elata, and Styrax japonicus. The height and root-collar diameter under wet conditions exhibited faster growth than those under dry conditions. Height growth by the root-collar diameter in dry habitat increased faster than that in wet habitat. It was also confirmed that seedling regeneration in wet habitat exhibited a rapid growth pattern 5 years after germination. These results suggest that the seedlings begin to grow more rapidly after a period of suppression by competition with surrounding plants. Considering an ecosystem or ecological management approach, specific practices, such as bush control and vine clearing in wet habitats, should be more intensively conducted, especially at the beginning of the management operations.

• Korean Journal of Medicinal Crop Science
• /
• v.14 no.3
• /
• pp.153-157
• /
• 2006

Floret flowering of Orostachys japonicus, a monocarpic and short day plant, should be controlled to continue cultivating. The study was done to examine the effect of transplanted seedling size (large, 18 leaves; medium, 13 leaves; small, 8 leaves) on growth, morphological characters, and flowering. Night-break treatment of 2 hours at midnight were done on August 25 and afterward samples were taken every 2 weeks. Growth, morphological and flowering related characters were measured from each sample. With larger seedling transplanted, plant height, inflorescence length, number of leaves including bracts and stem diameter were increased. Leaves and bracts, stem, root, shoot and total dry weights were increased as transplanted seedlings became larger. Although formed florets were inclined with larger transplanted seedling, they were not flowered because of the night-break treatment, meaning that the larger transplanted seedlings, the more economic yield.

• Journal of Korean Society of Forest Science
• /
• v.109 no.1
• /
• pp.31-40
• /
• 2020

This study aimed to investigate the effects of climate change on the survival and growth performance of Pinus densiflora and Larix kaempferi seedlings using open-field experimental warming and precipitation manipulation. We measured the survival rate, root-collar diameter, and height, and then calculated the seedling quality index (SQI) of 2-year-old seedlings under 6 treatments [2 temperatures (TC: Control; TW: Warming) × 3 precipitation manipulations (PC: Control; PD: Decreased; PI: Increased)] and performed a two-way ANOVA to test for differences.The air temperature of the warming plots was 3℃ higher than that of the control plots, while the precipitation manipulation plots received ±40% of the precipitation received by the control plots. Temperature and precipitation treatments did not significantly affect the survival rate of P. densiflora; however, the SQI of P. densiflora decreased with increasing precipitation. In contrast, the mortality rate of L. kaempferi increased with increasing temperature and decreasing precipitation. Furthermore, in L. kaempferi, TC × PI treatment resulted in the lowest SQI with a significant interaction effect observed between the two factors. In summary, low seedling production and quality should be expected in P. densiflora as precipitation increases and in L. kaempferi as temperature increases or precipitation decreases. These results indicate species-specific sensitivities to climate change of two plant species at the nursery stage. With the occurrence of global warming, the frequencies of drought and heavy rainfall events are increased, and this could affect the survival and seedling quality of tree species. Therefore, it is necessary to improve nursery techniques by establishing new adaptation strategies based on species-specific growth performance responses.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.12
• /
• pp.55-62
• /
• 1972

In order to study the biolgiocal effects of dry back following EMS (Ethyl methane sulfonate) treatment on seeds of 'Dunghan Shali' that belongs to indica-type rice with various presoaking(24, 36, and 40 hrs respectivily) and treatment time(l, 2 and 3 hrs respectivily), this experiment was done. Seedling heights of wet seeds presoaked for 36 hrs was only greatly decreased with EMS treatment compared with other periods. In germination rate of wet seeds, all of these damage was not changed. For the drying back seeds, otherwise, seedling height and germination rate were greatly reduced depend upon the time of treatment and presoaking as well as storage effects after drying back. Reduction patterns, both seedling height and germination rate, between 1 week and 8 weeks after dry back were quite similar. The other experiment was carried out in order to study for the influences on the seedling growth as biological damage with EMS and MMS(Methyl methane sulfonate) treatments among different varieties. The indica-type rice varieties; Taichung Native No.1, Dunghan Shali and IR-8, were used as the experimental materials. From this trial some results were obtained as follows; 1. Both seedling growth and germination rate on all varieties, used, MMS, treatment showed more toxic effects than those of EMS treatment. 2. Seeding growth injury of rice seeds dried back was increased gradually, and then was approached the maximum at 6-8 days after storing. In IR-s variety, otherwise, growth damage was appeared a little. Germination rate of these were quite smilar, even though chemical used is different and storage period was prolonged. 3. It was showed clearly that varietal differences of chemical mutagene treatments were recognized.