• Journal of Biosystems Engineering
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• v.30 no.1 s.108
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• pp.45-55
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• 2005

Knowledge of the relationship between crop yield and yield-limiting factors is essential for precision farming. However, developing this knowledge is not easy because these yield-limiting factors are interrelated and affect crop yield in different ways. In this study, data for grain yield and yield-limiting factors, including crop chlorophyll content, soil chemical properties, and topography were collected for a small (0.3 ha) rice paddy field in Korea and a large (36 ha) upland corn field in the USA, and relationships were investigated with path analysis. Using this approach, the effects of limiting factors on crop yield could be separated into direct effects and indirect effects acting through other factors. Path analysis provided more insight into these complex relationships than did simple correlation or multiple linear regression analysis. Results of correlation analysis for the rice paddy field showed that EC, Ca, and $SiO_2$ had significant (P<0.1) correlations with rice yield, while pH, Ca, Mg, Na, $SiO_2,\;and\;P_2O_5$ had significant correlations with the SPAD chlorophyll reading. Path analysis provided additional information about the importance and contribution paths of soil variables to rice yield and growth. Ca had the highest direct effect (0.52) and indirect effect via Mg (-0.37) on rice yield. The indirect effect of Mg through Ca (0.51) was higher than the direct effect (-0.38). Path analysis also enabled more appropriate selection of important factors limiting crop yield by considering cause-and-effect relationships among predictor and response variables. For example, although pH showed a positive correlation (r=0.35) with SPAD readings, the correlation was mainly due to the indirect positive effects acting through Mg and $SiO_2$, while pH not only showed negative direct effects, but also negatively impacted indirect effects of other variables on SPAD readings. For the large upland Missouri corn field, two topographic factors, elevation and slope, had significant (P<0.1) direct effects on yield and highly significant (P<0.01) correlations with other limiting factors. Based on the correlation analysis alone, P and K were determined to be nutrients that would increase corn yield for this field. With the help of path analysis, however, increases in Mg could also be expected to increase corn yield in this case. In general, path analysis results were consistent with published optimum ranges of nutrients for rice and com production. We conclude that path analysis can be a useful tool to investigate interrelationships between crop yield and yield limiting factors on a site-specific basis.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.6
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• pp.571-578
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• 2014

The garlic cultivation area is moved by change of grown environment due to global warming. It is important to predict changes in cultivation area, quantity and quality of each crop. This study was carried out to estimate the yield and response of garlic growth by the rapid temperature changes in the greenhouse with thermostat control system. Seedlings of Namdo garlic were planted on September 27, 2012 and harvested on May 30, 2013. The used treatments for a rapid temperature change in March-April-May were T0 (control): $6.0-10.4-17.2^{\circ}C$, T1: $6.0-5.4(-5)-17.2^{\circ}C$, T2: $6.0-10.4-22.2(+5)^{\circ}C$ and T3: $6.0-5.4(-5)-22.2(+5)^{\circ}C$. Total dried weight per plant of garlic significantly increased by 5.0% for T2, but T1 and T3 decreased by 12.5 and 4.6%, respectively, compared to T0. Total yields of bulb within the temperature change as T2 and T0 increased significantly (p<0.05), as compared to T1. Decreasing temperature significantly (p<0.05) reduced plant height, SPAD reading, crude protein and fiber contents etc., as compared to T0 and T2. ABA contents gradually increased with time but IAA content rapidly decreased. Conclusively, growth and yield of garlic were more affected by decreased temperature than increased temperature at bulb development stage.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.45 no.3
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• pp.163-166
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• 2000

Cassia mimosoides var. nomame was grown at five phosphate rates (0, 5, 15, 25 and 35 kg/10a) at Cheju in 1998 to determine the influence of phosphate rate on growth, forage yield and quality. As phosphate rate increased from 0 to 35kg/10a, the plant growth was increased such as days to flowering, plant height, the number of branches and green leaves per plant, stem diameter and SPAD (Soil Plant Analysis Development) reading values of leaves but the number of withering leaves per plant decreased. Fresh forage yield was 3, 291kg/10a at 0 kg/10a of phosphate rate and increased 5, 200 and 5, 230 kg/10a at 25 and 35 kg/10a of phosphate level, respectively. Dry matter, crude protein and total digestible nutrients (TDN) showed the same tendency of changes as the fresh forage yield. Crude protein, crude fat, nitrogen free extract and TDN content increased but crude ash and crude fiber content decreased as the increasing of phosphate rate increased.

• Journal of The Korean Society of Grassland and Forage Science
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• v.21 no.2
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• pp.53-58
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• 2001

Jeju Italian millet was grown at five planting densities(5$\times$5, 15$\times$15, 20$\times$20, 25cm) form May 13 to Aug. 14, 2000 at jeju island to determine influence of planting density on agronomic characters, forage yield and quality. Days to heading increased from 87 to 89 days as planting density was decreased. In 5$\times$5cm planting density plot, plant height was 185.4cm and it was gradually decreased as planting density was increased. So in 30$\times$30cm planting density plot, plant height was 173cm. As planting density increased, stem diameter, the number of nodes per plant, the umber of leaves, leaf width and SPAD reading values was increased, the longer leaf length as the broader planting density. Fresh forage yield increased from 29.99 to 55.01MT/ha, dry matter(DM) yield from 8.04 to 15.59MT/ha, crude protein(CP) yield from 0.78 to 2.26MT/ha and total digestible nutrients(TDN) yield from 3.65 to 7.93MT/ha as planting density was decreased. Crude protein content increased from 9.8 to 14.5% ether extract comtent from 1.4 to 1.9%, nitrogen free extract content from 38.4% to 38.9% and TDN content from 45.4 to 50.9%, but crude fiber content decreased from 34.5 to 30.1% and crude ash content from 9.1 to 8.0% as planting density was decreased.

• Journal of Animal Environmental Science
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• v.14 no.2
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• pp.119-128
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• 2008

This experiment was conducted to investigate the effects of concentrated pig slurry using membrane filter on growth of tomato in nutriculture. Pig slurry was filtered by ultra filtration and concentrated by reverse osmosis process. Filtration of pig slurry was necessary to prevent the hose clogging in nutriculture. The concentrated pig slurry (CS) and nutrient solution (NS) were mixed by six different mixing ratios of 0:100, 20:80, 40:60, 60:40%, 80: 20 and 100%:0% based on nitrogen content. The chemical nutrient solution was the solution of National Horticulture Research Station for the growth of tomato. The concentration of nutrient solution was adjusted a range of $1.6{\sim}2.0mS/cm$ in EC. The plant height of tomato treated with CS 20+NS 80% was similar with NS 100% control plot. Plant height was highest in the plot of CS 20+NS 80%. The treatment of 100% concentrated pig slurry was lowest in the gowth characteristics of tomato. Number of cluster was very lower in 100% concentrated pig slurry compared with plot of chemical nutrient solution. In the beginning of growth stage, SPAD reading value was reduced in plot treated with CS 100%, but CS 20+NS 80% plot was higher compared to 100% concentrated pig slurry. SPAD value of tomato leaves was decreased as the amount of CS was increased. The SPAD value also in treatment of concentrated pig slurry was lower in the middle growth stage compared to control plot. The dry weight of stem and leaf were 107.4, 104.2g in plot of NS 100% and CS 20%+NS 80%, respectively. The fruit number and weight were decreased at high application plots of concentrated pig slurry, The fruit setting of tomato showed lowest in the plot treated with 100% concentrated pig slurry, and the growth of tomato severely decreased after application of 100% CS treatment. In conclusion, the growth characteristics such as plant height and fruit weight of tomato were not significantly different between the plots treated with mixture of 20% CS +80%NS and 100% nutrient solution treatment. In conclusion, the mixture solution of 20% of concentrated pig slurry and 80% of nutrient solution could be used as a nutrition solution of tomato nuticulture.

• Korean Journal of Environmental Agriculture
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• v.29 no.1
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• pp.12-19
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• 2010

Optimum nitrogen fertigation level by soil testing was determined on the growth and yield of eleven-year-old 'Campbell Early' (Vitis labrusca L.) grapevine in a sandy loam soil from 2005 to 2007. Fifty percent of the annual application of the nitrogen rate (195 kg/ha/yr) was top-dressed as basal fertilizer in all treatments, and the remainders were drip-irrigated with fertigation rate at 25 (12.5% of total N, N 1/4 level of the remainder), 50 (25% of total N, N 1/2 level), and 100 mg/L (50% of total N, N 1 level) in intervals of twice (2.1 mm/times) a week for 12 weeks, and the effect of N drip fertigation was compared to control which the N remainder was applied with surface application as an additional fertilizer. The results showed that chlorophyll content reading in SPAD value and N contents of leaves increased as nitrogen fertigation level increased. Also observed was the growth of the internode and stem diameter of shoots which were longest at N 1/2 level among the treatments conducted both in 2005 and 2006. It was also noted that yield of the fruit was different every year, where average yield for three years was recorded highest in N 1/4 level, and lowest in N 1 level compared to control(surface application). Soluble solid content and titratable acidity of fruit juice were also not significant during the treatments, the maturation of fruits tended to be retarded in N 1 level. The study proved that N 1/4 (N 25 mg/L) levels of fertigation based on soil testing was most efficient in obtaining optimum yield and also, fertigation of grapevine at open field condition reduces the use of nitrogen fertilizer.

• Korean Journal of Soil Science and Fertilizer
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• v.41 no.2
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• pp.103-111
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• 2008

This study was carried out to investigate the optimal application rate and time of mixed expeller cake (MEC) for the replacement of chemical fertilizer. Dongjin-1, as cultivated rice was used at Fluvio-marine deposit in Honam plain paddy field. Soil chemical properties were improved by the application of MEC. Contents of total nitrogen and organic matter were higher in 70%, 100% plots of basal dressing than standard fertilizer application (SFA) plot. Cation exchangeable capacity was highly increased in 70% plot of basal dressing. Also, the content of organic matter in soil was increased with MEC application. Cation exchangeable capacity, total nitrogen and available phosphate were decreased according to late application time. The content of inorganic nitrogen in soil showed high tendency at more application rate of MEC, and nitrogen mineralization at harvest season have finished in 50%, 70% plots of basal dressing. The content of inorganic nitrogen in soil was increased according to late application time, however it was decreased in the late period of growth. Leaf color value became darker with increased application rate of MEC. Leaf color was dark green in MEC application plots at panicle formation stage, on the other hand, it was light green in 50%, 70% plots of basal dressing at heading stage. SPAD reading value of leaf-color was high during the whole growth stage in MEC application plots. More application rate of MEC showed higher tendency of fertilizer nitrogen absorption. Nitrogen use efficiency was the highest in 70% plot of basal dressing. Absorbed amount of fertilized nitrogen was increased in 10~15days before transplanting and nitrogen use efficiency was high according to the late application time. The ratio of perfect kernel and the content of protein on hulled rice showed high tendency at the less application rate of MEC. The ratio of head rice on milled rice showed high tendency at the less application rate of MEC. Rice yield increased 4% in 100% and 70% plots of basal dressing compare with SFA ($5.18Mg\;ha^{-1}$) plot respectively. Ear and culm length of rice were long according to the late application time, while the numbers of spikelet and ear were increased and the percentage of ripened grain was decreased. Rice yield was increased 2~5% in all MEC application plots compared to SFA plot and especially, increased 10~15days before transplanting in application plots. The optimal application rate and time of MEC on normal paddy field in plain were concluded that 70% basal dressing and 10~15days before transplanting

• Journal of The Korean Society of Grassland and Forage Science
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• v.23 no.2
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• pp.77-80
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• 2003

This study was conducted to determine the optimum organic fertilizer rate (0, 100, 200, 300, 400, 500, 600kg/10a) of worm casting on growth response and yield of Ieol´ radish in Jeiu island. The results obtained were summarized as follows; plant height was getting bigger as organic fertilizer increased from 0 to 500kg/10a and then became smaller at 600kg/10a. But was no significance from 200 to 600kg/10a. Number of leaves, leaf width and root diameter were the same trend with plant height response. Root length was not significantly affected by organic fertilizers. SPAD reading value of leaves increased as increasing of organic fertilizers. Fresh matter yield (top+root) increased significantly 2,949∼4,561kg/10a as fertilizer rate increased from 0 to 200kg/10a, increased 5.096∼5,707kg/10a from 300 to 500kg/10a of fertilizer rate and decreased to 4,873kg/10a at 600kg/10a. Top and root weight were the same trend with fresh matter yield.

• Korean Journal of Environmental Agriculture
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• v.33 no.4
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• pp.364-371
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• 2014

BACKGROUND: To evaluate the impact of rapid temperature change at spring and the early summer seasons in climate change, we have investigated the physiological response and yield of onion in a greenhouse with thermostat control system. METHODS AND RESULTS: Seedlings of onion(cv. Sunshine) were planted on October 30, 2012 and harvested on May 30, 2013. The used treatments(March-April-May) for a rapid temperature change were T0(control): $6.0-10.4-17.2^{\circ}C$, T1: $6.0-5.4(-5)-17.2^{\circ}C$, T2: $6.0-10.4-22.2(+5)^{\circ}C$ and T3: $6.0-5.4(-5)-22.2(+5)^{\circ}C$. Total yields of bulb within the temperature change as high temperature treatment T2 and control treatment T0 were increased significantly(p<0.05), as compared to the low temperature treatment T1. Low temperature conditions significantly (p<0.05) reduced plant height, SPAD reading, crude protein and fiber etc., as compared to the TO and T2. CONCLUSION: The rapid temperature changes were highly affected by low temperature than high temperature. These results suggest that rapid climate change of future could need systematic standard model for physiological characteristics and yields of onion.

• Journal of The Korean Society of Grassland and Forage Science
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• v.25 no.2
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• pp.119-124
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• 2005

This study was conducted from March 21 to July 8 in 2004 at JeJu Island to investigate the influences of split nitrogen application times on creeping bentgrass vegetation. Nitrogen rate was 20 kg/10a and it was applied from once to 5 times. The result obtained were summarized as follows; plant height was getting longer as nitrogen was split applied from once to 5 times. So it was longest at 5 times split nitrogen application, but it was no significance from 4 to 5 times. Root length, Minolta SPAD-502 chlorophyll meter reading value, leave and root weight n[e directly proportional plant height response. Degree of land cover Iud density of creeping bentgrass increased as nitrogen was split applied from once to 5 times. But degree of land cover md density of reed decreased. The number of reed species on decreased as nitrogen was split applied from once to 5 times. Then ranking of the dominant weeds were Portulaca oleracea Polygonum hydropiper and Stellaria media (at once split time nitrogen application), Portulaca oleracea, Polygonum hydropiper and Digitaria adscendens (at 2 split times nitrogen application), Digitaria adscendens and Portulaca oleracea Polygonum hydropiper, (at 3 split times nitrogen application), Portulaca oleracea, Poa annua and Polygonum hydropiper (at 4 md 5 split times nitrogen application). These results indicate that the optimum frequency of split N applications is four times for growth of creeping bentgrass in volcanic ash soils of Jeju island.