• Journal of Bio-Environment Control
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• v.32 no.3
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• pp.242-248
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• 2023

This study was conducted to evaluate the effects of trinexapac-ethyl (TE) and prohexadione-calcium (PC) on the growth and turf quality of perennial ryegrass (Lolium perenne L.). Treatments were designed as follows; control (non-treatment), TE (TE 0.01 a.i. g·m^-2·100mL^-1), and PC (PC 0.01 a.i. g·m^-2·100mL^-1). Compared with control, turf color index and chlorophyll content of TE and PC treatments were not significantly different. As applied plant growth regulators (PGRs), shoot length in the TE and PC was decreased by 8.9-12.4% and 6.7-13.6%, respectively, and clipping yield by 44.4-45.8% and 40.6-40.9%. When evaluated with the growth of shoot length after applying PGRs, residual days of TE and PC were 43.6 and 37.9 days after treatment of PGRs (DAT) in the 1st experiment (July 29-August 26), respectively, and 38.3 and 39.5 DATs in the 2nd experiment (September 30-October 28). These results indicated that an application of TE or PC decreased shoot length and clipping yield in the perennial ryegrass, and their residual time was about 40±3 DATs. Perennial ryegrass applied with PGRs like TE and PC was not significant seasonal difference, and might be not phytotoxic.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.5
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• pp.386-395
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• 2006

The core questions for determining nitrogen topdress rate (Npi) at panicle initiation stage (PIS) are 'how much nitrogen accumulation during the reproductive stage (PNup) is required for the target rice yield or protein content depending on the growth and nitrogen nutrition status at PIS?' and 'how can we diagnose the growth and nitrogen nutrition status easily at real time basis?'. To address these questions, two years experiments from 2001 to 2002 were done under various rates of basal, tillering, and panicle nitrogen fertilizer by employing a rice cultivar, Hwaseongbyeo. The response of grain yield and milled-rice protein content was quantified in relation to RVIgreen (green ratio vegetation index) and SPAD reading measured around PIS as indirect estimators for growth and nitrogen nutrition status, the regression models were formulated to predict PNup based on the growth and nitrogen nutrition status and Npi at PIS. Grain yield showed quadratic response to PNup, RVIgreen around PIS, and SPAD reading around PIS. The regression models to predict grain yield had a high determination coefficient of above 0.95. PNup for the maximum grain yield was estimated to be 9 to 13.5 kgN/10a within the range of RVIgreen around PIS of this experiment. decreasing with increasing RVIgreen and also to be 10 to 11 kgN/10a regardless of SPAD readings around PIS. At these PNup's the protein content of milled rice was estimated to rise above 9% that might degrade eating quality seriously Milled-rice protein content showed curve-linear increase with the increase of PNup, RVIgreen around PIS, and SPAD reading around PIS. The regression models to predict protein content had a high determination coefficient of above 0.91. PNup to control the milled-rice protein content below 7% was estimated as 6 to 8 kgN/10a within the range of RVIgreen and SPAD reading of this experiment, showing much lower values than those for the maximum grain yield. The recovery of the Npi applied at PIS ranged from 53 to 83%, increasing with the increased growth amount while decreasing with the increasing Npi. The natural nitrogen supply from PIS to harvest ranged from 2.5 to 4 kg/10a, showing quadratic relationship with the shoot dry weight or shoot nitrogen content at PIS. The regression models to estimate PNup was formulated using Npi and anyone of RVIgreen, shoot dry weight, and shoot nitrogen content at PIS as predictor variables. These models showed good fitness with determination coefficients of 0.86 to 0.95 The prescription method based on the above models predicting grain yield, protein content and PNup and its constraints were discussed.

• Journal of Environmental Science International
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• v.21 no.12
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• pp.1435-1447
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• 2012

The present study was conducted to determine the effect of hexaconazole (HEX), a triazole fungicide, on the growth, yield, photosynthetic response and antioxidant potential in cucumber (Cucumis sativus L.) plants subjected to UV-B stress. UV-B radiation and HEX were applied separately or in combination to cucumber seedlings. The growth parameters were significantly reduced under UV-B treatment, however, this growth inhibition was less in HEX treated plants. HEX caused noticeable changes in plant morphology such as reduced shoot length and leaf area, and increased leaf thickness. HEX was quite persistent in inhibiting shoot growth by causing a reduction in shoot fresh and dry weight. HEX noticeably recovered the UV-B induced inhibition of biomass production. Significant accumutation in anthocyanin and flavonoid pigments in the leaves occurred as a result of HEX or UV-B treatments. HEX permitted the survival of more green leaf tissue preventing chlorophyll content reduction and higher quantum yield for photosystemII under UV-B exposure. HEX treatment induced a transient rise in ABA levels in the leaves, and combined application of HEX and UV-B showed a significant enhancement of ABA content which activates $H_2O_2$ generation. UV-B exposure induced accumulation of $H_2O_2$ in the leaves, while HEX prevented UV-B induced increase in $H_2O_2$, indicating that HEX serves as an antioxidant agent able to scavenge $H_2O$ to protect cells from oxidative damage. An increase in the ascorbic acid was observed in the HEX treated cucumber leaves affecting many enzyme activities by removing $H_2O_2$ during photosynthetic processes. The activities of antioxidant enzymes including catalase(CAT), ascorbate peroxidase(APX), superoxide dismutase(SOD) and peroxidase(POD) in the leaves in the presence of HEX under UV-B stress were higher than those under UV-B stress alone. These findings suggest that HEX may participate in the enhanced tolerance to oxidative stress. From these results it can be concluded that HEX moderately ameliolate the effect of UV-B stress in cucumber by improving the components of antioxidant defense system.

• Horticultural Science & Technology
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• v.34 no.1
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• pp.15-23
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• 2016

A study was conducted to evaluate the effects of irrigation (amount, interval) on tree growth, fruit quality, and cracking of organic 'Campbell Early' grapevine in 2012 and 2013. Three irrigation treatments were applied using a sprinkler system from mid-June to mid-August in 2012 and 2013, as follows: 10 mm was applied daily (10 mm-IR), 20 mm was applied every two days (20 mm-IR), and 30 mm was applied every five days (30 mm-IR). Soil electrical conductivity (EC) and temperature were found to be greatest in the 10 mm-IR treatment in both years. Soil moisture content ranged between 20-40% in the 10 mm-IR, between 20-60% in the 20 mm-IR, and between 20-70% in the 30 mm-IR treatment plots. The total number of leaves per shoot and shoot growth were found to be greatest in the 20 mm-IR and 30 mm-IR treatments, respectively. Cluster and berry weights, and cluster and berry sizes were not consistently affected by the treatments. The 10 mm-IR treatment resulted in an increase in fruit SSC, SSC/acidity ratio, and berry skin pigmentation ($b^*$; blue). Approximately 5% of fruit cracking was observed on average over both years in the 10 mm-IR-treated fruit, while the 30 mm-IR treatment resulted in nearly 18% of cracking in 2012. Average marketable fruit yield per year over two years was greatest for the 10 mm-IR treatment ($24.4t{\cdot}ha^{-1}$) followed by the 30 mm-IR treatment ($22.7t{\cdot}ha^{-1}$) and lastly the 20 mm-IR treatment ($22.2t{\cdot}ha^{-1}$). Thus, the 10 mm-IR treatment represents a suitable irrigation regimen for controlling leaf and shoot growth of vines grown under a rain-shelter system in sandy loam soils, while improving fruit sugar contents and skin color and limiting fruit cracking.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.5
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• pp.390-394
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• 2002

Spikelet number per unit area(SPN) is a major determinant of rice yield. Nitrogen nutrition status and biomass during reproductive stage determine the SPN. To formulate a model for estimating SPN, the 93 field experiment data collected from widely different regions with different japonica varieties in Korea and Japan were analyzed for the upper boundary lines of SPN responses to nitrogen nutrition index(NNI), shoot dry weight and shoot nitrogen content at panicle initiation and heading stage. The boundary lines of SPN showed asymptotic responses to all the above parameters(X) and were well fitted to the exponential function of $f(X)=alphacdot{1-etacdotexp(gamma;cdot;X)}$. Excluding the constant, from the boundary line equation, the values of the equation range from 0 to 1 and represent the indices of parameters expressing the degree of influence on SPN. In addition to those indices, the index of shoot dry weight increase during reproductive stage was calculated by directly dividing the shoot dry weight increase by the maximum value ($800 extrm{g/m}^{-2}$) of dry weight increase as it showed linear relationship with SPN. Four indices selected by forward stepwise regression at the stay level of 0.05 were those for NNI ($I_{NNI}_P$) at panicle initiation, NNI($I_{NNI}_h$) and shoot dry weight($I_{DW}_h$) at heading stage, and dry weight increase($I_{DW}$) between those two stages. The following model was obtained: SPN=48683ㆍ $I_{DWH}$$^{0.482}$ㆍ $I_{NNIp}$$^{0.387}$ㆍ $I_{NNIH}$$^{0.318}$ㆍ $I_{DW}$ $^{0.35}$). This model accounted for about 89% of the variation of spikelet number. In conclusion this model could be used for estimating the spikelet number of japonica rice with some confidence in widely different regions and thus, integrated into a rice growth model as a component model for spikelet number estimation.n.n.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.39 no.5
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• pp.458-464
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• 1994

The partitioning of dry matter into seed and pod-shell is important because yield increase can be achieved by improving the distribution rate of assimilation products to seeds. The present study was undertaken to characterize whether the partitioning of dry matter into seed was shoot- or root-controlled through graftiong techniques. Self- and reciprocal-grafts were made among four soybean genotypes, which were 'Baekunkong', 'Suwon 168', and two local soybeans with black seed coat (hereafter referred to as the 'black soybean'), 'Kangleungjarae' and 'Keumleungjarae'. Self-grafted black soybeans showed lower ratio of seed to pod-shell dry wight than self-grafted Baekunkong and Suwon 168. Varying the shoot genotypes in grafts resulted in significant differences in growth characters as well as pod and seed dry weight per plant at physiological maturity. There were significant effects of shoot genotypes on the ratio of seed to pod-shell dry weight, indication that the partitioning of dry matter into seed and pod-shell should be shoot- rather than root-controlled. The grafts with large pod-shell dry weight tended to partition relatively smaller dry matter into seed than pod-shell.

• Journal of Bio-Environment Control
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• v.23 no.4
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• pp.309-313
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• 2014

This research was conducted to establish recommendable side shoot management methods in the growth and yield of tomato in winter. A cherry tomato, $^{\circ}{\times}Unicorn^{\circ}{\pm}$ (Monsanto Korea, Korea) was cultivated in coconut coir in the form of bag as substrate. There were four treatments related to side shoot removal methods; 1) To remove all side shoots and also each one of three leaves which gives shade to each cluster attached below (UP-FL), 2) To remove all side shoots and also each one of three leaves which gives shade to each cluster only with fruit attached below (UP-FR), 3) To remove all side shoots (AS-All), and 4) To remain two leaves of each side shoot coming from right below each cluster (AS-Part). The number of malformed leaves were more in UP-FL, UP-FR, AS-All, and AS-Part in descending order, which showed the severe the removal of leaves the more the malformed leaves. The malformed leaves were diminished after the development stage the second or third cluster bloomed. The yields until fifth cluster were not different among the treatments. Therefore removal of side shoots and leaves recommends not to be done severely in early growth stage when tomato plants are cultivated in winter.

• Horticultural Science & Technology
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• v.32 no.4
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• pp.493-498
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• 2014

The objective of this study was to make growth and yield models for common ice plant (Mesembryanthemum crystallinum L.) using expolinear functional equations in a closed-type plant production system. Three-band radiation type fluorescent lamps with a 12-hours photoperiod were used, and the light intensity was $200{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$. Nutrient film systems with three layers were used for plant growth. Environmental conditions, such as air temperature, relative humidity and $CO_2$ concentration were controlled by an ON/OFF operation. Leaf area, shoot fresh and dry weights, light use efficiency of common ice plant as function of days after transplanting, accumulative temperature and accumulative radiation were analyzed. Leaf area, shoot fresh and dry weights per area were described using an expolinear equation. A linear relationship between shoot dry and fresh weights was observed. Light use efficiency of common ice plant was $3.3g{\cdot}MJ^{-1}$ at 30 days after transplanting. It is concluded that the expolinear growth model can be a useful tool for quantifying the growth and yield of common ice plant in a closed plant production system.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.28 no.4
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• pp.481-487
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• 1983

The need to synchronize flowering in two lines of different maturities is frequently encountered in hybrid com (Zea mays L.) seed production. To establish the methods for synchrony of flowering in parent lines of different maturities be effects of clipping at 4 and 6-leaf stages of growth and two levels, clear polyethylene mulching and five different planting dates on flowering date growth and seed yield of two dent com inbred lines of different maturities were evaluated Clipping just above the shoot-apex delayed pollen sheeding 6 to 9days and silking 5 to 13 days but reduced stand and seed yield 30 to 70% and 67 to 81%. respectively. Clipping 5cm above the shoot apex delayed flowering 1 to 4 days without stand reduction but reduced yield 3 to 29%. Laterclipping was slightly more effective for delaying flowering than earlier clipping but reduced stand more severely when clipped just above the shoot apex. Under clear polyethylene film mulching, flowering of two lines was 13 to 15 days earlier and seed yield of B68 (late line) was significantly increased. As planting was delayed from April 18 to June 13, the number of days from planting to flowering of two lines decreased due to increase in air temperature. However, growing degree days (GDD) from planting to flowering of each lines was similar regardless planting dates indicating that GDD can be satisfactoryly used for choosing the planting dates of parent lines of different maturities. Seed yields of two lines were decreased with delaying planting dates.

• Journal of Sericultural and Entomological Science
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• v.36 no.2
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• pp.102-109
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• 1994

Profitability was analysed in the fields of various planting densities from 1,666 trees/10a to 4,166 with mulberry grafts or conventional saplings under the consideration of leaf yield and quality. Leaf yield per tree decreased with the higher planting densities. Seasonal and total leaf yield per area, however, increased by 20 to 63% as a mean for 3 years in the densities of 2,083~4,166 trees per 10a than in the conventional density of 1,666 trees per 10a. The increase in leaf yield per area was not so high in the densities over 2,083. Leaf yield in the sapling plots was a little higher than that in the graft plots. Topping of shoot tip affected neither on the branch length nor on yield. Yield was higher in the planting spacing with single raws than in that with double raws. Quality of leaves in the densities from 2,083 to 3,333 trees per 10a was relatively good judged based on the results of the pupation rate and cocoon yield and quality.