Korean J. Soil Sci. Fert. Vol.51, No.4, pp.482-49, 218 Korean Journal of Soil Science and Fertilizer Article https://doi.org/1.7745/kjssf.218.51.4.482 pissn : 367-6315 eissn : 2288-2162 Yield and Antioxidant Activity of Vegetable Under Salt Affected Greenhouse Soil in Saemangeum Reclaimed Land Hyeonsoo Jang, Jong-Tak Youn, Seunghyun Ahu, Uk-Han Kim, Won-Yeong Choi, and Hui-su Bae* National Institute of Crop Sciences, RDA, Wanju 55365, Korea *Corresponding author: huisu81@korea.kr A B S T R A C T Received: September 17, 218 Revised: November 29, 218 Accepted: November 3, 218 This study was conducted to examine the yield and antioxidant activity of vegetable crops under the salt affected greenhouse soil in order to evaluate the possibility of greenhouse farming in Saemangeum reclaimed land. Field experiment was conducted on a sandy loam soil and four different vegetable crops, Swiss chard (Beta vulgaris L.), Kale (Brassica oleracea ver. acephala), Red mustard (Brassica juncea L.), and Endive (Cichorium endivia L.) were cultivated. In the third year of the experiment, the soil salinity dramatically increased up to 23.5 ds m -1 from 2.2 ds m -1 in the first year of the experiment due to the resalinization of soil. The cumulative yield was 2,675 kg 1a -1 (Endive) > 2,56 kg 1a -1 (Red mustard) > 1,819 kg 1a -1 (Kale) > 1,795 kg 1a -1 (Swiss chard). Yield was inversely correlated with soil salinity (R 2 =.71-.77) but the red mustard was not significantly correlated with soil salinity. Both DPPH free radical activity and total phenol content were higher with red mustard. K/Na leaves ratio as an indication of the salt tolerance was in the order of Red mustard > Endive Swiss chard Kale. Keywords: Saemangeum reclaimed land, Vegetable crop, Yield, Antioxidant activity 1 8 DPPH radical scavenging activity(%) 9 8 7 6 5 4 Swiss chard Endive Kale Red mustard Total phenolics content as tannic acid equiv. (µg/mg) 6 4 2 Swiss chard Endive Kale Red mustard Total Phenolics content and DPPH assay of vegetable crops in plastic film house at Saemangeum reclaimed land. C The Korean Society of Soil Science and Fertilizer. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non- Commercial License (http://creativecommons.org/licenses/by-nc/4.) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Yield and Antioxidant Activity of Vegetable Under Salt Affected Greenhouse Soil in Saemangeum Reclaimed Land 483 Introduction 새만금간척지는세계최장의방조제를보유하고있으며그길이가 33 km에달한다. 전체면적은 282.9 km 2 로식량생산기지조성을위해 1991년에공사를시작하여 26년에방조제공사가완료되어현재내부공사가진행중에있다 (Shin, 211). 특히새만금간척지는사양질토양으로서투수성이양호하여밭으로이용하기유리한조건을지니고있으며첨단수출원예단지조성등으로미래형선진농업단지로개발하기위한계획이수립되어있다. 세계적으로간척사업은국토가좁은한국, 네달란드, 일본, 영국, 독일등의국가에서국토면적을확대하기위하여수행되었으나국토면적이넓은중국에서도간척사업을진행하기도한다 (Lee et al., 26). 우라나라는주로서남해안일대에주곡인쌀을생산할목적으로조성되었다. 그러나 2년대산업화가진전되면서쌀수요가줄어들고식량수급의불균형이심화되면서토지이용형태의변화가요구되고있다. 따라서토지이용의다변화가요구되고있는상황으로간척지에서벼이외에밭작물재배와더불어소득작물재배로전환될수있는토양관리기술이필요하고간척지적응성이높은소득작물을선발하여간척지의농업적활용도를높여야한다. 서남해안에분포하는대부분의간척지는높은염류농도와낮은토양유기물함량으로대부분논으로활용되고있다. 그러나제염기술과염해경감을위한작물재배기술을적용하면밭작물을충분히재배할수있는잠재력을지니고있다. 현재과거간척지였던전북김제시광활면에서재배되는벼후작겨울하우스감자재배는빠른출하시기로가격경쟁력을확보하고있으며국내감자생산량의많은부분을차지하고있다. 또한간척지에서재배된작물은바닷물로부터유래한미네랄성분이풍부하고척박한환경에서자라기때문에특수기능성물질이일반농경지재배작물보다많을것으로예상되어기능성강화에중점을둘경우충분히경쟁력을확보할수있을것으로예상된다. 국내쌀수입개방과소비감소로간척지에서수도작이외에고소득작물을생산하기위한종합적인연구를수행하여간척지의농지범용화에대비하고있다 (RRI, 26). 기존간척지에대한연구는간척지토양이화학성변화연구의기초조사연구 (Lee et al., 216) 와토양개량을위한제염기술연구 (Ryu et al., 21), 녹비작물재배에의한토양개량효과 (Kang et al., 214), 염에의한작물의생육반응 (Son et al., 29; Yeo et al., 21) 등에대한연구를수행하였다. 간척지에대한연구는주로벼에대한연구가대부분이며밭작물에대한연구는토양의재염화와배수문제로생육이불량하여연구가많이이루어지지않고있다. 특히외부강우가차단된비닐하우스를이용한작물재배에대한연구는재염화의위험성으로토경재배가거의이루어지지않고있는실정이다. 또한간척지는지반이연약하여중량온실을설치할경우기반작업에시설비가많이소요되는등경제적인측면에서도불리한여건을지니고있다. 따라서본연구는새만금간척지에서무게가가벼운비닐하우스를이용하여적절한물관리를통한재염화억제와토양관리로몇가지채소작물을재배하고작물별생육반응, 항산화활성및토양이화학성변화에대한연구결과를소개하고자한다. Materials and Methods 시험포장조성및토양특성본시험은전북부안군계화면에위치한국립식량과학원새만금간척지시험포장에서수행하였다 (Fig. 1). 시험포장이위치한곳은하해혼성충적토를모재로하는문포통이었으며미사의함량이높은미사질양토로투수성이양호한토양이었다. 재배전시험포장의표토 (-2 cm) 에대한토양의화학적특성결과는 Table 1과같다. 토양의전기전도도 (Electrical Conductivity, EC) 는 2.2 ds m -1 였으며토양유기물함량은 4.2 g kg -1 이하로매우낮았으며나트륨함량이높은전형적인간척지토양이었다.
484 Korean Journal of Soil Science and Fertilizer Vol. 51, No. 4, 218 Fig. 1. Experimental site located in Saemangeum reclaimed land at west coast. Table 1. Soil properties of this experimental field before crop cultivation. ph EC SOM T-N Avail. P 2 O 5 Exch. cations (cmol c kg -1 ) Clay content Soil texture 1:5 ds m -1 g kg -1 g kg -1 mg kg -1 K Ca Mg Na % 6.6 2.2 4.4.39 143 1.93 1.5 2.7 5.4 3.2 Sandy Loam 작물재배및관수처리시험작물은 2 m 2 면적의단동형비닐하우스 3동을이용하여작물별로 3반복난괴법으로배치하여재배하였다. 재배작물은비닐하우스에서주로재배되는적근대 (Beta vulgaris L.), 케일 (Brassica oleracea ver. acephala), 적겨자 (Brassica juncea L.) 및엔다이브 (Cichorium endivia L.) 4개의엽채류를육묘이식재배하였다. 이랑폭은 12 cm로하였으며 4월하순이식하여 7월중하순에작물별로수확적기에수확하였다. 작물재배전염해경감을위해담수제염후점적공의간격이 1 cm인점적테이프를이용하여작물이식직후점적관수하였다. 점적관수량은하루단위면적기준 6. mm 수준으로 1일 1회관수처리로근권의염을제거하여염해를최소화하였다. 작물별비료살포및병해충관리등기타재배관리는농촌진흥청주요원예작물재배력 (RDA, 27) 에준하여수행하였다. 항산화활성측정항산화활성분석을위해환류냉각법을이용하여동결건조분말 1 g에 8% ethanol 1 ml를가한후 3시간동안추출한다음 Whatman No. 2 여과지에감압여과하였다. 남은잔사에추출용매를다시가하여얻은여과액을모두합하여감압농축한후동결건조하여분말형태로이용하였다. 총페놀함량측정은 Folin- Ciocalteau의방법 (Richard-Forget et al., 1992) 을기준으로 96-well plate에맞도록변형하여측정하였다. 추출물 25 µl에 Folin-Ciocalteu s regent 5 µl를첨가한후 5분간반응시킨다음 7.5% sodium carbonate 5 µl를첨가하여 3 C에서 9분간다시반응시킨후이반응액을 spectrophotometer (Varian Cary, UV-Vis spectrophotometer) 를이
Yield and Antioxidant Activity of Vegetable Under Salt Affected Greenhouse Soil in Saemangeum Reclaimed Land 485 용하여 725 nm에서흡광도를측정하였다. 검량선은표준물질 tannic acid (Sigma Chemical Co. Germany) 를이용하여작성하였다. DPPH free radical scavening activity 항산화활성측정은 Blois의방법 (Blois, 1958) 을변형하여측정하였다. 각식물체추출물 2 µl에.2 mm DPPH 용액 18 µl를첨가하여암소에서 3분간반응시킨후 Spectrometer 로 517 nm에서흡광도를측정하였으며대조구로 ascorbic acid (Sigma Chemical Co. Germany) 를이용하였다. 토양및식물체분석시험전후에채취한토양은풍건후분석용시료로이용하여농촌진흥청토양및식물체분석법 (RDA, 2) 에준하여분석하였다. ph와 EC 측정은시료와증류수비율을 1:5로하여 3분간진탕한후 ph meter (ORION, US/52A) 및 EC meter (OIRON, US/16) 를이용해초자전극및전기전도도법으로측정하였고, 토양총탄소측정은건식연소법 (dry combustion) 으로 8-1, C에서토양중탄소를연소시켜발생하는이산화탄소를 CN automatic analyzer (Elementar Analysen Systeme, US/Vario Max CNS) 를이용하여분석하였다. 유효인산은 Lancaster 법으로 spectrophotometer (Biochrom, Libra S8) 를이용해 72 nm에서비색측정하였다. 치환성양이온은 1N-NH 4 OAc (ph 7.) 로추출한후추출한액을 ICP-OES (Varian, Vista MPX-ICP) 를사용하여정량분석하였다. 식물체분석은각작물별수확기에채취한식물체시료와비간척지대비성분분석을위해시중에서구입한시료를 7 C 항온건조기에서 72시간동안건조후 4 mesh 크기로분쇄후습식분해 (H 2 O 2 -H 2 SO 4 ) 하였다. 분해후분해액을여지에여과후여과액을이용하여 K, Ca, Mg 및 Na을정량하였다. 작물별생육및수량조사는농촌진흥청농업과학기술연구조사기준에준하여조사하였다 (RDA, 212). 토양염농도에따른수량반응토양염농도에따른작물별생육반응을알아보기위해작물별생육정도를육안으로등급으로나눠구분하고수확시기에작물별로 1주씩수확하여생체중을측정하고동일지점에서토양시료를채취하여토양전기전도도를측정하였다. 토양염농도와작물별생육의상관관계는 SigmaPlot 1. (Antro, SPSS UK, Ltd) 프로그램을이용하여토양염농도에따른수량반응곡선을이용하여구하였다. Results and Discussion 연차간토양이화학성변화새만금간척지비닐하우스에서 3년간작물을재배하는동안토양의화학성은 Table 2와같다. 토양 EC는재배 1년차시험전토양은 2.2 ds m -1 였으나 3년차에 23.5 ds m -1 까지급격히증가하였다. 이는비닐하우스내부는외부강우가차단된상태로자연적인제염이이루어지지않았으며재염화현상에의해염류의상승과연차가지속적인비료살포로근권의염류가증가하였기때문인것으로보인다. 또한양이온중나트륨의함량이급격하게증가하였는데이는바닷물의영향으로나트륨함량이높은간척지의토양과지하수로부터재염화에의해염류가지속적으로상승하여나타난현상으로판단된다. Kang et al. (213) 은국내시설재배지 2,651지점의토양염농도를분석한결과 2년도에는 2.8 ds m -1 에서 28년도에는 3.7 ds m -1 증가하였다고하였는데이는새만금간척지와비교하였을경우상대적으로낮은수치이다. 또한 Jang et al. (217) 이화옹간척지노지에서사료작물을 3년간재배한결과재배 1년차에는 21.4 ds m -1 였으나재배 3년차에는 16.3 ds m -1 로다소감소하는것으로나타났다. 따라서새만금간척지비닐하우스토양의재염화현상은작물재배의위험요인으로작용하므로간척지에서비닐하우스를이용하여작물을재배할경우재염화억제를위한적절한물관리가반드시수행되어야염해에의한수량감소를최소화할수있을것이다.
486 Korean Journal of Soil Science and Fertilizer Vol. 51, No. 4, 218 Table 2. Change in chemical properties of plastic film house soil during experimental period at the Saemangeum reclaimed land. Year ph EC O.M Avail. P 2 O 5 Exch. cations (cmol c kg -1 ) (1:5) (ds m -1 ) (g kg -1 ) (mg kg -1 ) K Ca Mg Na 213 6.6 2.2 4.2 143.93 1.5 2.7 5.4 214 6.4 6.4 6. 64 2.66 5.3 5.7 7.8 215 7.9 23.5 6.2 599 1.91 6.2 6.9 13.8 Fig. 2. Growth of vegetable crops in plastic film house at the Saemangeum reclaimed land (A, swiss chard; B, endive; C, kale; D, red mustard). 작물수량및염농도에따른수랑반응새만금간척지 213년부터 215년까지 3년간비닐하우스에서재배한채소작물별생육및수량은 Table 3과같다. 적근대, 엔다이브, 케일및적겨자의생체수량은각각 1,795, 2,675, 1,819, 및 2,56 kg 1a -1 이었다. Lee (23) 등은간척지에서채소작물을재배하고토양염농도수준에따른작물별생육반응을분석한결과생육이저해되기시작하는염농도는작물별로 1. 에서 6. ds m -1 까지다양하였으며작물별로내염성의차이가큰것으로보고하였다. 토양염농도에따른작물별수량과의상관관계를알아본결과는 Fig. 3 과같다. 토양염농도와작물별생체중과의결정계수 (R 2 ) 는.71-.77로뚜렷한부의상관을보였으나적겨자의경우결정계수 (R 2 ) 가.25로비교적낮게나타났다. 이는적겨자가상대적으로염해에둔감하게반응하는것으로다른작물에비해내염성이큰것으로판단된다. 따라서새만금간척지의투수성이양호한사질토양의특성상근권부위의염이비교적쉽게제거되므로내염성이높은작물을선발하고적절한물관리가이루어질경우어느정도작물재배가가능할것으로보인다. 그러나부분적으로관수가적절히이루어지지않은곳은염해피해로생육이매우저조하였다. 그러므로간척지비닐하우스에서작물을재배하기위해서는반드시토양제염을위한정밀한물관리기술이요구되며이에대한추가적인연구가진행되어야할것이다. Table 3. Yield and growth of vegetable crops in plastic film house at the Saemangeum reclaimed land. No. of leaves (ea plant -1 ) Leaf length (cm) Leaf width (cm) Fresh weight (kg 1a -1 ) Swiss chard 28 18.2 9.1 1,795 Endive 19 13.5 6.2 2,675 Kale 21 17.1 11.6 1,819 Red mustard 2 21. 11.8 2,56
Yield and Antioxidant Activity of Vegetable Under Salt Affected Greenhouse Soil in Saemangeum Reclaimed Land 487 3 Swiss chard 35 Endive 25 3 Fresh wt. (g plant -1 ) 2 15 1 Y = - 1.6x+23. (R 2 =.75, P=.52) Fresh wt. (g plant -1 ) 25 2 15 1 Y = - 14.8x+296.4 (R 2 =.769, P=.31) 5 5 2 4 6 8 1 12 14 16 18 Surface soil EC w (ds m -1 ) 2 4 6 8 1 12 14 16 18 Surface soil EC w (ds m -1 ) 35 Kale 35 Red mustard Fresh wt. (g plant -1 ) 3 25 2 15 1 Y = - 8.8x+239.8 (R 2 =.71, P=.41) Fresh wt. (g plant -1 ) 3 25 2 15 1 Y = - 3.7x+162. (R 2 =.25, P=.1661) 5 5 2 4 6 8 1 12 14 16 18 Surface soil EC w (ds m -1 ) 2 4 6 8 1 12 14 16 18 EC w (ds m -1 ) Fig. 3. Relation between soil salinity and fresh weight of vegetable crops in plastic film house at the Saemangeum reclaimed land. 식물체무기성분함량및 K/Na ratio 간척지비닐하우스에서채소작물을재배한후작물별무기성분함량특성과일반적으로알려진내염성지표계수인 K/Na ratio를비교한결과는 Table 4와같다. 내염성이높은작물일수록 K + 이온의배출을억제하고 Na + 의축적을방해하여높은 K/Na ratio 값을유지하는것으로알려져있다 (Shabala et al., 28). 본실험결과적겨자에서 Na + 의함량이가장낮게나타나다른작물에비해 Na + 의축적을억제하는능력이큰것으로보이며 K/Na ratio 값또한 3.33으로그값이유의적으로높게 4가지시험작물중에서내염성이가장높은것으로판단된다. Table 4. Inorganic content and K/Na ratio of vegetable crops in plastic film house at the Saemangeum reclaimed tidal land. Ca K Mg Na K/Na g kg -1 dry wt ratio Swiss chard 6.85d 73.1a 1.28a 52.9a 1.45b Endive 8.73c 47.6b 4.64c 3.11b 1.76b Kale 19.5a 34.49c 6.15b 32.53b 1.23b Red mustard 14.89b 54.5b 5.19c 18.19c 3.33a In the same column, significant differences according to Tukey s HSD at P.5 levels are indicated by different letters after one way ANOVA.
488 Korean Journal of Soil Science and Fertilizer Vol. 51, No. 4, 218 작물별항산화활성간척지비닐하우스에서채소작물을재배시작물별항산화활성은 Fig. 4과같다. 작물별총페놀함량은적겨자 > 케일 > 엔다이브 > 적근대순으로적겨자에서 7.5 µg mg -1 로가장높은함량을나타내었다. 일반적으로페놀성화합물의 Hydroxyl group (-OH) 은불안정한전자를물로환원하여항산화, 항노화등과같은다양한생리활성을나타내는데이러한항산화활성이높은작물은염스트레스에상대적으로적응력이우수한것으로알려져있다 (Fridovich, 1978; Baier and Dietz, 1998; Kim et al., 214). Mittal et al. (212) 의연구결과에의하면적겨자는염으로부터산화스트레스를줄이는항산화효소시스템을활용하여항산화효소의활성이높다고하였는데본시험결과다른시험작물에비해적겨자의항산화활성이상대적으로높은것으로나타났다. 작물별 DPPH 소거활성또한적겨자가가장높게나타났으며총페놀함량과유사한경향을보였다. Choi et al. (215) 은간척지에서재배한감자의경우일반농경지에서재배한감자보다항산화활성이증진된결과를보였는데이는염스트레스에대한작물의생존전략으로판단된다고하였다. 본시험에서는일반농경지와비교한자료는제시하지못하였지만유사한경향을보일것으로예상되며향후다양한작물을대상으로면밀한연구가추가적으로수행되어야할것으로생각된다. 1 8 DPPH radical scavenging activity(%) 9 8 7 6 5 4 Swiss chard Endive Kale Red mustard Total phenolics content as tannic acid equiv. (µg/mg) 6 4 2 Swiss chard Endive Kale Red mustard Fig. 4. Total phenolics content and DPPH assay of vegetable crops in plastic film house at the Saemangeum reclaimed land. Conclusions 새만금간척지비닐하우스를이용한소득작물재배가능성검토를위해 4가지채소작물을점적관수를통한정밀물관리기술을적용하여 3년간재배하고작물별수량과항산화활성을검정하였다. 시험기간중연차간시험전토양의염농도는지속적으로상승하여 1년차 4.2에서시험 3년차에는 23.5 ds m -1 까지상승하여간척지비닐하우스토양을이용하여작물을재배할경우재염화에의한염해방지를위한정밀한물관리기술이필요할것으로보인다. 또한작물별수량성은물관리가잘이루어진시험구의경우정상적으로생육하였으나부분적으로물관리가이루어지지않은곳은염피해로생육이매우저조한현상을보였다. 일반적으로내염성지표계수인 K/Na ratio 값은적겨자가다른작물에비해유의적으로높게나와시험작물중내염성이상대적으로가장높은것으로나타났으며항산화활성또한가장높게나타났다. 이는염스트레스에의한작물의생존반응으로보이며일반농경지와비교하여기능성강화에중점을두고안정적인수량확보를위해정밀물관리기술, 토양관리, 내염성작물선발등간척지에적합한재배기술개발에대한추가적인연구가필요할것으로생각된다.
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