塚越 覚

Suitability of Japanese radish (Raphanus sativus L. Daikon Group) cultivars for "Yakuzen" dishes was evaluatedbased on sensory tests and amounts of functional ingredients related to taste and functionality. In addition to F1cultivar, we examined the characteristics of 16 cultivars, which belonged to 11 local varietal groups, focusing onso-called local cultivars. As a result of preliminary evaluation by using a principal component analysis of the data,'Shinshu-ji-daikon' and 'Shogoin' was considered to contain higher amount of functional ingredients. Therefore,these two and general F1 cultivars were evaluated in detail. 'Shinshu-ji-daikon' showed higher contents of sucrose,GABA and total amino acids, and isothiocyanate than the other cultivars. Especially, GABA and isothiocyanatecontents of 'Shinshu-ji-daikon' were 5 and 4.5 times higher than those of F1 cultivar, respectively. 'Shogoin' alsocontained higher level of GABA and total amino acid contents than those of F1 cultivar. In conclusion, within therange of cultivars we used in this experiment, 'Shinshu-ji-daikon' was the most suitable material for "Yakuzen"dishes because it contained stronger taste and higher amount of functional ingredients.

The effects of simulated trampling on shoot morphology and ethylene production of a trampling-tolerant perennial forb asiatic plantain were investigated. Trampling increased the number of leaves or inflorescences per plant, the petiole diameter, and the leaf blade length to width ratio but decreased the leaf blade width to petiole diameter ratio and the inflorescence length. Ramets subjected to trampling produced more ethylene than did nontrampled ramets originating from the same root crown. Moreover, an ethylene releaser ethephon decreased the leaf blade width to petiole diameter ratio and increased the leaf blade length to width ratio, in a manner similar to the changes induced by trampling. These results suggested that trampling-induced ethylene might be closely related to some of the adaptive morphological changes in asiatic plantain in response to trampling.

Experiments were conducted in paddy fields at Shiga and Chiba Prefectures to study the effects of controlled-release coated urea (N-LP100) on soil microbial biomass and N uptake of rice plants by the N-15-tracer technique, during one cropping season. Three field fertilizer treatments (Zero N: 0 kgN ha(-1), N-15-LP100: 64 kg N ha(-1) and (NH4Cl)-N-15: 100 kg N ha(-1)) were set-up in the Shiga field experiment. After transplanting in the paddy fields at Shiga and Kashiwa (Chiba), a number of rice hills with standard growth were selected randomly and enclosed by polyacryl-plastic frames designated as microplots. N-15-LP100 (64 kg N ha(-1)) was applied in the Shiga and Kashiwa microplot experiments and the Shiga field experiment as deep-side placement (5 cm away from rice hill and 5 cm soil depth). Total N uptake of rice plants was analyzed in the course of plant growth. In addition, soils from the field fertilizer treatment plots and microplots (divided into 11 blocks) were taken and analyzed for microbial biomass N (B-N) and biomass N-15 (B-15N). The results indicated that; (1) Plant N uptake from basal-applied fertilizers at the end of the study in the Shiga field experiment was 71.9 and 26.0% for N-15-LP100 and (NH4Cl)-N-15, respectively. In the Kashiwa microplot experiment, plant N uptake from applied N-15-LP100 was 51.2% at 67 days after transplanting (DAT) (2) Throughout the cropping season, BN was the highest, intermediate and the lowest for (NH4Cl)-N-15, N-15-LP100 and Zero N field experimental plots in the Shiga experiment, respectively. (3) In the micro-plot experiments, BN and B-15N were generally higher in the soil block with deep-side application of N-15-LP100 compared with the other soil blocks. The deep-side placement of N-15-LP100 ensured a high efficiency of utilization of its N by rice plants. The method of N-15-LP100-placement also affected the spatial heterogeneity of microbial biomass N in the microplots.

Effect of spraying electrolyzed acid water and alkaline water obtained by electrolysis of KCl solution on the incidence of powdery mildew (Sphaerotheca macularis) is investigated in strawberry (Fragaria x ananassa Duch. cv. Nyoho) grown in hydroponics. Free effective chlorine concentration of the acid water at 0.5m from spraying nozzle ranged between 5.7 and 15.6 mg/l. pH and oxidation-reduction potential of the acid water ranged from 2.2 to 2.3 and from I 100 to 1140 mV, and those of the alkaline water ranged from 12.3 to 12.6 and from 30 to 280 mV, respectively. The treatment plots were 1. No spraying (NSp), 2. Acid water spraying (Ac), 3. Alkaline water spraying 30 minutes after acid water spraying (Ac+Al), and 4. Agricultural chemicals spraying (Chem). Those electrolyzed waters were sprayed onto the leaves and petioles once every week, and chemicals were sprayed once every two or three weeks. The occurrence of powdery mildew on the petioles was observed on January 5 in NSp, and on January 12 in Chem. The number of diseased petioles increased in NSp as the experimental period proceeded, but decreased in Chem and no diseased petiole was observed on February 16. In Ac or Ac+Al plot, the numbers of diseased petioles were lower than that in NSp or Chem plot. Very few disease symptoms were observed in Ac or Ac+Al. The results indicate that the acid water spraying and acid + alkaline water spraying can control the powdery mildew in strawberry and can reduce the use of chemical fungicide in protected cultivation.

NFT毛管水耕システムを用いたホウレンソウ(Spinacia oleracea L.品種'ジョーカー'および'オリオン')栽培において, 収穫前にNO_3-Nのみの補給停止(実験1 : 夏作), または全肥料成分の補給停止(実験2 : 秋作)が, 生育, 可食部の硝酸含量, 廃液の無機成分濃度に及ぼす影響を検討した.実験1 : 収穫6日前からのNO_3-Nの補給停止で, 可食部の硝酸含量は2, 199 ppm, 廃液のNO_3-N濃度は1.0 me・liter^<-1>と, 食品・廃液の許容基準を満たすことができた.NO_3-N以外の成分は初期濃度と同じか, それ以上に廃液中に残存した.実験2 : 2&acd;6日前からの追肥停止で, 廃液のNO_3-N濃度は0.7 me・liter^<-1>以下, 可食部の硝酸含量は2, 870 ppm以下となり, 食品・廃液の許容基準を満たすことができた.さらに, 他の主要無機成分についても, 残存濃度を低減できた.しかし, 6日前からの追肥停止では, 地上部生体重が低下した.以上より, 夏作で収穫予定日の6日前, 秋作では2&acd;4日前から, 肥料成分を含まない水を補給する方法が, 可食部の硝酸濃度の低いホウレンソウの生産と, 廃液中の主要無機成分含量の低減に有効と考えられた.

NFT毛管水耕システムを用いたホウレンソウ(Spinacia oleracea L.品種'ジョーカー'および'オリオン')栽培において, 収穫前にNO_3-Nのみの補給停止(実験1 : 夏作), または全肥料成分の補給停止(実験2 : 秋作)が, 生育, 可食部の硝酸含量, 廃液の無機成分濃度に及ぼす影響を検討した.実験1 : 収穫6日前からのNO_3-Nの補給停止で, 可食部の硝酸含量は2, 199 ppm, 廃液のNO_3-N濃度は1.0 me・liter^<-1>と, 食品・廃液の許容基準を満たすことができた.NO_3-N以外の成分は初期濃度と同じか, それ以上に廃液中に残存した.実験2 : 2&acd;6日前からの追肥停止で, 廃液のNO_3-N濃度は0.7 me・liter^<-1>以下, 可食部の硝酸含量は2, 870 ppm以下となり, 食品・廃液の許容基準を満たすことができた.さらに, 他の主要無機成分についても, 残存濃度を低減できた.しかし, 6日前からの追肥停止では, 地上部生体重が低下した.以上より, 夏作で収穫予定日の6日前, 秋作では2&acd;4日前から, 肥料成分を含まない水を補給する方法が, 可食部の硝酸濃度の低いホウレンソウの生産と, 廃液中の主要無機成分含量の低減に有効と考えられた.

ECメーターを用いた重炭酸濃度の測定法および原水の重炭酸濃度の調整法を検討した.試料100mlに0.01N硫酸を滴下していき,ECの変化を測定すると,傾きの異なる2本の直線が引ける.この交点に相当する酸の添加量に係数6.1を乗じることで,従来法と同精度で,重炭酸濃度を定量できた.さらに,原水中の重炭酸濃度を30〜50ppmに減少させうる酸を添加し,培養液を処方することで,培養液pHを適正に管理できると考えられた.

汁液分析による野菜苗の栄養診断法の確立のため,トマトセル成型苗を材料とし,汁液抽出時の適正な希釈倍率,抽出法の検討,施肥量と苗の生育,汁液中無機成分濃度との関係,試料の保存が汁液中無機成分濃度に及ぼす影響を調査した。各無機成分濃度の測定値およびそのばらつきを考慮し,試料と水の比率は1:19(gFW:ml)が適当であると判断した.一般に汁液中無機成分濃度は,施肥量を反映するが,生育抑制が起きるような,少肥あるいは多肥の場合には,必ずしも施肥量を反映するとは限らず,標準の植物に比べて,少肥で高い,あるいは多肥で低い値を示す可能性があることが明らかとなった.冷蔵条件下(5℃)において保存日数による無機成分濃度の変化が最も小さかったことより,試料の保存には,冷蔵が最適であると思われた.また,汁液分析に供試する植物試料は,採取後少なくとも3日以内に汁液の抽出,分析を行う必要があると考えられた.

ミニトマトおよびトマトセル成型苗を用い,灌液組成・濃度が汁液中無機成分濃度に及ぼす影響を調査し,栄養診断の基準値を検討した.ミニトマト,トマトにおいて,P, Kについては施用量と汁液中濃度に比較的明確な関連があったが,窒素については施用量が少くても,必ずしも汁液中窒素濃度に反映されないことが明らかとなった.しかしながら,Nが不足すると汁液中PO_4-P濃度の増加が認められた.従って,本実験の範囲では,汁液分析による栄養診断における汁液中無機成分濃度の基準値を以下のように考えた.窒素:PO_4-P濃度として500〜1000ppmであり,NO_3-Nより高いこと。リン:約150〜200ppm。カリウム:1100ppm前後。