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Home , Cardamine, Nasturtium (genus), Rorippa, Watercress

CROP REPORTS

are self-pollinated, and fruits, elon- gated capsules, are borne on pedicels, and seeds are produced plentifully (Bleasdale, 1964). Green is a diploid (2n = 32) and the brown watercress is an allotetraploid (2n = 64), whose other Crop parent may be sp. (Howard, 1976). A number of variet- ies of N. officinale have been distin- guished in the past including siifolium Reports (1831), microphyllum (1831), and var. parvifolium (1838). However, the two varieties, siifolium and parvifolium, appear to be merely different growth forms of N. officinale resulting from 1952), its large-scale cultivation did moist conditions and from dry condi- Watercress: A not start until 1750 in Germany, 1808 tions respectively (Howard and Lyon, Crop with in , and 1811 in France 1952). Though var. microphyllum re- (Manton, 1935). Two of wa- fers to the tetraploid species (Airy Shaw, Chemopreventive tercress, green watercress (N. officinale) 1947), it has been used in the past also and brown watercress (N. to refer to the small-leaved specimens Potential microphyllum), and a sterile hybrid (N. of N. officinale as well as to the triploid officinale x N. microphyllum) were in- (2n = 48) hybrid, N. officinale x N. troduced in about 1850 to New microphyllum. Usha R. Palaniswamy1 and Zealand from England and both spe- A number of commercial strains 2 cies were reported to be growing in were isolated and selections made for Richard J. McAvoy and North America (Michae- frost resistance, ability to maintain veg- lis, 1976). The Germans and French etative growth during summer time only cultivated green watercress while when watercress normally tends to ADDITIONAL INDEX WORDS. the English grew both green water- , and for resistance or tolerance officinale, nasturtium- cress and brown watercress on a large to turnip mosaic virus (Bleasdale, 1964; aquaticum, Phen(yl)ethyl scale during the 19th century. How- McHugh et al., 1987). However, there , Cruciferae ever, brown watercress soon was re- has been very little selective and sys- placed in commercial cultivation by tematic breeding and no standard com- Classification, origin, and green watercress because of ease of mercial cultivars seem to have been development propagation by seeds, and lower sus- developed. Many of the selections and ceptibility to the fungal crook root commercial strains appear to be un- Watercress [Nasturtium officinale disease caused by Spongospora named, and the only named strain (also known as Rorippa nasturtium- subterranea sp. nasturtii (Howard and recorded to be commercially cultivated aquaticum)] belongs to the family Lyon, 1952). Green watercress ap- is Sylvasprings, which was originally (Cruciferae). It is a native pears to be the only species currently developed in England. However, this of southeast Europe (Habegger et al., cultivated and consumed around the strain showed a lot of genetic diversity 1989), probably Germany (Humphrey, world. when grown in the and 1984) or England (Howard and Lyon, was further selected to obtain a ho- 1952). Watercress is a perennial her- Botanical description and mogenous crop stand in the commer- baceous reported widely in sev- cultivars cial watercress beds. eral parts of Europe, China, New Watercress is a perennial with Production, uses, and Zealand, and in North America, both a creeping habit that branches freely. as a wild growing species and a culti- Numerous exogenous adventitious composition vated crop. Although described as a roots are produced at the axils of the Watercress is a minor crop and medicinal plant since the first century under moist and humid grow- the actual area under cultivation is A.D. (Howard, 1976), and valued as a ing conditions. Leaves are glabrous, rather difficult to determine, because gift fit for royalty (Howard and Lyon dark green, pinnate, and form about it is mostly cultivated and marketed three to six pairs of well-separated locally. Annual consumption of water- The cost of publishing this paper was defrayed in part by payment of page charges. Under postal regulations, leaflets (Fig. 1). It under long cress is as low as 110 g (3.9 oz) per this paper therefore must be hereby marked advertise- day conditions and the is head in the United States (Humphrey, ment to indicate this fact. a short raceme with small white or 1984), and its cultivation and con- 1School of Allied Health/Asian American Studies In- yellow flowers that are about 5 to 7 sumption as a significant salad crop has stitute, U-2101, University of Connecticut, Storrs, CT-06269-2101; to whom reprint requests should be mm (0.20 to 0.28 inches) in diameter. declined overtime (Howard, 1976). addressed. The flowers have four green , In the United States, watercress is of 2Department of Plant Science, University of Connecti- four pale yellow or white , six considerable economic importance in cut, Storrs, CT 06269. stamens, and a solitary pistil. Flowers the state of Hawaii where watercress

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CropRpts 622 9/5/01, 11:59 AM component that imparts the character- istic biting and peppery-hot tastes of watercress (Freeman and Mossadeghi, 1972a). The and the corresponding isothiocyanate in wa- tercress are classic examples of chemi- cal defense (Feeny 1976, 1977). These compounds are deleterious to nonadapted herbivores (Blau et al., 1978) and reduce herbivore damage (Louda and Rodman, 1983) as well as damage by amphipods in water (Newman et al., 1990) during cultiva- tion. Interest in watercress as a salad for health promotion and disease prevention has been revived over the past decade because of the many studies that linked the intake of cruciferous to reduced risk of cancers (Cohen et al., 2000; Fig. 1. Watercress (Nasturtium officinale). Joshipura et al., 1999; Osborne, 1999). In particular, the are was produced on 14.2 ha (35 acres) of tionable and the flavor too strong. reported to be potent inhibitors of land in 1985, yielding 695 t (766 tons) More recently, with increasing carcinogenesis in several animal mod- with a total farm value of $1,212,000 interest in healthy diets, the nutri- els (Zhang and Talalay, 1994). Among (Hawaii Agricultural Reporting Ser- tional value of watercress has attracted the crucifer seeds studied, watercress is vice, 1985). the attention of a number of scientific the most abundant source of More recently, the total area un- investigators and the health-conscious gluconasturtin (gluconasturtiin) (the der watercress production increased public. Reportedly, watercress has high glucosinolate precursor that yields slightly from 204 ha (505 acres) in concentrations of a recently identified PEITC on hydrolysis), with 5.32 g of 1992, to 246 ha (608 acres) in 1997 chemopreventive of a number of to- gluconasturtin/100 g of defatted seeds (USDA, 1997). Currently it is grown bacco specific carcinogens-2- (53, 200 ppm) (Daxenbichler et al., in 122 ha (302 acres) in Florida, 48.6 phen(yl)ethyl isothiocyanate (PEITC) 1991). PEITC, inhibited cancers in ha (120 acres) in California and in [≈2 to 7 mg.g–1 (2,000 to 7,000 ppm) rats and mice that are caused by several 13.8 ha (34 acres) in Hawaii. Water- dry weight] (Palaniswamy, 1995b, tobacco specific carcinogens including cress is also grown on private farms in 1997). Watercress is also an excellent 4-(methylnitrosamino)-1-(3-pyridyl)- Connecticut, Massachusetts, Virginia source of the antioxidant α-tocopherol 1-butanone, N-nitrosomethyl and Maryland for which the exact areas [0.34 mg.g–1 (340 ppm) fresh weight] benzylamine, benzo(a)pyrene, and N- under production are withheld to avoid (Hadas et al., 1994), and other vita- nitrosobenzylmethyl amine (Siglin et disclosing confidential data. mins and minerals (Table 1) (USDA, al., 1995; Stoner et al., 1991, 1994; Watercress has been used as both 1984). Wattenberg, 1992). PEITC acts as food and medicine since the first cen- Watercress possesses glucosin- both a blocking agent and an inhibitor tury AD. As a medicinal plant, water- olates and myrosinase, which are char- of tumor initiation via inhibition of cress traditionally has been considered acteristic to all crucifers (Kjaer, 1976). enzymes and by in- a diuretic, expectorant, purgative, Glucosinolate is found in various con- duction of phase II enzymes such as stimulant, stomachic, and tonic. It also centrations throughout the various glutathione S-transferases (Meyer et has been used as a remedy against plant tissues. But the myrosinase en- al., 1995). anemia, eczema, kidney and liver dis- zyme is stored exclusively in special Steam distilled extracts of water- orders, tuberculosis, boils, warts, and cells that are dispersed throughout the cress containing 3-phenylpropionitrile tumors. The 16th century herbalist plant. Upon tissue damage, the and 3-phenylpropionic acid were re- Gerarde described watercress soup as a glucosinolate is hydrolyzed by the ported to exhibit auxin-like activity good blood cleanser, and good against myrosinase enzyme to yield and stimulate the elongation of wheat scurvy (Humphrey, 1984). Leaf ex- isothiocyanates and nitriles (Larsen, (Triticum aestivum) coleoptiles and tracts have been used to treat wounds, 1981; Van Etten and Tookey, 1979). ( sativum) hy- freckles, and external and internal ul- The relative proportion of these two pocotyl sections (Wheeler, 1980). cers. Tender shoots and leaves are used compounds depends on the condition Culture and management fresh or cooked alone or in mixtures of during hydrolysis. In watercress salad and as a garnish. Though most PEITC, and 3-phenylpropionitrile are Watercress can be propagated ei- find the biting peppery taste of water- the predominant hydrolytic products ther from seed or by vegetative means cress leaves rather appealing and its (MacLeod and Islam, 1975; Spence using shoot tip cuttings that root very flavor appetizing, some people may and Tucknott, 1983). easily. Until 1955 most watercress was find the pungency somewhat objec- PEITC is the predominant flavor propagated vegetatively, but this prac-

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tice was abandoned to eliminate the soil bottoms and moving water. Wa- Under controlled environmental spread of turnip mosaic virus tercress beds are covered with freely production with a short photoperiod (Tomlinson, 1974). Studies show that flowing spring water and the get (8 h), supplemental lighting during micropropagation and tissue culture most of the nitrogen (N) and other the week before produced plants with techniques also can be used, and that nutrients from the water. Plas- PEITC concentrations as high as plants these methods need to be optimized tic covers protect these commercial exposed to longer photoperiod (12 h) before use in commercial cultivation beds during winter months to ensure under similar temperatures (Gilby and Wainwright 1989; Wain- production of watercress year-round (Palaniswamy et al., 1995a, 1995b, wright and Marsh, 1986). for supply in local markets. The 1996, 1997). When growing water- Currently, although tissue-cul- waterbeds should be constructed so cress in open fields, harvesting plants tured propagules are used for propaga- that surface water or flooded water after 1 week of bright sunlight may tion in a few private farms in the United cannot run through it, because it may yield more flavorful and healthier pro- States, seed propagation is still a pre- damage the bed and the plants. Pro- duce than if harvested after a period of ferred method in commercial cultiva- viding an adequate and good-quality cloudy days. tion. Seeds germinate easily, and as- water supply is essential for successful sure the grower of healthy, virus-free commercial production. Beds of wa- Diseases, pests, and plants in the waterbeds. The color of tercress can be maintained for about management practices watercress seeds can vary from pale 10 years without resowing or replant- Diseases noted in watercress in- yellow when freshly harvested to the ing, and require about 1 month to clude crook root disease, which is a dark brown of old seeds. Storage at 20 reach a harvestable stage after a previ- serious problem for watercress grow- ºC (68 ºF) and high relative humidity ous harvest. Typically a number of ers particularly during the colder caused the seeds to darken during stor- beds are maintained by growers to months of the year (October to May). age and reduced the dormancy provide a continuous supply to local The plasmodial fungus (Spongospora (Biddington et al., 1983). Dark-col- markets. subterranean sp. nasturtii) that causes ored fresh seeds and pale- colored old The foundation of outdoor wa- crook root disease also transmits the seeds (≈2 years old) showed greater tercress beds may be clay, gravel or agents of watercress chlorotic leaf spot, germination compared to pale-colored crushed stone to provide a firm an- and the yellow spot virus (Tomlinson fresh seeds and dark-colored old seeds. chorage to the roots, and also to allow and Hunt, 1987, Walsh et al., 1989). Seed germination is best at 10 to 15 people working in the field to move Maintaining a zinc level of 1.0 mg.L–1 ºC (50 to 59 ºF) and in the absence of about while planting, weeding and controlled the crook root, the chlo- light. Since dormancy of fresh seeds harvesting (Shear, 1959). The sides of rotic leaf spot, and the yellow spot has been often reported, storage of the beds are normally constructed of virus (Tomlinson, 1960, 1988). fresh seeds at high temperature [40 ºC earth, parted by wood or concrete, Leaf spot (Cercospora sp.) that is (104 ºF)] for 3 d before sowing can be ensuring uniform flow of water across common during warm and humid sea- adopted to increase germination rate the bed. The floor of the waterbeds sons can be controlled by spray of tri- (Biddington and Ling, 1983). Trans- should be of 5 to 10 cm (2 to 4 inches) planting healthy seedlings to the wa- of muck. Table 1. Nutritional composition of 100 tercress beds is preferred to direct sow- Watercress fertilized with fertil- g (3.53 oz) of edible potion of fresh z ing in order to ensure an optimal stand izer containing a higher proportion of watercress. and to avoid thinning or filling large sulfur (S) is reported to yield a more areas at a later stage. flavorful crop. Hydroponic cultivation Nutrient Value Watercress conventionally can be gives the grower a chance to obtain Water (g) 95.1 grown in running water (Ryder, 1979), and maintain the necessary nutrient Energy (calories) 11, 000 in pots [7 to 8 cm (2.8 to 3.1 inches) levels in the growing medium more (g) 2.3 in diameter] with soil medium com- precisely to increase yield and flavor. (g) 0.1 posed of a mixture of poorly decom- In , growing watercress (g) 1.29 posed peat and intensely decomposed with a higher ratio of S to N can Fiber (g) 0.7 peat (Habegger et al., 1989), or in produce leaves of higher concentra- Ca (mg) 120 hydroponics with standard Hoagland tions of PEITC and hence a more P (mg) 60 nutrient solution or nutrient solutions flavorful product. When grown in Magnesium (mg) 21 containing the required minerals (Free- closed hydroponic systems containing Potassium (mg) 330 . –1 man and Mossadeghi, 1972a, 1972b; [in mg L (ppm)] 200 N and 64, 128 Sodium (mg) 41 Palaniswamy et al., 1995a, 1995b). or 192 S, to yield N to S ratios of Ascorbic acid (mg) 43 Watercress is reported as a cool-season 1:0.32, 1:0.64, or 1:0.96, leaves of Thiamin (mg) 0.09 crop growing well at temperatures of watercress plants grown with the 1:0.64 (mg) 0.12 15 to 25 °C (59 to 77 °F) but poorly N to S ratio produced 84% (dry weight Niacin (mg) 0.20 at higher temperatures (McHugh et basis) more PEITC than those grown Pantothenic acid (mg) 0.31 al., 1987; Shear, 1949, 1959); how- with the 1:0.32 N to S ratio, while B6 (mg) 0.13 ever, it can be grown successfully up to plants grown with the 1:0.96 N to S (International Units) 4,700 temperatures as high as 28 °C (82.4 ratio produced 61% more PEITC than ° zSource USDA, 1984. F) (Palaniswamy, 1998). those grown with the 1:0.32 N to S y1.0 g = 1000 mg = 0.035 oz; 1000 calories = 4.19 kJ; Generally watercress plants are ratio (Palaniswamy et al., 1995a, 1 International Unit = 0.6 µg of β-carotene or 1.2 µg grown in water tanks or beds having 1995b). of other provitamin A .

624 ● October –December 2001 11(4)

CropRpts 624 9/5/01, 11:59 AM basic copper sulfate (McHugh et al., salad crop and hence should be shipped Cohen J.H., A.R. Kristal, and J.L. Stanford. 1987). While cultivating in waterbeds, and marketed immediately after har- 2000. Fruit and vegetable intakes and pros- algae can be controlled by 2 to 10 vest. The leaves are bunched and pre- tate cancer risk. J. Natl. Cancer Inst. 92:61– mg.L–1 copper sulfate. Three species of cooled before packing in containers 68. duckweed (Lemna trisulca, L. minor, that are lined with heavy parchment Crane, M., P. Delaney, S. Watson, P. Parker, and Spirodela polyrhiza), that are preva- paper and the layers of watercress are and C. Walker. 1995. The effect of lent in watercress beds can be con- separated by ice. The harvested tender Malathion 60 on Gammarus pulex (L.) trolled by spraying saturated copper leaves are normally bunched and sold below watercress beds. Environ. Toxicol. sulfate just after the watercress leaves to local consumers. Chem. 14:1181–1188. have been cut (Shear, 1959). For best quality maintenance wa- Daxenbichler, M.E., F.G. Spencer, D.G. (Plutella tercress should be kept at 0 ºC (32 ºF) Carlson, G.B. Rose, A.M. Brinker, and xylostella) is a major insect pest in and 95% relative humidity (RH) or R.G. Powell. 1991. Glucosinolate compo- watercress that can be controlled ef- above throughout storage and mar- sition of seeds from 297 species of wild fectively by installing an overhead sprin- keting. During transit watercress leaves plants. Phytochemistry 30:2623–2638. kler system to disrupt mating and egg may be protected from moisture loss, Feeny, P. 1976. Plant apparency [suscepti- laying processes of the adult moth, or temperature rise and accompanying bility to discovery by insects] and chemical by adopting biological control using deterioration by using crushed ice defense, Recent Adv. Phytochem. 10:1– the parasitic wasp (Cotesia plutella) within and around the shipping and 40. (McHugh et al., 1987). More recently, storage crates. During retailing and Feeny, P. 1977. Defensive ecology of the high levels of resistance of diamond- home storage, they need the protec- Cruciferae. Ann. Mo. Bot. Garden 64: back moth to Bacillus thuringiensis tion afforded by packaging in mois- 221–234. have been observed. Effective ways ture-retentive film and by refrigera- suggested to reduce the moth infesta- tion. Watercress bunched in polyeth- Freeman, G.G. and N. Mossadeghi. 1972a. tion include use of vacuum cleaner to ylene bags and at 0 ºC and 95% RH Studies on sulfate nutrition and flavor pro- suck the adults (Tanaka, 1992), and remained marketable for up to 4 weeks duction in watercress (Rorippa nasturtium- aquaticum (L) Hayek). J. Hort. Sci. the use of nematodes (Steinernema (Hruschka and Wang, 1979). 47:375–387. carpocapsae) (Baur et al., 1998) as useful components of integrated pest Freeman, G.G. and N. Mossadeghi.1972b. management programs. Literature cited The influence of sulfate nutrition on flavor The terrestrial arthropod pest Airy Shaw, H.K. 1947. The components of three cruciferous plants, (Gammarus pulex) also feeds on the of the wild tetraploid watercress. Kew Bul. (Raphanus sativus) cabbage (Bras- 1:38–46. sica oleracea capitata) and white watercress which can be controlled by (Sinapis alba). J. Sci. Food Agr. 23:387– using diethyl mercaptosuccinate Baur, M.E., H.K. Kaya, B.E. Tabashnik, 402. (Crane et al., 1995). Other minor and C.F. Chilcutt. 1998. Suppression of insect pests include the cyclamen mites diamondback moth (: Gilby A.C. and H. Wainwright. 1989. Use (Steneotarsonemus pallidus), cotton Plutellidae) with an entomopathogenic of tissue culture in improvement of water- aphids (Aphis gossypii), green peach nematode (Rhabditida: Steinernematidae) cress (Rorippa nasturtium-aquaticum L. Hayek). Acta Hort. 244:105–113. aphids (Myzuz persicae), and turnip and Bacillus thuringiensis Berliner. J. Econ. aphids (Hyadaphis erysimi). Entomol. 91:1089–1095. Hadas, S.P., S. Meir, B. Akiri, and J. Kanner. Bible, B.B., H.Y. Ju, and C. Chong. 1980. 1994. Oxidative defense systems in leaves Harvest and postharvest Influence of cultivar, season, irrigation and of three edible herb species in relation to techniques date of planting on thiocyanate content in their senescence rates. J. Agr. Food Chem. 42:2376–2381. Harvestable watercress plants can cabbage. J. Amer. Soc. Hort. Sci. 105:88– be produced in about 35 d from sow- 91. Habegger, R., M. Kohl, and D. Fritz. ing during summer and about 50 d Biddington, N.L. and B. Ling. 1983. The 1989. A cultivation method for Nastur- during the cooler and darker months. germination of watercress (Rorippa nas- tium officinale (watercress) grown in green Normally the plants are harvested when turtium-aquaticum) seeds. I. The effects house. Acta Hort. 242:291–295. they reach a height of 17. 8 cm (7 of age, storage, temperature light and hor- Hawaii Agricultural Reporting Service. inches) and subsequent harvesting is mones on germination. J. Hort. Sci. 1985. Statistics of Hawaiian agriculture. done at 15-d intervals. 58:417–426. Hawaii Agr. Rpt. Serv., Honolulu. The concentrations of the flavor Biddington N.L., B. Ling, and R. Howard, H.W. and A.G. Lyon. 1952. component, 2-phen(yl)ethyl gluco- Dearman.1983. The germination of wa- Biological flora of the British Isles. Nastur- sinolate and PEITC in the young leaves, tercress (Rorippa nasturtium-aquaticum) tium officinale R.Br. (Rorippa nasturtium- is influenced by the stage of harvest as seeds. II. The relationship between seed aquaticum (L.) Hayek). J. Ecol. 40:228– also reported for other crucifers (Bible color and germination. J. Hort. Sci. 238. et al., 1980; Palaniswamy et al., 1995a, 58:427–433. Howard, H.W. 1976. Watercress Rorippa 1995b). The harvest stage for optimal Blau P.A., P. Feeny, L. Contardo, and D.S. nasturtium-aquaticum (Cruciferae) p. 62– flavor corresponds to the stage when Robson. 1978. Allyglucosinolate and her- 64. In: N.W. Simmonds (ed.). Evolution the plants have approximately 12 to 15 bivorous caterpillars: A contrast in toxicity of crop plants, Longman, London. internodes (about 3 to 4 weeks after and tolerance. Science 200:1296–1298. Hruschka, H.W. and C.Y.Wang. 1979. transplanting or 6 to 7 weeks after Bleasdale, J.K.A. 1964. The flowering and sowing). Storage and shelf life of packaged water- growth of watercress (Nasturtium officinale cress, parsley, and mint. Mkt. Res. Rpt. Watercress is a perishable leafy R. Br.). J. Hort. Sci. 39:277–283.

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USDA Sci. Educ. Administration. Wash., Palaniswamy, U., R.J. McAvoy, B. Bible, control in a watercress greenhouse, p. 165– D.C. S. Singha, and D.W. Hill. 1995a. Effect of 173. In: N.S Talekar (ed.). Diamondback different nitrogen-sulfur ratios on moth and other crucifer pests. Proceedings Humphrey, E. 1984. A vegetable with phenethyl isothiocyanate (PEITC) levels of the 2nd Intl. Wkshp., 10–14 Dec. 1990, potential. Nutr. Food Sci. 87:20–21. in watercress. HortScience 30:789. Tainan, Taiwan. Asian Veg.Res. Dev. Ctr. Publ. 92-368, Taipei, Taiwan. Joshipura K.J., A. Ascherio, J.E. Manson, Palaniswamy, U., R.J. McAvoy, B. Bible, M.J. Stampfer, E.B. Rimm, J.E. Speizer, S. Singha, and D.W. Hill. 1995b. Phenethyl Tomlinson, J. A. 1960. Crook root disease C.H. Hennekens, D. Spiegelman, and W.C. isothiocyanate concentration in watercress of watercress. A review of research. Natl. Willett. 1999. Fruit and vegetable intake in (Nasturtium officinale R.Br.) is altered by Agr. Advisory Serv. Quart. Rev. 49, Wash., relation to risk of ischemic stroke. J. Amer. the nitrogen to sulfur ratio in hydroponic D.C. Medical Assn. 282:1233–1239. solution, p. 280–283. In: D.L. Gustine and H.E. Flores (eds.). Tomlinson, J. A. 1974. Research on water- Kjaer, A. 1976. in the cress disease, p. 33–37. In: Symposium on Cruciferae, p. 207–219. In: J.G. Vaughan, and health. Amer. Soc. Plant Physiol., Rockville, Md. research on the watercress crop, University A.J. MacLeod, and B.M.G. Jones (eds.). of Bath, U.K. The biology and chemistry of the Palaniswamy, U., R.J McAvoy, and B. Cruciferae. Academic Press, New York. Bible. 1996. The effect of light intensity Tomlinson, J. A. 1988. Chemical control prior to harvest, on Phenethyl of Spongospora and Olpidium in hydro- Larsen, P.O. 1981. Glucosinolates, p. 501– ponic systems and soil, p. 293–303. In: J.I. 523. In: P.K. Stumpf and E.E. Conn (eds.). Isothiocyanate (PEITC) levels in water- cress (Nasturtium officinale R.Br.), de- Cooper and M.J.C. 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