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Sealy, R.L., E.L. McWilliams, J. Novak, F. Fong, and C.M. Kenerley. 1990. Vegetable amaranths: Cultivar selection for summer production in the south. p. 396-398. In: J. Janick and J.E. Simon (eds.), Advances in new crops. Timber Press, Portland, OR.

Vegetable Amaranths: Cultivar Selection for Summer Production in the South

Ramsey L. Sealy, E.L. McWilliams, J. Novak, F. Fong, and C.M. Kenerley


  1. INTRODUCTION
  2. EVALUATION STUDY
  3. CONCLUSIONS
  4. REFERENCES
  5. Table 1

INTRODUCTION

Amaranthus species are ancient cultivated crops that have long been neglected by western agriculturists and gardeners. The National Academy of Science lists amaranths (vegetable and grain) as one of 23 food plants that could be used to improve nutrition and the quality of life for people in developing countries (Marx 1977). The leaves of vegetable amaranths are high in protein (17.4-38.3% of dry matter); the protein is 5% lysine and 4.4% sulfur-containing amino acids, both limiting in many vegetables and cereal grains (Lloyd 1986, Makus and Davis 1984, Teutonico and Knorr 1985). In addition, leaves of amaranths are nutritionally significant sources of carbohydrates, several vitamins and minerals, and dietary fiber (Betschart et al. 1981, Mathai 1978, National Research Council 1975, Okuno and Sakaguchi 1981, Teutonico and Knorr 1985, Tucker 1986). Organoleptic judging panels have judged vegetable amaranths to be very acceptable (Abbott and Campbell 1982).

Amaranths are easy to grow and reasonable yields can be produced even in poor soils (Afolabi et al. 1981, Dean 1986, Uzo and Okorie 1983). Amaranths have few insect pest problems (Afolabi et al. 1981, Dean 1986), but damping-off of seedlings by species of Pythium is a problem that plagues producers and breeders (National Research Council 1984).

Leaves of vegetable amaranths are nutritionally significant sources of betacarotene (National Research Council 1975). There have been concerns about the presence of oxalates in vegetable amaranths which can bind calcium and so lower ionic calcium concentrations in the blood, leading to hypocalcemia. Oxalates can comprise 0.2-11.4% of the dry matter in vegetable amaranths (Teutonico and Knorr 1985), but levels of oxalates are significantly reduced by steaming or boiling leaves for ten minutes, which does not significantly reduce nutrient levels (Stafford et al. 1976).

The objectives of our investigation were to identify vegetable amaranth cultivars which possess: high productivity in the summer in the deep South, high levels of resistance to Pythium damping-off, high levels of betacarotene, low levels of oxalates, and acceptable taste characteristics.

EVALUATION STUDY

Five vegetable amaranth cultivars were evaluated:

Cultivar Species Source
'Ibondwe' A. dubius West Africa
'Quilete' A. hybridus Mexico
'Red' A. tricolor China
'Tampala A. tricolor USA
'Vleta A. hybridus Greece
Plants were grown in irrigated single-row raised beds. After two weeks, plants were thinned to 13 to 15 cm apart and mulched with a mixture of sawdust and manure. Five weeks after sowing, the plants were harvested, beginning at the lowest leaf. The design of the experiment was a randomized complete block with six plants per cultivar and three replications.

Resistance to Pythium damping-off was evaluated with a strain of P. myriotylum isolated from a diseased amaranth seedling and maintained on a modified form of Mitchell's CPV agar (Mitchell 1975). Oospores were produced on oatmeal agar while incubating for at least one week at 23-26deg.C in the dark- Free oospores were obtained by using a modification of the isolation of Ruben et al. (1980). A concentration of 1x107 oospores per liter which resulted in 50% mortality of the controls was used in the screening process. In a greenhouse study, 50 seedlings of each amaranth were challenged with 0.5 ml of the oospore suspension and dead seedlings determined after six days.

Betacarotene content was evaluated for spinach (Spinacia oleracea 'Bloomsdale Long Standing') and the amaranth cultivars based on the method of Jensen and Jensen (1971). Oxalate content was determined by a modification of the chromatographic method of Newton et al. (1986). A panel of 20 semi-trained taste judges evaluated vegetable amaranth cultivars, spinach, and mustard greens (Brassica juncea) which had been cooked in salted water for five minutes.

CONCLUSIONS

Results of all evaluations are summarized in Table 1. Two cultivars, `Vleta' and 'Ibondwe', produced exceptionally well in central Texas as a summer greens crop, but only 'Ibondwe' performed well in all the criteria. 'Vleta' was rated low by the taste panel due to bitterness. The oxalate content of most cultivars was higher than spinach but moderate compared to that of many commonly eaten vegetables (Marderosian et al. 1980). The significantly higher betacarotene content (fresh weight basis) of `Ibondwe' makes it an outstanding fresh vegetable from a nutritional standpoint. We recommend the use of 'Ibondwe' for summer production of a fresh greens crop in the deep South, based on the plant's productivity in central Texas during even the hottest part of the year, high level of resistance to Pythium damping-off, high betacarotene content (fresh weight basis), moderate oxalate content, and taste acceptability.

REFERENCES


Table 1. Productivity, Pythium damping-off resistance, betacarotene content, oxalate content, and organoleptic acceptability ratings of vegetable amaranth cultivars, spinach, and mustard greens.

Entries Productivity (t/ha) Pythium resistance (% mortality) Betacarotene content (mg/g fresh wt) Oxalate content (µg/g) Taste test (1 unacceptable-10 acceptable scale)
Amaranth
Vleta 24az 20ab 5.2c 14.5ab 4.5b
Ibondwe 14b 16a 15.4a 16.5ab 6.0a
Quilete 10bc 29ab 8.3bc 10.2b 5.9a
Tampala 7bc 20ab 8.5bc 12.0ab 6.6a
Red 4c 47abc 9.7b 20.7a 6.4a
Spinach 6.0bc 9.1b 6.9a
Mustard Greens 5.7ab
zMean separation in column by Duncan's multiple range test, 5% level.


Last update March 13, 1997 by aw