Table of Contents
Singh, B.P. and W.F. Whitehead 1993. Population density and soil pH effects
on vegetable amaranth production. p. 562-564. In: J. Janick and J.E. Simon
(eds.), New crops. Wiley, New York.
Population Density and Soil pH Effects on Vegetable Amaranth Production
Bharat P. Singh and Wayne F. Whitehead
- SOIL pH
- INTRA-ROW PLANT SPACING
- Table 1
- Table 2
The genus Amaranthus consists of nearly 60 species which can be broadly
categorized into grain, green leaf vegetable, and weed types. Cultivation of
amaranth (Amaranthus spp.) for their leaves dates back to more than
2,000 years. Presently, amaranth is extensively grown as a green leaf
vegetable in many tropical countries (National Research Council 1984). The
leaves are mostly consumed as pot-herb either alone or in combination with
other vegetables and/or meat. Amaranth leaves are good source of dietary fiber
and contains high amounts of proteins, vitamins, and minerals (Makus and Davis
1984; Teutonico and Knorr 1985; Willis et al. 1984).
Amaranth species utilized as a vegetable generally have short plants with wide
leaves and small inflorescence (Huang 1980). Two species, A tricolor
and A. dubius have the desired characteristics for the vegetable type
and are commonly grown for this purpose in Asia, West Africa, and the
Caribbean. A third species, A. cruentus is grown both for leaves and
grain. The production of A. cruentus for leaves is most prevalent in
humid tropical Africa (National Research Council 1984).
In the United States, amaranth is seldom used as a vegetable and production is
limited to a few ethnic growers. Most greens grown in the United States prefer
cool weather and perform poorly during hot summer months. There is a need to
introduce leafy vegetables which can successfully be grown during the summer
months. Amaranth may be such a candidate to fill this niche. Abbott and
Campbell (1982) and Makus and Davis (1984) obtained high green yields from
amaranth produced during summer months in Maryland and Arkansas, respectively.
Sealy et al. (1990) reported that a West African cultivar 'Ibondwe' yielded 14
t/ha in central Texas and was comparable to spinach in taste. The object of
this study was to establish optimum soil pH and intra-row plant spacing for
The greenhouse experiment was conducted during November-December 1990, to
compare the growth of amaranth at 6.4, 5.3, and 4.7 soil pH using Dothan sandy
loam soil (fine loamy, siliceous, thermic, Plinthic Paleudult). Seeds of
'Hinchoy' were started in flats and 11-day-old seedlings were transplanted in
thirty 3-liter pots, ten of each soil pH. The pots were arranged on the
greenhouse benches in a randomized complete block design. The greenhouse was
held at 32±3°C day/24±2°C night. Photoperiod was kept at 14 h and
supplemental lighting was provided with fluorescent lamps. Five week old
plants were harvested and the number of branches and leaves on the plants were
counted. Plants were then separated into root, stem, and leaf portions and the
fresh weight of plant components were determined. Leaf areas was measured with
an area meter (LI-COR Model 3100, Lincoln, Nebraska). All plant parts were
dried at 70°C in a forced air oven to a constant weight. The above
experiment was repeated during January-February 1991.
Plants grown in pH 6.4 soil were significantly taller and had greater leaf area
than plants grown in pH 5.3 or 4.7 soil (Table 1). There was a significant
decrease in all above ground plant parts with each increase in soil acidity.
The top fresh weight of plants grown in 5.3 and 4.7 pH soil were 27 and 73%
lower, respectively, than plants grown in 6.4 pH soil. Campbell and Foy (1987)
screened four grain amaranth populations of A. cruentus, A.
hypochondriacus, and A. hybridus and also found that each performed
poorly in Tatum soil (clayey, mixed, thermic, typic Hapludults) at 4.8 pH.
Makus (1989) found that growth of vegetable amaranth was restricted in low pH
Enders soil (clayey, mixed, thermic, typic Hapludults).
A field experiment to compare the performance of amaranth at six intra-row
plant spacings was conducted during summer of 1990. The genotype, RRC 241 was
planted on a Dothan sandy loam soil (fine loamy, siliceous, thermic, Plinthic
Paleudult) in 5 m long and 90 cm wide rows at six plant spacing of 4, 8, 16,
24, 32, and 40 cm in completely randomized blocks with three replications.
Weeding was done mechanically and plots were irrigated as needed. The crop was
harvested 40 days after planting. Data on plant height, branch number, and
leaf number were obtained from five random plants from each plot. Plants were
then separated into stem, petiole, and leaf parts. Plant component fresh
weight was recorded and leaf area of two plants/plot was measured. Holes were
made by a cork borer in the leaf blades of two random plants and 50 leaf discs
were collected. The cumulative leaf area of the discs were measured and the
leaf discs were dried to a constant weight at 70°C to calculate the specific
leaf weight (unit dry weight/unit leaf area).
The tallest plants were produced in the closest spacing (Table 2). The
relationship of plant height to intra-row spacing was quadratic in nature. The
highest leaf number and maximum leaf area were obtained with the widest
spacing. The regression of specific leaf weight on intra-row spacing was
non-significant indicating that intra-row spacing did not affect leaf
thickness. The maximum stem, petiole, and leaf fresh weights were produced in
the widest spacing; minimum values were produced in closest spacing. As a
result, the widest spacing had the highest and the closest spacing the lowest
per plant fresh weight among the six intra-row spacings. On an unit area
basis, however, green yield increased quadratically as intra-row spacing
decreased. The coefficient of determination (R2) of green yield
with intra-row spacing was 0.96, indicating that 96% of the total variation in
the mean yields could be explained by the quadratic regression equation.
Our results show that growth of vegetable amaranth was adversely affected by
soil pHs of 5.3 and 4.7. A soil with pH of 6.4 could produce high yielding
vegetable amaranth. Green yield increased quadratically as intra-row spacing
decreased. Maximum yield at 4 cm spacing within row was 1.50 kg/m2.
- Abbott, J.A. and T.A. Campbell. 1982. Sensory evaluation of vegetable
amaranth (Amaranthus spp.). HortScience 17:409-410.
- Campbell, T.A. and C.D. Foy. 1987. Selection of grain Amaranthus species for
tolerance to excess aluminum in an acid soil. J. Plant Nutr. 10:249-260.
- Huang, P.C. 1980. A study of the taxonomy of edible amaranth: an
investigation of amaranth both of botanical and horticultural characteristics.
Proc. 2nd Amaranth Conf. Rodale Press, Emmaus, PA. p. 142-150.
- Makus, D.J. 1989. Aluminum accumulation in vegetable amaranth in soil with
adjusted pH values. HortScience 24:460-463.
- Makus, D.J. and D.R. Davis. 1984. A mid-summer crop for fresh greens or
canning; vegetable amaranth. Ark. Farm Res. 33:10.
- National Research Council. 1984. Amaranth: modern prospects for an ancient
crop. National Academy Press, Washington, DC.
- Sealy, R.L., E.L. McWilliams, J. Novak, F. Fong, and C.M. Kenerley. 1990.
Vegetable amaranth: 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.
- Teutonico, R.A. and D. Knorr. 1985. Amaranth: composition, properties and
applications of a rediscovered food crop. Food Tech. 39(4):49-60.
- Willis, R.B.H., A.W.K. Wong, F.M. Scriven, and H. Greenfield. 1984. Nutrient
composition of chinese vegetables. J. Agr. Food Chem. 32:413-416.
Table 1. Growth parameters of amaranth at three soil pH levelsz
zExperiments 1 and 2 combined.
| ||Plant weight (g/plant)|
| ||Top ||Root|
|Soil pH ||Plant height (cm) ||Branch (no./plant) ||Leaf (no./plant) ||Leaf area (cm2/plant) ||Fresh ||Dry ||Fresh ||Dry|
|6.4 ||18.3ay ||8.5a ||47.1a ||1343a ||49.5a ||3.8a ||19.8a ||2.3a|
|5.3 ||16.0b ||7.2b ||42.4a ||1011b ||36.3b ||2.8b ||16.6b ||1.8a|
|4.7 ||10.2c ||5.3c ||28.5b ||412c ||13.3c ||1.0c ||4.2c ||0.6b|
yMean separation within column by Duncan's multiple range test, P =
Table 2. Growth parameters of amaranth at six intra-row plant
zC = cubic, Q = quadratic, L = linear
| ||Plant fresh wt (g/plant)|
|Intra-row spacing (cm) ||Plant height (cm) ||Branch (no./plant) ||Leaf (no./plant) ||Leaf area (cm2/plant) ||Specific leaf weight (mg/cm2) ||Stem ||Petiole ||Leaf ||Yield (kg/m2)|
|4 ||29.3 ||5.3 ||35.3 ||873 ||4.43 ||18.9 ||6.0 ||24.2 ||1.50|
|8 ||23.0 ||6.7 ||56.3 ||1420 ||5.54 ||21.2 ||8.9 ||51.9 ||1.15|
|16 ||21.7 ||8.0 ||69.7 ||1598 ||6.10 ||25.4 ||10.9 ||55.9 ||0.66|
|24 ||15.3 ||6.0 ||63.7 ||1370 ||3.05 ||18.4 ||8.2 ||52.4 ||0.41|
|32 ||16.0 ||7.0 ||65.7 ||1368 ||4.16 ||19.5 ||8.5 ||49.4 ||0.29|
|40 ||20.7 ||6.7 ||70.0 ||1882 ||4.16 ||27.7 ||14.5 ||65.7 ||0.35|
|Significancez ||Q**y ||NSx ||C**w ||C**v ||NSu ||NSt ||C**s ||C**r ||Q**q|
yR2 = 0.71
xR2 = 0.03
wR2 = 0.59
vR2 = 0.80
uR2 = 0.04
tR2 = 0.06
sR2 = 0.75
rR2 = 0.66
qR2 = 0.96
NS, *, ** Nonsignificant or significant at P = 0.05 or 0.01, respectively.
Last update April 29, 1997