Table of Contents
Francois, L.E., T.J. Donovan, and E.V. Maas. 1990. Salt tolerance of kenaf.
p. 300-301. In: J. Janick and J.E. Simon (eds.), Advances in new crops.
Timber Press, Portland, OR.
Salt Tolerance of Kenaf
L.E. Francois, T.J. Donovan, and E.V. Maas
- SALINE INJURY AND PERFORMANCE
- Table 1
Kenaf (Hibiscus cannabinus L.) has long been recognized as a possible
source of cellulosic fiber for pulp production in the United States (Ahlgren et
al. 1950). With the introduction of this crop into the and southwestern
states, plantings may be on soils where salinity problems already exist or may
develop from the use of saline irrigation water. Preliminary studies to
determine the effect of salt stress on germination and seedling growth of kenaf
have been conducted using solution cultures in the greenhouse (Curtis and
Lauchli 1985, 1986), but these studies provide no information on the effect of
salinity beyond the seedling stage of growth. Since salt-tolerance data are
not available to predict yield responses at later stages of growth, a field
plot study was initiated to determine the effect of salinity on vegetative
growth and yield of field-grown kenaf.
This study was conducted at the Irrigated Desert Research Station, Brawley,
CA. Two cultivars, '7818-RS10' and 'Everglade-41', were sown in 6.0 x 6.0 m
plots on 26 March 1987. Each plot contained 5 rows of each cultivar. The rows
were planted 0.5 m apart with the seed placed 50 mm apart within the row. The
initial plant population was 400,000 plants/ha.
To assure a uniform stand across treatments, differential salination was not
initiated until thirty days after planting when the plants were at the
five-leaf stage of growth. Irrigation water salinities for each treatment were
increased stepwise in two equal increments over a two-week period by adding
equal weights of NaCl and CaCl2 until desired salt concentrations were
achieved. The final electrical conductivities of the six irrigation waters
(ECiw) were 1.4, 2.0,3.0, 4.0,5.0, and 6.0 dS/m. Approximately 65 mm of water
were applied by flood irrigation to each plot every 7 to 10 days throughout the
Plants were harvested on 19 October 1987, 29 weeks after planting. Three
meters of the middle 3 rows (4.5 m2) were harvested from the center of each
half of each plot and fresh weights recorded. Ten plants were randomly
subsampled from the harvested material, weighed, and measured for height.
Leaves and side branches were removed and weighed separately from the stems.
Samples were air-dried and percent dry matter determined. Stem diameter
measurements were made 25 mm above the base of each plant. To determine the
bast and woody fiber weight ratio, a 0.1-m section of stem was sampled 0.5 to
0.6 m above the stem base.
The first injurious effect of salinity was noted approximately three months
after salination was initiated, when the older leaves of '7818-RS-10' and
`Everglade-41' from the 4.0, 5.0. and 6.0 dS/m plants developed tip and/or
marginal necrosis. Although injury was slightly more severe on '7818-RS-10',
the necrosis on both cultivars was correlated directly with the salinity level
of the irrigation water.
Reduction in total yield and stem yield, associated with increasing levels of
ECiw was nearly identical for the two cultivars (Table 1). Reduced plant
height, stem diameter, and percent dry matter all contributed to the overall
reduction in total vegetative growth and stem growth with increasing levels of
The yield data for the two cultivars were combined and statistically analyzed
with a piecewise linear response model (van Genuchten and Hoffman 1984). The
data indicate that the tolerance threshold, i.e. the maximum allowable ECiw
without a decline in yield, was 4.6 dS/m. Each unit increase in salinity above
the threshold reduced yield by 36%.
According to the salt tolerance categories established by Maas and Hoffman
(1977), kenaf would be classified as moderately tolerant to salinity. This
classification agrees with the seedling tolerance reported by Curtis and
Stem samples collected to determine bast to woody fiber weight ratios, which
ranged from 1.8 to 2.0, showed no significant difference among salinity
Kenaf can be grown successfully with moderately saline irrigation water.
However, salt levels in excess of 4.6 dS/m in the irrigation water will
severely restrict plant growth and development and will result in a significant
yield reduction. Irrigation waters currently used by most growers in the
Southwestern United States contain salt levels less than 4.6 dS/m. However,
poor irrigation water management with low salinity water can result in
detrimental salt buildup in the soil profile, which will also restrict plant
growth and development.
- Ahlgren, G., H. Dotzenko, and A. Dotzenko. 1950. Kenaf, a potential new crop.
J. New York Bot. Gard. 51:77-80.
- Curtis, P.S., and A. Lauchli. 1985. Responses of kenaf to salt stress:
Germination and vegetative growth. Crop Sci. 25:944-949.
- Curtis, P.S., and A. Lauchli. 1986. The role of leaf area development and
photosynthetic capacity in determining growth of kenaf under moderate salt
stress. Austral. J. Plant Physiol. 13:553-565.
- Maas, E.V., and G.J. Hoffman. 1977. Crop salt tolerance-current assessment. J.
Irrig. Drain Div., Am. Soc. Civ. Eng. 103:115-134.
- van Genuchten, M.T., and G.J. Hoffman. 1984. Analysis of crop salt tolerance.
p. 255-271. In: I. Shainberg and J. Shalhevet (eds.). Soil salinity under
irrigation: Process and management. Ecological Studies 51. Springer-Verlag
Table 1. Total vegetative and stem growth of two Kenaf cultivars,
'7818-RS-10' and 'Everglade-41', grown under six irrigation water salinities.
zSingle degree of freedom comparisons
| ||Total vegetative growth ||Stem growth|
| ||wt (kg/m2) || ||wt (kg/m2)|
|Fresh ||Dry ||Plant |
|Fresh ||Dry ||Dry |
|1.4 ||6.13 ||1.28 ||2.96 ||3.80 ||0.84 ||22 ||25.3|
|2.0 ||7.17 ||1.63 ||3.12 ||4.42 ||1.02 ||23 ||26.9|
|3.0 ||7.64 ||1.52 ||2.89 ||4.53 ||0.97 ||21 ||24.7|
|4.0 ||6.85 ||1.34 ||2.63 ||3.53 ||0.76 ||21 ||25.5|
|5.0 ||6.30 ||1.15 ||2.27 ||3.34 ||0.65 ||19 ||24.0|
|6.0 ||3.75 ||0.66 ||1.84 ||2.17 ||0.40 ||18 ||22.3|
|Linear ||*** ||*** ||*** ||*** ||*** ||*** ||*|
|Quadratic ||*** ||*** ||*** ||** ||** ||NS ||NS|
|1.4 ||6.99 ||1.53 ||3.16 ||4.51 ||1.06 ||24 ||23.9|
|2.0 ||7.42 ||1.54 ||3.13 ||4.78 ||1.06 ||22 ||24.3|
|3.0 ||7.44 ||1.47 ||2.85 ||4.44 ||0.93 ||21 ||23.7|
|4.0 ||7.67 ||1.49 ||2.64 ||4.48 ||0.91 ||20 ||22.7|
|5.0 ||6.14 ||1.11 ||2.20 ||3.73 ||0.70 ||19 ||21.1|
|6.0 ||3.53 ||0.57 ||1.72 ||2.48 ||0.40 ||16 ||17.8|
|Linear ||*** ||*** ||*** ||*** ||*** ||*** ||***|
|Quadratic ||*** ||*** ||*** ||** ||** ||* ||**|
NS,*,**,*** Correlation nonsignificant (NS) or significant at 5% (*) 1% (**) or
Last update March 11, 1997