Effects of salinity stress on growth, Water use efficiency and biomass partitioning of Vernonia hymenolepis in screenhouse potted soil amended with NPK 20:10:10 | IJAAR-Vol-18-No-4-p-1-11

Int. J. Agron. Agri. R.
Leaf area (LA)
Leaf area of the plants are presented in Table 2. Plants of
the control treatments (0 ppt at 0 g NPK fertilization)
had high LA similar to those of the other treatments. As
fertilizer rates increased within the freshwater treated
plants, RLA statistically reduced (p<0.05). Relative leaf
areas of plants under the 2 ppt salinity treatments were
statistically similar across fertilizer rates, while those
under the 4 ppt salinity treatments increased as
fertilization rates increased (Table 2).
Table 2. Interactive effect of salinity and fertilization
on LA of V. hymenolepis in screen house.
Salinity (ppt) Fertilizer (g/plant) LA (cm 2 )
0 0 24.16ab
4 18.27bc
8 16.59c
2 0 24.87ab
4 25.94a
8 22.40abc
4 0 17.56c
4 24.71a
8 27.72abc
Values represent means. Means separated through
GLM ANOVA with Dunnett test at α=0.05. Means
with the same letter within the column are not
statistically different. LA = Leaf area.
Biomass partitioning
Table 3 shows analysis of variance results of the main
and interaction effects of salinity and fertilization on
biomass partitioning in V. hymenolepis. Salinity did not
have a significant effect on any of the measured
parameters (p>0.05 in all cases). On the other hand,
fertilizer significantly affected biomass partitions,
harvest index, WUE and RGR (p<0.05 in all cases). The
interaction of fertilizer and salinity did not significantly
affect any of the parameters measured (Table 3).
Biomass, RGR, HI and WUE values of plants treated
with salinity regimes ranging from 0 to 4 ppt were
statistically similar. Table 4 therefore shows that
salinity of 2 to 4 ppt had a similar effect on biomass
partitions of V. hymenolepis as the control (0 ppt).
On the other hand, the fertilizer effect varied
significantly across salinity levels. The highest values
of shoot mass, root mass, biomass, WUE and RGR
were recorded in plants grown on saline and nonsaline
soils amended with 4 g/plant NPK 20:10:10
fertilizer (Table 4).
Table 3. Analysis of variance results on statistical significance of salinity and fertilization effects on growth and
yield of Vernonia hymenolepis in screenhouse.
Source Shoot FM/g Shoot DM/g Root FM/g Root DM/g R:S ratio HI Biomass WUE RGR
S 0.091 0.829 0.100 0.136 0.603 0.171 0.365 0.365 0.402
F 0.001 0.003 0.003 0.013 0.010 0.005 0.004 0.004 0.004
S*F 0.427 0.591 0.709 0.742 0.992 0.611 0.420 0.420 0.412
Values represent levels of significance. P-Value less than 0.05 indicate statistical variation in the effect of the
measured factor on the response variable
Table 4. Growth and yield responses of Vernonia hymenolepis to salinity and fertilization with NPK 20:10:10, in
screenhouse.
Salinity (ppt) Shoot FM/g Shoot DM/g Root FM/g Root DM/g R:S ratio HI Biomass (g) WUE RGR
0 66.00a 23.00a 36.44a 9.67a 0.43a 2.02a 32.67a 2.72a 0.23a
2 76.44a 24.56a 38.44a 12.22a 0.52a 2.06a 36.78a 3.07a 0.24a
4 60.22a 24.00a 28.44a 10.33a 0.51a 1.77a 34.33a 2.86a 0.23a
Fert. (g/plt)
0 49.78a 18.89a 41.89a 12.00a 0.68a 1.61a 30.89a 2.57a 0.22a
4 81.44b 29.11b 37.67a 11.89a 0.42b 2.02b 41.00b 3.42b 0.25b
8 71.44b 23.56a 23.78b 8.33b 0.37b 2.22b 31.89a 2.66a 0.22a
Values represent means. Means separated through GLM ANOVA with Dunnett test at α=0.05. Means with the
same letter within the column for each main effect are not statistically different. Fert. = fertilizer, FM= fresh
mass, DM = dry mass, HI = harvest index, R:S ratio = root:shoot ratio, WUE = water use efficiency, RGR =
relative growth rate
Tabot et al. Page 6