Morphological characteristics
the results of the study relating to the above and below ground morphological characteristics have been represented on table one and table two respectively. there were an average of 2.33 shoot sprouts per comb in the plants sown in ch100 sn0, this did not significantly differ from the value obtained in Ch25 sn75 (5.67) (P>0.05) the implication been that the composition of charcoal to soil did not affect the number of sprouted shoots per corm or rhizome. Change in plant height was reportedly lowest in the 75-25.
Table 1
Selected above-ground morphological characteristics of the test plant at 60 days after sowing
|
No. of shoot sprouts per corm/rhizome
|
Plant height (cm)
|
Plant width (cm)
|
Leaf Number
|
Leaf length (cm)
|
Leaf breadth (cm)
|
Foliar yield (g/plant)
|
Plant dry wt. (g)
|
No of chlorotic leafs
|
No of necrotic leafs
|
Ch100%,Sn0%
|
2.33a
|
45.83d
|
2.83 a
|
14.33b
|
16.67d
|
7.33b
|
29.15d
|
71.65d
|
3.00 a
|
3.33 a
|
Ch75%,Sn25%
|
3.00 a
|
4.50a
|
2.27 a
|
2.33 a
|
2.60 a
|
3.17 a
|
8.55 a
|
14.48 a
|
1.33 a
|
2.33 a
|
Ch50%,Sn50%
|
4.00 a
|
31.83c
|
2.83 a
|
14.33b
|
11.53c
|
4.53 a
|
23.54c
|
54.21c
|
2.33 a
|
2.33 a
|
Ch25%,Sn75%
|
5.67 a
|
23.83b
|
3.50 a
|
10.67b
|
9.10b
|
4.27 a
|
16.03b
|
46.11b
|
3.33 a
|
3.00 a
|
Ch0%,Sn100%
|
3.00 a
|
34.83c
|
2.67 a
|
14.00b
|
12.17c
|
5.83 a
|
20.51c
|
51.45b
|
2.00 a
|
3.00 a
|
P-value
|
0.293
|
0.00
|
0.717
|
0.010
|
0.00
|
0.035
|
0.00
|
0.00
|
0.316
|
0.785
|
Significance
|
P>0.05
|
P<0.01
|
P>0.05
|
P<0.05
|
P<0.01
|
P<0.05
|
P<0.01
|
P<0.01
|
P>0.05
|
P>0.05
|
charcoal-ultisol mix(10.50cm) compared to the 100-0 charcoal ultisol-mix(45.83 cm) generally there were different changes in plant height in the various charcoal ultisol-mix levels. Only two leaves were present at sixty days after sowing in 75-25 charcoal ultisol-mix, however in the 100-0, 50-50, 25-75 and 0-100 charcoal-ultisol mix respectively there were a range of between 10 and 14 leaves per plant. Foliar yield again was lowest in the 75-25 charcoal ultisol-mix (8.55 grams per plant) compared to 29.15 grams per plant in the 100-0 charcoal ultisol-mix. The study show that there was no significant differences in the number of leaves that showed both chlorotic and necrotic signs (P>0.05) (Table 1)
Table 2
Selected below-ground morphological characteristics of the test plant at 60 days after sowing
|
Av. length of root
|
No. of primary roots
|
No. primary branches per root
|
Dry wt. of root
|
Shoot-root ratio
|
Ch100%,Sn0%
|
8.933b
|
17.00b
|
20.00c
|
20.85c
|
54.47d
|
Ch75%,Sn25%
|
5.167a
|
12.00a
|
21.40c
|
13.10a
|
11.72a
|
Ch50%,Sn50%
|
8.167b
|
15.00a
|
22.80c
|
15.32a &b
|
40.22c
|
Ch25%,Sn75%
|
11.233c
|
33.67d
|
4.83a
|
12.76a
|
34.67b
|
Ch0%,Sn100%
|
8.833b
|
27.00c
|
13.97b
|
17.30b
|
33.15b
|
P-value
|
0.000
|
0.000
|
0.000
|
0.001
|
0.000
|
Significance
|
P<0.01
|
P<0.01
|
P<0.01
|
P<0.01
|
P<0.01
|
The selected below ground morphological characteristics of the test plant at sixty days after sowing, there were between twelve and thirty three primary (fibrous) roots in the test plant. The plants with the highest number of roots were the one sown in the 25-75 charcoal ultisol-mix. Dry weight of roots was highest in the 100-0 charcoal ultisol-mix (20.85 grams) compared to 13.10 grams in the 75-25 charcoal ultisol-mix.Charcoal only had the highest values for change in plant height, leaf number, leaf length, leaf breadth, foliar yield and plant dry weight when compared to other treatments, meaning that treatment had a higher growth. This contradicts what Asai et al. (2009) and Gaskin et al., (2010) reports, which stated that decreased growth is regularly reported with charcoal amendments when not associated with fertilizer additions. Although, hydroquinone was introduced in this study, this may have been the reason for improved growth yield. Li et al. (2009) identified hydroquinone from Podophyllum hexandrum, as a growth enhancer for wheat seedling growth (Li et al., 2009). It was concluded by that hydroquinone increased the morphological growth parameters of plants at low concentration.
Nitrogen accumulation
At sixty days after planting nitrogen accumulation in the plant leaves was determined, result showed that there were significant changes in nitrate nitrogen accumulation in plants sown in the different level of charcoal ultisol-mix, the highest been obtained in the 75-25 charcoal ultisol-mix (9.76 × 103 ppm of nitrate nitrogen and 2.44 × 103 ppm of ammonia nitrogen) the question therefore arises why these plants with the highest nitrogen accumulation had low results when above ground morphological characteristics of the test plant at sixty days was accessed. As also presented in Table 3 total nitrogen ranged from 1.89-2.81% in all the treatments (p<0.05).
Table 3
N accumulation into plant leaf
Samples
|
Nitrate nitrogen
(x103 ppm)
|
Ammonia nitrogen (x103 ppm)
|
Total nitrogen
(%)
|
Ch100%,Sn0%
|
4.90a
|
1.71c
|
2.8133b
|
Ch75%,Sn25%
|
9.76d
|
2.44d
|
1.8900a
|
Ch50%,Sn50%
|
6.35b
|
1.16b
|
2.6967b
|
Ch25%,Sn75%
|
5.93b
|
0.89b
|
2.6000b
|
Ch0%,Sn100%
|
8.90c
|
0.46a
|
1.8900a
|
P-value
|
0.00
|
0.00
|
0.11
|
Significance
|
P<0.01
|
P<0.01
|
P<0.05
|
High accumulations of free NH4+ in tissues are toxic because they dissipate pH gradients in the mitochondria and plastids (Epstein and Bloom, 2005). This might explain why the banana in that 75-25 charcoal ultisol mix had low growth rate. As also presented in Table 3 total nitrogen ranged from 1.89-2.81% in all the treatments (p<0.05). Accumulation of nitrate in plants can be limit growth if the rate of its uptake exceeds the rate of its reduction to ammonium (Luo et al., 1993). As suggested by McCall and Willumsen (1998), high rates of nitrate application increase the plant nitrate content without increasing the yield. Investigations have indicated that a high nitrate accumulation in plants results in nitrite production, which is converted into nitric oxide (NO) which, together with O2–, could be rapidly catalyzed by nitrate reductase into peroxynitrite (ONOO–) which is highly toxic to plants (Durner and Klessig, 1999; Lamattina et al., 2003). Therefore, high nitrate accumulation in plants is harmful to human health (Ikemoto et al., 2002; Ishiwata et al., 2002) as well as to plant growth (Reddy and Menary, 1990). Also Weerasuriya and Yogaratnam (1989); Anderson et al. (2011) reported, that decrease in growth of Zea mays with increase in charcoal concentration may be attributed to the supra-optional concentration of nutrients in the plant. Lehmann (2007) also observed that crops respond positively to charcoal additions and may show growth reductions at very high applications, this could also be another reason while ch 75-25 charcoal ultisol mix had a low growth.
Percentage nitrate and ammonia nitrogen utilization by the plant was determined (Table 4) as presented, 58.96% of total nitrogen utilization by the plant was in the nitrate nitrogen form when the plant was sown in 75-25 charcoal ultisol-mix however, the lowest nitrate nitrogen utilization percent (17.77%) was obtained in the 100-0 charcoal ultisol-mix. similarly 15.1% of nitrogen utilization was attributed to ammonia nitrogen accumulation in the plants exposed to 75-25 charcoal ultisol-mix as compared to 3.22% in the 0-100 charcoal ultisol-mix (P<0.01).
Table 4
Percentage Nitrate and ammonia-N utilization by plant
PLANT SAMPLE
|
Nitrate nitrogen(%)
|
Ammonia nitrogen (%)
|
Ch100%,Sn0%
|
17.7705a
|
5.5678b
|
Ch75%,Sn25%
|
58.960e
|
15.1990c
|
Ch50%,Sn50%
|
31.4339c
|
6.0922b
|
Ch25%,Sn75%
|
25.6034b
|
4.0766a
|
Ch0%,Sn100%
|
51.7984d
|
3.2243a
|
p-value
|
0.000
|
0.000
|
Significance
|
P<0.01
|
P<0.01
|
the plants, in this presentation when the index was greater than unity, it therefore implied that nitrogen was significantly hyper acummulated in the leaves as presentedresult showed that efficiency index ranged from 8.6-24.8 an indication that accumulation was significant but at different rates. The highest rate of hyper accumulation was reported in the plant sown in the 50-50 charcoal ultisol-mix (index = 24.88)
Correlation of selected plant growth and yield parameter
An attempt was made to correlate selected plant growth and yield parameter of the test plant on exposure to hydroquinone in the charcoal ultisol-mix. Result showed that plant height significantly correlated with leaf number (R = 0.781, P<0.01) leave length (R= 0.98, P<0.01). These also included leaf number, leaf breadth, plant dry weight, average length of root, dry weight of shoot and dry weight of root. Result showed that foliar yields highly negatively correlated with total foliar nitrate nitrogen (R = -0.79, P<0.01), the implication been that significant accumulation of nitrate nitrogen reduced foliar yield in the test plants on exposure to hydroquinone in the charcoal ultisol-mix. These negative correlationship also existed between plant dry weight and nitrate nitrogen as well as the incidence of chlorosis and nitrate nitrogen. The question therefore, what is the implication of hydroquinone in nitrogen metabolism in plants? Study shows that hydroquinone not only inhibits the seed borne fungi but also has an effect in improving the growth of the plants and raise the yield by up to 50% more comparing to the untreated treatments. (Mohamed, 2003) this phenomenon has also been shown by Chinese author (Boeckx et al., 2000) who indicated that hydroquinone functions as urease inhibitor and improve the urea nitrogen recovery by spring wheat with 34% as compared to the treatment where only urea was applied. Because hydroquinone in this study was at low concentration, it ended up improving the growth of the plant. The literature revealed that hydroquinone is suppressive to plants but at the same time, it ameliorates growth of plants.bla et al results also showed a similar pattern of increased lettuce seed growth at lower concentrations and inhibition on higher concentrations
Table 5
Correlation of selected plant growth and yield parameter
|
Plant height
|
Leaf Number
|
Leaf length
|
Leaf breadth
|
Foliar yield
|
Plant dry wt.
|
No of chlorotic leafs
|
No of necrotic leafs
|
Av length of root
|
No of primary roots
|
Dry wt of root
|
Nitrate N
|
Ammonia N
|
Plant height
|
1
|
|
|
|
|
|
|
|
|
|
|
|
|
Leaf Number
|
0.781**
|
1
|
|
|
|
|
|
|
|
|
|
|
|
Leaf length
|
0.98**
|
0.725**
|
1
|
|
|
|
|
|
|
|
|
|
|
Leaf breadth
|
0.759**
|
0.578*
|
0.715**
|
1
|
|
|
|
|
|
|
|
|
|
Foliar yield
|
0.961**
|
0.736**
|
0.959**
|
0.678**
|
1
|
|
|
|
|
|
|
|
|
Plant dry wt.
|
0.976**
|
0.776**
|
0.952**
|
0.709**
|
0.959**
|
1
|
|
|
|
|
|
|
|
No of chlorotic leafs
|
0.381
|
0.487
|
0.407
|
0.205
|
0.429
|
0.472
|
1
|
|
|
|
|
|
|
No of necrotic leafs
|
0.251
|
0.352
|
0.221
|
0.244
|
0.122
|
0.242
|
0.17
|
1
|
|
|
|
|
|
Av length of root
|
0.557*
|
0.502
|
0.542*
|
0.279
|
0.46
|
0.634*
|
0.584*
|
0.102
|
1
|
|
|
|
|
No of primary roots
|
0.173
|
0.235
|
0.147
|
0.033
|
-0.02
|
0.205
|
0.292
|
0.168
|
0.811**
|
1
|
|
|
|
Dry wt of root
|
0.782**
|
0.477
|
0.763**
|
0.813**
|
0.792**
|
0.73**
|
0.178
|
-0.06
|
0.154
|
-0.19*
|
1
|
|
|
Nitrate N
|
-0.68**
|
-0.53**
|
-0.71*
|
-0.42
|
-0.73**
|
-0.79**
|
-0.600*
|
-0.22
|
-0.66
|
-0.17
|
-0.38
|
1
|
|
Ammonia N
|
-0.49
|
-0.6**
|
-0.46
|
-0.22
|
-0.34
|
-0.48
|
-0.3
|
-0.19
|
-0.69**
|
-0.72**
|
-0.07
|
0.181
|
1
|
Total percentage N
|
0.508
|
0.262
|
0.538*
|
0.209
|
0.612*
|
0.588*
|
0.369
|
-0.19
|
0.542*
|
0.047
|
0.284
|
-0.80**
|
-0.03
|
**. Correlation is significant at the 0.01 level (2-tailed).
*. Correlation is significant at the 0.05 level (2-tailed).
Table 6
Rotated Component Matrixa
|
RescaledComponent
|
|
1
|
2
|
Nitrate.N
|
-0.995
|
-0.099
|
Total.perc.N
|
0.810
|
-0.040
|
Plant.dry.wt..
|
0.750
|
0.419
|
Foliar.yield..
|
0.708
|
0.285
|
Leaf.length.
|
0.669
|
0.403
|
Plant.height
|
0.644
|
0.434
|
No.of.chlorotic.leafs
|
0.580
|
0.249
|
Leaf.breadth.
|
0.402
|
0.188
|
Dry.wt..of.root
|
0.383
|
0.034
|
Plant.width..cm
|
0.279
|
0.134
|
No.of.necrotic.leafs
|
0.205
|
0.175
|
Ammonia.N
|
-0.083
|
-0.997
|
No..of.primary.roots
|
0.104
|
0.717
|
Av..length.of.root
|
0.596
|
0.639
|
Leaf.Number
|
0.476
|
0.563
|
No..primary.branches.per.root
|
-0.095
|
-0.504
|
No.of.shoot.sprouts.per.corm.rhizome
|
0.137
|
0.282
|
aRotation converged in 3 iterations. |
Extraction Method: Principal Component Analysis.
Rotation Method: Varimax with Kaiser Normalization.
The matrix is not positive definite.
A principal component analysis was conducted to establish possible standout parameters in the realization of the research aims and objectives. As presented in table six in the rotated component matrixes of the selected parameters showed highly significant positive loadings of above 0.7 for nitrate nitrogen, total percentage nitrogen, plant dry weight and foliar nitrogen under rescaled component one but none in the rescaled component two, it is eventually suggested that rescaled component one could therefore be a possible factor that affected the outcome of the results. The implication of the results of the principal component analysis may just imply that nitrate nitrogen had a highly significant negative impact on the achievement of possible growth responses in the present studies which draw us back to the earlier question; does hydroquinone have a negative effect on nitrogen metabolism? On the basis of nitrogen accumulation, 75-25 charcoal ultisol mix had higher nitrogen accumulation but did badly in terms of above ground growth, although these study was only done within sixty days it is suggested therefore that perhaps if the plants was allowed to grow till maturity result might eventually differ (also see figure 2).Figure 3 shows the dendrogram for hierarchical cluster analysis of research data using the word method. It was observed that clusters were mostly formed within replicates but most importantly there was cluster formation between some replicates of the plant in 0-100 charcoal ultisol-mix and those in the 50-50 charcoal ultisol- mix.Figure 4 shows Box and Whisker plots for residual soil nitrogen at the end of the experiment, (sixty days after sowing) results showed that residual soil nitrogen in the 100-0 charcaol-ultisol mix was an average of 0.32% whereas total soil nitrogen in 0-100 charcoal ultisol-mix was an average of 0.19%.