Table 1 Physico-chemical properties of the soil used in the study before and after the experiment
Soil parameters
|
Before the experiment
|
After the experiment
|
Extractants/Methods
|
At 0 N kg ha-1
|
At 60 N kg ha-1
|
At 120 N kg ha-1
|
pH
|
5.15
|
5.38
|
5.58
|
5.53
|
Soil water ratio 1:2
|
Sand (g kg-1)
|
852.0
|
845.3
|
845.3
|
825.3
|
Hydrometer method
|
Silt (g kg-1)
|
94.0
|
94.0
|
100.7
|
114.0
|
Hydrometer method
|
Clay (g kg-1)
|
54.0
|
60.7
|
54.0
|
60.7
|
Hydrometer method
|
Texture
|
Loamy sand
|
Loamy sand
|
Loamy sand
|
Loamy sand
|
Soil textural triangle
|
Ca (cmol kg-1)
|
4.39
|
4.22
|
4.48
|
4.23
|
Ammonium acetate
|
Mg (cmol kg-1)
|
1.01
|
0.87
|
0.98
|
0.94
|
Ammonium acetate
|
K (cmol kg-1)
|
0.39
|
0.11
|
0.09
|
0.07
|
Ammonium acetate
|
Na (cmol kg-1)
|
0.36
|
0.21
|
0.25
|
0.22
|
Ammonium acetate
|
Al+H (cmol kg-1)
|
0.12
|
0.1
|
0.1
|
0.1
|
Potassium chloride / acid-base titrimetric method
|
ECEC (cmol kg-1)
|
6.27
|
5.51
|
5.90
|
5.56
|
Ammonium chloride/
volumetric method
|
Base Saturation (%)
|
98.09
|
98.12
|
98.29
|
98.20
|
Estimation method
|
Total N (g kg-1)
|
1.8
|
1.4
|
1.4
|
1.7
|
Semi-micro-Kjeldahl
|
Organic Carbon (g kg-1)
|
21.8
|
18.5
|
19.7
|
18.5
|
Potassium dichromate
|
Av_P (mg kg-1)
|
26.29
|
14.92
|
13.32
|
14.99
|
Bray No. 1
|
Table 2 Effect of nitrogen fertilizer rates on culm morphological traits of main stem and primary tiller of upland rice cultivars.
Sources of variation
|
Levels of variation
|
WPP
(g)
|
PL
(cm)
|
HCG (cm)
|
CH
(cm)
|
PH
(cm)
|
IL
(cm)
|
b1 (mm)
|
b2 (mm)
|
a1 (mm)
|
a2 (mm)
|
INW (g0
|
Tiller types
|
Main culm
|
3.62a
|
24.91a
|
47.30a
|
72.50a
|
97.41a
|
11.14a
|
6.20a
|
4.40a
|
5.52a
|
3.72a
|
1.75a
|
(TT)
|
Primary tiller
|
3.82a
|
23.57b
|
46.73b
|
70.66a
|
94.23b
|
11.12a
|
5.82b
|
4.15b
|
5.00b
|
3.33b
|
1.43b
|
|
LSD
|
0.40
|
0.79
|
2.07
|
2.48
|
2.65
|
1.17
|
0.19
|
0.18
|
0.18
|
0.18
|
0.21
|
|
Significance
|
ns
|
**
|
ns
|
ns
|
*
|
ns
|
***
|
**
|
***
|
***
|
**
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Nitrogen rates
|
0
|
3.59a
|
23.33b
|
45.76a
|
69.98a
|
93.31b
|
12.19a
|
5.75b
|
4.19a
|
4.94c
|
3.37b
|
1.59a
|
(N, kg ha-1)
|
60
|
3.93a
|
23.89b
|
47.83a
|
71.96a
|
95.85ab
|
11.62a
|
6.04a
|
4.29a
|
5.24b
|
3.48b
|
1.55a
|
|
120
|
3.64a
|
25.50a
|
47.46a
|
72.80a
|
98.30a
|
9.58b
|
6.23a
|
4.36a
|
5.59a
|
3.72a
|
1.63a
|
|
LSD
|
0.49
|
0.97
|
2.54
|
3.04
|
3.25
|
1.43
|
0.23
|
0.23
|
0.22
|
0.22
|
0.25
|
|
Significance
|
ns
|
***
|
ns
|
ns
|
*
|
**
|
***
|
ns
|
***
|
**
|
ns
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Cultivars
|
NERICA 1
|
3.86ab
|
23.54b
|
44.54b
|
61.70c
|
84.24d
|
11.19b
|
5.46d
|
3.79c
|
4.87c
|
3.20c
|
1.30c
|
(C)
|
NERICA 4
|
3.23c
|
23.37b
|
45.64b
|
67.03b
|
90.40c
|
13.26a
|
5.76c
|
4.21b
|
5.00c
|
3.45b
|
1.59b
|
|
NERICA 6
|
4.41a
|
25.19a
|
52.44a
|
80.53a
|
105.73a
|
12.33ab
|
6.22b
|
4.48a
|
5.34b
|
3.60ab
|
1.89a
|
|
Moroberekan
|
3.38bc
|
24.86a
|
45.44b
|
77.05a
|
101.91b
|
7.75c
|
6.60a
|
4.63a
|
5.81a
|
3.84a
|
1.57bc
|
|
LSD
|
0.56
|
1.12
|
2.93
|
3.51
|
3.75
|
1.65
|
0.26
|
0.26
|
0.25
|
0.25
|
0.29
|
|
Significance
|
***
|
**
|
***
|
***
|
***
|
***
|
***
|
***
|
***
|
***
|
**
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Interactions
|
TT x N
|
ns
|
ns
|
ns
|
ns
|
ns
|
ns
|
ns
|
ns
|
ns
|
ns
|
ns
|
|
TT x C
|
*
|
ns
|
*
|
**
|
**
|
ns
|
*
|
*
|
*
|
ns
|
ns
|
|
N x C
|
ns
|
ns
|
ns
|
ns
|
ns
|
*
|
ns
|
*
|
ns
|
ns
|
ns
|
|
TT x N x C
|
ns
|
ns
|
ns
|
ns
|
ns
|
ns
|
ns
|
ns
|
ns
|
ns
|
ns
|
|
|
|
|
|
|
|
|
|
|
|
|
|
∗p < 0.05, ∗∗p < 0.01, and ∗∗∗p < 0.001; ns = non-significant; means with the same letter(s) along the same column are not significantly different from one another using Fischer’s Protected LSD; ns= non-significant; LSD = Least significant difference. WPP = Weight of primary panicle; HCG = Height at center of gravity; CH = Culm height; PH = Plant height; IL= Internode length; b1 = outer major diameter; b2= inner major diameter; a1= outer minor diameter; a2= inner minor diameter; IW = Internode weight;
Table 3 Effect of nitrogen fertilizer rates on culm morphological traits of main stem and primary tiller of upland rice cultivars continued
Sources of variation
|
Levels of variation
|
CWT (mm)
|
SBF
(N)
|
CSM (mm3)
|
LuV (mm3)
|
SL
(cm)
|
FW
(g)
|
BM
(g cm)
|
BrS
( g cm)
|
BeS
(g mm-2)
|
W L-1
( g cm-1 )
|
LI
|
Tiller types
|
Main culm
|
0.90a
|
22.56a
|
14.81a
|
1459a
|
89.59b
|
8.22a
|
760a
|
6019a
|
4199a
|
0.16a
|
0.13b
|
(TT)
|
Primary tiller
|
0.84b
|
18.53b
|
11.63b
|
1188b
|
85.80a
|
7.41b
|
647b
|
4333b
|
3897a
|
0.15a
|
0.16a
|
|
LSD
|
0.04
|
2.39
|
1.22
|
194.6
|
2.57
|
0.69
|
81.9
|
687.5
|
445.5
|
0.03
|
0.02
|
|
Significance
|
**
|
**
|
***
|
**
|
**
|
*
|
**
|
***
|
ns
|
ns
|
***
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Nitrogen rates
|
0
|
0.78c
|
15.45c
|
10.92c
|
1359a
|
84.42c
|
7.13b
|
617.3b
|
4435b
|
4155a
|
0.14a
|
0.15a
|
(N, kg ha-1)
|
60
|
0.88b
|
20.67b
|
13.27b
|
1377a
|
87.74b
|
8.04a
|
724.3a
|
5267ab
|
4159a
|
0.15a
|
0.15a
|
|
120
|
0.94a
|
25.53a
|
15.48a
|
1235a
|
90.92a
|
8.27a
|
769.1a
|
5826a
|
3831a
|
0.18a
|
0.14a
|
|
LSD
|
0.05
|
2.93
|
1.49
|
238.4
|
3.15
|
0.85
|
100.3
|
842.0
|
545.7
|
0.03
|
0.02
|
|
Significance
|
***
|
***
|
***
|
ns
|
***
|
*
|
*
|
**
|
ns
|
ns
|
ns
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Cultivars
|
NERICA 1
|
0.84bc
|
17.63b
|
10.31c
|
1063b
|
77.12b
|
6.75b
|
524.9b
|
4671b
|
4564a
|
0.12c
|
0.12c
|
(C)
|
NERICA 4
|
0.77c
|
14.24c
|
10.93c
|
1507a
|
80.53b
|
6.21b
|
503.7b
|
4700b
|
4387ab
|
0.12c
|
0.11c
|
|
NERICA 6
|
0.87b
|
18.84b
|
14.09b
|
1592a
|
96.79a
|
9.37a
|
920.5a
|
5216ab
|
3766bc
|
0.17b
|
0.19a
|
|
Moroberekan
|
0.99a
|
31.49a
|
17.55a
|
1132b
|
96.34a
|
8.93a
|
865.1a
|
6117a
|
3477c
|
0.21a
|
0.15b
|
|
LSD
|
0.06
|
3.38
|
1.72
|
275.2
|
3.64
|
0.98
|
115.8
|
972.2
|
630.1
|
0.04
|
0.02
|
|
Significance
|
***
|
***
|
***
|
***
|
***
|
***
|
***
|
*
|
**
|
***
|
***
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Interactions
|
TT x N
|
ns
|
ns
|
ns
|
ns
|
ns
|
ns
|
ns
|
ns
|
ns
|
ns
|
ns
|
|
TT x C
|
ns
|
ns
|
*
|
*
|
*
|
ns
|
ns
|
ns
|
ns
|
ns
|
*
|
|
N x C
|
***
|
**
|
ns
|
*
|
ns
|
ns
|
ns
|
ns
|
ns
|
ns
|
*
|
|
TT x N x C
|
ns
|
ns
|
ns
|
ns
|
ns
|
ns
|
ns
|
ns
|
ns
|
ns
|
*
|
|
|
|
|
|
|
|
|
|
|
|
|
|
∗p < 0.05, ∗∗p < 0.01, and ∗∗∗p < 0.001; ns = non-significant; means with the same letter(s) along the same column are not significantly different from one another using Fischer’s Protected LSD; ns= non-significant; LSD = Least significant difference. CWT = Culm wall thickness; SBF = Stem breaking force; CSM = Cross section modulus; LV = Lumen volume; SL = Stem length; FW = Fresh weight; BM = Bending moment; BrS = Breaking strength; WL = Weight per unit length; BeS = Bending stress; LI = Lodging index.
Table 4 Pearson moment correlations of culm morphological traits with lodging index of main culm and primary tiller of upland rice across rates of nitrogen fertilizer
Culm morphological traits
|
Main culm
|
Primary tiller
|
Internode length (cm)
|
-0.40*
|
-0.05ns
|
Outer major diameter (mm)
|
0.39*
|
0.07ns
|
Inner majot diameter b2, (mm)
|
0.38*
|
0.23ns
|
Outer minor diameter (mm)
|
0.41*
|
-0.27ns
|
Inner minor diameter (mm)
|
0.40*
|
-0.26ns
|
Internode weight (g)
|
0.13ns
|
0.17ns
|
Culm wall thickness (mm)
|
0.14ns
|
-0.17ns
|
Stem bending force ( N)
|
0.10ns
|
-0.26ns
|
Cross section modulus (mm3)
|
0.38*
|
-0.18ns
|
Lumen volume (mm3)
|
0.00ns
|
-0.08ns
|
Stem length (cm)
|
0.65***
|
0.50**
|
Fresh weight from breaking point to panicle tip (cm)
|
0.57***
|
0.50**
|
Bending moment (g cm)
|
0.62***
|
0.53***
|
Breaking strength (g cm)
|
-0.25ns
|
-0.55***
|
Bending stress (g mm-2)
|
-0.79***
|
-0.43**
|
Weight per unit length (g cm-1)
|
0.62***
|
0.18ns
|
Panicle length (cm)
|
0.35*
|
0.23ns
|
Panicle weight (g)
|
0.40*
|
0.48**
|
Height at centre of gravity (cm)
|
0.48**
|
0.59***
|
Culm height (cm)
|
0.60***
|
0.53***
|
Plant height (cm)
|
0.60***
|
0.54***
|
∗p < 0.05, ∗∗p < 0.01, and ∗∗∗p < 0.001; ns = non-significant