Agriculture Reference
In-Depth Information
TABLE 2.2
Maximum Root Length and Root Dry Weight of Lowland Rice
Genotypes as Influenced by N and Genotype Treatments
Root Dry Weight (g plant
−
1
)
N Rate/
Genotype
Maximum Root
Length (cm)
N 0 mg kg
−
1
N 300 mg kg
−
1
26.58a
0 mg N kg
−1
23.61b
300 mg N kg
−1
BRS tropical
29.00a
6.04a
5.59d
BRS Jaçanã
24.00ab
4.85abc
2.67e
BRA 02654
25.83ab
5.88ab
8.56bc
BRA 051077
23.83ab
5.59ab
13.10a
BRA 051083
26.00ab
3.09c
6.29d
BRA 051108
27.66ab
6.76a
9.03b
BRA 051126
24.50ab
5.06abc
6.41d
BRA 051129
21.17b
5.85ab
8.88b
BRA 051130
25.67ab
3.73bc
8.64bc
BRA051134
23.50
5.96ab
5.91d
BRA 051135
23.00ab
4.66abc
5.33d
BRA 051250
27.00ab
4.57abc
6.81cd
Average
24.84
5.17b
7.27a
F-test
N rate (N)
**
**
Genotype (G)
*
**
NS
**
N × G
CV (%) N rate
8.94
CV (%) Genotype
11.77
*,**,NS: Significant at the 5% and 1% probability level and nonsignificant, respectively.
Means followed by the same letter in the same column (separate for N rate and genotypes)
are not significantly different at the 5% probability level by Tukey's test.
there is deficiency of a determined nutrient, roots try to grow longer to take nutrients from the lower
soil depth (Fageria and Moreira, 2011). Visually, roots at a lower N rate were having less and smaller
hairs as compared to higher N rate.
Root dry weight was significantly influenced by N rate and genotype treatments (Table 2.2). The
N × G interaction was also significant for root dry weight, suggesting that genotypes responded
differently under two N rates. At a lower N rate, the root dry weight varied from 3.09 g plant
−1
produced by the genotype BRA 051083 to 6.76 g plant
−1
produced by genotype BRA051108, with
an average value of 5.17 g plant
−1
. At a higher N rate, the root dry weight varied from 2.67 g plant
−1
produced by genotype BRS Jaçanã to 13.10 g plant
−1
produced by genotype BRA 051077, with an
average value of 7.27 g plant
−1
. The application of 300 mg N kg
−1
produced 41% higher dry weight
compared with 0 mg N kg
−1
of soil. Figures 2.4 and 2.5 show the root growth of the genotypes BRA
02654 and BRA 051108, respectively, at low and high N rates.
2.9.9 I
nterCalatIon
of
u
rea
In
m
ontmorIllonIte
Soil particles could inhibit the volatilization of NH
3
through adsorption reactions, dissolution by
adsorbed water, and the physical disturbance of sunlight, heat, airflow, and so on. In fact, a notice-
able decrease in n loss could be achieved by simply covering the broadcast urea with soil (Griggs
et al., 2007; Kwon et al., 2009), which is rarely put into practice due to the labor cost. Therefore,
