Agriculture Reference
In-Depth Information
indicating variable responses of cover crops in N uptake with changing P levels. The uptake of N
increased with increasing P levels, indicating a positive interaction between these two elements.
Nitrogen can increase P concentration in plants by increasing root growth and by increasing the
ability of roots to absorb and translocate P (Wilkinson et al., 2000). One of the important aspects
of improving P uptake with the addition of N is vigorous root growth. Data in Table 6.3 show the
influence of N levels on root growth of upland rice grown on a Brazilian Oxisol. Nitrogen × geno-
type interaction was significant for root length and root dry weight; therefore, data are reported
separately for the two N rates (Table 6.3). Root length varied from 27 cm produced by genotype
BRA01600 to 43 cm produced by genotype BRA032039, with an average value of 30.49 cm at a low
N rate (0 mg N kg
−1
). Similarly, at a high N rate (300 mg N kg
−1
), the root length ranged from 21 cm
produced by genotype BRA01506 to 40.33 cm produced by genotype BRS Sertaneja, with an aver-
age value of 31.99 cm. Overall, the root length was 5% higher at the higher N rate compared to the
lower N rate. However, 35% genotypes produced a lower root length at the higher N rate compared
TABLE 6.3
Root Length and Root Dry Weight of 20 Upland Rice Genotypes as Influenced
by Nitrogen Fertilization
Root Length (cm)
Root Dry Weight (g Plant
−1
)
Genotype
0 mg N kg
−1
300 mg N kg
−1
0 mg N kg
−1
300 mg N kg
−1
BRA01506
34.67ab
21.00cd
0.92a
0.40f
BRA01596
30.00b
15.67d
0.87a
0.45f
BRA01600
27.00ab
25.33bcd
1.14a
1.03ef
BRA02535
31.67ab
30.00abcd
1.33a
3.25abcd
BRA02601
28.00b
32.67abc
1.11a
3.73ab
BRA032033
30.00a
28.00abcd
1.12a
2.41cd
BRA032039
43.00a
34.67abc
1.24a
3.77ab
BRA032048
28.50b
32.00abc
1.05a
3.62abc
BRA032051
30.67ab
35.67ab
1.31a
2.82bcd
BRA042094
30.33b
38.00ab
1.78a
2.31de
BRA042156
29.33b
33.00abc
1.19a
2.84bcd
BRA042160
29.67b
32.50abc
1.51a
3.33abcd
BRA052015
31.00ab
35.00abc
1.67a
2.83bcd
BRA052023
29.67b
26.50abcd
1.48a
4.14a
BRA052033
30.33b
31.33abc
1.56a
3.38abcd
BRA052034
29.00b
37.67ab
1.78a
2.58bcd
BRA052045
28.67b
37.67ab
1.75a
3.66abc
BRA052053
29.00b
36.50ab
1.65a
2.72bcd
BRS Primavera
29.33b
36.33ab
1.68a
2.49bcd
BRS Sertaneja
30.00b
40.33a
1.45a
2.68bcd
Average
30.49
31.99
1.38
2.72
F-test
N rate (N)
NS
*
Genotype (G)
**
**
N × G
**
**
CV (%)
14.25
15.86
Source:
Adapted from Fageria, N. K. 2010. Root growth of upland rice genotypes as influenced by nitrogen fertil-
ization. Paper presented at the 19th World Soil Science Congress, Brisbane, Australia. 1-6 August, 2010.
*, **, NS: Significant at the 5% and 1% probability levels and not significant, respectively. Means followed by the
same letter in the same column are not significant at the 5% probability level by Tukey's test.
