Agriculture Reference
In-Depth Information
TABLE 1.13
Relationship between N Rate (X) and Grain Yield of 12 Lowland
Rice Genotypes
Genotype
Regression Equation
R
2
BRS Jaçanã
0.77**
Y = 1899.03 + 19.40X
CNAi 8860
0.74**
Y = 2642.53 + 17.01X
BRS Fronteira
Y = 2630.31 + 26.79X − 0.0611X
2
0.70**
CNAi 8879
Y = 2511.89 + 29.09X − 0.0703X
2
0.77**
CNAi 8880
Y = 2213.08 + 39.69X − 0.1131X
2
0.87**
CNAi 8886
Y = 2430.88 + 32.92X − 0.0848X
2
0.83**
CNAi 8885
Y = 2516.87 + 28.93X − 0.0669X
2
0.84**
CNAi 8569
Y = 2590.43 + 24.28X − 0.631X
2
0.82**
BRSGO Guará
Y = 2797.53 + 20.30X
0.92**
BRS Alvorada
Y = 2912.43 + 18.17X
0.66**
BRS Jaburu
Y = 1816.19 + 18.21X
0.88**
BRS Biguá
Y = 1814.42 + 19.83X
0.93**
Source:
Adapted from Fageria, N. K., A. B. Santos, and V. A. Cutrim. 2008.
J. Plant
Nutr
. 31:788-795. With permission.
Note:
Values are averages of 2 years field experimentation.
**Significant at the 1% probability level.
small additions can result in greater yields but with decreased protein concentrations (Novoa and
Loomis, 1981).
D'Andrea et al. (2006) reported that the grain yield of corn was significantly reduced by N
deficiencies, and the response was mainly related to variations in kernel number per plant. Data in
Table 1.13 show the influence of N on the grain yield of 12 lowland rice genotypes. Grain yield was
significantly increased with the addition of N. Six genotypes were having significant linear increase
in grain yield while the remaining six were having quadratic increase in grain yield. The variability
in grain yield was 66-93% with the addition of N. The average grain yield of 12 lowland rice geno-
types was plotted against the N rate (Figure 1.13). The increase in grain yield was significant and
quadratic with the addition of N in the range of 0-200 kg ha
−1
.
Maximum grain yield was obtained with the addition of 229 kg N ha
−1
(Figure 1.13). In fertil-
izer experiments, 90% of the maximum yield is often considered as an economical rate (Fageria
6000
90% of maximum yield
4000
2000
Y = 2341.8650 + 26.6062X - 0.0477X
2
R
2
= 0.8885**
0
50
100
150
200
Nitrogen appliction rate (kg N ha
-1
)
FIGURE 1.13
Grain yield of lowland rice as influenced by N application rate. Values are averages of 12
genotypes and 2 years field trial. (Adapted from Fageria, N. K., A. B. Santos, and V. A. Cutrim. 2008.
J. Plant
Nutr
. 31:788-795. With permission.)
