Agriculture Reference
In-Depth Information
BRS Primavera
0
300 mg N kg
-1
FIGURE 6.1
Root growth of upland rice genotype BRS Primavera at two N levels.
to the lower N rate. Fageria (1992) reported a higher root length of rice at the low N rate compared
to the high N rate in nutrient solution. Fageria (1992) also reported that at nutrient deficient levels,
the root length is higher compared to the high nutrient levels because of the tendency of plants to
tap nutrients from deeper soil layers.
Root dry weight varied from 0.87 g plant
−1
produced by genotype BRA01596 to 1.78 g plant
−1
produced by genotype BRA052034, with an average value of 1.38 g plant
−1
at the lower N rate (0 mg
N kg
−1
). At the higher N rate (300 mg N kg
−1
), the root dry weight ranged from 0.40 g plant
−1
pro-
duced by genotype BRA01506 to 4.14 g plant
−1
produced by genotype BRA052023, with an average
value of 2.72 g plant
−1
. Overall, the root dry weight was 97% higher at the higher N rate compared
to the lower N rate. Fageria and Baligar (2005) and Fageria (2009) reported that N fertilization
improved the root dry weight in crop plants, including upland rice. The positive effect of N on root
dry matter has been previously documented (Fageria, 2009). Figures 6.1 through 6.3 show the influ-
ence of N on the root growth of upland rice genotypes.
NUE was determined in selected field crops without N and with N + P by several authors and
the results are presented in Table 6.4. In corn, in one case, it was 31% higher, and in another case, it
was 23% higher with the addition of N + P compared to the treatment that did not receive P. In case
of wheat, the increase was 28% in the treatment that received N + P in comparison to the treatment
BRA 02535
300 mg N kg
-1
0
FIGURE 6.2
Root growth of upland rice genotype BRA 02535 at two N levels.
