Agriculture Reference
In-Depth Information
TABLE 7.5
Grain Yield (g Plant
−
1
) of 15 Dry Bean Genotypes at Different N and Rhizobium
Inoculation Treatments
Genotype
N
0
N
1
N
2
N
3
Average
Aporé
7.19de
5.71g
8.54d
11.10de
8.13f
Pérola
11.30a
11.05bc
8.41d
13.16bc
10.98bc
BRSMG Talisma
8.90bcd
5.28g
5.42e
4.57g
6.04g
BRS Requinte
11.71a
10.37cd
8.13d
16.56a
11.69ab
BRS Pontal
5.57e
11.00bc
8.31d
14.04b
9.73de
BRS 9435 Cometa
10.50abc
9.20cde
8.62d
9.54ef
9.46e
BRS Estilo
7.28de
11.25bc
9.09cd
12.67bcd
10.07cde
CNFC 10408
8.82bcd
10.03cde
10.84bc
7.71f
9.35e
CNFC 10470
8.55cd
13.68a
9.60cd
14.29b
11.53ab
Diamante Negro
8.55cd
13.58a
13.33a
14.25b
12.43a
Corrente
11.38a
8.36de
8.90cd
11.48cde
10.03cde
BRS Valente
7.59de
12.90ab
5.76e
13.49b
9.93de
BRS Grafite
11.22a
6.10fg
9.67cd
10.83de
9.45e
BRS Marfim
10.88ab
8.12ef
8.40d
10.57e
9.49de
BRS Agreste
8.71cd
10.79c
11.71ab
10.70de
10.47cd
Average
9.21c
9.83b
8.98c
11.66a
F-test
N levels (N)
**
Genotypes (G)
**
N × G
**
CVN (%)
3.39
CVG (%)
7.03
Source:
Adapted from Fageria, N. K. et al. 2014.
Commun. Soil Sci. Plant Anal.
45:111-125.
**Significant at the 1% probability level. Means in the same column followed by the same letter are not significantly different
at the 5% probability level by Tukey's test. Average values were compared in the same line for significant differences among
N rates. N
0
= 0 mg N kg
−1
(control); N
1
= 0 mg N kg
−1
+ inoculation with rhizobial strains; N
2
= inoculation with rhizobial
strains + 50 mg N kg
−1
; and N
3
= 200 mg N kg
−1
.
Variability in root growth among crop species and among genotypes of the same species is widely
reported in the literature (O'Toole and Bland, 1987; Gregory, 1994; Fageria, 2009). This variability
can be used in improving the yield of annual crops by incorporating vigorous root growth into desir-
able cultivars. Vigorous root growth is especially important when nutrient and water stresses are
significant (Gregory, 1994). Ludlow and Muchow (1990), in their review of traits likely to improve
yields in water-limited environments, place a vigorous rooting system high in their list of properties
to be sought.
The genotypic variability in root growth of annual crops has been used to identify superior
genotypes for drought-prone environments (Hurd et al., 1972; Gregory, 1994). Gregory and Brown
(1989) reviewed the role of root characters in moderating the effects of drought and concluded that
roots may have a direct effect, by increasing the supply of water available to the crop, or an indirect
effect by changing the rate at which the supply becomes available. Where crops are grown on deep
soils and water is stored throughout the whole soil profile, the depth of rooting has a major influ-
ence on the potential supply of water (Gregory, 1994). Rain may replenish the upper soil during
the season, but later growth and grain filling in many crops are accomplished during periods of
low rainfall when soil moisture stored deep in the profile must be utilized. Sponchiado et al. (1989)
