Agriculture Reference
In-Depth Information
TABLE 7.12
Root Dry Weight of 10 Tropical Cover Crops as Influenced by N and Bradyrhizobial
Inoculants
Root Dry Weight (g Plant
−
1
)
Cover Crops
N
0
N
1
N
2
N
3
Average
1. Crotalaria
0.18d
0.13f
0.19d
0.14d
0.16e
2. Smooth crotalaria
0.23d
0.48ef
0.81bc
0.38d
0.47d
3. Showy Crotalaria
0.48bcd
0.51ef
0.77bc
0.43d
0.55d
4. Calopo
0.30cd
0.42ef
0.46cd
0.31d
0.37d
5. Pueraria
0.16d
0.15f
0.15d
0.16d
0.16e
6. Pigeon pea
0.73b
0.68de
0.48cd
0.21d
0.53d
7. Lablab
0.74b
1.42bc
1.72a
1.64b
1.38b
8. Black velvet bean
1.66a
1.74ab
0.50cd
2.08a
1.49b
9. Gray velvet bean
2.01a
1.91a
1.84a
1.71ab
1.87a
10. Jack bean
0.65bc
1.10cd
1.12b
0.94c
0.95c
Average
0.72a
0.85a
0.80a
0.80a
0.79
F-test
N rate (N)
NS
Cover crops (C)
**
N × C
**
CVN (%)
25.59
CVC (%)
19.71
Source:
Adapted from Fageria, N. K. et al. (In press).
Commun. Soil Sci. Plant Anal
.
**, NS: Significant at the 1% probability level and not significant, respectively. 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
; N
1
= 0 mg N kg
−1
+ Bradyrhizobial inoculants; N
2
=
100 mg N kg
−1
+ Bradyrhizobial inoculants; and N
3
= 200 mg N kg
−1
.
7.10 through 7.12 show the root growths of showy crotalaria, calopo, and lablab, respectively. The
root growth varied with N treatments and overall, a more vigorous root system was produced at the
N
2
(100 mg N kg
−1
+ inoculant) treatment compared with the other three N treatments in three cover
crops. Baligar et al. (1998) reported that the root dry weight of legume crops was higher with the
addition of N compared with without N application treatment.
15
10
Y = 1.88 + 15.41X - 4.33X
R
2
= 0.90**
5
0
0
1
2
Root dry weight (g plant
-1
)
FIGURE 7.9
Relationship between the root dry weight and shoot dry weight of tropical legume cover crops.
