Effects of Boron Nutrition and Water Stress on Nitrogen Fixation, Seed δ15N and δ13C Dynamics, and Seed Composition in Soybean Cultivars Differing in Maturities
Table 4
Effects of water stress on seed sugars (mg g−1) and nitrogen fixation rate (ARA: [(μmol C2H2 g nodule−1 h−1)] in maturity group (MG) III (Williams 82 and Pella 86) and MG V (Hutcheson and Freedom) soybean cultivars. Plants were grown under well-watered and water-stressed conditions and boron was foliar applied at 0.45 kg⋅ha−1 at flowering and seed-fill stages.
Genotype
Well-watered plants (soil water potential = −15 to −20 kPa)
B treatment
Sucrose (C12H22O11)
Raffinose (C18H32O16)
Stachyose (C24H42O21)
Glucose (C6H12O6)
Fructose (C6H12O6)
ARA (μmol C2H2 g nodule−1 h−1)
Williams 82 (MG III)
−B
30.4 d
5.3 c
25.5 b
1.3 c
0.76 b
657 c
+B
38.6 c
6.5 b
26.5 b
2.5 ab
0.99 a
878 a
Pella 86 (MG III)
−B
33.5 d
7.5 a
24.7 b
1.1 c
0.65 b
576 d
+B
41.8 b
6.8 b
25.4 b
2.4 ab
0.92 a
745 b
Hutcheson (MG V)
−B
44.7 b
7.5 a
32.5 a
1.6 c
0.65 b
658 c
+B
48.6 a
6.9 b
30.6 a
2.7 a
0.98 a
895 a
Freedom (MG V)
−B
38.6 c
7.4 a
31.5 a
2.3 b
0.76 b
758 b
+B
53.6 a
8.0 a
33.6 a
2.8 a
1.23 a
976 a
Genotype
Water-stressed plants (soil water potential = −90 to −100 kPa)
B treatment
Sucrose (C12H22O11)
Raffinose (C18H32O16)
Stachyose (C24H42O21)
Glucose (C6H12O6)
Fructose (C6H12O6)
ARA (μmol C2H2 g nodule−1 h−1)
Williams 82 (MG III)
−B
21.4 e
6.5 b
34.3 b
0.85 c
0.56 c
352 b
+B
25.4 d
6.3 b
33.5 b
1.3 b
0.63 b
436 a
Pella 86 (MG III)
−B
20.5 e
6.6 b
32.5 b
0.75 c
0.40 d
267 d
+B
33.2 b
7.5 a
33.8 b
1.3 b
0.56 d
315 c
Hutcheson (MG V)
−B
32.5 b
6.4 b
45.3 a
0.94 c
0.53 b
365 b
+B
39.6 a
6.7 b
43.7 a
1.2 b
0.82 a
476 a
Freedom (MG V)
−B
28.6 c
7.1 a
45.7 a
1.4 b
0.63 b
326 b
+B
35.7 b
6.5 b
42.8 a
2.1 a
1.10 a
476 a
Means within a column of each water treatment followed by the same letter are not significantly different at the 5% level as determined by Fishers’ LSD test. Values are means of four replicates.
