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 2

Analysis of variance for the effect of experiment (E), cultivar (Cv), water treatment (W: well-watered plants and water-stressed plants), boron treatments (foliar boron was applied at 0.45 kg⋅ha⁻¹ at flowering and seed-fill stages), and their interactions on seed sugars (mg g⁻¹), nitrogen fixation rate (ARA), and natural abundance of nitrogen and carbon isotopes (¹⁵N/¹⁴N ratio; ¹³C/¹²C ratio).

Source effect	Sucrose	Raffinose	Stachyose	Glucose	Fructose	ARA	^15N/^14N	^13C/^12C
Experiment (E)	NS	NS	NS	NS	NS	NS	NS	NS
Cultivar (CV)	**	**	**	***	**	**	NS	NS
Water treatment (W)	*	NS	***	**	**	***	**	**
Treatment (Treat)	**	**	***	*	*	**	NS	NS
E × CV	NS	NS	NS	NS	NS	NS	NS	NS
E × W	NS	NS	NS	NS	NS	NS	NS	NS
E × Treat	NS	NS	NS	NS	NS	NS	NS	NS
CV × W	*	NS	**	**	*	**	*	*
CV × Treat	NS	NS	NS	NS	NS	NS	NS	NS
W × Treat	*	*	**	*	*	*	NS	NS
E × CV × W × Treat	*	NS	*	*	*	*	NS	NS

*: significance at ≤ 0.05; **: significance at ≤ 0.01; ***: significance at ≤ 0.001.