The influence of nitrogen availability on anatomical and physiological responses of Populus alba × P. glandulosa to drought stress

Table 2 Stem anatomical properties under each combination of water and nitrogen condition

Nitrogen Conditions	Water Conditions	VF (number mm⁻²)	VLD (μm)	FLD (μm)	XT (mm)	XCL	PT (mm)
Well Watered	Low Nitrogen	68.8 c±4.6	45.4 a ±2.5	13.5 b ±0.3	0.51 b ±0.02	37.9 b ±0.9	0.10 b ±0.01
Well Watered	Adequate Nitrogen	72.9 c ±13.0	45.6 a ±2.5	15.7 a ±0.3	0.77 a ±0.03	49.3 a ±2.2	0.11 ab ±0.01
Drought	Low Nitrogen	97.8 b ±3.9	45.2 a ±2.3	13.2 b ±0.6	0.34 c ±0.03	26.1 c ±1.9	0.11 ab ±0.01
Drought	Adequate Nitrogen	139.6 a ±9.5	39.5 a ±5.5	12.7 b ±0.7	0.5 b ±0.02	39.6 b ±2.3	0.12 a ±0.01
F Value of Two-way ANOVA	Nitrogen (N)	10.7*	1.9	8.3*	345.1**	133.2**	5.8*
	Water (W)	49.6**	2.4	31.9**	378.8**	105.6**	1.4
	N × W	8.8*	2.2	20.7**	19.6**	1.2	0.00

VF vessel frequency; VLD vessel lumen diameter; FLD fiber lumen diameter; XT xylem thickness; XCL xylem cell layers; PT phloem thickness. Means with different letters are statistically different in multiple comparisons between treatments at the 5% level in ANOVAs. Level of significance of F value in two-way ANOVA is denoted by: *0.05 > p > 0.01, **p < 0.01

ISSN: 1471-2229