Table 4. Effect of nitrogen levels and ratios on diameter, wall thickness and filling degree of basal internodes.

N level (kg ha -1)	N ratio	2012–2013						2013–2014
		Diameter (mm)		Wall thickness (mm)		Filling degree (mg DW cm-2)		Diameter (mm)		Wall thickness (mm)		Filling degree (mg DW cm-2)
		I	II	I	II	I	II	I	II	I	II	I	II
180	7:1:2:0	4.20ab α	4.56a	0.62ab	0.55ab	23.34ab	22.91abc	4.51ab	4.96a	0.60abc	0.53b	22.10abc	21.20ab
	5:1:2:2	4.49ab	4.86a	0.65ab	0.63a	28.80ab	30.28abc	4.58ab	5.06a	0.63abc	0.55ab	26.07ab	25.75a
	3:1:3:3	4.60a	4.89a	0.66a	0.63a	34.45a	33.69a	4.83a	5.17a	0.69a	0.61a	26.49a	25.37ab
225	7:1:2:0	4.15ab	4.55a	0.58ab	0.53b	22.00b	20.71bc	4.46ab	4.94a	0.58bc	0.55ab	20.58bc	20.86ab
	5:1:2:2	4.57a	4.80a	0.64ab	0.63a	28.13ab	28.52abc	4.57ab	4.96a	0.61abc	0.57ab	24.65ab	24.07ab
	3:1:3:3	4.60a	4.85a	0.66a	0.63a	32.01ab	32.09ab	4.54ab	4.97a	0.64ab	0.58ab	24.05abc	23.38ab
270	7:1:2:0	4.03b	4.48a	0.56b	0.53b	20.40b	20.08c	4.44b	4.86a	0.54c	0.53b	18.69c	19.67b
	5:1:2:2	4.47ab	4.80a	0.61ab	0.61ab	26.85ab	25.66abc	4.56ab	4.92a	0.58bc	0.53b	21.41abc	20.22ab
	3:1:3:3	4.52a	4.77a	0.62ab	0.61ab	29.32ab	28.68abc	4.68ab	4.95a	0.56bc	0.53b	22.13abc	22.55ab
F
Nitrogen levels(NL)		1.37	0.59	5.33*	0.76	1.82	2.89	2.36	4.10	7.60*	6.53*	12.50**	7.07*
Nitrogen ratio(NR)		24.89**	9.18**	11.10**	29.05**	16.46*	18.22**	7.12*	2.02	16.27*	6.24*	13.08**	7.73*
NL×NR		0.27	0.06	0.61	0.08	0.14	0.13	1.26	0.47	1.46	2.18	0.22	1.10

^α Values in a column followed by the same letter are not significantly different at P < 0.05 as determined by the LSD test. The test was conducted separately between the two years.

* F-test significant at 5% level.

** F-test significant at 1% level.