Remobilization of dry matter in wheat: effects of nitrogen application and post-anthesis water deficit during grain filling

Figures & data

Table 1  Soil physical and chemical properties of the experimental site.

	Year
Property	2006–07	2007–08
Texture	Silty-clay	Silty-clay-loam
pH	7.96	7.85
EC (dS m^−1)	1.88	1.25
Organic matter (%)	0.25	0.39
N (%)	0.023	0.036
P (mg kg^−1)	5.4	16
K (mg kg^−1)	340	206
Fe (mg kg^−1)	3.7	5.4
Zn (mg kg^−1)	0.64	0.1
Mn (mg kg^−1)	5.8	9.9
Cu (mg kg^−1)	0.48	0.98

Table 2  Summary of October–June precipitation and temperature data for 2006–08 at the experimental site.

	October	November	December	January	February	March	April	May	June
				2006–07
Precipitation (mm)	13	57	95	98	35	20	8	1	0
Temperature – max (°C)	21.9	12.9	11.4	9.9	12.4	15.1	22	25.4	30.0
– min (°C)	4.4	−1.9	−4.6	−6.4	−5.3	0.8	4.3	9.3	14.3
				2007–08
Precipitation (mm)	10	19	78	151	24	14	1	0	0
Temperature – max (°C)	23	15.6	13.2	11.6	14.1	16.7	23.0	26.2	32.3
– min (°C)	6.1	−0.7	−3.4	−5.4	−4.3	−1.1	6.7	9.6	16.1
				1978–2008 average
Precipitation (mm)	10.7	30	84	120	61	25	10	7	0.5
Temperature – max (°C)	19.6	16.2	12.0	10.8	7.5	15.7	20.1	24.4	27.9
– min (°C)	6.7	1.5	−4.1	−7.2	−6.6	−1.2	3.0	9.2	13.1

Table 3a  Mean values of dry matter remobilisation (DMR) and DMR efficiency (DMRE) of spike, flag leaf, stem and lower leaf of three wheat cultivars under three N applications and two water regimes in 2006–08.

Treatments	DMR of spike (mg plant^−1)	DMR of flag leaf (mg plant^−1)	DMR of stem (mg plant^−1)	DMR of lower leaves (mg plant^−1)	DMRE of spike (%)	DMRE of flag leaf (%)	DMRE of stem (%)	DMRE of lower leaves (%)
Irrigation
WW	139	4	186	30	22.57	20.57	13.91	19.322
WD	173	9	277	39	27.09	26.49	18.21	22.99
LSD (0.05)	19	0.9	21	5	3.2	3.2	1.6	2.1
Nitrogen (N) kg ha^−1
0	143	2.6	212	33	28.13	23.60	14.80	20.51
80	146	16	227	49	24.18	23.94	16.97	23.59
160	190	16	271	37	22.01	23.04	16.42	19.36
LSD (0.05)	21	1.1	20	5.1	2.8	3.1	1.4	2
Cultivar (C)
Shiraz	158	16	269	34	22.03	26.38	16.48	19.58
Marvdasht	173	18	200	43	24.26	23.92	13.52	21.78
Chamran	153	1.5	241	37	28.20	20.29	18.18	22.10
LSD (0.05)	21	1.3	19	4.6	2.6	3.1	1.1	1.9
WW = well-watered treatment.
WD = post-anthesis water deficit.
LSD = least significant difference.

Table 3b  Total dry matter remobilisation (DMR) and DMR efficiency (DMRE), and mean values of contribution of dry matter to grain, active grain-filling period, grain-filling rate, NSC residue, kernel weight, grain yield and harvest index, of three wheat cultivars under three N applications and two water regimes in 2006–08.

Treatments	Total DMR (mg plant^−1)	Total DMRE (%)	Contribution of DMR to grain (%)	Active grain-filling period (days)	Grain filling-rate (mg day^−1)	NSC residue (mg g^−1 DW)	Kernel weight (g)	Grain yield (kg ha^−1)	Harvest index (%)
Irrigation
WW	377	17.01	7.88	37	0.8	232	33.78	5897	31.7
WD	513	22.01	14.54	25	1.9	120	27.57	4410	28.0
LSD (0.05)	35	0.9	1.7	4.8	0.2	19	4.7	1177	5
Nitrogen (N) kg ha^-1
0	427	19.96	14.35	29	1.9	67	31.08	5135	33.9
80	448	20.51	10.86	35	1.6	188	35.94	5832	34.0
160	459	18.06	8.42	41	1.1	222	36.02	5823	38.7
LSD (0.05)	37	1	1.8	4.9	0.3	22	4.9	1185	5.1
Cultivar (C)
Shiraz	482	19.05	13.77	42	0.7	219	30.83	4799	28.5
Marvdasht	427	18.18	14.69	38	1.3	162	27.49	4908	28.7
Chamran	525	21.30	9.17	27	1.8	113	33.72	5853	32.5
LSD (0.05)	37	1	1.8	5	0.2	23	4.7	1298	5.1
NCS = non-structural carbohydrates.
WW = well-watered treatment.
WD = post-anthesis water deficit.
LSD = least significant difference.

Table 4  Mean values of dry matter remobilisation (DMR) and DMR efficiency (DMRE) of spike, flag leaf, stem and lower leaf; contribution of dry matter to grain, active grain-filling period, grain-filling rate, NSC residue, kernel weight, grain yield and harvest index, as affected by N application and irrigation regime in 2006–08.

Treatments		DMR of spike (mg plant^−1)	DMR of flag leaf (mg plant^−1)	DMR of stem (mg plant^−1)	DMR of lower leaves (mg plant^−1)	DMRE of spike (%)	DMRE of flag leaf (%)	DMRE of stem (%)	DMRE of lower leaves (%)	Total DMR (mg plant^−1)
Irrigation	Nitrogen (kg ha^−1)
WW	0	147	1.1	234	19	23.95	20.71	14.77	15.60	401
	80	139	13	135	58	21.70	19.36	9.78	25.75	338
	160	146	13	204	27	22.05	21.63	9.78	16.60	391
WD	0	149	5	307	47	24.38	26.48	19.16	25.42	462
	80	240	18	288	41	34.92	28.51	19.80	21.42	495
	160	145	20	250	47	21.96	24.45	15.65	22.12	581
	LSD (0.05)	22	1.6	27	4.6	2.9	2.8	1.8	2.6	37
Source of variation
	Irrigation (I)	*	**	**	*	*	**	**	*	**
	Nitrogen (N)	NS	*	*	NS	NS	NS	*	NS	*
	I×N	NS	*	*	NS	NS	NS	NS	NS	*
CV,%		22.3	9.3	25.6	5	6.7	9.1	11.2	10.9	17.9
		Total DMRE (%)	Contribution of DMR to grain (%)	Active grain- filling period (d)	Grain- filling rate (mg day^−1)	NSC residue (mg day^−1)	Kernel weight (g)	Grain yield	Harvest index (%)
WW	0	18.10	8.16	29	1.7	106	35.13	5931	35.45
	80	16.33	8.05	38	1.2	232	33.56	5884	29.25
	160	16.58	7.42	41	0.9	263	32.66	5873	30.31
WD	0	21.80	13.55	19	1.4	73	29.02	4337	29.16
	80	24.68	18.63	30	0.9	184	26.30	4320	24.79
	160	19.53	11.42	33	0.8	203	27.38	4572	30.33
	LSD (0.05)	2.5	1.4	3.1	0.2	25	2.9	1201	4.7
Source of variation
	Irrigation (I)	*	*	**	*	*	*	*	*
	Nitrogen (N)	*	NS	*	*	*	*	*	*
	I×N	NS	NS	*	*	*	*	*	NS
CV,%		13.5	5.3	9.9	8.5	14	10.2	13.1	17.5
NSC = non-structural carbohydrates.
WW = well-watered treatment.
WD = post-anthesis water deficit.
LSD = least significant difference.
*,** significant at 0.05 and 0.01 probability levels, respectively.
NS = non-significant at P>0.05.
CV=Coefficient of variation.

Table 5  Mean values of dry matter remobilisation (DMR) and DMR efficiency (DMRE) of spike, flag leaf, stem and lower leaf; contribution of dry matter to grain, active grain-filling period, grain-filling rate, NSC residue, kernel weight, grain yield and harvest index of three wheat cultivars as affected by N-fertiliser application rate.

Treatments		DMR of spike (mg plant^−1)	DMR of flag leaf (mg plant^−1)	DMR of stem (mg plant^−1)	DMR of lower leaves (mg plant^−1)	DMRE of spike (%)	DMRE of lag leaf (%)	DMRE of stem (%)	DMRE of lower leaves (%)	Total DMR (mg plant^−1)
Nitrogen (kg ha^-1)	Cultivar
0	Shiraz	152	9	293	32	23.16	25.85	17.27	19.25	488
	Marvdasht	145	11	278	47	21.26	27.89	17.27	24.55	483
	Chamran	145	0.2	241	20	28.09	17.05	16.35	17.74	473
80	Shiraz	153	16	214	47	20.78	25.28	14.88	23.31	432
	Marvdasht	227	28	159	43	30.89	22.23	11.37	21.70	437
	Chamran	190	4	262	57	33.26	24.30	18.13	25.74	509
160	Shiraz	169	34	299	25	22.15	28.01	17.27	16.18	527
	Marvdasht	145	15	163	38	20.65	21.61	11.91	19.09	361
	Chamran	123	0.9	219	48	23.23	19.51	20.05	22.81	391
	LSD (0.05)	23	1.2	26	3.9	2.5	2.6	1.8	2.1	35
Source of variation
	Nitrogen (N)	NS	*	*	NS	NS	NS	*	NS	*
	Cultivar (C)	*	*	*	NS	NS	*	*	NS	*
	N×C	NS	*	NS	NS	NS	*	NS	NS	NS
CV,%		8.4	4.7	11.4	9.2	15.6	16.2	8.9	13.5	12.1
		Total DMRE (%)	Contribution of DMR to grain (%)	Active grain-filling period (day)	Grain-illing rate (g day^–1)	NSC residue (mg g^−1 DW)	Kernel weight (g)	Grain yield (kg ha^−1)	Harvest index (%)
0	Shiraz	20.07	11.53	35	1.2	280	32.44	4946	32.39
	Marvdasht	19.83	11.57	28	1.5	223	28.93	5091	32.25
	Chamran	19.95	9.46	19	1.9	150	34.85	5365	34.05
80	Shiraz	17.52	11.99	38	0.9	311	30.44	4882	26.11
	Marvdasht	20.23	15.33	32	1.3	254	26.76	4783	25.67
	Chamran	23.77	12.71	23	1.6	173	32.60	5641	29.23
160	Shiraz	19.55	11.55	42	0.8	343	29.58	4568	26.91
	Marvdasht	14.48	8.39	36	1.1	285	26.77	4847	28.24
	Chamran	20.15	8.32	27	1.3	197	33.69	6253	34.05
	LSD (0.05)	2.1	0.9	3.8	0.2	29	3.5	1211	4.9
Source of variation
	Nitrogen (N)	*	NS	*	*	*	*	*	*
	Cultivar (C)	NS	NS	*	*	*	*	*	*
	N×C	NS	NS	*	*	NS	NS	NS	NS
CV,%		7	5.6	13.6	9.5	17.3	11.5	14.2	17.3
NSC = non-structural carbohydrates.
WW = well-watered treatment.
WD = post-anthesis water deficit.
LSD = least significant difference.
*,** significant at 0.05 and 0.01 probability levels, respectively.
NS = non-significant at P>0.05.
CV=Coefficient of variation.

Table 6  Mean values of dry matter remobilisation (DMR) and DMR efficiency (DMRE) of spike, flag leaf, stem and lower leaf; contribution of dry matter to grain, active grain-filling period and grain-filling rate of three wheat cultivars as affected by N-fertiliser application rate and irrigation treatments.

Treatments			DMR of flag leaf (mg plant^−1)	DMR of stem (mg plant^−1)	DMRE of flag leaf (%)	DMRE of stem (%)	Active grain-filling period (day)	Grain-filling rate (mg day^−1)
Irrigation	Nitrogen (kg ha^−1)	Cultivar
WW	0	Shiraz	8	229	23.43	13.40	34	1.2
		Marvdasht	7	311	24.95	19.02	30	1.4
		Chamran	0.1	163	13.76	11.90	24	1.7
	80	Shiraz	13	80	24.45	5.86	38	1.0
		Marvdasht	28	62	13.52	5.17	34	1.2
		Chamran	1	263	20.12	18.35	29	1.4
	160	Shiraz	29	284	25.36	16.41	41	0.8
		Marvdasht	11	129	21.27	10.05	37	1.0
		Chamran	0.5	198	18.27	25.05	31	1.2
WD	0	Shiraz	11	358	28.27	21.15	26	1.2
		Marvdasht	15	245	30.83	15.52	25	1.4
		Chamran	0.1	320	20.33	20.81	18	1.7
	80	Shiraz	19	348	26.12	23.91	33	0.9
		Marvdasht	27	256	30.93	17.57	30	1.2
		Chamran	8	260	28.47	17.93	23	1.4
	160	Shiraz	38	314	30.65	18.13	35	0.8
		Marvdasht	18	196	21.96	13.77	32	1.1
		Chamran	3	239	20.76	15.06	26	1.3
	LSD (0.05)		1.3	25	2.7	2	3.6	0.3
Source of variation
	I×N×C		*	*	*	*	*	*
CV,%			5.1	12.3	18.9	11.1	14.8	10.2
WW = well-watered treatment.
WD = post-anthesis water deficit.
LSD = least significant difference.
*,** significant at 0.05 and 0.01 probability levels, respectively.
NS = non-significant at P>0.05.
CV=Coefficient of variation.