Winter Wheat Quality Responses to Water, Environment, and Nitrogen Fertilization

Figures & data

Table 1 Influences of year, water-stress environment, and N rate on grain yield (kg ha⁻¹), grain protein (g kg⁻¹), and yield loss due to nitrogen stress (YLNS) and water stress (YLWS)

	Treatment
	N	Water	Yield	Protein	YLNS	YLWS
Year	fertilizer	environment	(kg ha^−1)	(g kg^−1)	(kg ha^−1)	(kg ha^−1)
2007	0	Water stressed	3,280	120.3	1,513	707
	1X	Water stressed	4,241	152.5	927	333
	0	Well watered	4,255	128.5	608	637
	1X	Well watered	4,835	156.8	172	493
	P value		0.0002	<0.0001	0.0002	0.07
	LSD0.05^a		501	9.2	434	NS^b
	0		3,768	124.4	1,060	672
	1X		4,538	154.6	549	413
	P value		0.011	<0.0001	0.068	0.015
		Water stressed	3,760	136.4	1,220	520
		Well watered	4,545	142.6	390	565
	P value		0.009	0.477	0.001	0.703
2008	0	Water stressed	4,277	133.5	792	1,753
	1X	Water stressed	4,701	147.8	409	1,711
	0	Well watered	4,360	118.8	1,234	1,227
	1X	Well watered	5,591	133.8	457	773
	P value		0.003	0.003	0.010	0.002
	LSD0.05		642	12.5	478	455
	0		4,318	126.1	1,013	1,490
	1X		5,146	140.8	433	1,241
	P value		0.005	0.017	0.004	0.328
		Water stressed	4,489	140.6	600	1,732
		Well watered	4,975	126.3	846	1,000
	P value		0.142	0.019	0.279	0.001

^aLSD, least significance difference.

^bNS, not significant at P = 0.05.

Note. In 2007 and 2008 the recommended N rates were 200 and 160 kg N ha⁻¹, respectively.

Table 2 Influence of year, water-stress environment, and N rate on protein (g kg⁻¹) and selected dough quality parameters

	Treatment
	N	Water	Flour protein	Peak	Stability	MTI^a	Breakdown
Year	fertilizer	environment	(g/kg)	(min)	(min)	(BU^b)	(min)
2007	0	Water stressed	104	4.90	4.9	35.5	9.25
	1X	Water stressed	139	9.50	9.5	16.0	17.9
	0	Well watered	114	5.50	5.5	31.3	11.4
	1X	Well watered	141	10.4	10.5	15.4	17.6
	P value		<0.0001	0.097	0.011	0.021	0.009
	LSD0.05		9.4	NS	4.13	14.01	5.46
	0		108	5.20	5.20	33.4	10.3
	1X		140	9.95	10.0	15.7	17.8
	P value		<0.0001	0.018	0.001	0.004	0.001
		Water stressed	122	7.20	7.20	25.8	13.6
		Well watered	128	7.90	8.00	23.4	14.5
	P value		0.496	0.609	0.544	0.461	0.724
2008	0	Water stressed	115	8.0	11.25	14.3	19.5
	1X	Water stressed	129	10.4	11.8	12.5	20.5
	0	Well watered	93	3.6	7.25	26.3	11.3
	1X	Well watered	109	8.4	8.88	25.6	15.0
	P value		0.0001	0.016	0.043	0.133	0.02
	LSD0.05		11.1	3.85	4.83	NS	5.99
	0		104	5.81	9.28	20.3	15.4
	1X		119	9.38	10.34	19.1	17.8
	P value		0.040	0.030	0.479	0.572	0.376
		Water stressed	122	9.19	11.5	13.4	20.0
		Well watered	101	6.00	8.1	25.9	13.1
	P value		0.001	0.056	0.013	0.018	0.003

^aMTI, mixing tolerance index.

^bBU, Brabender unit.

Note. In 2007 and 2008 the recommended N rates were 200 and 160 kg N ha⁻¹, respectively.

Figure 1. Relationship between N additions (N fertilizer + mineralized N) and protein content over 2 years.

Figure 2. Relationship between protein and dough stability (A) and a comparison between predicted stability, based on protein content and water stress, and measured dough stability (B).

Figure 3. Relationships between yield loss due to nitrogen stress and percentage of glutenin (A), gliadin/glutenin ratio (B), and HMW-GS/LMW-GS ratio (C) in 2007 and 2008.

Table 3 Influences of water-stress environment and N rate on protein characterization in 2007 and 2008

	Treatment
Year	N fertilizer	Water environment	Glutenine (g/kg)	Gliadin (g/kg)	Ratio of gliadin to glutenine	UPP (g/kg)	Ratio of HMW-GS to LMW-GS
2007	0	Water stressed	255	685	2.71	165	0.20
	1X	Water stressed	301	638	2.13	263	0.27
	0	Well watered	286	647	2.27	179	0.22
	1X	Well watered	352	584	1.68	354	0.28
	P value		0.0003	0.004	0.0002	0.0001	0.002
	LSD0.05		3.36	4.64	0.33	6.55	0.04
	0		270	666	2.49	172	0.21
	1X		327	621	1.90	308	0.28
	P value		0.002	0.011	0.002	0.0001	0.0002
		Water stressed	278	662	2.42	214	0.24
		Well watered	319	616	1.97	266	0.25
	P value		0.043	0.039	0.031	0.238	0.464
2008	0	Water stressed	264	677	2.57	202	0.23
	1X	Water stressed	317	610	1.93	253	0.27
	0	Well watered	289	642	2.22	182	0.24
	1X	Well watered	335	59.57	1.78	272	0.31
	P value		<0.0001	<0.0001	<0.0001	0.182	0.0002
	LSD0.05		1.45	2.05	0.15	NS	0.03
	0		277	659	2.39	192	0.24
	1X		326	603	1.86	263	0.29
	P value		<0.0001	<0.0001	<0.0001	0.028	0.0001
		Water stressed	290	644	2.25	227	0.25
		Well watered	312	619	2.00	227	0.27
	P value		0.146	0.149	0.131	0.993	0.240

Notes. Glu, glutenin; Gli, gliadin; UPP, unextractable polymeric protein; HMW-GS/LMW-GS, ratio of high-molecular-weight-glutenin subunits to low-molecular-weight-glutenin subunits. In 2007 and 2008 the recommended N rates were 200 and 160 kg N ha⁻¹, respectively.

Figure 4. Relationships between protein fraction [percentage of glutenin (A), gliadin/glutenin ratio (B), and HMW-GS/LMW-GS ratio (C)] and stability in 2007 and 2008.