Effects of tillage, crop rotation and nitrogen fertilization on wheat-grain quality grown under rainfed Mediterranean conditions

Field Crops Research 57 Ž1998. 265–276

Effects of tillage, crop rotation and nitrogen fertilization on wheat-grain quality grown under rainfed Mediterranean conditions L. Lopez-Bellido ´ a

a,)

, M. Fuentes

a,1

, J.E. Castillo

a,1

, F.J. Lopez-Garrido ´

b

Departamento de Ciencias y Recursos Agrıcolas y Forestales, UniÕersity of Cordoba, P.O. Box 3048, 14080 Cordoba, Spain ´ ´ ´ b Departamento de Produccion ´ Vegetal y Tecnologıa ´ Agraria, UniÕersity of Castilla-La Mancha., Ciudad Real, Spain Received 18 July 1997; revised 29 October 1997; accepted 30 October 1997

Abstract The grain quality of wheat is influenced by the protein content, which in turn depends on environmental conditions and cropping practices. We carried out a 3-year field study in a rainfed Mediterranean region on the effects of tillage, crop rotation and nitrogen fertilization on the grain quality of hard red spring wheat ŽTriticum aestiÕum. in terms of protein content, test weight and alveogram indices. Tillage treatments were no tillage ŽNT. and conventional tillage ŽCT.. Crop rotations were wheat–sunflower Ž Helianthus annus L.. ŽWS., wheat–chickpea Ž Cicer arietinum L.. ŽWCP., wheat–fababean Ž Vicia faba L.. ŽWFB., wheat–fallow ŽWF. and continuous wheat ŽCW.. Fertilizer nitrogen was used at three different rates: 50, 100 and 150 kg N hay1. A split–split plot design with four replicates was used. Grain protein content was found to be inversely proportional to rainfall during the growing season. The tillage method was also found to affect grain protein content, test weight and some grain quality indices. Through its effect on moisture and nitrate in the soil. The crop rotations that included a legume ŽWCP and WFB. had marked effects on wheat quality. The increased grain protein content and resulted in improved rheological properties of the dough Žviz. a higher alveogram index and a more balanced tenacityrextensibility ratio.. However, no differences due to N dilution in the plant were observed in the wettest year studied, which was also the highest yielding. Increasing the fertilizer N rate increased the grain protein content; this variable had the most marked influence on grain quality indices, though in the year that gave the highest yield the N dilution effect was observed. The many significant interactions among experimental variables reveal a close relationship among grain yield, protein content, grain quality and the wheat growth conditions. Specifically, the amount of rainfall and its distribution in the growing season strongly influenced N availability and uptake by the crop, as well as wheat-grain quality indices. q 1998 Elsevier Science B.V. All rights reserved. Keywords: Grain quality; Crop rotation; N fertilizer; Rainfed conditions; Tillage; Wheat

1. Introduction

)

Corresponding author. Tel.: q34-57-218495; fax: q34-57298343; e-mail: [email protected]. 1 Tel.: q34-57-218495; Fax: q34-57-298343.

The baking quality of wheat flour has, for some time, been known to increase with increasing protein content in the wheat grain ŽRandall et al., 1990., and protein content is regarded as a major index for

0378-4290r98r$19.00 q 1998 Elsevier Science B.V. All rights reserved. PII S 0 3 7 8 - 4 2 9 0 Ž 9 7 . 0 0 1 3 7 - 8

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L. Lopez-Bellido et al.r Field Crops Research 57 (1998) 265–276 ´

wheat quality ŽStoddard and Marshall, 1990.. In fact, the quality of wheat is ranked according to the protein concentration in the grain ŽCanada Grains Council, 1989.. According to Terman et al. Ž1969., the breadmaking quality of hard spring wheat is directly related to the protein content of the gluten. Some authors, including Timms et al. Ž1981. and Randall et al. Ž1990., have questioned, however, the widespread assumption that an increased protein content always results in increased breadmaking quality because of the imbalance in N and S content as protein contents increase. The protein content in wheat grains is largely dependent on genotype ŽJohnson et al., 1985; Stoddard and Marshall, 1990. but is also influenced by environment ŽRao et al., 1993.. Prominent among environmental factors are climate ŽJohnson and Mattern, 1987., residual N in the soil ŽOlson et al., 1976., the rate and application time of fertilizer N ŽHunter and Stanford, 1973; Fowler and Brydon, 1989., crop rotation ŽBorghi et al., 1995., and interactions among them ŽSmika and Greb, 1973.. Temperature, rainfall, and solar radiation are the climatological factors with the most marked effects on protein concentration in wheat during the grainfilling period. High temperature during grain-filling has a favourable effect on the grain protein content, as does water stress ŽRao et al., 1993.. Under drought conditions, the protein concentration is usually higher. According to Johnson and Mattern Ž1987., the length of the grain-filling period is also important, though this itself is directly affected by temperature and water availability. Those conditions leading to long grain-filling periods Že.g., in northwestern Europe. should result in well-filled grains with a low protein content. By contrast, under conditions of heat and drought such as those in the US High Plains and the Mediterranean regions, where the grain-filling period is shorter and grain yields lower, wheat generally contains more protein. In broad terms, wheat yield and protein content are negatively and linearly related ŽHaunold et al., 1962; Pearman et al., 1978; Halloran, 1981.. The most frequently quoted reasons for this are energy constraints and dilution effects. The dilution effect is the most consistent source of this negative relationship. Under favourable growing conditions, starch and protein build up simultaneously and protein con-

tent may vary by "2% ŽBechtel et al., 1982.. Water stress and high temperature during the grain-filling period hinder the conversion of sucrose into starch but have less effect on protein formation ŽBrooks et al., 1982; Bhullar and Jenner, 1986.. Tillage method and crop rotation Žincluding legumes and fallow. may also influence the protein content and breadmaking quality of wheat ŽZentner et al., 1990; Cox and Shelton, 1992; Borghi et al., 1995.. The fertilizer N rate and application time have important effects on wheat yield and protein content. According to Campbell et al. Ž1977., the effects of N and water stress on protein content are related. In general, the primary effect of fertilizer N applied to soil of appropriate moisture is increased yield, with little effect on grain protein. Severe water stress increases protein content and reduces yield. Between the two extremes, fertilizer N increases both grain yield and protein content ŽTerman et al., 1969.. Delayed application of N favours protein build-up in the grain over an increased yield ŽSowers et al., 1994. and influences the breadmaking quality of the resulting flour ŽAyoub et al., 1994.. These authors claim that split application of fertilizer N increases the protein concentration in grain and improves wheat baking quality; in addition, smaller N rates can be used, resulting in decreased N losses from the soil– plant system. Fertilizer N also affects the NrS ratio and can result in a shortage of S and hence in sulphur-containing amino acids, which influence breadmaking quality ŽTimms et al., 1981.. A long-term experiment was started in 1986, to study the effects of tillage method, crop rotation and N fertilizer rate on wheat production and soil N dynamics under rainfed conditions. This work presents the results in wheat-grain quality for a 3-year period. 2. Material and methods Field experiments were conducted at Cordoba, ´ southern Spain Ž37846X N, 4831X W, 280 m above sea level. on a Vertisol ŽTypic Haploxerert. typical of the Mediterranean region. The experiment was carried out in 1988–1989, 1989–1990 and 1990–1991 in a 135 = 185 m2 Ž24,975 m2 . area, and was designed as a randomized complete block with a split–split plot arrangement and four blocks. Main

L. Lopez-Bellido et al.r Field Crops Research 57 (1998) 265–276 ´

plots were tillage system wno tillage ŽNT. and conventional tillage ŽCT.x. Subplots were 2-year crop rotations wwheat–sunflower ŽWS., wheat–chickpea ŽWCP., wheat–fababean ŽWFB. and wheat–fallow ŽWF.x and continuous wheat ŽCW.. Finally, sub-subplots were fertilizer N rates Ž50, 100 and 150 kg N hay1 . applied only to wheat. Each rotation was duplicated in the reverse crop sequence in order to obtain data for all crops on a yearly basis. The area of each sub-subplot was 100 m2 Ž10 = 10 m2 .. The NT treatment was performed with a no-till drill ŽGreat Plains.. Weeds were controlled with glyphosateq MCPA prior to planting. The CT treatment involved plowing, disc harrowing, andror vibrating tine cultivation. Crop residues were not removed in either tillage method; rather, they remained as mulch in the NT treatment and were incorporated into CT treatments. Hard red spring wheat Žcv. Cajeme. was usually sown in November. Nitrogen fertilizer was applied to wheat plots as urea granules. At all application rates, half was applied before sowing Žincorporated by disc harrowing in CT plots and surface-broadcast in NT plots.; the remaining N was applied as top dressing at the beginning of wheat tillering. No N was applied to the other crops. Every 2 years, wheat plots were also supplied with P fertilizer at a rate of 55 kg P hay1 , which was soil-incorporated under CT and surface-broadcast in NT plots. The high levels of available K present in the soil made application of this nutrient unnecessary. Wheat was harvested early in June each year, using a 1.5-m wide Nursemaster elite plot combine Ž30 m2 per sub-subplot.. Grain protein contents were determined by near infrared reflectance spectroscopy, using a Technicon Infra Analyzer 300 B instrument. Test weights Žweights per unit volume. were obtained with a Schopper chondrometer. Wheat-grain quality was evaluated by using a Chopin alveograph in accordance with the ICC 121 Standard Method of the International Association of Cereal Chemistry ŽICC, 1986.. The alveograph was used to measure the rheological properties of dough prepared from flour and water under standard conditions. The dough was formed into disc-shaped pieces that were inflated into bubbles. The pressure variation inside each bubble was recorded in graphical form as an ‘alveogram’ ŽBorghi et al., 1995.. The maximum

267

height of the curve provides an estimate of dough tenacity Ž P denotes overpressure, in mm. and its length is a measure of dough extensibility Ž L is the abscissa at rupture, in mm. and swelling index Ž G, in ml.. Finally, the area under the curve is proportional to the energy required to cause the test piece Žor dough bubble. to break ŽW is the alveogram index, in J = 10y4 . ŽRasper, 1991.. The Spanish ranking based on the alveogram index is as follows: class 1 Žimproved wheat., W ) 200 = 10y4 J; class 2 Žordinary wheat for direct breadmaking., 200 = 10y4 ) W ) 100 = 10y4 J; class 3 Žwheat for biscuits., W - 100 = 10y4 J. To be appropriate for breadmaking, wheat should also have a tenacity-to-extensibility ratio PrL - 1. The results were subjected to analysis of variance ŽANOVA., and significance among means as LSD. Correlations among annual grain yield, protein content, test weight and dough quality indices were also determined. 3. Results and discussion 3.1. Weather conditions Fig. 1 shows the monthly distribution of rainfall and changes in the 10-day mean temperature during the growing season for the 3 years studied. The total rainfall was 416,700 and 569 mm in the 1988–1989, 1989–1990 and 1990–1991 season, respectively. The greatest amounts of precipitation were always recorded prior to heading ŽOctober to March. and accounted for 71%, 80% and 65% of all rainfall for

Fig. 1. Ten-day average temperatures and monthly rainfall at Cordoba, Spain. ´

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L. Lopez-Bellido et al.r Field Crops Research 57 (1998) 265–276 ´

the 1988–1989, 1989–1990 and 1990–1991 season, respectively; however, there were marked differences in rainfall distribution among years. In 1990–1991, rainfall peaked during the reproductive and grainripening periods ŽMarch to early June., while for the same period in the 1989–1990 season Žthe wettest of the three. rainfall was the lowest. The mean winter temperatures were almost always highest in the 1989–1990 season and lowest in the 1990–1991 season. The mean temperature ranged from about 15 to 228C during the grain-formation period in the three seasons. The number of thermal units Žbasis 08C. for the grain-formation period ŽApril–June. were 12608C in 1988–1989, 13098C in 1989–1990 and 12428C in 1990–1991. The total solar radiation for the grain-formation period Žmeasured with a Moll CM5 thermopile pyranometer. was 1576, 1597 and 1613 MJ my2 in 1989, 1990 and 1991, respectively. 3.2. Grain yield Grain yield varied significantly among years, in a similar manner to rainfall during the growing season ŽTables 1 and 2.. In fact, the 1989–1990 season, the wettest of the three gave a much higher grain yield than the other two. Other data obtained during the long-term experiment Žbetween 1988 and 1994. reveal a direct relationship between grain yield and the amount of rainfall during the vegetative period of wheat ŽLopez-Bellido et al., 1996.. The Vertisols ´ used in this study, with a high proportion of clay Ž73 " 5%., absorbed abundant water that they retained over long periods. The rainfall for 1990–1991 was similar to the average for the area and that for 1989–1990 well below average. The smaller differences in grain yield between these two seasons can be ascribed to the more favourable rainfall distribution pattern of the driest year Ž203 mm tony1 of grain in 1988–1989 vs. 223 mm tony1 in 1990– 1991., but only was 146 mm tony1 of grain in 1989–1990 Žthe wettest year.. Tillage method had no significant effect on grain yield for the 3 years as a whole ŽTable 1.. Differences, however, were significant in the wettest Ž1989–1990. and driest year Ž1988–1989.; yields were higher with CT in the former and with NT in the latter ŽTable 2.. The year = tillage interaction was significant ŽTable 1..

Crop rotation had a significant influence on grain yield, both over the 3 years as a whole and in each individual season ŽTables 1 and 2.. Grain yield decreased in the following rotation sequence during the three years as a whole: WFB ) WF ) WCP ) WS ) CW. Wheat grain yield following fababean exceeded that of fallow, which in turn was greater than that of chickpea. In the wettest year Ž1989– 1990., wheat yield in the WFB rotation was significantly higher than that in WF, which was essentially the same as in WCP and WS. In the driest season Ž1988–1989., grain yield was highest in the WF rotation and identical for WS and CW. Finally, in the season with the intermediate rainfall, the WFB rotation produced a significantly increased grain yield, with no significant differences between the WF and WCP rotations. The year = rotation interaction was significant ŽTable 1. as was the year = tillage = rotation three-way interaction ŽTable 1.. Fertilizer N rate had a significant effect on grain yield, both in the three years as a whole ŽTable 1. and in the wetter years Ž1989–1990 and 1990– 1991.ŽTable 2.. There were differences among the three rates used in 1989–1990; by contrast, there were no differences between the higher two Ž100 and 150 kg N hay1 . in 1990–1991 ŽTable 2.. The amount of rainfall is, therefore, correlated with the response to fertilizer N. None of the N rates used influenced grain yield in the driest season Ž1988–1989.. The year = N rate interaction was significant ŽTable 1.. 3.3. Grain protein content The grain protein content varied significantly and inversely with the amount of rainfall for the 3 years as a whole ŽTable 1.. The driest season Ž1988–1989. gave rise to the highest protein content ŽTable 2.. According to Johnson and Mattern Ž1987., and Rao et al. Ž1993., the protein concentration in the grain increases with drought and decreases with abundant rainfall. The protein content and grain yield were weakly and negatively correlated Ž P - 0.05. for the 3 years as a whole Ž r s y0.13, n s 360.. According to Kramer Ž1979., the correlation between grain yield and protein content for the same phenotype Žour case. can be zero, positive or negative, depending on

Source

df

Year ŽYR. 2 Tillage ŽTILL. 1 YR=TILL 2 Error a 9 Rotation ŽROT. 4 YR=ROT 8 TILL=ROT 4 YR=TILL=ROT 8 Error b 72 N rate ŽN. 2 YR=N 4 TILL=N 2 YR=TILL=N 4 ROT=N 8 YR=ROT=N 16 TILL=ROT=N 8 YR=TILL=ROT=N 16 Error c 180

Grain yield Žkg hay1 .=10 4 )))

24,646

1097) ) 87 2177) ) ) 273) ) ) 84) ) ) 13 242) ) ) 164) ) )

15

Protein Žg kgy1 . )))

8.77 16.21) ) )

Test weight Žkg hly1 .

Chopin alveograph parameters W Ž=10y4 J.

)))

1561.32 16.04 )

)))

167,959

0.55 3.59 ) ) ) 2.64 ) ) ) 1.73 ) )

3.04 5.25 ) ) 8.97 ) ) ) 3.05 )

17,525) ) ) 697 10,649) ) 11898) ) ) 9234) )

0.36 77.17 ) ) ) 20.67 ) ) )

1.16 89.57 ) ) ) 35.65 ) ) )

2104 148,089) ) ) 33,495) ) )

1.70 ) 1.18 ) 1.57 ) ) )

4577)

0.53

1649

0.46

P Žmn.

L Žmm.

)))

23,577 2979) ) ) 3859) ) ) 58

66,190 5787) ) 8733) ) ) 323 1649) ) ) 1055) ) )

106 1111) ) )

239 7849) ) ) 2423) ) )

71

)))

181

Pr L

G Žml. )))

88.77 1.05 ) 6.47 ) ) ) 0.17 1.35 ) ) ) 0.72 ) ) ) 0.54 ) ) 0.49 ) ) 0.13 3.60 ) ) ) 2.71) ) )

0.18

1246.1) ) ) 55.1) ) 141.2 ) ) ) 3.4 26.9 ) ) ) 17.5 ) ) ) 10.1) 8.1) 3.4 136.5 ) ) ) 47.7 ) ) )

2.8

L. Lopez-Bellido et al.r Field Crops Research 57 (1998) 265–276 ´

Table 1 Analysis of variance Žmean square. of grain yield, protein content, test weight and alveograph parameters for a hard red spring wheat Žcv. Cajeme., as affected by year, tillage, ŽSpain. crop rotation and N rate in a 3-year Ž1988–1989 to 1990–1991. experiment at Cordoba ´

) ,) ) ,) ) )

: Significant at the 0.05, 0.01 and 0.001 probability levels, respectively. W, alveogram index; P, dough tenacity; L, dough extensibility; G, swelling index.

269

270

L. Lopez-Bellido et al.r Field Crops Research 57 (1998) 265–276 ´

soil fertility. Johnson and Mattern Ž1987. believe that grain yield and protein content are not always negatively correlated, and that when they are, the correlation is not large enough for protein content differences to be unequivocally ascribed to grain yield differences. The tillage method used affected the grain protein content; however, differences were significant only in 1990–1991 ŽTables 1 and 2.. Other data from this experiment ŽLopez-Bellido et al., 1996. revealed ´ higher NOy –N contents within the first 60 cm of 3 soil for CT than for NT. Crop rotation had a significant influence on grain protein content, both in the 3 years as a whole and in each individual season ŽTables 1 and 2.. Rotations including a legume ŽWFB and WCP. gave higher contents than the rest except in the wettest season Ž1989–1990.. The increased grain yield in this wet year may have led to N dilution in the plant, as previously shown by Zentner et al. Ž1990. and Borghi et al. Ž1995.. The significant year = rotation interaction may be accounted for by the differential effect of season on precipitation differences ŽTable 1.. The tillage= rotation interaction was also significant, possibly as a

result of available NOy 3 –N differences between treatments ŽFig. 2a.. Increasing the fertilizer N rate significantly increased the grain protein content ŽTables 1 and 2. except in the wettest season Ž1989–1990. owing to the above-described N dilution effect. For this reason, the year = N rate interaction was significant as well ŽTable 1.. 3.4. Test weight Test weight was significantly greater with NT ŽTables 1 and 2. than with CT. However, differences in individual years were only significant in the 1990–1991 season Žalso in favour of NT, Table 2.. Crop rotation had no effect on this index in the first two seasons Ž1988–1989 and 1989–1990. but it did in the third Ž1990–1991. and in the 3 years as a whole ŽTable 2.. Regarding crop rotations, the largest test weights in the last year were obtained with CW, WFB and WF ŽTable 2.. The fertilizer N rate was inversely related to test weight, which decreased with increasing rate except in the wettest season Ž1989–1990, Table 2.. The year = crop rotation,

Fig. 2. Effect of tillage method and crop rotation on wheat grain protein, test weight, and breadmaking quality according to the Chopin Alveograph parameters ŽW and G . at Cordoba, Spain, over 3 years ŽCW: continuous wheat; WS: wheat–sunflower; WCP: wheat–chickpea; ´ WFB: wheat–fababean; WF; wheat–fallow..

Treatment 1

Grain yield Žkg hay1 .

Protein Žg kgy1 .

Test weight Žkg hly1 .

1988–1989

1989–1990

1990–1991

Mean

1988–1989

1989–1990

1990–1991

Mean

1988–1989

1989–1990

1990–1991

Mean

Tillage NT CT

2350a2 1750b

4500b 5060a

2510a 2790a

3120a 3200a

110a 113a

104a 108a

107b 113a

107b 111a

75.6a 74.8a

82.1a 82.4a

77.6a 76.8b

78.5a 78.0b

Rotation CW WS WCP WFB WF

1630d 1580d 1920c 2270b 2830a

3720c 4870b 4830b 5430a 5020b

1700d 2430c 2740b 3580a 2800b

2350e 2960d 3170c 3760a 3550b

107d 109cd 113ab 116a 112bc

110a 105b 107ab 104b 106b

108b 104c 114a 115a 108b

109b 106c 111a 112a 109b

75.0a 75.3a 75.4a 74.8a 75.7a

82.4a 82.2a 82.2a 82.4a 82.1a

77.9a 76.8c 75.9d 78.2a 77.2b

78.5a 78.1bc 77.9c 78.5a 78.4ab

N rate (kg ha y 1) 50 2020a 100 2130a 150 1990a Mean 2050C

4400c 4820b 5110a 4780A

2560b 2730a 2650a 2650B

2990b 3230a 3250a 3160

99c 113b 122a 112A

106a 107a 106a 106B

99c 108b 123a 110A

101c 110b 117a 109

76.1a 75.1b 74.5c 75.3C

82.2a 82.3a 82.3a 82.3A

78.9a 77.5b 75.2c 77.2B

79.1a 78.3b 77.4c 78.3

1 2

NT, no tillage; CT, conventional tillage; CW, continuous wheat; WS, wheat–sunflower; WCP, wheat–chickpea; WFB, wheat–fababean; WF, wheat–fallow. Within year and treatment Žtillage, rotation, or N rate. means followed by the same letter are not significantly different at P - 0.05 according to LSD.

L. Lopez-Bellido et al.r Field Crops Research 57 (1998) 265–276 ´

Table 2 ŽSpain. Hard red spring wheat grain yield, protein and test weight, as affected by tillage methods, crop rotation and nitrogen rate at Cordoba ´

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L. Lopez-Bellido et al.r Field Crops Research 57 (1998) 265–276 ´

year = N rate, tillage= rotation and rotation= N rate interactions were all significant ŽTable 1 and Fig. 2b.. Test weight exhibited a highly significant positive correlation with grain yield Ž r s 0.78, n s 360. and negative with protein content Ž r s y0.45, n s 360.. 3.5. Dough quality Grain yield, dough quality and wheat growing conditions are interrelated. However, interactions among these factors are not well enough understood to account for their influence on quality. Figs. 3–5 show the extreme variability of rheological properties as reflected in the alveograms obtained for the same cultivar under different treatments in different years. Some studies suggest that an increased protein content improves the viscoelastic properties of the resulting dough and hence the breadmaking quality as expressed by the alveogram index, W ŽMartin and Taureau, 1992.. Others have shown that variations in protein content account only partly for differences in alveogram index, even though the tenacity-to-extensibility ratio, PrL, is dependent on such a content: low protein concentrations result in overstrong

dough whereas protein contents above 11% lead to an optimum PrL ratio ŽBorghi et al., 1995.. Our results for the first two seasons Ž1988–1989 and 1989–1990. are consistent with these statements; however, those for the third season Ž1990–1991. are not because an intermediate protein content gave rise to a decreased W value and a very high PrL ratio relative to the previous two. These disparate results can be ascribed to the effect of cooler temperature in delaying grain development. According to Randall and Moss Ž1990., and Blumenthal et al. Ž1991., high temperatures Žup to 308C. at a late grain-development stage result in increased dough strength and can thus significantly alter the breadmaking quality of wheat. The 1990–1991 season was cooler than the previous two. The difference was especially marked in May Ži.e., near the end of the grain development phase.. Tillage method had no effect on the alveogram index for the three years as a whole; however, it was higher under NT in the driest season Ž1989–1990. and under CT in the season with intermediate rainfall ŽTables 1 and 3.. CT gave rise to higher tenacity Ž P . than NT; conversely, NT led to higher extensibility

Fig. 3. Representative Alveograms ŽChopin Alveograph. for hard red spring wheat Žcv. Cajeme. obtained in 1989, 1990 and 1991, according to the tillage method ŽNT: no tillage; CT: conventional tillage. at Cordoba, Spain ŽW: alveogram index; PrL: tenacityrextensibility; G: ´ swelling index..

Treatment 1

W Ž=10y4 J.

P Žmm.

L Žmm.

Pr L

G Žml.

1989

1990

1991

Mean

1989

1990

1991

Mean

1989

1990

1991

Mean

1989

1990

1991

Mean

1989

1990

1991

Mean

Tillage NT CT

297a2 280b

274a 270a

203b 232a

258a 261a

84a 79a

83b 101a

107a 112a

91b 97a

92a 90a

96a 68b

44b 49a

77a 69b

1.02a 0.92b

0.90b 1.54a

2.62a 2.41a

1.52a 1.62a

21.1a 21.1a

21.5a 18.3a

14.6b 15.4a

19.1a 18.3b

Rotation CW WS WCP WFB WF

236c 280b 296a 316a 314a

284a 272a 278a 266a 261a

205b 218b 220b 243a 201b

242c 257bc 265ab 275a 259b

79a 83a 81a 82a 83a

97a 92a 91a 91a 88a

107a 114a 108a 108a 110a

94a 97a 93a 94a 94a

72b 89a 97a 99a 99a

82a 81a 87a 80a 81a

45bc 43c 50ab 53a 42c

66c 71bc 78a 77a 74ab

1.27a 0.98b 0.87b 0.85b 0.87b

1.31a 1.23a 1.17a 1.24a 1.17a

2.59a 2.81a 2.34b 2.12b 2.73a

1.72a 1.67ab 1.46c 1.40c 1.59b

18.8c 20.7b 21.7ab 22.2a 22.0ab

19.9a 19.8a 20.2a 19.7a 19.8a

14.7b 14.5b 15.5a 16.1a 14.3b

17.8c 18.4bc 19.2a 19.3a 18.7ab

N rate (kg ha y 1) 50 226c 100 303b 150 338a Mean 289A

266a 279a 271a 272B

173c 215b 264a 217C

222c 266b 291a 259

77b 83a 85a 82C

90a 92a 93a 92B

105b 113a 110a 109A

91b 96a 96a 94

74c 96b 103a 91A

81a 83a 82a 82B

39c 44b 57a 47C

65c 74b 81a 73

1.15a 0.90b 0.86b 0.97C

1.18a 1.22a 1.27a 1.22B

2.82a 2.73a 2.00b 2.52A

1.71a 1.62a 1.38b 1.57

19.0c 21.7b 22.6a 21.1A

19.9a 20.1a 19.7a 19.9B

13.7c 14.6b 16.7a 15.0C

17.6c 18.8b 19.7a 18.7

1 2

NT, no tillage; CT, conventional tillage; CW, continuous wheat; WS, wheat–sunflower; WCP, wheat–chickpea; WFB, wheat–fababean; WF, wheat–fallow. Within year and treatment Žtillage, rotation, or N rate. means followed by the same letter are not significantly different at P - 0.05 according to LSD.

L. Lopez-Bellido et al.r Field Crops Research 57 (1998) 265–276 ´

Table 3 Breadmaking quality of hard red spring wheat Žcv. Cajeme., according to the Chopin Alveograph parameters ŽW: alveogram index; P: dough tenacity; L: dough extensibility; ŽSpain. Pr L: tenacity–extensibility ratio; G: swelling index., as affected by tillage method, crop rotation and nitrogen rate at Cordoba ´

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Ž L. and swelling indices Ž G .. The PrL ratio for the 3 years as a whole was independent of the tillage method ŽTable 3, Fig. 4.. The rotations that included a legume ŽWFB and WCP. exhibited higher alveogram indices ŽW ., extensibility Ž L. and swelling indices Ž G . than the others; there were no differences, however, in the wettest year, which was also that resulting in the highest grain yields ŽTables 1 and 3, Fig. 5.. The alveogram index = protein content correlation was highly significant Ž r s 0.64, n s 360., consistent with previous results of Martin and Taureau Ž1992.. The alveogram index ŽW . was also highly significantly correlated with extensibility Ž L. Ž r s 0.78, n s 360. and the swelling index Ž G . Ž r s 0.8, n s 360.. On the other hand, tenacity Ž P . was not affected by crop rotation ŽTables 1 and 3.. The PrL ratio was more balanced also in the rotations including a legume. As a consequence, the presence of legumes in the preceding rotation had a marked effect on wheat quality and improved the viscoelastic properties of the resulting dough. This effect can be ascribed to biologically fixed residual N present in the soil profile which was efficiently taken up by the wheat. Similar results were previously reported by Borghi et al. Ž1995.. The fertilizer N rate had significant effects on all wheat quality indices ŽTable 1.. Thus, the alveogram index, P, L and G increased with increasing N rate except in the 1989–1990, the season, that with the largest rainfall and greatest grain yield, where differences in these parameters were negligible ŽTable 3.. The PrL ratio decreased with increase in the N rate. Fig. 5 shows the variation of the alveogram with fertilizer N rate. As can be seen, the alveogram shape improved as the N rate was increased by increases in the dough extensibility Ž L. and the swelling index Ž G ., which, according to Gate Ž1995., can be ascribed to changes in the NrS ratio that affect the synthesis of sulphur-containing amino acids and the formation of some gliadins. Fertilizer N thus has a favourable effect on wheat quality that is more consistent than its effect on grain yield. In fact, it was the treatment with greatest effect dough on quality in our experiment. The year = tillage interaction was significant for all the wheat quality indices defined by the alveogram ŽTable 1.. The year = rotation and year = N rate

interactions were also significant, except for tenacity Ž P . ŽTable 1.. The weather conditions during the growing season Žspecifically, the total rainfall and its distribution. therefore have a marked influence on wheat quality and alter the effects of experimental variables Žparticularly N availability and uptake by the crop at specific growth stages, which influence grain yield and hence wheat quality indices, to which it is closely related.. Dough tenacity Ž P . is less sensitive to environmental variations and the test treatment possibly because it is a genetic feature dependent on the particular cultivar ŽGate, 1995.. Finally, the tillage = rotation interaction was signifi-

Fig. 4. Representative Alveograms ŽChopin Alveograph. for hard red spring wheat Žcv. Cajeme. obtained in 1989, 1990 and 1991, according to the crop rotation ŽCW: continuous wheat; WS: wheat–sunflower; WCP: wheat–chickpea; WFB: wheat–fababean; WF: wheat–fallow. at Cordoba, Spain ŽW: alveogram index; ´ Pr L: tenacityrextensibility; G: swelling index..

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Fig. 5. Representative Alveograms ŽChopin Alveograph. for hard red spring wheat Žcv. Cajeme. obtained in 1989, 1990 and 1991, according to the nitrogen fertilizer at Cordoba, Spain ŽW: alveogram index, PrL: tenacityrextensibility, G: swelling index.. ´

cant for the alveogram index and swelling index ŽTable 1, Fig. 2..

4. Summary Under Mediterranean rainfed conditions, the amount of rainfall and its distribution during the growing season has a marked influence on wheat yield and quality. Increased availability and more thorough extraction of N by the crop in wet years result in increased grain yield and reduced protein contents by effect of N dilution in the plant, which affects wheat quality. Continuous NT is a viable alternative to CT in terms of wheat production and quality. The decreased protein contents produced by NT had no effect on dough quality expressed as alveogram indices. Rotations including a legume were the most effec-

tive of all, particularly WFB; they increased wheat yield and grain protein content, and improved the rheological properties of the resulting dough. Wheat yield was influenced by the fertilizer N rate in the years where the amount of rainfall exceeded 450 mm during the growing season. Grain protein content and dough quality increased with increase in the fertilizer N rate. This favourable effect of fertilizer N was more marked on wheat quality indices than on wheat yield. The frequent significant interactions observed Žyear = treatment. reveal a close relationship among wheat yield, quality indices and weather conditions in the growing season. Acknowledgements This work was funded by the Spain’s Plan Nacional I q D ŽProject CICYT AGF95-0553.. The authors wish to thank Assistant Technician Joaquın ´

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Munoz ˜ for his invaluable help and cooperation in the laboratory and in field work. References Ayoub, M., Guertin, S., Fregeau-Reid, J., Smith, D.L., 1994. Nitrogen fertilizer effect on breadmaking quality of hard red spring wheat in eastern Canada. Crop. Sci. 34, 1346–1352. Bechtel, D.B., Gaines, R.L., Pomeranz, Y., 1982. Protein secretion in wheat endosperm-formation of the matrix protein. Cereal Chem. 59, 336–343. Bhullar, S.S., Jenner, C.F., 1986. Effects of temperature on the conversion of sucrose to starch in the developing wheat endosperm grain physiology of wheat and barley. Aust. J. Plant Physiol. 13, 605–615. Blumenthal, C.S., Batey, I.L., Bekes, F., Wrigley, C.W., Barlow, E.W., 1991. Seasonal changes in wheat-grain quality associated with high temperatures during grain filling. Aust. J. Agric. Res. 42, 21–30. Borghi, B., Giordani, G., Corbellini, M., Vaccino, P., Guermandi, M., Toderi, G., 1995. Influence of crop rotation, manure and fertilizers on bread making quality of wheat ŽTriticum aestiÕum L... Eur. J. Agron. 4, 37–45. Brooks, A., Jenner, C.F., Aspinall, D., 1982. Effects of water deficit on endosperm starch granules and on grain physiology of wheat and barley. Aust. J. Plant Physiol. 9, 423–436. Campbell, C.A., Davidson, H.R., Warder, F.G., 1977. Effects of fertilizer N and soil moisture on yield, yield components, protein content and N accumulation in the aboveground parts of spring wheat. Can. J. Soil Sci. 57, 311–327. Canada Grains Council, 1989. Statistical Handbook. Winnipeg, Manitoba. Cox, D.J., Shelton, D.R., 1992. Genotipe-by-tillage interactions in hard red winter wheat quality evaluation. Agron. J. 84, 627– 630. Fowler, D.B., Brydon, J., 1989. No-till winter wheat production on the Canadian prairies: Timing of nitrogen fertilization. Agron. J. 81, 817–825. Gate, Ph., 1995. L’elaboration de la teneur en proteines du grain ŽElaboration of the grain protein content.. Perspectives Agricoles No. 203, pp. 44–48. Halloran, G.M., 1981. Cultivar differences in nitrogen translocation in wheat. Aust. J. Agric. Res. 32, 535–544. Haunold, A., Johnson, V.A., Schmidt, J.W., 1962. Variation in protein content of the grain of four varieties of Triticum aestiÕum L. Agron. J. 54, 121–125. Hunter, A.S., Stanford, G., 1973. Protein content of winter wheat in relation to rate and time of nitrogen fertilizer application. Agron. J. 65, 772–774. International Association of Cereal Chemistry ŽICC., 1986. Standard Methods of the ICC. Vienna. Johnson, V.A., Mattern, P.J., Peterson, C.T., Kurh, S.L., 1985. Improvement of wheat protein by traditional breeding and genetic techniques. Cereal Chem. 62, 350–355. Johnson, V.A., Mattern, P.J., 1987. Wheat, rye, and triticale. In:

Olson, R.A., Frey, K.J. ŽEds.., Nutritional Quality of Cereal Grains: Genetic and Agronomy Improvement, No. 28. Agronomy American Society of Agronomy, Madison, WI, pp. 133– 182. Kramer, T.H., 1979. Environmental and genetic variation for protein content in winter wheat ŽTriticum aestiÕum L... Euphytica 28, 209–218. Lopez-Bellido, L., Fuentes, M., Castillo, J.E., Lopez-Garrido, F.J., ´ ´ Fernandez, E.J., 1996. Long-term tillage, crop rotation, and ´ nitrogen fertilizer effects on wheat yield under rainfed Mediterranean conditions. Agron. J. 88, 783–791. Martin, G., Taureau, J.C., 1992. Ble´ tendre: qualite´ et fumure azotee. ´ wSoft wheat: quality and nitrogenous fertiliserx Perspect. Agricoles 165, 16–25. Olson, R.A., Frank, K.D., Deibert, E.J., Dreier, A.F., Sander, D.H., Johnson, V.A., 1976. Impact of residual mineral N in soil on grain protein yields of winter wheat and corn. Agron. J. 68, 769–772. Pearman, I., Thomas, S.M., Thorne, G.N., 1978. Effect of nitrogen fertilizer on growth and yield of semi-dwarf and tall varieties of winter wheat. J. Agric. Sci. 91, 31–45. Randall, P.J., Freney, J.R., Smith, C.J., Moss, H.J., Wrigley, C.W., Galbally, I.E., 1990. Effect of additions of nitrogen and sulfur to irrigated wheat at heading on grain yield, composition and milling and baking quality. Aust. J. Exp. Agric. 30, 95–101. Randall, P.J., Moss, H.J., 1990. Some effects of temperature regime during grain filling on wheat quality. Aust. J. Agric. Res. 41, 603–617. Rao, A.C.S., Smith, J.L., Jandhyala, V.K., Papendick, R.I., Parr, J.F., 1993. Cultivar and climatic effects on the protein content of soft white winter wheat. Agron. J. 85, 1023–1028. Rasper, W.F., 1991. Quality evaluation of cereals and cereal products. In: Lorenz, K.J., Kulp, K. ŽEds.., Handbook of Cereal Science and Technology, Marcel Dekker, New York, pp. 595–638. Smika, D.E., Greb, B.W., 1973. Protein content of winter wheat grain as related to soil and climatic factors in the semiarid Central Great Plains. Agron. J. 65, 433–436. Sowers, K.E., Miller, B.C., Pan, W.L., 1994. Optimizing yield and grain protein in soft white winter wheat with split nitrogen applications. Agron. J. 86, 1020–1025. Stoddard, F.L., Marshall, D.R., 1990. Variability in grain protein in Australian hexaploid wheats. Aust. J. Agric. Res. 41, 277–288. Terman, G.L., Ramig, R.E., Dreier, A.F., Olson, R.A., 1969. Yield-protein relationships in wheat grain, as affected by nitrogen and water. Agron. J. 61, 755–759. Timms, M.F., Bottomley, R.C., Ellis, J.R.S., Schofield, J.D., 1981. The baking quality and protein characteristics of a winter wheat grown at different levels of nitrogen fertilisation. J. Sci. Food Agric. 32, 684–698. Zentner, R.P., Bowren, K.E., Edwards, W., Campbell, C.A., 1990. Effects of crop rotations and fertilization on yields and quality of spring wheat grown on a black Chernozem in north central Saskatchewan. Can. J. Plant Sci. 70, 383–397.