Introduction

In 2013 in México, 683 044 ha of wheat wheat (Triticum aestivum L. and wheat macaroni (T. durum L.) were harvested and harvested 3 357 306 t, the previous occurrence was 94.4% under irrigation conditions during the In the same cycle, in Guanajuato, 100% of its surface under irrigation was planted, which was 42 213 ha and contributed 60 250 t, placing it in the third place of the planted area and the sixth place in in the national production. Also this crop occupied the second place in area planted in the state (^{SIAP, 2015}). According to ^{Bolaños et al. (2001)} of twelve crops analyzed, wheat ranked third with the highest expenditure on its irrigation sheet with 0.97 m per crop cycle, surpassed by strawberry and alfalfa with 1.45 and 1.1 m, respectively. Its irrigation blade is superior to the average of the chickpea, tomato, tomato, onion, broccoli, asparagus, corn, beans and beans.

This indicates the dependence of national wheat production on irrigation water and partially explains why Mexico spends more than 80% of its volume of water in agriculture. In 2010 in Guanajuato of the 4 134 hm³ year^-1 consumed, 83.1% of water was destined for agriculture and 66.5% came from the aquifers (^{CONAGUA, 2010}). So that in the municipality of Celaya, Guanajuato, in 2004 there were 2 000 wells with a depth of extraction of 80 to 100 m, which supplied 593*106 m³ of water per year. While for 2009 they increased to 2 887 and 600*106 m³ were extracted at a depth greater than 110 m (^{Huizar et al., 2011}). This has contributed to the fact that Guanajuato has been declared as having medium-strong pressure since 2005 (the degree of pressure on the water resource is defined as the total volume of water granted between natural availability) on this resource (^{CONAGUA, 2010}). Based on the above and according to ^{Geerts and Raes (2009)}, under these conditions of irrigation water deficiency, the yields and the anthropocentric quality of the crops must be maintained.

In this context, the United States of America, the main exporter of wheat flour to México, bases its production under temporary conditions, which reduces its production costs. In addition, the winter red durum wheat of which more than one million tonnes (^{CANIMOLT, 2013}) are imported annually, is characterized as being of good quality bakery for presenting protein content of 12.6%, hectolitric weight of 79.4 kg hL^-1, mass strength of 350*10^-4 J, tensile-extensibility ratio of 1.2 and pan volumes of 842 mL (^{Maghirang et al., 2006}).

Thus, the production of irrigated wheat flour produced in Mexico must compete, in price and industrial quality, with imported wheat. Based on the above, it is necessary to evaluate the amount of water in this crop associated with the industrial quality characteristics (^{Solís et al., 2014}). Since breeding programs in Mexico for irrigation areas usually evaluate grain yield and irrigation water use; however, there is a need to characterize their industrial quality in relation to this factor. Therefore, the objective of the present investigation was to determine the behavior of industrial quality characteristics of commercial varieties of wheat flour in relation to the application of the number of irrigations.

Materials and methods

Results and discussion

Significant differences were found between irrigation schedules and genotypes for all industrial quality variables analyzed, which agrees with that reported by ^{Huang et al. (2004)}, ^{Ghanbari (2010)}, ^{Seleiman et al. (2011)} and ^{Weiwei et al. (2015)}. For genotype interaction by irrigation timing differences were found in most of the parameters tested except for grain hardness (Table 1).

^*, ^**= significativas con p≤ 0.05 y p≤ 0.01; Gen= genotipo; FV= fuente de variación; gl= grados de libertad; PHL= peso hectolítrico; DG= dureza de grano; PH= proteína en harina; TAM= tiempo de amasado; W= fuerza de la masa; PL= relación tenacidad/extensibilidad; VP= volumen de pan; CV= coeficiente de variación

Table 1 Mean squares grain yield and industrial quality variables bread wheat under different irrigation schedules. 

The protein content in flour, bread strength and volume of bread showed their highest values when the schedule of two irrigations were applied, and decreased with those of three and four (Table 2).

^†= Valores medios con diferente letra en una columna son estadísticamente diferentes. PHL= peso hectolítrico; DG= dureza de grano; PH= proteína en harina; TAM= tiempo de amasado; W= fuerza de la masa; PL= relación tenacidad/extensibilidad; VP= volumen de pan; CV= coeficiente de variación. DSH= diferencia significativa honesta.

Table 2 Comparison of means of industrial quality variables of wheat flour by irrigation schedule. 

The increase of protein and the force of the mass, according to the indicated by ^{Konopka et al. (2007)} and ^{Flumignan et al. (2013)}, in association with good extensibility, by PL< 1, caused volumes of bread larger than 900 mL (Table 2). This supports what ^{Aslani et al. (2006)} and ^{Chang et al. (2009)} who found that the high volumes of bread are favored by the greater extensibility of the mass. By using three rescue irrigations it was possible to obtain strong mass characteristics with excellent extensibility, with W greater than 300*10^-4 J and PL= 0.7, which produced bread volumes above 800 mL, suitable for industry of breadmaking (Table 2).

In addition, it was associated with hectoliter weights greater than 75 kg hL^-1, which will favor flour yield in the milling industry, which is in agreement with ^{Baasandorj et al. (2015)} who indicated that grains with high hectoliters weights favor the extraction of flour. The application of the fourirrigation schedule yielded the highest values in hectoliter weight; however, it was associated with the lowest values of protein, kneading time, mass strength and bread volume, while a with an only irrigation of aid, the industrial quality characteristics presented acceptable values for the national industry (Table 2).

The best bread volume was obtained with the 0-35-70 calendar; that is, when there was drought during flowering, this coincides with the higher protein content in the flour and with the greatest strength. The irrigation schedule 0-35- 70-105, when the drought was presented in grain filling the second best bread volume was obtained, coinciding with the second best protein content and mass strength. The third value of bread volume was obtained when the drought was presented in the state of embouchure with the calendar 0-35 and the smaller volume of bread was obtained without drought with the calendar 0-35-70-105- 125 associating with the lower values of protein in the flour and strength of the dough. These results are consistent with those reported by ^{Konopka et al. (2007)} and ^{Flumignan et al. (2013)}. As found in this study ^{Kimball et al. (2001)} who reported that quality decreases when wheat grows in stress-free conditions.

With the exception of the variety Galvez M87, which showed soft grain, all varieties were characterized by hard grain at values lower than 47%, (Table 3), which is appropriate to improve the baking quality according to what is reported by ^{Barrera et al. (2007)}, since there is an amount of starch damaged during grinding, which causes greater absorption of water and facilitates the action of the enzymes, which increases the production of gas during fermentation. All varieties gave rise to masses that were classified as strong by their W> 300*10^-4 J, which is due in part to the quality of their protein alleles present in the flour that favor the gluten strength (^{Espitia et al., 2008}).

Valores medios con diferente letra en una columna son estadísticamente diferentes. PHL= peso hectolítrico; DG= dureza de grano; PH= proteína en harina; TAM= tiempo de amasado; W= fuerza de la masa; PL= relación tenacidad/extensibilidad; VP= volumen de pan; CV= coeficiente de variación. DSH= diferencia significativa honesta.

Table 3 Comparison of means of industrial quality variables of wheat wheat varieties under different irrigation schedule conditions. 

Based on their PL, most of the varieties were grouped as extensible for their values lower than 1.1. The exceptions were Tlaxcala F2000 and Rebeca F2000, which were classified as balanced and tenacious by their PL= 1 and greater than 1.2, respectively (Table 3). Therefore, most of the genotypes combined strong and extensible masses, which consequently favor the bread volume.

The variety Temporalera M87 presented the second place of protein in refined flour associated with strong and extensible dough, which was reflected in its bulk bread. This was corroborated by the positive correlations of bread volume with protein in flour and mass strength (Table 4). On the other hand, the bread volume was negatively correlated with the PL, which indicates that the masses must have greater extensibility; that is, low PL values associated with high protein values and mass strength, which had already been pointed out by ^{Sánchez et al. (2015)}.

VP= volumen de pan; *, **= significativas con p≤ 0.05 y p≤ 0.01; ns= no significativo.

Table 4 Pearson correlations between industrial quality variables of wheat wheat varieties under different irrigation schedules. 

These correlations are corroborated in schedules one and two of irrigation, as the bread volume correlated positively with protein content in flour, and negatively with the tenacity/extensibility ratio; while in the condition of two irrigations was positively related to kneading time. On the other hand, the grain hardness was negatively correlated with the percentage of protein in flour in all the irrigation regimes; however, since high values of this variable are indicative of soft grains, it is concluded that soft grains are associated with a lower percentage of protein in flour (Table 5), it is evident that the association of bread volume varies through the calendars of irrigation, due to the increase in the expression of some characters and the decrease in others.

*, **= significativas con p≤ 0.05 y p≤ 0.01; ns= no significativo; PHL= peso hectolítrico; DG= dureza de grano; PH= proteína en harina; TAM= tiempo de amasado; W= fuerza de la masa; PL= relación tenacidad/extensibilidad; VP= volumen de pan.

Table 5 Pearson correlations by irrigation timing between industrial quality variables of wheat wheat varieties. 

The variety Rebeca F2000 was associated to the greater weight hectolitric; however, their bread volume was the smallest. This is explained by its PL> 1.2, which is characteristic of tenacious masses, which have little extensibility of the mass, which consequently decreases the volume of bread according to ^{Sánchez et al. (2015)}.

By applying the three irrigation schedule, the varieties Romoga F96, Náhuatl F2000, Juchi F2000, Rebeca F2000, Tlaxcala F2000 and Batán F96 presented bread volumes greater than 900 ml (Figure 1d). This is due to the fact that they combined protein contents greater than 12% (Figure 1a), mass strength greater than 550*10^-4 J (Figure 1b) and toughness / extensibility values lower than 1.1 (Figure 1c), which indicates balanced masses that associate with high mass strength favor the baking quality, which agrees with the one indicated by ^{Verheyen et al. (2015)}.

Figure 1 Performance of protein flour (a), force the mass (b), regarding tenacity/extensibility PL (c) and bread volume (d) of bread wheat varieties by irrigation schedules. 1: 0-35, 2: 0-35-70, 3: 0-35-70-105 and 4: 0-35-70-105-125. DSH= significant honest difference.  

On the other hand, with the application of four irrigations the majority of the genotypes presented values superior to 800 ml of volume of bread with the exception of Rebeca F2000 and Juchi F2000, which in the case of Rebeca F2000 is explained by its greater PL to 1.2, which indicates tenacious masses which demerits the volume of bread. By applying five irrigations, most of the genotypes decreased their bread volume with values lower than 800 ml. However, the Náhuatl F2000 and Tlaxcala F2000 genotypes exceeded this value and were therefore associated with acceptable bread volumes, both genotypes presented strength of the mass greater than 450*10^-4 J and values smaller than 1.2 of PL.

With the application of the one irrigation calendar the genotypes Temporalera M87, Pavan F76, Gálvez M87, Romoga F96, Náhuatl F2000 and Zacatecas VT74 presented bread volumes greater than 800 ml, since they combined mass strength higher than 350 x 10-4 J and PL less than 1.2; contrary behavior showed Rebeca F2000, Tlaxcala F2000 and Batán F96, which by their PL greater than 1.2 were associated with tenacious masses, which decreased their bread volume, which is in agreement with what was found by ^{Martínez et al. (2010)}. Therefore, since the bread quality measured as bread volume is a function of the amount of protein in the flour, strength, extensibility and tenacity of the dough, through the application of different irrigation schedules it was possible to modify these variables depending on the genotype.

Conclusions

The baking quality is affected by the number of irrigations, the date or phenological stage of its application and the characteristics of the mass of each variety used in the production of wheat flour. As a result of the application of three irrigations favored the protein concentration in the grain which associated with strong and extensible mass presented the largest volumes of bread and the application of five irrigations showed the lower percentages of protein in flour, as well as mass strength and consequently decreased bread volume. Therefore, by managing the number of irrigations, date of application and varieties, it is possible to modify the industrial quality.