Grain yield assessment of 55 triticale lines in the Mexicali Valley

In the arid zones of Mexico, low soil fertility and water availability are some of the limiting factors in the production of forage and grain for livestock feed (Ballesteros et al., 2015). In these regions, triticale is postulated as an alternative crop to corn and wheat because it produces forage and grain of ideal quality for feeding dairy and fattening cattle (Ballesteros et al., 2015).

Recent studies mention that triticale is used for feeding farm animals because it has between 10 and 20% higher protein content compared to wheat and has 0.13% and 0.04% more lysine and phosphorus compared to corn (García-Ramírez et al., 2023). Triticale represents an option for the preparation of products for human consumption, such as breads, cookies, tortillas, liquor, and beer, as an alternative to wheat, barley, and corn grains due to its high protein content and essential amino acids (Zhu, 2017).

From the agronomic point of view, the triticale crop presents adaptability to adverse drought conditions, low soil fertility, and resistance to diseases; in addition, the new varieties show grain yield potential similar to wheat, between 8 and 12.72 t ha^-1 (Mellado et al., 2005). Nevertheless, the grain yield of triticale varieties is mainly defined by their genetics and the environmental conditions of the crop, so these factors affect the profitability and efficiency of triticale production (Lalević and Biberdžić, 2015).

Under the above context, field evaluation of triticale lines with diverse genetic bases is necessary to determine their productive potential; therefore, this study aimed to evaluate the grain yield and its components in 55 advanced triticale lines in the Mexicali Valley because this area is outstanding in the production of milk and beef cattle, where the outstanding lines would be used for the production of feed.

The study was carried out during the cycle of the fall-winter (A-W) 2015-2016 in the experimental field of the Institute of Agricultural Sciences of the Autonomous University of Baja California, in the ejido Nuevo León, Mexicali, Baja California, Mexico. Fifty-five triticale lines of spring growth habit were evaluated and a variety of triticale (Bicentennial TCL 2010) was used as a control; they were established in a randomized complete block design with two replications. Triticale materials were provided by the International Maize and Wheat Improvement Center (CIMMYT, for its acronym in Spanish) and the experimental plot consisted of four rows/plot, with row spacing of 0.3 m by 2 m long (2.4 m²).

Sowing was carried out manually in dry and flat soil (December 19, 2015) with a density of 120 kg ha^-1, the fertilization was with the formula 120N-80P-00K, and four supplemental irrigations were applied during the phenological stages of tillering, stem elongation, flowering, and grain filling. The grain yield and its components were estimated for the evaluated lines; for this purpose, 2 m linear of plants were cut with a sickle in two central rows of each plot.

The yield components were estimated by randomly collecting 10 spikes from each plot, which had the following variables measured: spike length in cm (SL) and number of spikelets/spike (SS). Subsequently, the spikes were threshed individually and the remaining variables were measured: grains/spike (GS) and weight of grains/spike in g (WGS). The number of spikes m^-2 (SM2) at the time of the harvest stage was also estimated, where the spikes were counted with two representative replications in a linear meter of two central rows of each of plot (Bendada, 2022).

Analyses of variance, comparison of means with Tukey’s test (α= 0.05), and correlation analyses were performed for each of the variables recorded using the SAS 9.0 statistical package (SAS, 2002). The results of the analyses of variance showed significant differences (p≤ 0.01) between the triticale lines evaluated for grain yield and its components (spike m², spike length, spikelets/spike, grains/spike, and weight of grains/spike).

The average grain yield of the total triticale lines evaluated was 5 t ha^-1 (Table 1). For the yield components, the average values in this study were 362 spikes m^-2, 28 spikelets spike^-1, 75 grains spike^-1, 10.9 cm in spike length and 3.3 g grains spike^-1 (Table 1).

In the Tukey mean comparison tests, for the grain yield variable, 11 triticale lines were observed with yields ranging from 6.5 to 8.3 t ha^-1, which were higher than the control variety (Bicentenario TCL 2010), with a yield of 3.8 t ha^-1 (Table 2). These results are within the range of what was reported by Güngör et al. (2022), who evaluated eight triticale genotypes and obtained yields of 4.1 to 9.1 t ha^-1 in arid and semiarid regions of Turkey.

In addition, the MX-13, MX-23, MX-53, and MX-12 lines, which have the highest yields with 8.3, 8, 7.5, and 7.5 t ha^-1 (Table 1), respectively, have a similar genetic base, they share parents, such as Pollmer, which is a variety with yield potential of 10 t ha^-1 under optimal irrigation and fertilization conditions (Hede, 2001).

The results of this study showed that the 11 triticale lines with grain yields greater than 6.5 t ha^-1 can compete with the durum wheat yields produced in the Mexicali Valley, where Borbón et al. (2022) reported average yields of 6.3, 6.6, 6.6, and 6.9 t ha^-1 of the main cultivated varieties, CIRNO C2008, CENEB Oro C2017, Quetchehueca Oro C2013 and Don Lupe Oro C2020, respectively. This place triticale as a cost-effective alternative to replace wheat grain or to be a complement in cattle feed without consequences for their growth and development (Gheorghe et al., 2022).

For the yields components, 40 triticale lines were found with values of 27 and 32 spikelets spike^-1; likewise, 31 lines were observed with values of 345 and 575 spikes m^-2, higher than the control with 26 spikelets spike^-1 and 290 spikes m^-2 (Table 1 y 2). The values observed are similar to those found in a study evaluating triticale genotypes conducted by Ramírez-Calderón et al. (2003), where 27.7 to 30.8 spikelets spike^-1 were counted.

For the number of spikes m^-2, the results of this study are superior to those observed by Miranda-Domínguez et al. (2016), who reported 266 spikes m^-2. For the rest of the components, 23 superior lines were observed with values of 11.3 and 13.8 cm in spike length, 26 superior lines with values between 76 and 95 of grains spike^-1, 47 superior lines with values between 2.9 and 4 g of grains spike^-1 (Table 1 y 2).

These lines were statistically equal to the control variety, which produced 12 cm spikes, with 85 grains spike^-1 and 3.3 g of grains spike^-1. These values are similar to those recorded in studies evaluating triticale yield components conducted by Miranda-Domínguez et al. (2016); Güngör et al. (2022), where they found that the spike length ranged from 15 to 16.3 cm, number of grains spike^-1 from 79.9 to 95.7 and weight of grains spike^-1 from 2.6 to 3.8 g.

The correlation analyses showed that the spikes m^-2 component has a significant and positive correlation with grain yield (r= 0.65^**) unlike the rest of the components that did not show a significant correlation for this study. These results coincide with what was reported by Ramírez-Calderón et al. (2003), who observed a significant high correlation between the number of spikes m^-2 and grain yield (r= 0.7^**).

The correlation results showed that the spike m^-2 component can be considered as an indirect selection criterion of triticale lines for grain yield, without leaving aside the environmental and interaction conditions since the yield components are mainly influenced by changes in the genetic composition of triticale materials in response to environmental and genetic-environmental interaction conditions (Lalević and Biberdžić, 2015; Oral, 2018; Güngör et al., 2022; Lalević et al., 2022).