Pinto beans are the second most widely grown and consumed in the country, only after the Black type, they are widely marketed in the North and in recent years they have expanded with the acceptance of producers and consumers in the Central-West region. The main producing states are Chihuahua, Durango, Zacatecas and San Luis Potosí, and to a lesser extent Querétaro, Guanajuato, Sonora, Coahuila and Aguascalientes (^{SIAP-SAGARPA, 2016}).

Most of the improved varieties and pinto creoles are susceptible to rust (Uromyces appendiculatus var. appendiculatus) and anthracnose (Colletotrichum lindemuthianum), so the incorporation of resistance to these diseases has been one of the objectives of the Bean Improvement Program of the Bajío Experimental Field, the incorporation of resistance is done through the use of diverse sources of germplasm (^{Beaver et al., 2003}; ^{Singh and Shwartz, 2010}), the direct selection against rust is carried out in temporary environments, the inoculation with breeds of anthracnose of wide distribution in the Plateau of Mexico (^{Rodríguez-Guerra et al., 2006}), and recently through the use of molecular markers linked to resistance genes.

Salinas was derived from a backcross between Pinto Saltillo as a recurrent parent and line 97-RS-101 made at the Bajío Experimental Field, Celaya, Guanajuato, in 2002. Pinto Saltillo is a variety of seeds with slow darkening cover developed by selection by Pedigree of a multi-parental cross (^{Sánchez- Valdéz et al., 2004}). The line 97-RS-101 is a type II semi-erect growth habit, resistant to rust and seeds with normal darkening cover (^{Stavely et al., 1998}). The objective of the cross was to recover lines with resistance to rust and seed cover of slow darkening.

The F₁ plants self-pollinated in the greenhouse in the autumn-winter 2002-2003 and individual selections of F₂ plants were made under rainfed conditions; based on resistance to diseases that occurred naturally. Subsequently, selections were made between and within the segregating families during two growing cycles per year until generation F₉. Selections in the field were based on precocity, disease resistance and pod load, while in the cabinet they were based on seed characteristics such as size, color and cover darkness. The selection process is detailed in Table 1.

Salinas has a habit of prostrate growth type III and good capacity to cover the soil, which makes it suitable for the marginal seasonal environments prevalent in the Semi-Arid Plateau of North-Central Mexico, including northern Guanajuato and the semiarid Queretaro. The plants produce white flowers, their flowering begins between 39 to 46 days after sowing, and matures between 82 and 92 days.

The number of days to flowering is reduced as planting is delayed at the end of july. Salinas is a short-day reaction to photoperiod, as was found under greenhouse conditions by extending day length with supplementary light, and under field conditions in North Dakota, USA. UU (Osorno, 2017. Com. Pers.). Because they are sensitive to photoperiod, Salinas plants can show phenological plasticity, an adaptive characteristic under temporary conditions (^{Acosta and White, 1995}) and morphological plasticity, so in delayed plantings the plant accelerates its development, modifies the distribution of assimilates and reduces its size. The pods are flat, light green, with four to six seeds, and before reaching physiological maturity they show reddish spots. The color and shape of the seed (Figure 1) and the weight of one hundred seeds (33 ±3 g) are similar to those of Pinto Saltillo, and like this one, the seed coat is of slow darkening.

Figure 1 Typical grain of the Salinas bean variety. The seed is light cream with brown spots, elliptical in its cross section with an external rhombohedral and semi-kidney shape. 

In the adaptation and yield evaluations (Table 2), irrigation, seasonal and rainy environments with supplementary irrigation and three previously registered varieties were included. In some temporary environments (Ocampo, Guanajuato, in 2012 and 2015 and Jamaica, Dolores, Guanajuato, in 2013), low yields were obtained; while in the other environments that included the Ranch of Peña (Pénjamo, Guanajuato), Ranch The Prado (San Luis of the Paz, Guanajuato), The Calera (Salvatierra, Guanajuato) and the Bajío Experimental Field (Celaya, Guanajuato), they obtained the highest yields. In general, the yield of the varieties was modified according to the environment, mainly due to the presence of diseases and the amount and distribution of precipitation.

On average, the San Rafael yield was 1 665 kg ha^-1, varying from 668 kg ha^-1 to 3 216 kg ha^-1; that of Raramuri was 1 861 kg ha^-1, varying from 535 kg ha^-1 to 2 996 kg ha^-1, that of Pinto Saltillo was 1 581 kg ha^-1, varying from 743 kg ha^-1 to 2 113 kg ha^-1, and that of Salinas was 1 728 kg ha^-1, varying from 775 kg ha^-1 to 3 209 kg ha^-1. The minimum harvest value was higher in Salinas, while in the maximum value there are no significant differences between Salinas and San Rafael, which demonstrates the high potential of Salinas in different environments.

Salinas grain, produced in 2012 under rainfed and rainfed conditions with supplemental irrigation, was compared with that of Pinto Saltillo and San Rafael for its water absorption capacity and cooking time (characteristics related to grain quality), as well as in the content of iron, zinc and total proteins (related to nutritional quality). The water absorption capacity of the Salinas grain was superior to 100% in both cultivation conditions and similar to that of the other varieties, with the exception of Pinto Saltillo grain produced under storms that was 96.3 ±3.29%, this indicates that the grain of Salinas doubles its weight with hydration and does not present problems of impermeability or hardening, which makes it a suitable variety for the canning industry.

At cooking time, which is considered one of the most important quality parameters of the grain, Salinas had a time of 140 ±4 min under temporary conditions and 139 ±13 min under rainy conditions with an additional irrigation, similar values to those of the other two varieties, which hovered around 139 and 145 min.

In relation to the nutritional quality, the Salinas grain produced in temporary conditions had intermediate content of iron (5.1 ±0.07 mg 100 g^-1) and protein (22.3 ±0.08%) in comparison with San Rafael and Pinto Saltillo and the content more low zinc (2.7 ±0.21 mg 100 g^-1), similar to that of Pinto Saltillo; while in temporary conditions with supplemental irrigation, the protein content remained similar to that obtained in rainfed conditions (22.8 ±1.19%), but the iron and zinc content increased, although it remained at intermediate values compared to the of the other varieties.

With respect to diseases, in the tests conducted between 2013 and 2017 under rainy conditions in the Bajio Experimental Field, Salinas and Pinto Saltillo behaved similarly showing resistance to common blight and halo blight with damage values between 2 and 3 (on a scale of 1 to 9), except in the year 2015 in which Pinto Saltillo had an intermediate resistance reaction to common blight with a damage value of 4. The Salinas’ main advantage is resistance to rust with a value average damage of 2.5 in the three years of evaluation, while Pinto Saltillo had an average of 4.2. Rust is one of the most important diseases because it causes yield losses of 25% to 100% in susceptible varieties (^{Souza et al., 2013}), it also has a wide genetic variability of races, of which tens have been identified throughout the world (^{Jochua et al., 2008}).

In 2015, the rust severely affected Pinto Saltillo under rainfed conditions in Ocampo, Guanajuato; The Calera, Guanajuato; Zacatecas, Zacatecas and San Juan of Río, Queretaro, with an average damage value of 6.5 compared to the average value of Salinas 3.

Among the molecular markers that were identified in Salinas is SAS13 (^{Young et al., 1998}) associated with the Co4² gene that confers broad resistance to anthracnose; SW13 (^{Melotto et al., 1996}) associated with gene I that confers resistance to the common mosaic, the Sk14 markers Sk14 (^{Nemchinova y Stavely, 1998}), SA14 (^{Meine et al., 2004}), and SI19 (^{Melotto y Kelly, 1998}) associated to the genes Ur-3, Ur-4 and Ur-5, respectively, that confer resistance to rust, and Pvsd1157 (^{Felicetti et al., ‎2012}) associated with slow darkening of the seed coat.