Introduction

In the plateau of North Central Mexico pinto beans type of race Durango (^{Singh et al., 1991}) has gained popularity in recent years. In the country's annual demand for this type of grain among consumers, it is 350 thousand tons; the major producing states are Chihuahua, Durango, Zacatecas and San Luis Potosi, and to a lesser extent Sonora, Coahuila, Nuevo Leon and Guanajuato.

The variety Pinto Saltillo for its drought resistance characteristics, wide adaptation and slow darkening of the grain (^{Sanchez et al., 2004}) moved in a short time to other varieties of its kind, both native and improved. Thus, at present the production of this type of bean relies on a single variety, with the risk posed by the possible occurrence of devastating diseases by genetic uniformity. To solve the above, in recent year’s five new varieties were recorded of this type of bean for the state of Durango: Bravo, Centauro, Centenario, Freedom and Coloso (^{Rosales et al., 2010}; ^{Rosales et al., 2011}; ^{Rosales et al., 2012}) and one for Chihuahua, Pinto Gold (^{Herrera et al., 2012}). Because this type of bean is gaining popularity being producers and consumers of Guanajuato, a new variety of pinto American (oval) with the characteristic of slow darkening of the seed coat and neutral reaction to photoperiod for irrigation conditions described and Rentals in Guanajuato and areas with similar climatic conditions.

Origin

San Rafael originated from the cross between Pinto Bayacora and Pinto Saltillo (^{Sanchez et al., 2004}) (^{Acosta et al., 2001}); Pinto Bayacora bean is American pinto type is normal dimming (genotype SD SD) and Pinto Saltillo national pinto type of slow dimming (genotype sd sd). Pinto Bayacora plant reaction is neutral to photoperiod (genotype ppd ppd), while Pinto Saltillo is sensitive (genotype Ppd Ppd). The photoperiod sensitivity, coupled to the phenological and morphological plasticity, is considered an adaptive feature to erratic rainfall in the semiarid highlands of Mexico (^{Acosta and White, 1995}), while neutrality photoperiod is favored under conditions of good time and under irrigation.

The crosses that led to San Rafael was conducted in 2004 in the Bajio Experimental Station of the National Institute of Forestry, Agriculture and Livestock with the aim of combining the main features of the grain of both parents, i.e. grain of American pinto type dimming slow. The selection process of the F2 to F8 was performed in alternating cycles under irrigation and temporary, for this the health of the plant crop cycle and cargo pods and tolerance darkening the grain was considered following the method of evaluation proposed by ^{Junk et al. (2007)} that is to accelerate the darkening testa by exposing the seed to ultraviolet light for 72 h. This procedure was performed to seed lines in advanced generations, discarding the normal dimming (genotype SD SD).

Characteristics

The San Rafael is indeterminate growth habit prostrate type 3 short guide, white flower, intermediate cycle and neutral photoperiod (genotype ppd ppd) reaction. Begins flowering around 42 ± 3 days after sowing (DDS) and reaches physiological maturity at about 95 ± 5 DDS. It fits irrigation conditions and time in the Bajio region of Guanajuato state. The grain is oval in shape; testa is slow darkening background of cream and light brown spots which are the features that consumers demand this type of grain.

San Rafael is tolerant to common blight (Xanthomonas campestris pv phaseoli) and root rots caused by Fusarium spp. and Rhizoctonoa solani; and resistant to halo blight (Pseudomonas syringe pv phaseolicola), rust (Uromyces appendiculatus var. appendiculatus) and anthracnose (Colletotrichum lindemutianum). San Rafael showed the presence of molecular markers associated with resistance genes to rust: Ur 4, Ur 3, Ur 5, Ur 6, Ur 7 and GB; anthracnose: Co1, Co2, Co4, Co4 ² and Co 6 (^{Miklas et al., 2006}). The presence of these markers gives most of the races of those two diseases present in the plateu (^{Rodriguez et al., 2006}; ^{Montero et al., 2010}) resistance. Moreover, San Rafael is susceptible to damage by weevils store Acanthocelides obtectus (brown weevil) and Zabrotes subfaciatus (weevil pinto) and field to attack whitef lies (Trialeuroides vaporariorum), leafhopper (Empoasca kraemeri) and conchuela (Epilachna varivestis). To avoid damage caused by these insects biological or chemical protection is required.

The weight of 100 seeds of San Rafael is 38 g capacity for water absorption during soaking por16 h is greater than 100%, suggesting that no problem for cooking and that could be used for canning (^{Hosfield et al., 1997}).

The description of San Rafael was carried out following the parameters of the Union for the Protection of Plant Organisms (^{UPOV, 2012}) and registered with the National Service for Inspection and Seed Certification (SNICS-SAGARPA) in 2013, registering is FRI-085-010313.

Adaptation and performance

San Rafael was evaluated in various localities of Guanajuato in 2009-2013 under irrigation and temporary; evaluations in 2009 and 2010 he was part of a preliminary performance test consisting of 71 lines and a shopping witness the first year and 55 lines in the second. From 2011 to 2013 San Rafael was part of a statewide performance test in which 15 commercial lines and a witness were included in a simple lattice duplicate assay 4 × 4 (Table 1).

Table 1 Agronomic features of two bean varieties established under two conditions of humidity and planting seasons during the period 2010-2013 in Celaya, Guanajuato.  

¹Días a floración; ²días a la madurez fisiológica; ³reacción a la incidencia natural del tizón común (Xanthomonas campestris pv phaseoli); ⁴peso de 100 semillas en g; ⁵reacción a la incidencia natural del tizón de halo (Pseudomonas syringae pv phaseolicola); ND: no determinado.

The underperformance observed in the watering cycle established in February 2012 was due to the occurrence of high temperatures above 35°C causing abscission of flowers and small pods, affecting similar to all varieties tested manner. The performance San Rafael was similar to Pinto Saltillo in most evaluations conducted (Table 1).

Considering the global trend towards consumption of nutritious and natural foods, such as organically produced (^{Willer and Kilcher, 2008}), San Rafael and two other varieties they were included in 2013 in an essay organic production conducted under irrigation in a sandy soil poor in organic matter and free from contamination by fertilizers or any chemical. Four treatments were tested compost 3% nitrogen in equivalent amounts to be applied 0, 20, 40 and 60 units of nitrogen per hectare and a uniform dose of 30 kg of phosphorus per hectare was applied across phosphate rock. To control insects like leafhopper and whitefly, biological products authorized for organic production were used as the base ca prepared 'Neem'. The highest yield and weight of 100 seeds of the three varieties was obtained in treatment with greater amount of compost (Table 2), of the three varieties studied San Rafael showed the lowest average yield without significant differences between varieties. That probably lower yield was associated with a lower crop cycle of 95 days from sowing compared to other varieties, 105 days. The protein content in the grain of San Rafael was slightly less than the range of higher content by treatments compost, while the iron content was slightly higher, especially in the treatment equivalent compost to 40 units of N per hectare (Table 2).

Table 2 Yield and grain characteristics of three bean varieties under four doses of nitrogen provided through composting. 

¹Valores promedio de cuatro determinaciones.

Conclusion

The characteristic of neutral reaction to photoperiod gives San Rafael the advantage to be planted at any time, avoiding dates risk due to low temperatures, as their cycle will not be affected by the length of the day, just for the temperature and moisture availability.