Introduction

In the center of Mexico, the Flor de Junio ​​(FJ) bean type has high demand; it is produced under irrigated and rainfall conditions in Zacatecas, San Luis Potosi and Guanajuato. In general, the grain of FJ type cultivars darkens during storage. The objective was to identify bean lines FJ type, previously selected based on seed coat darkening, of stable high yield and grain weight under rainfall conditions.

Method

An experiment was established under rainfall conditions with 42 F9 lines from the biparental cross between Pinto Saltillo / Dalia at Calera, Zac., and Celaya, Gto. In Celaya, the parents were established in a separate trial within the same locality. The variables evaluated were weight of one hundred seeds and yield per hectare. A combined analysis was carried out, considering the effects of localities, lines and genotype x environment interaction (IGA). To determine the IGA level of each line, the AMMI model was used. The five lines with superior yield performance were exposed for 72 h to UV rays, in order to evaluate accelerated seed coat darkening; the intensity of the color and degree of clarity of the coat was determined together with the slow darkening check, Pinto Saltillo.

Results and Discussion

For both studied traits, there were significant differences between environments, genotypes and interaction (P ≤ 0.05). Some lines showed greater seed weight and yield than the trial average, compared with the parents established in Celaya, which could be attributed to complementary genes with additive action, in addition to observing transgressive segregation, both positive and negative. The highest yielding lines, from 2,203 to 2,334 kg ha-1 were PS / D-M-M-26-1-M, PS / D-M-M-38-1-M, PS / D-M-M-17-1-M, PS / D-M-M-42-1-M and PS / D-M-M-39-1-M. The AMMI analysis for hundred seed weight variable, indicated that 47.27 % of the variation was due to the locality, 38.66 by the genotypes and 14.07 % by the interaction. For seed yield, 13.79 % of the variation was explained by the locality, 40.77 % by the genotype and 45.44 by the interaction. The line PS / D-M-M-38-1-M showed low IGA, therefore is highly stable. The lines at the beginning of the UV treatment were slightly darker than Pinto Saltillo but their gradual increase during the process was lower than that of the check.

Conclusions

Average of both test locations, high yielding lines were superior to the average of the lines. The higher yielding lines also presented the slow darkening trait. Line PS / D-M-M-38-1-M, of low IGA, resulted outstanding in all recorded traits.

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