Evaluation of Compatibility and Yield Stability of Green Bean (Phaseolus vulgaris L.) Lines

Green beans are one of the vegetables with high nutritional value in the food basket of Iranian households. However, the domestic variety of green beans has not been improved and released so far. Therefore, in order to obtain high-yielding cultivars of high quality green beans, this experiment was performed.

Eight lines (KS10008, KS10069, KS10071, KS10072, KS10073, KS940102, KS94014 and KS940144) were compared with the commercial cultivars Sunray and Valentino in a randomized complete block design with three replications in three regions: Karaj, Sari and Zarghan over two years (2017-2018). In both years, at the end of April and the beginning of May, the seeds of each line were planted in six rows of five meters long with a seed spacing of 10 cm and a distance between lines of 60 cm. Morphological traits such as the number of pods per plant, length of pods, weight of pods per plant, as well as phenology traits (such as days after planting to emergence of the third trifoliate leaf, flowering and maturity) and finally green pod yield of each genotype were recorded. The marketability of pods (size, shape, color, crispness and taste) was also checked in each genotype. The results related to the yield of the green pods of the lines were analyzed. Non-parametric rank method was used to determine the degree of compatibility and grouping of genotypes.

The results of combined analysis of variance of green pod yield in three regions during two years showed that the effect of year and location was not significant, but the interaction of year×location, genotype× year, genotype× location and genotype×year× location were significant. Also, the results showed that the genotypes were significantly different in the green pod yield. The comparison of average yield of green pods showed that KS940144 line had the highest pod weight per unit area. Lines KS10071 and KS940102 ranked second and third in terms of green pod yield. The lowest green pod weight was related to KS10072 line. The KS940144 line also showed the highest number of pods per plant. The highest and lowest weight of green pods belonged to KS940144 and KS10072 lines in Karaj, respectively. In Sari, the highest and lowest green pod weight belonged to KS940144 and Valentino and in Zarghan, the highest and lowest green pod weight belonged to KS940144 and KS10072 lines, respectively. One of the factors affecting the production of crops is the interaction between genotype and environment. The less this interaction is, the more stable the production will be. Yield stability analysis by non-parametric ranking method showed that KS940144 and KS10071 lines were the most stable lines. One of the important characteristics of green beans, apart from stringless of pod, is the length of the pod or its elongation. The crispness of the pod and its color are also prominent features in the marketability of green beans. KS10073 line, although it was identified as a stringless line in the previous steps, but in this experiment, it was observed that for this trait, it is variable with the change of environmental conditions and its crispiness is also different. KS10008 line is one of the early mature lines and can be suggested for areas with a shorter growing season. Of course, the greater thickness of its pod compared to other lines and commercial cultivars reduces its marketability. Lines KS940143 and KS940144 are similar in pod and have good pod elongation. These two lines are similar in appearance to Sunray variety and even better than it. Their difference is the lighter color of the KS940143 line compared to the KS940144 line and the Sunray variety. Also, the KS940144 line has an elongated and slender pod, while the pods of Sunray variety and KS940143 line are sword-shaped. Lines KS10071 and KS940102 are similar to each other in terms of pod shape and also similar to Valentino variety. These three genotypes have elongated pods. Their difference is the lighter color of the KS940102 line compared to the KS10071 line and the Valentino variety.

In general, according to the results obtained in the regions, the stability analysis of green pod yield and also considering the important trait of marketing, KS940144, KS10071, KS10008 and KS940102 were selected as the superior lines.