*4.3. Selenium*

Soil and weather conditions play important roles in Se concentration in harvested pulse crop seeds. Among soil factors, aeration, water availability, pH, and texture are important, as these affect the availability of Se [195]. Diapari et al. [13] observed that variation in Se concentration in peas was mainly due to environment, whereas the effect of genotype was minimal (only 2.7% of the total). Se concentration was higher at the Saskatoon location than Rosthern, and differences in Se concentration were not significant across the 94 genotypes.

Soils of Saskatchewan are generally rich in Se, so pulses grown in this region provide a natural dietary source of this element [180,182,196]. Lentils grown in the Dark Brown and Brown soil zones of Western Canada had a high concentration of Se (425–672 μg kg−1) [180] (Table 1). In comparison, lentils grown in six major lentil-producing countries, Nepal (180 μg kg−1), Southern Australia (148 μg kg−1), Turkey (47 μg kg−1), Morocco (28 μg kg−1), Northwestern USA (26 μg kg−1), and Syria (22 μg kg−1), had a substantially lower Se concentration [181]. A wide range of variation was observed for Se concentration in common beans (381–500 μg kg−1), peas (405–554 μg kg−1), chickpeas (629–864 μg kg−1), and lentils (990–1637 μg kg−1) grown at several locations in Saskatchewan [11]. A 100 g dry weight of any of these pulses could provide 100% of the RDA. Nair et al. [176] observed significant variation for Se concentration (210–910 μg kg−1) in mungbean lines grown in two environments near Hyderabad, India.

Total Se concentration varied from 373 to 519 μg kg−<sup>1</sup> in 17 field pea cultivars grown at six locations for 2 years in Saskatchewan [182], and this provided 68–94% of the RDA upon the serving of 100 g peas. Evaluation of 80 pea breeding lines obtained from Australia, Czech Republic, Serbia, and the United States had relatively low concentration of Se; however, these lines showed greater concentration of Se when planted in Saskatoon [182]. Similarly, Gali et al. [27] observed a considerable variation in Se concentration in pea populations, PR-02 and PR-07, with a greater range in variation among RILs at the Saskatoon location compared with Rosthern. Compared to Fe and Zn, Dissanayaka [29] observed a substantially di fferent pattern for Se at di fferent locations, with a high coe fficient of variation, and the concentration varied from 0.06 to 8.75 ppm. The e ffects of genotype, genotype × year, and genotype × location were not significant, with the exception of the genotype e ffect at the trial grown in 2014 at Fargo, North Dakota.

Several QTLs were identified for Se concentration in the PR-02 pea population on LGs 4a, 5a and 7, and in the PR-07 pea population on LG4 and 5b [27] (Table 1). Using a pea GWAS panel of 177 accessions, 44 significant SNP markers were identified for Se concentration, but the majority of the markers were not common among the location-years [29], and this could be due to substantial variation in Se concentration and high coe fficient of variation at di fferent locations.
