Variation in Grain Zinc and Iron Concentrations, Grain Yield and Associated Traits of Biofortified Bread Wheat Genotypes in Nepal

Abstract

Wheat (Triticum aestivum L.) is one of the major staples in Nepal providing the bulk of food calories and at least 30% of Fe and Zn intake and 20% of dietary energy and protein consumption; thus, it is essential to improve its nutritional quality. To select high-yielding genotypes with elevated grain zinc and iron concentration, the sixth, seventh, eighth, and ninth HarvestPlus Yield Trials (HPYTs) were conducted across diverse locations in Nepal for four consecutive years: 2015–16, 2016–17, 2017–18, and 2018–19, using 47 biofortified and 3 non-biofortified CIMMYT-bred, bread wheat genotypes: Baj#1, Kachu#1, and WK1204 (local check). Genotypic and spatial variations were found in agro-morphological traits; grain yield and its components; and the grain zinc and iron concentration of tested genotypes. Grain zinc concentration was highest in Khumaltar and lowest in Kabre. Likewise, grain iron concentration was highest in Doti and lowest in Surkhet. Most of the biofortified genotypes were superior for grain yield and for grain zinc and iron concentration to the non-biofortified checks. Combined analyses across environments showed moderate to high heritability for both Zn (0.48–0.81) and Fe (0.46–0.79) except a low heritability for Fe observed for 7th HPYT (0.15). Grain yield was positively correlated with the number of tillers per m2, while negatively correlated with days to heading and maturity, grain iron, grain weight per spike, and thousand grain weight. The grain zinc and iron concentration were positively correlated, suggesting that the simultaneous improvement of both micronutrients is possible through wheat breeding. Extensive testing of CIMMYT derived high Zn wheat lines in Nepal led to the release of five biofortified wheat varieties in 2020 with superior yield, better disease resistance, and 30–40% increased grain Zn and adaptable to a range of wheat growing regions in the country – from the hotter lowland, or Terai, regions to the dryer mid- and high-elevation areas.

Effect of foliar applied zinc sulphate on phenotypic variability, association and heritability of yield and zinc biofortification related traits of wheat genotypes

“…In current study, strong association of Zn biofortification traits with grain yield depicts potential of simultaneous improvement in both traits. Simultaneous improvement in grain Zn traits and yield has also been reported by the other researchers [ 37 , 38 ]. Thapa et al [ 37 ] demonstrated that improvement in grain Zn contents does not compromise the grain yield in wheat.…”

“…Simultaneous improvement in grain Zn traits and yield has also been reported by the other researchers [ 37 , 38 ]. Thapa et al [ 37 ] demonstrated that improvement in grain Zn contents does not compromise the grain yield in wheat. The change in correlation values under different fertilization conditions may be attributed to differential response of the genotypes for specific traits under different fertilization conditions [ 14 , 20 ].…”

“…A plant breeder often selects a number of traits in any breeding program, therefore information about relationship of these traits plays a crucial role in a successful selection [ 37 ]. In current study, strong association of Zn biofortification traits with grain yield depicts potential of simultaneous improvement in both traits.…”

Variability in Indian wheat germplasm for important quality and physiological traits

“…PC and N were found to be highly correlated with a value of r = 0.99 (P < 0.01). Quality parameters Zn, Fe, PC, and N showed a positive correlation with each other with a significant P-value of 0.001 [19,[58][59][60][61].…”

Zinc and Provitamin A Biofortified Maize Genotypes Exhibited Potent to Reduce Hidden—Hunger in Nepal

“…Similarly, five iron and zinc biofortified varieties of wheat (Himganga, Bheriganga, Khumal Shakti, Zinc Gahu-1, and Zinc Gahu-2) were released by the National Wheat Research Program (NWRP) and National Plant Breeding and Genetics Research Centre (NPBRC) in 2021 [ 15 , 17 ]. The iron and zinc content in the kernel of these varieties ranged between 32.3–41 and 34.5–54 mg kg −1 , respectively [ 18 ]. The Nepal Seed and Fertilizer Project initiated the introduction and evaluation of provitamin A and zinc biofortified maize varieties, and some of these are in the pipeline to release or register in the country.…”