Site-Specific Factors Influence the Field Performance of a Zn-Biofortified Wheat Variety

Abstract

Background: Biofortification of wheat with zinc (Zn) through breeding and agronomy can reduce Zn deficiencies and improve human health. "High-Zn" wheat varieties have been released in India and Pakistan, where wheat is consumed widely as a dietary staple. The aim of this study was to quantify the potential contribution of a "high-Zn" wheat variety (Triticum aestivum L. var. Zincol-2016) and Zn fertilizers to improving dietary Zn supply under field conditions in Pakistan. Methods: Grain Zn concentration of Zincol-2016 and local reference varieties were determined at three sites of contrasting soil Zn status: Faisalabad (Punjab Province; diethylenetriamine pentaacetate-(DTPA-)extractable Zn, 1.31 mg kg −1 soil; gross plot size 13.3 m 2 ; n = 4; reference var. Faisalabad-2008), Islamabad (Capital Territory; 0.48 mg kg −1 ; 4.6 m 2 ; n = 5; reference var. NARC-2011), and Pir Sabak (Khyber Pakhtunkhwa, KPK, Province; 0.12 mg kg −1 soil; 9.1 m 2 ; n = 4; reference vars. Pirsabak-2015, Wadhan-2017). Eight Zn fertilizer treatment levels were tested using a randomized complete block design: control; soil (5 or 10 kg ha −1 ZnSO 4 .H 2 O; 33% Zn applied at sowing); foliar (0.79 or 1.58 kg of ZnSO 4 .H 2 O ha −1 applied as a 250 L ha −1 drench at crop booting stage); three soil × foliar combinations. Results: At the Faisalabad site, the grain Zn concentration of Zincol-2016 was greater than Faisalabad-2008, with no yield penalty. Zincol-2016 did not have larger grain Zn concentrations than reference varieties used at Islamabad or Pir Sabak sites, which both had a lower soil Zn status than the Faisalabad site. Foliar Zn fertilization increased grain Zn concentration of all varieties at all sites. There were no significant effects of soil Zn fertilizers, or variety•fertilizer interactions, on grain Zn concentration or yield. Conclusions: Environment and management affect the performance of "high-Zn" wheat varieties, and these factors needs to be evaluated at scale to assess the potential Zia et al. Field Performance of Zn-Biofortified Wheat nutritional impact of Zn biofortified crops. Designing studies to detect realistic effect sizes for new varieties and crop management strategies is therefore an important consideration. The current study indicated that nine replicate plots would be needed to achieve 80% power to detect a 25% increase in grain Zn concentration.

Micronutrient Status and Dietary Diversity of Women of Reproductive Age in Rural Pakistan

“…This is lower than the serum selenium concentrations reported from healthy adult females in Rawalpindi and Islamabad (239.92 ± 138 µg/L) [43]. The discrepancy could be explained by spatial variation in grain selenium in Pakistan, since selenium levels in plants vary accoording to the soil selenium concentrations [7].…”

“…This may result in multiple micronutrient deficiencies, particularly of iron, zinc, vitamin A, and iodine [5,6]. Selenium deficiency may also be prevalent in areas where the soil selenium content is low or unavailable for uptake by crops due to the soil type [7]. This combination of increased obesity and increased undernutrition in the same population, together with micronutrient deficiency, is often referred to as the triple burden of malnutrition [8].…”

Zinc deficiency is highly prevalent and spatially dependent over short distances in Ethiopia

“…Potential strategies to alleviate Zn deficiency include the promotion of dietary diversity and biofortification, i.e. the application of Zn to crops via fertilizers 43 , 44 and the release of crop varieties containing higher concentrations of Zn 45 . The spatial analysis of these data show that, while there is spatial dependence in the biomarker, this is limited to short distances.…”

Zinc lability and solubility in soils of Ethiopia – an isotopic dilution study

“…which they adsorb Zn. This is an important consideration for a site-specific strategy to ensure a more effective agronomic biofortification of staple crops with Zn fertilizers (Joy et al, 2015;Manzeke et al, 2014Manzeke et al, , 2020Zia et al, 2020). For instance, these results indicate that in soils with pH >6.5 foliar fertilisers are most appropriate because Zn is strongly adsorbed, while in soils with low pH applying fertilizers to the soil might be feasible.…”