Soil and foliar zinc biofortification in field pea (Pisum sativum L.): Grain accumulation and bioavailability in raw and cooked grains

• Soil and foliar Zn fertilization was tested for biofortification of field pea grains.
• Foliar application prompted increases above 60 mg Zn kg−1 in grain.
• Processing (cooking) caused a decrease of about 30% in grain Zn concentration.
• Adequate bioavailability of Zn in raw and cooked field peas was achieved.

To evaluate the potential of cooked field peas to be used in Zn biofortification programs, all combinations of soil Zn application of 0, 4 and 8 mg ZnSO4·7H2O kg−1 and foliar Zn application of 0 and two sprays of 0.25% or 0.5% (w/v) ZnSO4·7H2O before flowering and at early grain-filling stage were tested. Soil Zn application increased Zn-DTPA concentration 3.7- to 5.6-times depending on the Zn soil treatments. Grain Zn concentrations higher than 60 mg Zn kg−1 were obtained with all foliar Zn applications, alone or in combination with soil Zn applications, and grain Zn bioavailability was adequate (phytate:Zn ratios lower than 15). Processing (freezing and cooking) caused a decrease of about 30% in grain Zn concentration and a 17%-increase in phytate:Zn ratios (to ⩽9.5). The combined application of 8 mg ZnSO4·7H2O kg−1 soil + 0.25% (w/v) ZnSO4·7H2O foliarly could be a good option for biofortifying field peas.