Enhancing Zinc Biofortification of Wheat through Integration of Zinc, Compost, and Zinc-Solubilizing Bacteria

Zinc (Zn) deficiency is a fairly widespread agronomic constraint in many of the world's cereal (wheat, rice, corn, barley, etc.) production regions. Zinc is an imperative micronutrient required for optimum plant growth and development. Low Zn availability in about 50% of global land has resulted in Zn deficiency in cereal grains. A two-year field experiment was conducted at the Agronomy Research Farm, The University of Agriculture, Peshawar, during Rabi season 2018-19 (Y1) and 2019-20 (Y2) to study the impact of Zn levels (0, 5, 10 and 15 kg Zn ha(-1)), compost types (control, composted sheep manure (SMC), composted poultry manure (PMC) and farmyard manure compost (FYMC), and Zn-solubilizing bacteria (ZnSB) (with (+) and without (-) on Zn biofortification in order to overcome Zn deficiency. The experiment was set up in three replications in a randomized complete block design. The wheat variety "Pirsabak-2013" was planted in a 30 cm row-to-row spacing. The plot size was kept at 9 cm(2), with 10 rows plot(-1), and the seed was sown at a rate of 100 kg ha(-1). The results showed that ZnSB application increased ShZnC (shoot Zn concentration) to a maximum level of 29.3 mg kg(-1), ShZnUp (shoot Zn uptake) to 176.0 g ha(-1), SZnUp (straw Zn uptake) to 116.67 g ha(-1), and TZnUp (total Zn uptake) to 230.3 g ha(-1). In the case of compost types, PMC resulted in maximum grain Zn uptake (GZnUp) (28.9 mg kg(-1)), ShZnUp (192.9 g ha(-1)), GZnC (33.4 mg kg(-1)), GZnUp (125.06 g ha(-1)), SZnUp (125.26 g ha(-1)), and TZnUp (250.3 g ha(-1)). In the case of Zn levels, higher ShZnC (31.5 mg kg(-1)), ShZnUp (191.3 g ha(-1)), GZnC (34.4 mg kg(-1)), SZnC (23.5 mg kg(-1)), GZnUp (128.98 g ha(-1)), SZnUp (129.29 g ha(-1)), and TZnUp (258.3 g ha(-1)) were calculated with the use of the highest rate of 15 kg Zn ha(-1), which was either statistically similar to or followed by 10 kg Zn ha(-1). A strong positive correlation was found among uptake by different plant parts (ZnG, ZnS, ShZnUp, GZnUp, SZnUp, and TZnUp). It was concluded that the combined application of PMC and 10 kg Zn ha(-1) along with ZnSB (+) improved Zn biofortification and uptake in wheat crop under Zn-deficient soils.