Article Info Received : 24.01.2017 Accepted : 07.04.2017 Our daily diet is largely contributed by cereals, which have low genetic abilities to amass higher concentrations of micronutrients in their grains. Hence, wide spread deficiencies iron, zinc and other essential nutrients have prevailed. Present study focuses the biofortification of Zn in wheat grains, taking advantage of nutrient-nutrient synergy between Zn and N. Three wheat genotypes (NIA-Amber, BWQ-4 and SD-998) were tested in a field experiment following randomized complete block factorial design with three replicates. Urea fertilizer was applied at the rates of 120 (recommended), 150 and 180 kg N ha -1 in combination with three levels of Zn (0, 5 & 10 kg ha -1 ). Outcomes of the experiment revealed that NIA-Amber had the highest grain yield of 6.03 tons/ha against 150 kg N ha -1 and 10 kg Zn ha -1 . Maximum Zn contents of 447.86, 429.56 and 395.56 g ha -1 were observed in BWQ-4, SD-998 and NIA-Amber at 180 kg N ha -1 in combination with 10 kg Zn ha -1 . Maximum enhancement in protein contents was observed in BWQ-4 (743 kg ha -1 ) at 180 kg N ha -1 and combined with 5 kg Zn ha -1 . For NIA-Amber, 180 kg N ha -1 in combination of 10 kg Zn ha -1 proved the most suitable in terms of Zn concentration and other quality attributes. Nitrogen @ 180 kg N ha -1 with 5 kg Zn ha -1 depicted appreciable zinc and protein contents in grains of BWQ-4 and SD-998.

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Zinc (Zn) deficiency causes low crop production and malnutrition in human. Agronomic biofortification of food crops can resolve the issues of global food security and human nutrition on sustainable basis. Field experiments were conducted to improve Zn bioavailability, growth and yield of wheat in response to varying Zn application rates for two consecutive years (2016-17 & 2017-18). Significant increase in grain yield was recorded with the application of Zn. Highest grain yield (5.41 t ha-1) was recorded with the application of 5.00 kg Zn ha-1. Human available Zn fraction was also improved in response to Zn application. Zn application resulted in lowering phytate/Zn molar ration in wheat grains. Higher Zn accumulation (338.72 g ha-1) was observed by applying 7.5 kg Zn ha-1. Zinc application was found critical to meet internal (36.53 µg g-1) and external (4.48 kg Zn ha-1) Zn requirements to achieve near maximum yield of wheat. The results reinforced the concept of Zn fertilization to achieve better productivity and quality.

Most of the arable soils in Pakistan are deficient in plant available phosphorus (P) and boron (B) primarily due to alkaline and calcareous nature along with low organic matter. A combined deficiency of these nutrients may intensify the plant growth suppression by reducing their efficient utilization. A pot experiment was conducted to investigate the interactive effect of P and B on growth, nutrient accumulation and grain yield of wheat grown on calcareous soil. Wheat crop was grown at three P levels (45, 90 and 135 kg P ha-1) in combination with five B levels (0, 0.5, 1.0, 1.5 and 2.0 kg B ha-1) following completely randomized design. The results revealed that yield and yield related attributes increased linearly with the addition of B at each P level. Nonetheless, the significant interactive effect of both nutrients was most pronounced in the treatment having 90 kg P ha-1 and 1.5 kg B ha-1. Applied B rates resulted in relatively higher P concentration in grains and straw at P level of 90 kg ha-1 contrarily to 45 and 135 kg P ha-1. The B concentration in grains and straw increased with corresponding addition of B at each P level but at variable rate, with the maximum response at higher P level. Grain and straw yield illustrated positive correlation with total P uptake (R 2 = 0.96 and 0.81) and total B uptake (R 2 = 0.95 and 0.70) respectively. Likewise, positive correlation (R 2 = 0.94) between total P uptake and total B uptake under combined application of P and B indicated their synergistic relationship. Overall, the treatment combination of 90 kg P ha-1 with 1.5 kg B ha-1 was found as the most suitable dose for better plant growth, nutrient accumulation and grain yield of wheat.

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