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Fluid Journal : Winter 2012
6 The Fluid Journal Winter 2012 Dr. Cakmak is a Professor at Sabanci University, Istanbul, Turkey. Figure 3. Changes in Zn concentrations of endosperm part of bread wheat grains harvested at the Adana locations in Turkey. For further details see Cakmak et al. 2010b. contributing to mobility and transport (and re-translocation) of Fe and Zn by chelation (e.g., nicotianamine, amino acids) 5. increasing amount of seed proteins that bind/store Zn. The positive impacts of N nutrition on grain Zn indicate that increasing attention should be paid to N management in cultivation of food crops and in establishing breeding programs for an effective biofortification of grains with Zn. Agronomic benefits Increasing seed concentration of micronutrients by soil and/or foliar applications of Zn also provides additional positive impacts in terms of seed vitality and seedling vigor. Earlier reviews show that when seeds with low concentration of Zn are sown, the ability of the new crop to withstand environmental stresses at the early growth stages is greatly impaired. Plants emerging from seeds with low Zn have poor seedling vigor and field establishment on Zn-deficient soils. Under rain-fed conditions, wheat plants derived from seeds containing 1.5μg Zn per seed had better seedling establishment and two-fold higher grain yields than wheat plants that emerged from seeds containing only 0.4μg Zn per seed. Similarly, another study showed that increasing seed Zn contents from 0.25μg per seed to 0.70μg per seed significantly improved root and shoot growth of wheat plants under Zn deficiency. Priming seeds in Zn-containing solutions is an alternative way to increase seed Zn prior to sowing. High Zn concentrations in seeds ensure good root growth and contribute to better protection against soilborne pathogens. Table 1. Effect of Zn-enriched urea (ZEU) on grain yield and grain Zn concentrations of aromatic rice grown under field conditions in India, 2008. Treatments Zn Added Grain Yield Grain Zn Concentration (kg ha-1) (ton ha-1) (mg kg-1) Prilled Urea - 3.87 27 0.5% ZEU 1.3 4.23 29 1.0% ZEU 2.6 4.39 33 2.0% ZEU 5.2 4.60 39 3.0% ZEU 7.8 4.76 42 Table 2. Zn concentrations of the whole grain and the bran, embryo, and endosperm fractions of wheat grown under field conditions with foliar spray of 0.5% ZnSO4.7H2O at different growth stages. Zn concentration (mg kg-1) Konya Adana Foliar Zn Treatment Stages Whole Grain Bran Embryo Endosperm Whole Grain Bran Embryo Endosperm Control (No Zn appl.) 12 20 38 8 32 42 70 11 Stem + Booting 19 28 47 10 51 72 96 15 Milk + Dough 25 41 63 15 57 88 98 16
Early Spring 2012