Genetic Variability in Micronutrients Composition of Orchardgrass (Dactylis glomerata L.)

Abstract

In this study, it is hypothesized that plants selected and/or bred for improved desired characteristics (e.g., macronutrients) may affect other characteristics (e.g., micronutrients) negatively. To test the hypothesis, we evaluated the metal micronutrient concentrations of four experimental strains viz., HighMgE, HighMgM, LowEq and LowMg and two commercial cultivars viz., Okamidori and Akimidori of orchardgrass. There were no genetic differences among the experimental strains/cultivars of orchardgrass for dry matter accumulation. The concentration of micronutrients varied with genetic differences among the four strains and the two commercial cultivars of orchardgrass. The amounts of Mn, Fe, Zn, Cu, Mo, Co, Ni, Se and I in the shoot, irrespective of strain or cultivars used, were 76.36, 74.83, 14.03, 9.36, 2.19, 5.00, 5.17, 2.00 and 19.33 μg g-1 at first harvest and 85.89, 74.56, 15.06, 12.30, 3.84, 6.14, 4.99, 2.54 and 19.53 μg g-1 at second harvest, respectively. The average amounts at the third harvest were 119.97, 90.36, 17.67, 13.39, 3.36, 4.56, 4.89, 2.36 and 20.06 μg g-1, respectively, whereas the corresponding amounts at the fourth harvest were 128.22, 156.00, 21.92, 10.31, 4.25, 4.53, 4.54, 1.47 and 28.72 μg g-1, respectively. Apart from few exceptions, Mn, Fe, Zn, Mo and I levels were highest in the fourth harvest, whereas the levels of Co and Se were highest in the second harvest. The level of Cu was the highest in the third harvest. The levels of Mn, Fe, Ni, Se and Mo were higher in low Mg containing plants irrespective of strain or cultivar. On the other hand, Co, Cu and I tended to peak in plants containing higher amounts of Mg. The Cu/Mo ratio was highest in the first harvest followed by the third, second and fourth harvests. The amounts of Mn, Fe, Ni, Co, Zn and Mo were within the optimum levels required for maintaining forage quality.