Manganese Deficiency and Toxicity in Wheat: Influence on Growth and Forage Quality of Herbage¹

Abstract

There is little information concerning critical Mn deficiency and toxicity levels in forage plants, or how plant Mn concentration affects other plant constituents associated with forage quality. This study was undertaken to investigate possible interactions between plant Mn concentration and the growth and forage quality of wheat (Triticum aestivum L. cv. Stacy). Wheat plants were grown in nutrient solution containing 0.005, 0.02, 0.05, 0.25, 1, 5, 25, 100, 200, and 500 µg/g Mn. Plants were grown for 30 days after transplanting into nutrient solution and were harvested at the three‐leaf stage, lyophilized, and weighed. Manganese concentration, in vitro dry matter disappearance (IVDMD), neutral detergent fiber (NDF), in vitro cell wall disappearance (IVCWD), total nonstructural carbohydrates (TNC), and Ca and Mg concentrations were determined on wheat shoot. Critical Mn deficiency and toxicity levels affecting normal growth of wheat shoot were determined to be 35 and 475 µg/g dry wt, respectively. These values are useful in determining deficiency and toxicity in wheat production. Percentage NDF, IVDMD, TNC, and IVCWD were reduced in tissue from plants that were critically Mn‐deficient. In vitro dry matter disappearance and TNC were increased in tissue from critically Mn‐toxic plants. In vitro dry matter disappearance ranged from 71 to 89%, with the lowest values observed for Mn‐deficient and the highest for Mn‐toxic plants. The high IVDMD of the Mn‐toxic plants appeared to be related to an accumulation of TNC, while the relatively lower IVDMD of the Mn‐deficient plants was related to reduced cell wall digestibility. Both Ca and Mg concentrations decreased as Mn concentration in the plants increased above 475 µg/g. Results of this study indicate that Mn deficiency and toxicity in wheat have a significant effect on amount of growth and the concentration of plant constituents associated with forage quality. These constituents remain relatively constant over the adequate range of Mn nutrition and plant Mn concentration should be kept within the 35 and 475 µg/g range.

Poultry Litter Ash as a Potential Phosphorus Source for Agricultural Crops

“…The lower Mn concentrations in the PLA treatments may have been due to the higher pH of the PLA (Table 1). These tissue Mn levels are near or exceed the phytotoxic threshold levels of 475 mg Mn kg −1 reported by Fales and Ohki (1982) Copper and Mn concentrations increased with lime treatment while Fe, Ni, and Cd concentrations were reduced (Table 7)…”

Aluminum Toxicity Effects on Growth and Nutrient Composition in Wheat1

“…The use of Stacy wheat was based on two primary reasons. This cultivar has been adapted to the Experiment, GA region and is commonly grown with high yields (1), and several studies (6,23,24) on Stacy have reported critical Mn deficiency levels for growth and physiological processes.…”

Effects of Salinity on Accumulation of Mineral Nutrients in Wheat Grown With Nitrate–nitrogen or Mixed Ammonium:nitrate–nitrogen

“…However, even the highest shoot concentration was slightly lower than the value of 475 mg kg À 1 that was found to be the shoot concentration above which manganese toxicity was deemed to have started in a study of 30-day wheat seedlings in hydroponic culture. [28] Fresco, the cultivar that was less affected by salinity, contained higher concentrations of Mn on a dry mass basis at most rates of salt supply, although for both cultivars the plants that grew best (those with low rates of NaCl supply) tended to have lower concentrations of Mn in shoots and roots than the other plants. If Mn concentrations are related to plant growth, Fresco must have a higher threshold of tolerance to the element than Hussar.…”