Oat Response to Manganese and Zinc¹

Abstract

Leaf symptoms that resembled Mn deficiency were observed on certain oat (Avena sativa L.) cultivars grown on a De Voignes series, fine‐silty, mixed, nonacid, frigid, Histic Humaquepts soil where Mn deficiency had not been previously reported. Results of preliminary field studies confirmed that Mn was deficient for optimum oat growth and suggested that Zn was marginally deficient. In addition, a Mn‐efficient oat cultivar (‘Park’) and a Mn‐efficient oat cultivar (‘Cayuse’) were identified. The objective of this field study was to measure the yield, protein, and test weight responses of Park and Cayuse to applications of Mn and Zn made over a 3‐year period. Foliar applications of 1.8 and 3.6 kg/ha Mn to Park and Cayuse, respectively, increased grain yield an average of 588 and 1,097 kg/ha, respectively. One application of Mn at tillering increased yield as much as Mn applications made at both tillering and boot stages of oat development. Grain protein of Park and Cayuse was increased 2.65 and 0.6% by applications of 9.0 and 3.6 kg/ha Mn respectively in 1971. Neither cultivar showed increased protein from Mn application in subsequent experiments. Test weight was not influenced by Mn application. Zinc did not significantly alter yield, protein, or test weight. However, Zn tended to increase test weight in dry years and tended to increase yield in wet years. Combinations of foliar applied MCPA (sodium salt of 2‐methyl‐4‐chlorophenoxyacetic acid) and Mn, or foliar applied Diuron (3‐(3,4 dichlorophenyl)‐1,1‐dimethylurea) and Mn gave yield increases comparable to Mn alone. Combinations of Mn and Zn were not better than Mn alone.