Storage Protein Accumulation in ‘Scio’ Barley Seed as Affected by late Foliar Applications of Nitrogen
1986
Turley, Robert H. | Ching, Te May
Late foliar applied N (LFAN) can improve seed protein content but the mechanisms involved are not well known. This study was conducted to determine how LFAN is accumulated in small grains so that cultural or biotechnological procedures can be developed to increase cereal proteins for food. ‘Scio‘ barley (Hordeum vulgare L.) was foliar sprayed with urea-ammonium nitrate (UAN, 1:1 by weight) at 9 days before anthesis and 18 days after anthesis (DAA) at 72 and 87 kg (N) ha ', respectively, in 1983. In 1984, 28 kg (N) ha⁻¹ of urea was applied on soil 8 weeks before anthesis and two foliar UAN at 50 kg (N) ha⁻¹ were sprayed at 4 and 18 DAA. No yield increase or change in harvest index was observed either year by N, but seed protein concentration increased from 89 to 119 g kg⁻¹ seed weight in 1983 and from 78 to 113 g kg⁻¹ seed weight in 1984. In 1984, rates of hordein synthesis in seeds from N treated plots were 93, 38, and 40% higher than the control at 16, 22, and 35 DAA, respectively. Seeds from N treated plots contained 13 and 37% higher amino acids and 26 and 31% lower sugars than the control at 16 and 22 DAA, respectively. The elevated amino acids apparently favored the synthesis of seed protein that increased 27, 67, and 40% in the globulin and albumin, hordein, and glntelin fractions, respectively with LFAN. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of hordeins revealed that hordein subunits were 33, 35.5, 38, 40.5, 42, 44, 50, 52, 54, 57, 61, 72, and 79 kD, and all increased by LFAN.
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