Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/1/2009
Publication Date: 9/1/2009
Citation: Jackson, C.A., Windes, J.M., Bregitzer, P.P., Obert, D.E., Price, W., Bradford, B. 2009. Low Phytic Acid Barley Responses to Phosphorus Rates. Crop Science. 49:1800-1806. Interpretive Summary: Barley seeds, as well as seeds of other crops, contain phosphorus. This important nutrient, unfortunately, is tied up in a molecule--phytic acid--that is difficult for non-ruminant animals such as pigs and fish to digest. To provide better phosporus nutrition, barley varieties have been produced that have decreased phytic acid phosphorus and increased inorganic phosphorus (available). However, it is not know whether these types of barley will require different production conditions to realize optimal yield and phosphorus content. In this study, we studied yield and phosphorus content of two normal and two low phytic acid barley cultivars as it was affected by different levels of soil phosphorus fertility. The results showed that, except at very low levels of phosphorus, both the normal and the low phytic acid cultivars were unaffected by phosphorus fertility. Only at very low phosphorus fertility levels were changes noted: for both types of barleys, both the total amount of phosphorus, inorganic phosphorus, and yield were reduced. Our conclusion is that over the range of soil phosphorus levels that would typically be encountered in a farmers field, both normal and low phytic acid barleys showed no changes, and in all conditions both types responded similarly. Therefore, low phytic acid barleys can be managed identically to normal barleys with respect to phosphorus fertilization.
Technical Abstract: Low phytic acid (LPA) barley (Hordeum vulgare L.) cultivars partition phosphorus in seed tissue differently than conventional barley cultivars through a reduction in seed phytic acid (myo-inositol-1,2,3,4,5,6-hexkisphosphate) coupled with an increase in inorganic phosphorus. The response of the LPA characteristic to phosphate fertilization has not been previously investigated; therefore the effect of phosphate fertility on barley seed yield, total seed phosphorus, inorganic seed phosphorus, and flag leaf phosphorus was investigated at four locations over two years. Two conventional cultivars, Baronesse and Colter, were compared to one LPA cultivar, Herald (lpa1-1 mutation), and one advanced breeding line, 01ID451H (mutation 640). At three locations, phosphate fertilizer (P2O5) was applied in the form of triple superphosphate (0-45-0) at rates of 0, 56, 112, 168 kg ha-1. At these locations, no responses to phosphate fertilization were observed except for flag leaf phosphorus levels which increased with increasing phosphate application. At a fourth location, differential soil phosphorus fertility was achieved via previously established plots varying from very low to adequate phosphorus fertility. These tests showed that limiting phosphorus fertility reduced yield, test weight, height, delayed maturity, and reduced total seed phosphorus content, with the LPA cultivars responding similar to the wildtypes. In conclusion, the LPA traits in barley originating from lpa1-1 and 640 mutations are stable under a wide range of soil phosphorus fertility conditions in comparison to the wildtypes.