Acid phosphatase activity of intact roots and phosphorus nutrition in plants. 2. Variations among wheat roots

Abstract

Variation in phosphatase activity (E.C. 3.1.3.41) in some cultivated wheats and wild progenitors was examined and a comparison made. The limits likely to occur in wheat were estimated, and the usefulness of phosphatase activity as an indicator of plant potential for exploiting low phosphorus status situations was explored. Under the test conditions, within the cultivated wheats, the phosphatase activity varied in optical density from 4.6 to 9.3 per g fresh weight (P < 0.001), and selections among wheats on this basis could be made. Phosphorus uptake and total dry matter yield were negatively related to phosphatase activity (r = - 0.80 and - 0.82 respectively, each P < 0.00l), providing further supportive evidence of the proposition that plants with lower phosphatase activities may gain and use phosphorus more readily than plants with higher ones. The phosphatase activity of wild and cultivated progenitors of modern wheats ranged in optical density from 15.5 to 45.4 per g fresh weight. All the cultivated species had low phosphatase activities which, on the basis of the proposition, suggests that some unconscious selection for ability to use low fertility situations may have occurred with the domestication of wheat. On the other hand, there was no apparent grouping according to geographic origin of earlier cultivars used in Australia with respect to phosphatase activity to suggest any conscious selection for ability to grow well on low phosphorus status soils.