NITROGEN PHYSIOLOGICAL EFFICIENCY INDEX IN SOME SELECTED SPRING BARLEY CULTIVARS

The efficient use of nitrogen is one of the most important goals in crop and soil management. The physiological efficiency index of absorbed nitrogen (PEN) is defined as the ratio of kg grain production to kg of nitrogen absorbed in the above-ground (grain and straw) dry matter production at maturity. If the grain yields of cultivars are related to the PEN, which is a genetic trait of the genotype, than this index can be used in the breeding program to detect the high yielding potential genotypes. The objective of this study was to determine the genetic variation in nitrogen physiological efficiency and its relation with grain yield in spring barley (Hordeum vulgare L.) cultivars. Seven cultivars were used in greenhouse conditions with two nitrogen fertility levels: unfertilized (check) and fertilized with 160 mg of N kg-1 of dry soil. The results showed that there was a highly significant variation among cultivars in both yield (F=23.1) and PEN (F=20.5) values. The PEN varied from 54.6 to 66.2 and from 44.9 to 57.4 g grain g-1 of absorbed nitrogen in the check and in the fertilized treatment respectively. Furthermore, the grain yield was significantly related to PEN (r=0.81* and r=0.98 for the two fertility levels respectively). The absorbed nitrogen varied much less among the cultivars (F=2.9) and was also less related to grain yield. These results suggest that the PEN can be successfully used in the breeding program to detect the potentially high yielding cultivars. © 1990, Taylor & Francis Group, LLC. All rights reserved.