Preliminary evaluation of irrigated rice cultivars for higher efficiency of nitrogen utilization

Abstract

Sixty irrigated rice cultivars were used to determine their N utilization efficiency. Most part of entries included cultivars grown as irrigated rice for Brazilian conditions. Two levels of N were utilized (25 and 80 kg/ha) and the soil type was slightly humic-gley hydromorphic. Based on the N utilization efficiency parameter N (E_N), these cultivars were classified into four groups. Nonresponsive efficient (NRE), responsive efficient (RE), responsive inefficient (RIE), and non-responsive inefficient (NRIE). The most desirable cultivars/lines from the point of view of tolerance to low level of N were those belonging to the groups (NRE) and (RE). Cultivars in the group RIE, can be used in genetic programs to incorporate their characteristics of high N utilization efficiency. Cultivar in the group NRIE may be ellminated.