LIMITED NITROGEN AND PLANT GROWTH STAGES DISCRIMINATE WELL NITROGEN USE, UPTAKE AND UTILIZATION EFFICIENCY IN POPCORN

Nitrogen use efficiency (NUE) could be an ultimate prospect that can help in sustaining corn production even at low nitrogen availability, which could result in low economic costs and environmental complication. In this context, two popcorn inbred lines (P2 and L80) and their hybrid (F1: P2 x L80) were evaluated under two pot experiments in a factorial randomized complete block design. The study aimed to evaluate the performance of these genotypes for root, shoot dry weight and N content and to investigate the N use, uptake and utilization efficiency (with the inclusion and exclusion of root N content) based on the dry weight, to find the contrasting N levels and vegetative stage that effect NUE, and to understand the relationship between the traits related to N use efficiency. In the first experiment (Expt. 1) five nitrogen (N) levels (100%, 75%, 50%, 25% and 10%) were used, and plants were harvested at the V6 (six fully expanded leaf ) stage. In contrast, in the second experiment (Expt. 2) two nitrogen levels (100% and 50%) were used and plants were harvested at the VT (tasseling stage). At both of the stages, the hybrid and P2 were confirmed better than L80 for all the studied traits. NUE is mainly effected by shoot dry weight, uptake and utilization efficiency. Extremely low N (N10%) and high N (N100%) were found more discriminating for N use and dry weight evaluation, respectively. At the early stage (V6), root N content (RNC) should be considered while measuring the uptake and utilization efficiency. At the later stage (VT), RNC should not be important to consider for uptake and utilization efficiency. The genetic parameter performance for N use, uptake, shoot dry weight, and N content could favour the achievement of the genetic gain in advanced segregating generations.