Generation mean analysis for nitrogen and phosphorus uptake, utilization, and translocation indexes at vegetative stage in tropical popcorn

Abstract

Understanding the genetic control of the nitrogen (N) and phosphorus (P) uptake, utilization, and translocation is essential to develop superior popcorn genotypes with high N and P use efficiency. The main objective of this study was to determine the genetic control for N and P uptake, utilization, and translocation efficiency indexes and shoot and root traits under low-N and -P conditions at early vegetative stage in tropical popcorn. We estimated linear and quadratic genetic components from replicated early evaluation (V6 stage) of six generations derived from two crosses involving contrasting inbred lines for N and P uptake and translocation efficiency indexes under low-N and -P conditions. In general, the linear non-additive components were greater than the additive component. Dominance effect was important for increasing N uptake and translocation, while for P uptake and translocation both dominance and epistatic genetic effects were important. For most of the shoot and root traits, dominance and epistatic effects were important as well. Excepting P uptake efficiency, the average degree of dominance indicated partial dominance for several of the measured traits. Efficient direct selection for early N efficiency can be achieved and also provides indirect gains in several shoot and root traits via N uptake. Concerning the early P efficiency, efficient selection can be achieved for P uptake via shoot dry weight and root surface area. Our results evidenced that reciprocal recurrent selection based on early evaluation of progeny might be useful to develop popcorn genotypes with superior N and P efficiency under low-nutrient conditions.