To define breeding strategies, the understanding of trait inheritance is critical. The objective of this study was to determine the inheritance of popcorn under different water regimes. To this end, Hayman’s diallel methodology was used, with 8 parents and 28 hybrids. The experiment was carried out under well-watered conditions (WW) and water stress (WS). For popping expansion (PE) under both water regimes, the effects of complete dominance and greater importance of the components associated with the dominance effects were observed. In contrast, the number of dominant genes was zero and the determination coefficient in the narrow sense was >50%; additive effects were also present. For the number of grains per row (GR), ear length (EL), and grain yield (GY) under WS and WW conditions, the dominance effects were the most relevant, and the mean degree of dominance with overdominance effects and greatest relevance of the components associated with this effect were also observed. The same breeding methods can be applied under the studied WS and WW conditions. Exploiting heterosis for GY and related components is a promising way to adapt popcorn to WS. To be able to capitalize on additive and dominance effects, a reciprocal recurrent selection is recommended.

The objective of this study was to evaluate the effects of additive and non-additive genes on the efficiency of nitrogen (N) use and N responsiveness in inbred popcorn lines. The parents, hybrids and reciprocal crosses were evaluated in a 10x10 triple lattice design at two sites and two levels of N availability. To establish different N levels in the two experiments, fertilization was carried out at sowing, according to soil analysis reports. However, for the experiments with ideal nitrogen availability, N was sidedressed according to the crop requirement, whereas for the N-poor experiments sidedressing consisted of 30% of that applied in the N-rich environment. Two indices were evaluated, the Harmonic Mean of the Relative Performance (HMRP) and Agronomic Efficiency under Low Nitrogen Availability (AELN), both based on grain yield at both N levels. Both additive and non-additive gene effects were important for selection for N-use efficiency. Moreover, there was allelic complementarity between the lines and a reciprocal effect for N-use efficiency, indicating the importance of the choice of the parents used as male or female. The best hybrids were obtained from inbred popcorn lines with contrasting N-use efficiency and N responsiveness.

Water stress reduces the yield of agricultural crops severely. The objectives of this study were to investigate genotypic differences between 20 popcorn lines in environments under wellirrigated (WW) and water stressed (WS) conditions to determine phenotypic, genetic and environmental relations among agronomic and root traits. The experiment was arranged in a randomized complete block design with three replications per environment. The following traits were evaluated: volume of expanded popcorn per hectare (PV), grain yield (GY), popping expansion (PE), number of rings of adventitious roots (NRAR), number of adventitious roots (NAR), number of tap roots (NTR), number of crown roots (NCR), adventitious root density (ARD), tap root density (TRD), crown root density (CRD), tap root angle (TRA), and crown root angle (CRA). Under WS, the values of the agronomic traits PV, GY and PE were reduced by 74.03, 67.15 and 28.76%, respectively. Water stress had little influence on NRAR, NAR, DR, NTR, and NCR. Due to an adaptive response to WS, increases were observed in TRA and CRA. In general, the estimates of genetic parameters evaluated under WS were higher. Negative genetic associations between agronomic traits and TRD, and CRD were observed in cultivation under WS; selection for trait PV will produce simultaneous gains in GY and PE under this ©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 17 (3): gmr18078 S. H. Kamphorst et al 2 regime. Under well-watered conditions, the development of genotypes with satisfactory GY and PE is difficult. This reinforces the hypothesis that root phenotypes adapted to particular environments should be identified.

Drought is a common abiotic stress in tropical and subtropical regions that limits the growth and development of agricultural crops, mainly impacting grain yield. Acting through plant breeding is the most viable alternative for obtaining genotypes more tolerant of environments with stress. This work aims to select popcorn genotypes for environments with drought and to identify discriminating traits for the evaluation of drought tolerance in popcorn germplasm. Fifteen Latin American populations of popcorn were evaluated in water stress (WS) and well-watered (WW) conditions. The evaluated traits were based in morpho-agronomic, physiological and radicular descriptors. Data were submitted to individual and joint ANOVA and GT Biplot analysis. Variability was detected between populations for all traits in both conditions. The drought caused a reduction of 30.61% and 3.5% in grain yield and popping expansion, respectively. Based in GT biplot analysis, 880POP was the most stable in WS and WW, being indicated as a promising population for cultivation in environments with water limitation. This study is going to allow the establishment of a collection of great importance to maize germplasm and to provide information to facilitate the process of selection in breeding programs focused on drought tolerance.

The UENF WS01 is a hybrid that has an early cycle and high grain yield capacity under low water and nitrogen availability. It maintains popping expansion even under abiotic stress, thus being recommended for cultivation in the North and Northwest of the State of Rio de Janeiro.