ResumoA resistência genética constitui-se em alternativa sustentável para o controle de doenças em culturas agrícolas, sendo esta, no entanto, dependente da avaliação de populações naturais ou tradicionais visando à ampliação da base genética. Este trabalho relata a avaliação fenotípica de 24 progênies de mamoeiro, oriundas de genótipos crioulos, cultivados por pequenos agricultores no sul do Estado do Espírito Santo. Avaliaram-se características associadas à resistência à pinta-preta, importante doença desta cultura, causada pelo fungo Asperisporium caricae. Para fins comparativos, foram incluídas uma variedade resistente ('Maradol') e uma suscetível ('Golden') à pinta-preta. Pelos parâmetros genéticos estimados, concluiu-se que na população estudada há variabilidade genética quanto à resistência à pinta-preta suficiente para indicar a seleção recorrente como método de melhoramento.Palavras-chave: Asperisporium caricae, Carica papaya, herdabilidade, resistência genética, variabilidade genética. Pathometry, genetic parameters and papaya progenies reaction to black-spot disease AbstractGenetic resistance is a sustainable alternative to control diseases in crops, being indispensable the enlargement of the genetic base to introduce new resistance genes on developing cultivars. This study reports the phenotypic evaluation of 24 papaya progenies, originated of landraces cultivated for small farmers in south of the Espírito Santo State, Brazil. Characteristics related to the resistance to black-spot disease, induced by the fungi Asperisporium caricae were evaluated. For comparison one genotype resistant ('Maradol') and one susceptible ('Golden') to black-spot disease were included on the study. Based on the genetic parameters estimated, the studied population has genetic variability for resistance to black spot diseases appropriates for use of recurrent selection as crop breeding method.

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.

further root deepening in WS conditions. Under WS P7 maintained higher net photosynthesis values, stomatal conductance, and transpiration, than L75. Additionally, L75 exhibited a lower (i.e., more negative) carbon isotope composition value than P7 under WS, confirming a lower stomatal aperture in L75. In summary, besides leaf greenness, traits related to leaf photosynthetic status, and stomatal conductance were shown to be good indicators of the agronomic performance of popcorn under water constraint.

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Landrace genotypes present sources of genes for adaptation, rusticity and resistance to diseases and environmental stress. This study evaluated the potential of landrace papaya genotypes in contributing to phoma-spot resistance genes. The experiment was a randomized block design with six replications consisted of 24 half-sib progenies of dioecious papaya -which segregated for sex. Only plants with female flowers were evaluated. We used mixed models to estimate variance components and the genetic value of landraces to incidence and severity of phoma-spot. Heritability estimates and selective accuracy demonstrated a favorable situation to the selection of resistant progenies ,especially 'STA-02', 'STA-04', 'STA-05', 'STA-06', 'STA-07', 'STA-11', 'STA-12', 'STA-16', 'STA-21' and 'STA-22', which showed negative values of additive genetic effects for both incidence and severity of phoma-spot.