Heterosis and combining ability for ear yield in a diallel cross among six maize varieties

Este estudo teve o objetivo de estimar os efeitos das capacidades geral e específica de combinação, e os valores de heterose, na produção de espigas de cruzamentos dialélicos parciais entre seis variedades de milho (Zea mays L.) em melhoramento, no Centro Nacional de Pesquisa de Milho e Sorgo, (CNPMS), em Sete Lagoas, MG. Os tratamentos compreenderam as variedades CMS 05, CMS 04, CMS 22, CMS 11, CMS 12 e CMS 28, além dos seus quinze híbridos intervarietais (F1). A análise conjunta de variância para produção de espigas mostrou efeitos significativos (P <0.01) para as capacidades geral e específica de combinação e para as interações com locais. Tais resultados indicam variabilidade originada de efeitos gênicos aditivos e não-aditivos. As variedades CMS 04 e CMS 05 apresentaram, respectivamente, os maiores valores para efeitos de capacidade geral de combinação, 142,82 e 233,93, e média geral para peso de espigas de 4.528 kg/ha e 4.445 kg/ha, respectivamente. Os maiores efeitos para capacidade específica de combinação corresponderam aos cruzamentos CMS 05 x CMS 28 com 462,28 e CMS 11 x CMS 28 com 392,87. Os valores percentuais de heterose em relação a média dos pais foram de 21,16% e 17,49%e em relação ao pai mais produtivo foram de 12,92% e 13,28%, para os dois híbridos intervarietais citados. A média de produção das variedades paternais (4.127 kg/ha) foi inferior à média dos seus quinze híbridos (4.433 kg/ha). A maior produção média, 5.026 kg/ha, resultou do cruzamento entre as variedades CMS 05 e CMS 28.The objective of this study was to estimate the general and specific combining ability effects and heterosis value for ear yield from e diallel cross among six varieties of maize (Zea mays L.) under breeding at the Centro Nacional de Pesquisa de Milho e Sorgo (CNPMS) at Sete Lagoas, MG, Brazil. The treatments were: CMS 04, CMS 05, CMS 11, CMS 12, CMS 22, CMS 28 and their 15 possible F1 hybrids. The combined analysis showed general and specific effects to be highly significant (P < 0.01), as well as their interactions with locations. There is an indication of variability among varieties with the presence of additive and nonadditive gene effects. The varieties CMS 04 and CMS 05 presented the highest values for general combining ability effects, 142.82 and 233.93, and mean ear weights of 4.528 kg/ha and 4.445 kg/ha, respectively. The hybrids CMS 05 x CMS 28 and CMS 11 x CMS 28 presented the highest values for specific combining ability effects of 462.28 and 392.87, respectively. Heterosis percentual values related to parental mean were 21.16% and 17.49% and to the highest yialding parent were 12.92% and 13.28% for the hybrids CMS 05 x CMS 28 and CMS 11 x CMS 28, respectively. Mean yield of parentals (4.127 kg/ha) was lower tham mean yield of the 15 hybrids (4,433 kg/ha). The highest mean yield was 5.026 kg/ha for the hybrid CMS 05 x CMS 28

The CORDEX Flagship Pilot Study in southeastern South America: a comparative study of statistical and dynamical downscaling models in simulating daily extreme precipitation events

The aim of this work is to present preliminary results of the statistical and dynamical simulations carried out within the framework of the Flagship Pilot Study in southeastern South America (FPS-SESA) endorsed by the Coordinated Regional Climate Downscaling Experiments (CORDEX) program. The FPS-SESA initiative seeks to promote inter-institutional collaboration and further networking with focus on extreme rainfall events. The main scientific aim is to study multi-scale processes and interactions most conducive to extreme precipitation events through both statistical and dynamical downscaling techniques, including convection-permitting simulations. To this end, a targeted experiment was designed considering the season October 2009 to March 2010, a period with a record number of extreme precipitation events within SESA. Also, three individual extreme events within that season were chosen as case studies for analyzing specific regional processes and sensitivity to resolutions. Four dynamical and four statistical downscaling models (RCM and ESD respectively) from different institutions contributed to the experiment. In this work, an analysis of the capability of the set of the FPS-SESA downscaling methods in simulating daily precipitation during the selected warm season is presented together with an integrated assessment of multiple sources of observations and available CORDEX Regional Climate Model simulations. Comparisons among all simulations reveal that there is no single model that performs best in all aspects evaluated. The ability in reproducing the different features of daily precipitation depends on the model. However, the evaluation of the sequence of precipitation events, their intensity and timing suggests that FPS-SESA simulations based on both RCM and ESD yield promising results. Most models capture the extreme events selected, although with a considerable spread in accumulated values and the location of heavy precipitation.Thanks to CORDEX for endorsing the FPS-SESA. This work was supported by the University of Buenos Aires 2018- 20020170100117BA grant; JMG, MLB, SAS, RPR funding from the Spanish Research Council (CSIC) I-COOP+ Program “reference COOPB20374”. JMG, JF and AL-G acknowledge support from the Spanish R&D Program through projects MULTI-SDM (CGL2015-66583-R) and INSIGNIA (CGL2016-79210-R), co-funded by the European Regional Development Fund (ERDF/FEDER). AL-G acknowledges support from the Spanish R&D Program through the predoctoral contract BES-2016-078158. Universidad de Cantabria simulations have been carried out on the Altamira Supercomputer at the Instituto de Física de Cantabria (IFCA-CSIC), member of the Spanish Supercomputing Network. MB acknowledges support from the Simons Associateship of the Abdus Salam International Centre for Theoretical Physics. RH acknowledges support from the project LTT17007 funded by the Ministry of Education, Youth, and Sports of the Czech Republic