Indirect Selection for Drought Tolerance in Maize Through Agronomic Traits and Seeds

Abstract

-High prolificacy, stay green, and a reduced anthesis-silking interval are among the traits most used for indirect selection for drought tolerance. The objective of this research was to evaluate five maize lines from the maize breeding program of the company Geneseeds Recursos Genéticos Ltda, to drought tolerance, grown at four plant population sizes, 40, 60, 80 and 100 thousand plants ha -1 . In these conditions, the following traits were evaluated: prolificacy, stay green and interval between female and male flowering, which are indirectly related to drought tolerance. The physiological quality of seeds and expression of the enzymes alpha amylase, esterase, catalase, superoxide dismutase, alcohol dehydrogenase, malate dehydrogenase, and heat resistant proteins were also evaluated. The experiment was conducted in a randomized block design in a split plot layout. Differences were observed between the lines for all traits analyzed. Lines 63, 64 and 91 showed the greatest yields and prolificacy, and lines 63, 64, 54 and 91 had the lowest intervals between male and female flowering. No effetc of plant population on the physiological quality of maize seeds was detected, and the highest values of germination and seed vigor were observed in lines 64, 44 and 91. Lines 63, 64 and 91 are considered as promising for drought tolerance. Keywords: Zea mays, Abiotic stress, Flowering, Plant population, indirect selection. SELEÇÃO INDIRETA PARA TOLERÂNCIA À SECA EM MILHO POR MEIO DE CARACTERÍSTICAS AGRONÔMICAS E DE SEMENTESRESUMO -Alta prolificidade, stay green, o reduzido intervalo entre florescimento masculino e feminino estão entre os caracteres mais utilizados para seleção indireta para a tolerância à seca. O objetivo nesta pesquisa foi avaliar cinco linhagens de milho do programa de melhoramento da empresa Geneseeds Recursos Genéticos Ltda., quanto à tolerância à seca, cultivadas em quatro populações de plantio, 40, 60, 80 e 100 mil plantas ha -1 . Nessas condições foram avaliados os seguintes caracteres indiretos relacionados à tolerância à seca: stay green, prolificidade, intervalo entre os florescimentos feminino e masculino. Foi avaliada também a qualidade fisiológica das sementes e a expressão das enzimas alfa amilase, esterase, catalase, superóxido desmutase, álcool desidrogenase, malato desidrogenase e proteínas resistentes ao calor. O experimento foi conduzido em delineamento em blocos casualizados, no esquema de parcelas subdividas. Houve diferenças entre as linhagens para todos os caracteres analisados.

Germination under stress simulation and image analysis as tools for water deficit phenotyping of maize

“…Subsequently, the seeds were stored in a cold room at 10 °C. These seeds (from both lines and from F 1 and reciprocal hybrids) were obtained by Abreu et al (2017) and used in this study.…”

“…Considering this, the germination under stress simulation in laboratory may be a faster alternative. This can be observed based on the studies of Abreu et al (2017;, which used germination tests in laboratory as indirect methods to phenotype maize lines. Marques et al (2019;2020) also studied seed, seedling, and reserve tissue gene expression under stress conditions, with significant differences among genotypes regarding the response to water deficit.…”

Enzymatic activity and gene expression related to drought stress tolerance in maize seeds and seedlings

“…In relation to the transcript expressions, the 91-T line had greater expression of the ZmLEA3, ZmAN13, ZmCPK11 and ZmPP2C genes was observed in seeds. Abreu et al (2017) also evaluated this line and considered it promising for drought tolerance by evaluations of grain yield, prolificacy, and intervals between female and male flowering. When evaluating genotypes with different levels of tolerance at high temperatures, Dutra et al (2015) concluded that the 91-T line is more tolerant in high-temperature conditions.…”

Reciprocal recurrent selection for obtaining water-deficit tolerant maize progeny

“…Over 90% of the maize area grown worldwide is non-irrigated, and annual yield losses resulting from drought are estimated at approximately 15% of total yield potential. Losses are significant in tropical countries that rely on a relatively unpredictable rainy season for crop growth (ABREU et al, 2017). The study conducted by ADEBAYO et al (2014) reported that water stress leads to lower grain yield, and losses can be as high as 80% during the flowering and grain-filling stages.…”