Desempenho Agronômico De Genótipos De Milho Submetidos Ao Estresse Hídrico No Sul Do Estado Do Tocantins

Abstract

RESUMO - A cultura do milho apresenta sensibilidade à variação climática, sendo o déficit hídrico uma das causas frequentes de redução de produção na cultura. O presente trabalho teve como objetivo avaliar a performance de genótipos de milho sob estresse hídrico, no sul do Estado do Tocantins. O experimento foi implantado no município de Gurupi - TO, utilizando 64 híbridos de milho. O delineamento experimental utilizado foi Látice 6x6, com três repetições. As características avaliadas foram altura da planta, floração masculina, floração feminina, altura de inserção da espiga e produtividade de grãos. Em ambiente sem estresse foram observadas maiores médias de altura da planta em comparação ao ambiente com estresse. No ambiente com estresse o genótipo 8 apresentou a maior média de altura de plantas (129 cm). Não houve diferença estatística entre os ambientes quanto ao número de dias para o florescimento masculino. A produtividade de grãos foi significativamente maior em ambiente sem estresse. O genótipo 59 apresentou a maior média de produtividade de grãos sob estresse (7.317,6 kg ha-1) e o genótipo 9 apresentou a maior média de produtividade de grãos em ambiente sem estresse (11.551,3 kg ha-1). Os resultados demonstraram que os cultivares de milho apresentam comportamento distinto quanto à tolerância ao estresse hídrico. Os genótipos que apresentaram as menores médias de produtividade no ambiente sem estresse foram 35 e 40. Os genótipos com maiores médias de produtividade no ambiente sem estresse foram 57, 7, 15 e 61.Palavras-chave: Zea mays, condições adversas, estiagem.AGRONOMIC PERFORMANCE OF MAIZE GENOTYPES SUBJECTED TO WATER STRESS IN THE SOUTH OF TOCANTINS STATE ABSTRACT - The maize crop is sensitive to climatic variability and water deficit is one of the frequent causes of yield decrease. The objective of this work was to evaluate the performance of maize genotypes under water stress in the southern Tocantins State. The experiment was carried out in the municipality of Gurupi - TO, using 64 maize hybrids. A 6x6 lattice design was used, with three replications. The evaluated characteristics were plant height, male flowering, female flowering, height of insertion of the ear and grain yield. For plant height it was observed that the stress-free environment provided higher PA means compared to the stress environment. In the environment with stress, the cultivar 8 presented the highest average plant height (129, cm). No statistical difference between environments was observed in the number of days for male flowering. Regarding grain yield, the stress-free environment provided significantly higher values of grain yield compared to the stress environment. The cultivar 59 presented the highest grain yield (7317.6 kg ha-1) under stress and cultivar 9 had the highest grain yield (11551.3 kg ha-1) in the environment without stress. The results showed that maize cultivars presented different behavior regarding tolerance to the water stress. The cultivars with the lowest productivities in the environment without stress were 35 and 40. The cultivars with the highest productivities in the environment without stress were 57, 7, 15 and 61.Keywords: Zea mays, adverse conditions, drought.

Drought Tolerance in Intervarietal Maize Hybrids

“…Plants under irrigated conditions grew more, being around 2.37 m tall, while plants under water stress were on average 2.07 m tall, that is, under stress there was an average reduction of 30 cm in plant height. Melo et al (2018), studying maize genotypes subjected to water deficit during the tasseling period, also found lower PH compared to genotypes grown in environment without water deficit. A similar result was also observed for ear height, as there was a reduction of 15 cm in the main ear height in plants under water stress.…”

Reciprocal recurrent selection for obtaining water-deficit tolerant maize progeny

“…In order to select the superior genotypes in this experiment, the following traits were utilized: flowering interval (FI), ear weight (EW), yield (YIE), prolificacy (Pr), and total chlorophyll index (TCI R6), for decision making in this research since, in breeding programs, the EW, YIE, and Pr traits are the most relevant, and the FI and TCI R6 traits are secondary traits, which have been used by maize breeders for to improve drought tolerance (CAMERA et al, 2007;SILVA et al, 2010;MELO et al, 2018).…”

“…The mean value obtained in the variable ear weight was of 1.97 kg, and in the variable yield, the mean value of 4649.74 kg/ha -1 was reported, which is already above the yield of the state of Espírito Santo, which is of 2,896 kg/ha -1 (CONAB, 2018), even the experiment being under water deficit. Evaluating the performance of maize genotypes under water stress, Melo et al (2018) reported a value of 4823.4 kg/ha -1 for yield. KASSIE et al (2017) reported that ;although, farmers normally considered yield of crop varieties when making adoption decisions, they also take into consideration the suitability of such varieties to the conditions of the local environment, particularly when they live in drought prone environments.…”

Maize genetic breeding for tolerance to abiotic stress with focus on sustainable use of environmental resources

“…The productive performance of maize is influenced by several abiotic factors that occur simultaneously or at different stages of crop development. Recurrent water stress and low soil fertility are among the main causes of abiotic stresses that limit maize agronomic performance (Melo, Santos, Varanda, Cardoso, & Dias, 2018;Song, Jin, & He, 2019). With the increase in the maize area cultivated in the off-season (Companhia Nacional de Abastecimento [CONAB], 2023), it is expected that the crop will be even more exposed to abiotic stress conditions, such as water deficit, low incidence of solar radiation and variations in air temperature, especially during the final stage of development.…”