Estimates of genetic parameters in diallelic populations of cotton subjected to water stress

Abstract

The objective of this study was to estimate the general combining ability (GCA) and specific combining ability (SCA) of cotton genotypes subjected to water stress, based on fiber quality traits. Irrigated cotton plants were grown in the dry season in the Northeast region of Brazil and subjected to 23 days without irrigation at the beginning of the flowering stage. GCA and SCA analyses were based on the partial diallel model. Significant differences were found for GCA for all traits, with predominance of additive effects. The crossing between the genotypes FM-966 and CNPA-5M was the most promising hybrid combination, showing great potential for improvements in fiber quality in environments subjected to water stress, such as the Semiarid region of the Northeast of Brazil.

Selection of cotton genotypes for yield and fiber quality under water stress

“…The water conditions during the experiment period were quite severe, considering the rainfed planting and that there was no water complementation during planting. The water precipitation during planting was 174.4 mm in 2018 and 279.0 mm in 2019 (FUNCEME, 2019) far below the ideal for this crop (600 mm) and below the values found by Carvalho et al (2019) and Vasconcelos et al (2020).…”

“…Cotton genotypes with the best fiber quality also had the lowest fiber percentage and lower fiber yields, being less productive than medium fiber lines. However, high quality fiber cotton lines had lower SFI, favoring the yarn process (Cordão Sobrinho et al, 2015;Vasconcelos et al, 2020).…”

“…The harvest was carried out after 128 days and samples were collected in each plot (20 bolls) to be analyzed according to Vasconcelos et al (2020). The following agronomic and fiber characteristics were measured: boll weight (g) -PC, cottonseed production (kg ha -1 ) -CY, fiber percentage (%) -LP, fiber production (kg ha -1 ) -LY, fiber length (mm) -UHM, uniformity index (%) -UNF, hardwood index (%) -SFI, fiber strength (gf tex -1 ) -STR, fiber elongation (%) -ELG, micronaire index -MIC and spinning consistency index -CSP.…”

Métodos de Griffing: revisión sobre su importancia y aplicación en fitomejoramiento convencional

“…Con dos gradientes de heterogeneidad ambiental, uno perpendicular al otro, se ha empleado un cuadrado latino o algún látice (Gomez y Gomez, 1984;Martínez, 1988;Borojevic, 1990), pero han sido más usadas las series de experimentos en tiempo y espacio en bloques completos al azar o en látices (González et al, 2007a, b;Martínez, 1988;Moore y Dixon, 2015;González et al, 2019). Los diseños de apareamiento y experimentales se usan para estimar efectos y varianzas genéticas y ambientales, heredabilidad, heterosis, respuesta a la selección, predicción de híbridos, como material para nuevos programas de fitomejoramiento o como sugerencia para siembra comercial (Rodríguez et al, 2016;Vesali et al, 2020;Aditika et al, 2020;Vasconcelos et al, 2020). En el contexto anterior, se hará énfasis en los cuatro métodos de Griffing (1956a, b), que son los más utilizado desde los 1950's.…”