The number of measurements needed to obtain high reliability for traits related to enzymatic activities and photosynthetic compounds in soybean plants infected with Phakopsora pachyrhizi

Abstract

Asian rust affects the physiology of soybean plants and causes losses in yield. Repeatability coefficients may help breeders to know how many measurements are needed to obtain a suitable reliability for a target trait. Therefore, the objectives of this study were to determine the repeatability coefficients of 14 traits in soybean plants inoculated with Phakopsora pachyrhizi and to establish the minimum number of measurements needed to predict the breeding value with high accuracy. Experiments were performed in a 3x2 factorial arrangement with three treatments and two inoculations in a random block design. Repeatability coefficients, coefficients of determination and number of measurements needed to obtain a certain reliability were estimated using ANOVA, principal component analysis based on the covariance matrix and the correlation matrix, structural analysis and mixed model. It was observed that the principal component analysis based on the covariance matrix out-performed other methods for almost all traits. Significant differences were observed for all traits except internal CO2 concentration for the treatment effects. For the measurement effects, all traits were significantly different. In addition, significant differences were found for all Treatment x Measurement interaction traits except coumestrol, chitinase and chlorophyll content. Six measurements were suitable to obtain a coefficient of determination higher than 0.7 for all traits based on principal component analysis. The information obtained from this research will help breeders and physiologists determine exactly how many measurements are needed to evaluate each trait in soybean plants infected by P. pachyrhizi with a desirable reliability.

Physiological response and earliness of soybean genotypes to soil base saturation conditions

“…It is important to highlight that the coefficient of variation (CV) over the two crop seasons were less than 10%, revealing high experimental accuracy. The CV obtained here was similar to the values reported other studies assessing physiological traits in soybean (Oliveira, de Azevedo Peixoto, et al., 2018; Oliveira, Peixoto, et al., 2018; Teodoro et al., 2019; Zobiole et al., 2010).…”

“…At 60 days after emergence (DAE), physiological traits were analysed using a portable photosynthesis analyser ( Infrared Gas Analyser —IRGA) model Li‐6400XT (LiCor Inc., Lincoln, Nebraska, USA). Photosynthetically active photon flux of 1,044 μmol m −2 s −1 and environment CO 2 concentrations (372 ± 10 mol m −2 s −1 ) were used, according to similar studies evaluating gas exchange in soybean crop (Oliveira, de Azevedo Peixoto, et al., 2018; Oliveira, Peixoto, et al., 2018). The physiological traits measured were as follows: net photosynthesis (A, μmmol CO 2 m −2 s −1 ), transpiration (E, mmol H 2 O m −2 s −1 ), stomatal conductance (gs, mol m −2 s −1 ) and internal CO 2 concentration (Ci, μmmol m −2 s −1 ).…”

Understanding the combining ability for physiological traits in soybean

“…The coefficients of variation (CV) less than 4% show high experimental accuracy and are lower than the values reported in the literature [30, 31, 37, 38]. After conducting the experiments in two crop seasons, it was observed that the genotype x environment interaction was not significant for all traits evaluated.…”

“…At 60 days after emergence (DAE), physiological traits were analyzed using a portable photosynthesis analyzer ( Infrared Gas Analyzer —IRGA) model Li-6400XT (LiCor Inc., Lincoln, Nebraska, USA). Photosynthetically active photon flux of 1044 μmol m -2 s -1 and environment CO 2 concentrations (372 ± 10 mol m -2 s -1 ) were used, according to similar studies evaluating gas exchange in soybean crop [30, 31]. The physiological traits measured were: net photosynthesis (A, mmol CO 2 m -2 s -1 ), transpiration (E, mmol H 2 O m -2 s -1 ), stomatal conductance (gs, mmol m -2 s -1 ), and internal CO 2 concentration (Ci, mmol m -2 s -1 ).…”

Agronomic performance and water‐use efficiency of F3 soybean populations grown under contrasting base saturation

“…At 60 days after emergence (DAE), physiological traits were analysed using a portable) photosynthesis analyser (Infrared Gas Analyzer-IRGA) model Li-6400XT (LiCor Inc.). Photosynthetically active photon flux of 1,044 μmol m -2 s -1 and environment CO 2 concentrations (372 ± 10 mol m -2 s -1 ) were used, according to similar studies evaluating gas exchange in soybean crop (Oliveira, de Azevedo Peixoto, et al, 2018;. The physiological traits measured were as follows: net photosynthesis (A, µmmol CO 2 m -2 s -1 ) and transpiration (E, mmol H 2 O m -2 s -1 ).…”