Repeatability and genotypic stability of agronomic characteristics in Panicum maximum Jacq.

Abstract

In experiments with selection of perennial plants, the initial performance is expected to be maintained throughout the productive life. The probability of repeating the agronomic response can be evaluated by the repeatability coefficient. The objective was to estimate repeatability coefficients of agronomic characteristics in Panicum maximum Jacq. using different methods and identify the best combinations between harvests according to the genotypic stabilization. Seventeen genotypes were evaluated in a randomized complete block design with three replicates. The coefficients of repeatability were estimated by the methods: ANOVA, structural analysis based on the mean of the correlation coefficients (SACOR), analysis of principal components based on the covariance matrix (PCCOV) and correlation matrix (PCCOR). In the genotypic stabilization, coefficients estimated by ANOVA and PCCOR were used. For total DM, repeatability coefficients ranged from 0.3500 to 0.4300 by the ANOVA and PCCOR methods, respectively. High repeatability coefficients were found for the characteristic leaf DM, while low coefficients were observed for leaf and stem percentages and leaf:stem ratio. For the genotypic stabilization of total DM and leaf:stem ratio, the best coefficients were observed for the combination of harvests 5 to 8. There are variations in the estimate of repeatability by different methods and the highest coefficients were those of the principal components based on the correlation and covariance matrices. For the genotypic stabilization, the best coefficients of repeatability and determination were observed for the harvests performed in the second rainy period.

Repeatability and genotypic stability in intraspecific hybrids of Paspalum notatum Flügge

“…Therefore, several studies have been conducted to estimate the repeatability (ρ̂) of characteristics of interest in forage plants including Urochloa spp. (Basso et al, 2009;Souza Sobrinho et al, 2010;Teixeira et al, 2011;Martuscello et al, 2013;Matias et al, 2016;Coêlho et al, 2018;Figueiredo et al, 2019), Megathyrsus maximus (Martuscello et al, 2007;Braz et al, 2015;Martuscello et al, 2015;Coêlho et al, 2018;Ferreira et al, 2019), Medicago sativa L. (Botrel et al, 2000;Ferreira et al, 2010), Pennisetum purpureum Schum. (Shimoya et al, 2002;Rodrigues et al, 2020), and Lolium multiflorum Lamarck (Rios et al, 2019).…”

“…For most traits studied here, genotypic stabilization between two harvests showed the highest correlation (Table 5). The evaluation between successive harvests may not represent genotypic stabilization, but the occurrence of two very similar harvests (Ferreira et al, 2019). This probably reflects they have been exposed to similar environmental conditions, rather than non-adjacent harvests, which likely experience less similar environmental conditions due to seasonal changes.…”

Non-Destructive Methods Used to Determine Forage Mass and Nutritional Condition in Tropical Pastures

“…To determine the reduction in forage mass in Axonopus catarinensis pastures established in silvopastoral systems under intermittent grazing management by Brahman cattle, Benvenutti et al [84] used a quadratic model: FM (kg ha −1 ) = β0 + β1 × CH + β2 × CH 2 , where MF is the accumulated forage mass during the pre-grazing period, CH is the canopy height (cm), and β0, β1, and β2 are the equation parameters (values not provided by the author). Thus, with the use of this equation, it was possible to determine the residual forage mass and quantify the effects of three forage allowances (low, moderate, and high) on animal grazing behavior.…”

“…Brachiaria spp.) [1][2][3][4]. Additionally, destructive methods are also employed to assist in obtaining the accumulation rate and availability of forage mass in research assessing the effect of different defoliation intensities on animal performance in continuous stocking, rotational stocking, and integrated production systems [5][6][7][8][9], as well as in research on feed supplements (e.g., mineral, energy, protein) with forage for ruminant production [10][11][12][13][14].…”

Morphology, accumulation and survival of Desmanthus under different planting densities and harvest heights

“…The repeatability analysis allows measuring the ability of the characteristics to be repeated throughout the evaluations (Ferreira et al, 2019), being applied to determine the number of measurements necessary so that the real value of the analysed variable is estimated with the desired precision and with the minimum cost and labor (Coêlho et al, 2018).…”