Repeatability and divergence among genotypes of Desmanthus sp. in a semiarid region

Abstract

The objective of this work was to evaluate the divergence among genotypes of Desmanthus sp. regarding morphological, productive, and qualitative characteristics, as well as to estimate the number of observations necessary to predict the real value of these characteristics. The experiment was conducted in the semiarid of the state of Pernambuco, Brazil, using 26 genotypes of Desmanthus sp. from different locations in the region. Seven evaluations were carried out from July 2013 to July 2014. Tocher’s grouping method and standardized average Euclidean distance were used. The coefficients of repeatability (r) and determination (R2) were estimated using two models of the analysis of variance, principal components based on the correlation or covariance matrix, and structural analysis based on the correlation matrix. The variables with the greatest weights were stem diameter, leaf area index, and forage yield, with frequencies of 22.05, 17.57, and 14.58%, respectively. Morphological, productive, and qualitative variability was observed among the genotypes of Desmanthus sp. All characteristics presented r and R2 of high magnitude in the methods of analysis. Up to four evaluation cycles are required to predict (R2=95%) the real value of stem diameter, peduncle length, plant height, leaf length and width, number of leaves, and pod length.

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

“…The increase in SD observed from July/2018 to February/2020 (Table 4) can be associated with the age of the plants and the performance of subsequent harvests that naturally promote the thickening of the stem. Stem diameter becomes important because it affects the transport of water and nutrients in the plant (Cunha et al, 2021), which can influence the regrowth capacity and adaptation to conditions of low water availability, due to the possibility of greater allocation of water and organic reserves in the stem (Diniz et al, 2021).…”

“…Plant height, LI, LL, LW, NLL, BD, SD and LBR showed high magnitude of r and R 2 (Table 5), indicating reliability in estimating the number of evaluations necessary for predict its real value (Rodrigues et al, 2020). Cunha et al (2021) evaluated genotypes of Desmanthus sp . in semiarid region and also observed high magnitude of r and R 2 for the variables plant height (0.85% and 97.62%), SD (0.91% and 98.73%), LL (0.97% and 99.59%) and LW (0.99% and 99.94%).…”

“…When increasing the number of measurements performed for a given variable, the variance caused by the environment is reduced as well as the phenotypic variance, increasing the precision of the repeatability coefficient (Cunha et al, 2021). On the other hand, when a trait has high repeatability, the increase in the number of measurements performed will add little to the inference of the individual genotypic value.…”