Combining ability of physiological traits in forrage maize

Greice Daiane Rodrigues Gomes Redivo,Elizabeth Orika Ono,Jocimar Costa Rosa,Marcos Ventura Faria,João Domingos Rodrigues,Elisa Adriano

doi:10.1590/1413-7054202044018520

Abstract

ABSTRACT The exploitation of the existing genetic variability for the physiological traits related to the yield and quality of maize forage can assist in the development of superior inbred lines and hybrids. The objective of this work was to evaluate the general and the specific combining ability and the nature of gene effects of physiological and chemical traits of forage maize genotypes. Two groups of genotypes and 16 hybrids resulting from a 4x4 partial diallel scheme were evaluated. Group I consisted of two commercial hybrids (AG8025, P30B39) and two elite inbred lines (LEM2 and LEM3). Group II consisted of four experimental inbred lines originated from different populations of forage maize breeding program. In total, 24 treatments were evaluated, formed by the genotypes of both groups and the respective crossings. The traits evaluated were: CO2 assimilation (A), stomatal conductance (gs), internal CO2 concentration (Ci), transpiration (E), calculated activity of Rubisco (A/Ci) and efficiency of water use (A/E). Forage acid detergent fiber (ADF), neutral detergent fiber (NDF) and digestibility in situ were obtained. There was a predominance of non-additive gene effects for most of the chemical and physiological traits. Crossings LEM2 x 203-218.3, LEM3 x 201-107.2, LEM2 x 101-7.2 and LEM3 x 101-7.2 stood out regarding CO2 assimilation, and are indicated for future research considering the physiological traits. Inbred lines 101-7.2 and 203-218.3 presented high concentration of favorable alleles to increase carboxylation efficiency, in which inbred line 101-7.2 stood out for NDF, ADF and DIG. Inbred line 201-107.2 has a high concentration of favorable alleles for efficiency of water use. Physiological parameters can assist the selection of inbred lines and hybrids in maize breeding for forage purpose.

Highlights

Physiological and chemical variables are important to understand the differences in the performance of vegetal species and selection of superior genotypes
The mean squares regarding the general combining ability (GCA) and specific combining ability (SCA) (Tables 1 and 2), when significant, indicate that the genitors of both groups differed from each other in the frequency of favorable alleles, and indicate that the traits evaluated can be used as parameters of selection aiming at the obtainment of hybrids with better physiological efficiency (Ali et al, 2014a; Peixoto et al, 2011; Tiwari et al, 2014)
For most of the traits there was the predominance of non-additive effects, since the quadratic components of the SCA were higher than those of the GCA (Tables 1 and 2), agreeing with the results by Ali et al (2014b), which favors the high complementarity of parentals considering physiological efficiency

Summary

Introduction

Physiological and chemical variables are important to understand the differences in the performance of vegetal species and selection of superior genotypes These traits are used to verify the culture adaptation to new environments, interspecific competition and effects of handling systems, in addition to the yield potential of different genotypes (Alvarez; Crusciol; Nascente, 2012; Chen et al, 2018). Propitious conditions to carbon fixation favor the opening of the stoma, while the propitious conditions to water loss promote its closing (Taiz; Zeiger, 2013).This mechanism limits the flow of CO2 to the internal side of the leaf and may limit the CO2diffusion rate to the internal part of the leaf, with direct effects on photosynthesis and growth, while it restricts the water flow of the leaf to the atmosphere, decreasing transpiration and directly influencing plant productivity (Huang et al, 2017; Sun et al, 2014)

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