Genetic Parameters for Phenotypic Traits in Annual Ryegrass

Abstract

Characterizing phenotypes in germplasm collections and making data publicly available is crucial to ensure the utilization of the accessions in breeding programs. Variance component estimates are used to calculate genetic parameters needed to make strategic decisions for germplasm conservation and its utilization in plant breeding. This information is lacking for annual ryegrass (Lolium multiflorum Lamarck) germplasm from the USDA National Plant Germplasm System (NPGS). In this study, we estimated variance components, repeatability, genotypic values, genetic correlations, and genotype × year correlations for 18 traits in 167 annual ryegrass populations. Repeatability (H2) ranged from 0.11 to 0.93 for single‐year analyses, and from 0.03 to 0.86 for traits evaluated during two growing seasons, evidencing the presence of genetic variability. Genotype × year correlations ranged from 0.17 up to 0.99, demonstrating variable consistency in phenotypic performance across years. Combining multiple traits in one cultivar is a challenge for breeders, particularly for traits negatively correlated. Establishment, plant vigor, leaf width and length, and chlorophyll content were negatively correlated with disease traits. Heading date was positively correlated with number of tillers, crown size, and biomass production. High positive correlations were also found between biomass and plant height, crown size, tiller number and size, and leaf/stem ratio. The data presented in this study will become publicly available via the Germplasm Resource Information Network (GRIN)‐Global database of the NPGS.

Phenotypic diversity for phenological and agronomic traits in the UC‐Riverside cowpea (Vigna unguiculata L. Walp) mini‐core collection

“…In common bean ( Phaseolus vulgaris L.), the temporal control of flowering initiation determined the time invested in vegetative growth and, consequently, the vegetative resources available during reproduction (González et al., 2016). A negative correlation between two traits suggests that an increase in time or in number of one trait has an adverse effect on the other trait (Rios et al., 2019). The high negative correlation found in our study between DFPM and DTF indicates that the longer the plant takes to set flowers, the shorter the period for pod formation and/or maturity.…”

“…The reproduction index ranged from .51 to .52 for M. enterolobii and between .86 and .92 for M. incognita (Dareus et al., 2021). Combining multiple traits into one cultivar is a challenge for breeders, especially for traits with negative correlations, and indirect selection using various positively correlated traits may reduce phenotyping efforts (Rios et al., 2019). Moderate correlations between days to flowering and dry biomass yield ( r g = .54) and plant height ( r g = .51) were reported in cowpea (Gerrano et al., 2015).…”

Breeding forages with climate resiliency in temperate/tropical transition zones

“…Red clover, particularly in Europe, and annual ryegrass are species with commercial success of tetraploid cultivars. Rios et al, 2015, 2019) recently reported ploidy characterization of 139 annual ryegrass accessions obtained from the USDA Germplasm Resources Information Network (GRIN) germplasm collection of annual ryegrass plus 15 Florida experimental lines and 13 commercial cultivars. Only 16% (27 out of 167) of accessions evaluated were tetraploid, all developed through doubling chromosome numbers since tetraploid annual ryegrass is not known to exist in the wild.…”

“…In the last century, autopolyploidy has been viewed as a breakthrough tool for yield enhancement, but research soon demonstrated otherwise in most major food crops.Commercial success of polyploidy in cultivar development has primarily been limited to some floriculture crops and to certain forage species. Red clover, particularly in Europe, and annual ryegrass are species with commercial success of tetraploid cultivars Rios et al, 2015Rios et al, , 2019. recently reported ploidy characterization of 139 annual ryegrass accessions obtained from the USDA Germplasm Resources Information Network (GRIN) germplasm collection of annual ryegrass plus 15 Florida experimental lines and 13 commercial cultivars.…”

Sowing rate and its effects on forage yield of tetraploid ryegrass

“…Tetraploid accessions, for example, have significantly larger seeds compared to diploid seeds (Sugiyama, 1998). In addition to these, ploidy determines morphological changes in the plant, which must be considered for the indication of the sowing rate to be used (Rios et al, 2019).…”