Abstract
Evaluation of forage yield and antioxidant activity in Poa pratensis with high quality and good spring green-up forage might help variety improvement for use under water deficit condition. Germplasm and phenotypic diversity evaluations lay a foundation for genotype selection and improvement of varieties for drought tolerance in P. pratensis. The present study was conducted to assess the genetic potential of a collection of P. pratensis accessions for drought stress and to identify the association between polyphenol compounds and forage yield traits. Vegetative clone samples of 100 accessions collected from a diverse geographical area of Iran were clonally propagated in a greenhouse and evaluated in the field under two moisture regimes (non-stress and drought stress) in 2018 and 2019. Drought stress had negative effects on fresh and dry forage yields and reduced phenotypic variances. On average, drought stress reduced fresh and dry forage yields by 45% and 28%, respectively. The results of Mantel test showed no significant correlation between forage yield traits and geographical distances. Genetic coefficients of variation for forage yield and most of the phytochemicals were lower under drought stress, suggesting that deficit irrigation may reduce genetic variation for the tested traits. The estimates of heritability were higher under non-stress conditions than under drought stress treatment for forage yield traits and few polyphenols. However, the majority of polyphenol compounds had higher heritability than forage yield traits under drought stress, which suggests the potential for indirect selection. The ‘Ciakhor’, ‘Damavand’, ‘Karvandan’, ‘Abrumand’, and ‘Abr2’ accessions had high quantities for polyphenols and yield traits under both moisture regimes. These accessions are promising candidates for use in variety crossing programs and for developing high-yielding varieties under water-deficit conditions.
Highlights
The sessile nature exposes plants to changing e nvironments[1,2]
The Kentucky bluegrass of our study accumulated higher polyphenol compounds under drought stress treatment compared to the nonstress conditions that was in line with results of previous studies in g rasses[55–57]
The results of genetic variation analysis in our study revealed that the genotypic coefficients of variation (GCV) for agronomic traits was higher for accessions tested under irrigation conditions than under drought conditions, implying that drought stress restricts the phenotypic response of accessions
Summary
The sessile nature exposes plants to changing e nvironments[1,2]. Drought and heat stresses are the environmental side effects of climate change caused by increasing greenhouse gases[3]. Long-term historical climate records revealed that some Iran provinces have been affected by moderate, severe, and extreme droughts Despite these conditons and due its habitat diversity, Iran continues to maintain high species diversity with over 8000 recorded[24]. Germplasm evaluation including assessment of available phenotypic diversity and estimation of the heritability of desired traits is a preliminary step in the early phase of breeding programs to provide raw material from genetic resources and develop high forage yield varieties with higher antioxidant activity and polyphenol c omponents[31,32]. Previous studies show that physiological traits, the plant persistence and recovery and antioxidant enzyme activities have been assessed in lawn Kentucky bluegrass varieties under drought stress[37–39] These studies focused on the lawn perspective of this species and the assessment of variation in forage yield traits and phytochemical compositions is missing in such studies. The aim of the current study was to assess the genetic diversity of a collection of P. pratensis accessions for forage yield and phytochemical compositions under drought stress conditions and to pre-breed possible drought tolerant candidates for use in breeding programs
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