Waterlogging (WL) affects the growth and physiological responses of turfgrass. The objectives of this study were to compare the relative WL tolerance of Kentucky bluegrass (Poa pratensis L.) cultivars and to investigate the physiological responses of shoots and roots to WL. Ten cultivars differing in growth habit were subjected to 30 d of WL. The turf quality (TQ) and soil redox potential (Eh), as well as the chlorophyll concentration (Chl), decreased with increasing periods of WL. Among all cultivars, root dry weight (RDW) decreased 16.7% to 39.9% under 10 d and 30.0% to 60% under 30 d of WL, respectively. Waterlogging increased the root electrolyte leakage (REL) from 0.6% to 53.2% under 10 d and from 29.1% to 98.0% under 30 d of WL for all cultivars, respectively. The best correlations were observed between Eh and TQ (r = 0.74), REL and TQ (r = 0.75), RDW and root water-soluble carbohydrate content (RWSC) (r = 0.74), and root oxidase activity and RWSC (r = 0.63), respectively. ‘Moonlight’, ‘Serene’, and ‘Champagne’ showed better tolerance to short-term WL conditions, whereas ‘Kenblue’ and ‘Eagleton’ were the least tolerant cultivars. ‘Limousine’, ‘Unique’, ‘Awesome’, ‘Julia’, and ‘Midnight II’ ranked in the middle group. Variations in WL tolerance among Kentucky bluegrasses could potentially be used for enhancing turfgrass management.

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BackgroundFeed contributes to over 60 % of the total production costs in the poultry industry. Increasing feed costs prompt geneticists to include feed intake and efficiency as selection goals in breeding programs. In the present study, we used an F2 chicken population in a genome-wide association study (GWAS) to detect potential genetic variants and candidate genes associated with daily feed intake (FI) and feed efficiency, including residual feed intake (RFI) and feed conversion ratio (FCR).MethodsA total of 1534 F2 hens from a White Leghorn and Dongxiang reciprocal cross were phenotyped for feed intake and efficiency between 37 and 40 weeks (FI1, RFI1, and FCR1) and between 57 and 60 weeks (FI2, RFI2, and FCR2), and genotyped using the chicken 600 K single nucleotide polymorphism (SNP) genotyping array. Univariate, bivariate, and conditional genome-wide association studies (GWAS) were performed with GEMMA, a genome-wide efficient mixed model association algorithm. The statistical significance threshold for association was inferred by the simpleM method.ResultsWe identified eight genomic regions that each contained at least one genetic variant that showed a significant association with FI. Genomic regions on Gallus gallus (GGA) chromosome 4 coincided with known quantitative trait loci (QTL) that affect feed intake of layers. Of particular interest, eight SNPs on GGA1 in the region between 169.23 and 171.55 Mb were consistently associated with FI in both univariate and bivariate GWAS, which explained 3.72 and 2.57 % of the phenotypic variance of FI1 and FI2, respectively. The CAB39L gene can be considered as a promising candidate for FI1. For RFI, a haplotype block on GGA27 harbored a significant SNP associated with RFI2. The major allele of rs315135692 was favorable for a lower RFI, with a phenotypic difference of 3.35 g/day between opposite homozygous genotypes. Strong signals on GGA1 were detected in the bivariate GWAS for FCR.ConclusionsThe results demonstrated the polygenic nature of feed intake. GWAS identified novel variants and confirmed a QTL that was previously reported for feed intake in chickens. Genetic variants associated with feed efficiency may be used in genomic breeding programs to select more efficient layers.Electronic supplementary materialThe online version of this article (doi:10.1186/s12711-015-0161-1) contains supplementary material, which is available to authorized users.

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