Unraveling phenotypic diversity in Cynodon spp. germplasm for forage accumulation and nutritive value in the transition zone

Authors: DE SOUZA, C.H.L. - University Of Florida; CANNY, R - Noble Research Institute; SHARMA, N - Noble Research Institute; SAHA, M - Noble Research Institute; WALLAU, M - University Of Florida; Anderson, William - Bill; BAXTER, L - University Of Georgia; Harris-Shultz, Karen; RIOS, E - University Of Florida

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/19/2022
Publication Date: 3/17/2023
Citation: De Souza, C., Canny, R.S., Sharma, N., Saha, M., Wallau, M.O., Anderson, W.F., Baxter, L., Harris-Shultz, K.R., Rios, E.F. 2023. Unraveling phenotypic diversity in Cynodon spp. germplasm for forage accumulation and nutritive value in the transition zone. Crop Science. 63:690-704. https://doi.org/10.1002/csc2.20871.
DOI: https://doi.org/10.1002/csc2.20871

Interpretive Summary: Bermudagrass (Cynodon spp.) is an important perennial warm-season forage grass for southeastern United States. Increased yields while decreasing inputs such as nitrogen fertilizer are important for livestock and hay producers. There is a large amount of genetic variation among a collection of plant introductions present in the USDA Germplasm Resources Information Network and in plant breeding nurseries in the United States. To better determine the best genotypes to use in breeding for yield and quality improvement, there is a need to evaluate the diverse lines in different environments and management conditions. This study was done in Ardmore, Oklahoma and all lines were replicated under two management conditions (0 nitrogen applied after each harvest and 150 kg ha-1 per harvest) and harvested five time over two years (2016 and 2017). Dry matter yield (DMY) and nutritive values (NV) were determined for each harvest. There was significant variation among genotypes and nitrogen levels for yield and crude protein. Though there were some interactions between the genotypes and harvests and nitrogen levels, there was generally good stability for genotypes across harvest times and nitrogen levels. This information will be used by plant breeders to select genotypes for further evaluation and genetic improvement.

Technical Abstract: Characterizing phenotypic variation in germplasm collections is crucial for plant breeding. Cynodon spp. accessions maintained at the USDA National Plant Germplasm System (NPGS), and the core forage collection were screened in a replicated trial under two nitrogen rates (0 and 150 kg ha-1 per harvest) in Ardmore, Oklahoma. The goals for this study were: (i) estimate genetic parameters for dry matter yield (DMY) and nutritive value (NV), (ii) estimate genotype by harvest (rGH) and genotype by environment (rGE) interaction for all traits, (iii) quantify DMY and NV for commercial cultivars and selected accessions, and (iv) estimate trait correlations. The experiment was setup as a row-column design with two replicates and augmented representation of controls: Tifton 85, Wrangler, Midland, and Cheyenne. The trial was harvested five times (twice in 2016 and three times in 2017), and data were analyzed using linear mixed models. Genetic parameters revealed the presence of significant phenotypic variation for DMY and NV. Low genotype by harvest and genotype by environment interactions indicated genotypic stability and potential for selecting improved accessions for DMY and NV. Several PIs were selected for their improved DMY and NV. The application of N increased DMY and CP concentration in all harvests but did not significantly impact phenotypic variation in other NV traits. Phenotypic data will be deposited in the Germplasm Resource Information Network (GRIN)-Global database.