03371naa a2200337 a 450000100080000000500110000800800410001902200140006002400270007410000200010124501450012126000090026650003410027552019670061665300110258365300230259465300160261765300270263365300400266065300240270065300410272470000200276570000180278570000200280370000170282370000180284070000200285870000190287870000170289777301190291410644732024-02-26       2024    bl uuuu     u00u1 u    #d  a0931-22507 a10.1111/jac.126822DOI1 aJÁUREGUI, J.M.  aTall fescue tiller survival over summer in a subtropical environmentbThe role of the size and depth of root systems.h[electronic resource]  c2024  aArticle history: Received 5 May 2023; Revised 20 October 2023; Accepted 1 November 2023. -- Correspondence: J. M. Jáuregui, Facultad de Ciencias Agrarias, Universidad Nacional del Litoral, Esperanza, Argentina. Email: josemartinjauregui@gmail.com -- Funding information: Consejo Nacional de Investigaciones Científicas y Técnicas. --  aABSTRACT.- Pasture persistence is a key determinant of the economic and environmental performance of pastoral animal production systems. Large and deep root systems that help resist summer water stress have been proposed as a relevant trait for vegetative persistence of perennial temperate forage species growing in subtropical climates or under future climatically challenging scenarios. In a previous study [Jauregui et al., 2017. Persistence of tall fescue in a subtropical environment: Tiller survival over summer in response to flowering control and nitrogen supply. Grass and Forage Science 72, 454-466] we have shown that nitrogen fertilization and grazing management aimed at 'control flowering' increased the survival of tall fescue tillers during harsh summers in Uruguay (lat. 32°S). Here we assessed: (i) to what extent tiller survival is mediated by root system size in spring and (ii) what consequences tiller survival entails for root mass, depth and morphology the following autumn. In two field experiments, significant increases in tiller survival in response to nitrogen fertilization and grazing management (+60% and +80% in 2011/12 and 2012/13, respectively) were not related to concomitant effects on the size or depth of the root system in spring (p >.10). Even when six-fold within-treatment variation in root mass was observed, within-treatment variation in summer tiller survival was little affected (<15%, p =.08). In turn, differences in tiller survival over summer affected little root system characteristics the following autumn. Therefore, we found scant support for the hypothesis that large and deep root systems contribute to survival of tall fescue tillers in this subtropical humid climate. Except for soils with less than 30 mm of plant available water holding capacity, summer water deficits did not induce severe tiller mortality in tall fescue in this climate. © 2024 Wiley-VCH GmbH. Published by John Wiley & Sons Ltd.  aForage  aGrazing management  aHeat stress  aNitrogen fertilisation  aPartnership for the goals - Goal 17  aPasture persistence  aSustainable Development Goals (SDGs)1 aMICHELINI, D.F.1 aSEVILLA, G.H.1 aBERHONGARAY, G.1 aBERONE, G.D.1 aBAUDRACCO, J.1 aCHILIBROSTE, P.1 aAGNUSDEI, M.G.1 aLATTANZI, F.  tJournal of Agronomy and Crop Science. 2024, Volume 210, Issue 1, article e12682. https://doi.org/10.1111/jac.12682