Aello, M. S.

Agnusdei, Mónica G.

Di Marco, Oscar Norberto

Nennin, F.

English

University of Kentucky

University of Kentucky UKnowledge International Grassland Congress Proceedings XXI International Grassland Congress / VIII International Rangeland Congress Leaf Growth Dynamics and Forage Quality in Temperate and Tropical Grasses Mónica G. Agnusdei Instituto Nacional de Tecnología Agropecuaria, Argentina F. Nennin Instituto Nacional de Tecnología Agropecuaria, Argentina Oscar Norberto Di Marco Universidad Nacional de Mar del Plata, Argentina M. S. Aello Universidad Nacional de Mar del Plata, Argentina Follow this and additional works at: https://uknowledge.uky.edu/igc  Part of the Plant Sciences Commons, and the Soil Science Commons This document is available at https://uknowledge.uky.edu/igc/21/15-1/41 The XXI International Grassland Congress / VIII International Rangeland Congress took place in Hohhot, China from June 29 through July 5, 2008. Proceedings edited by Organizing Committee of 2008 IGC/IRC Conference Published by Guangdong People's Publishing House This Event is brought to you for free and open access by the Plant and Soil Sciences at UKnowledge. It has been accepted for inclusion in International Grassland Congress Proceedings by an authorized administrator of UKnowledge. For more information, please contact UKnowledge@lsv.uky.edu. 瞯 688　 瞯 　 Multifunctional Grasslands in a Changing World 　 Volume Ⅱ 　Grasslands/Rangelands Production Systems ——— Forage Quality ,Conservation and UtilizationLeaf growth dynamics and forage quality in temperate and tropical grassesAgnusdei M .G .1 , Nennin F . 1 , Di Marco O . N .2 , Aello M . S .2 . 1 Instituto Nacional de Tecnolog ía Agropecuaria( I NTA ) . 2 Fac . Ciencias . Agrarias , Universidad Nacional de Mar del Plata . CC 276 . 7620 Balcarce . A rgentina .magnusdei ＠ balcarce .inta .gov .arKey words : C３ / C４ species , forage quality , indigestible NDF , leaf agingIntroduction In grasses , maximum leaf‐blade size is achieved at ligulae appearance . However , cell wall ( CW) accumulation , aswell as the occurrence of changes in CW chemical and structural features continues during leaf aging . Such ontogenic changes inforage quality are currently described by the increase of indigestible NDF ( INDF) . At present , many studies are focused on theINDF kinetics during leaf development with modeling purposes . The aim of this study was to evaluate the in vitro kinetic ofINDF accumulation in individual leaves along their development in three species differing in their potential leaf length andphotosynthetic path‐way .Materials and methods Studied species : temperate/ C３ : perennial ryegrass ( Lolium perenne , PRG) ; tropical/ C４ : grama rhodes( Chloris gayana , CG) and pangola grass ( Digitaria eriantha , PG) . The experience was carried out in a glasshouse underadequate nutrient and water availability conditions . Leaf appearance was recorded on marked tillers . Blades were clipped at eachleaf appearance interval . The material was immediately frozen with liquid N and further separated into leaf insertion classes .Leaf blade length was measured and leaves of the same insertion level were pooled , lyophilized and ground to １ mm . INDF wasdetermined in samples incubated in heat sealed F５７ filter bags for ２４ hours (Daisy , ANKOM Tech . Corp . , Fairport , NY) .Results and discussion INDF accumulation during leaf development was properly described , in the three species , by linealfunctions ( Figure １ ) . This indicates the period of indigestible cell wall formation would have lasted the whole leaf life spans .This pattern differs with the negative exponential saturation curve used in annual ryegrass by Groot and Neuteboom (１９９７ ) todescribe the evolution of the indigestible cell wall during leaf development . Slopes did not differ between PRG and PG , bothbeing significantly lower than CG ( the half , on average) . Average final leaf lengths were １８０ ± １６ , １２０ ± １０ and ４６３ ± １９ forPRG , PG and CG . These results stress the influence that leaf length might have on forage quality associated attributes .Moreover , they do not support the idea that forage quality is strictly associated with plant metabolic pathways . The commonpattern of INDF increase with leaf aging observed in PRG and PG might , in part , have been associated with the later beingshorter leaved than the former at a same leaf age . The obtained results underline the close link existing between plantmorphology , leaf aging and forage quality .Figure 1 Relationship between indigestible neutral detergent f iber ( I NDF)and lea f aging( growing degree days :GDD) in C3and C4 perennial grasses .ReferenceGroot J .J . and J .H . Neuteboom １９９７ . Composition and digestibility during ageing of Italian Ryegrass leaves of consecutiveinsertion levels . Sci Food Agric . , ７５ , ２２７‐２３６ .

Leaf Growth Dynamics and Forage Quality in Temperate and Tropical Grasses

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Leaf Growth Dynamics and Forage Quality in Temperate and Tropical Grasses

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