Easton, H. S.

Matthew, Cory

Sartie, A. M.

English

University of Kentucky

University of Kentucky UKnowledge International Grassland Congress Proceedings 21st International Grassland Congress / 8th International Rangeland Congress Tiller Weight versus Tiller Number in a Perennial Ryegrass Population: A Productivity Index Cory Matthew Massey University, New Zealand A. M. Sartie Massey University, New Zealand H. S. Easton Palmerston North, New Zealand 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/21/1-3/5 The 21st International Grassland Congress / 8th 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 ]104　 瞯 　 Multifunctional Grasslands in a Changing World 　 Volume Ⅰ 　Grasslands/Rangelands Resources and Ecology ——— Ecology of Grasslands/RangelandsTiller weight versus tiller number in a perennial ryegrass population : a productivity indexC . Matthew 1 , A .M . Sartie 1 ,2 , and H .S . Easton21 Institute o f Natural Resources , Massey University , Priv ate Bag 11‐222 , Palmerston North , New Zealand , and2 A gresearch , Priv ate Bag 11‐008 , Palmerston North , New Zealand . E‐mail : c .matthew＠ massey .ac .nzKey words : plant dry weight , productivity index , size‐density compensationIntroduction In defining agronomic indicators of sward status , tiller population density is often intuitively linked with swardvigour and presumed to be indicative of productivity potential . However , grass swards are subject to tiller size‐densitycompensation and exhibit considerable plasticity , with shoot size and density subject to genetic variation , and varying withfactors such as change in grazing height or seasonal light influx . A productivity index ( PI) representing combinations of tillersize and density predicted to result in higher ( or lower ) sward leaf area index ( LAI) and DM productivity ( Matthew et al . ,１９９５) has been shown to be useful when comparing genetically similar swards under differing managements , but it is knownthat the cultivar Grasslands Ruanui has an anomalously high PI when compared with Grasslands Ellett (Bahmani et al . ,１９９７) .Here we report further investigation into factors affecting PI .Materials and methods ３ clonal replicates of each of ２００ full sib F１ seedlings of a Grasslands Impact x Grasslands Samson crosswere cultivated in １０cm diameter plastic bags in a glasshouse at AgResearch Palmerston North from April to July ２００３ . Onceestablished , plants were monitored for ４ leaf appearance intervals to determine leaf length ( LL ) , leaf appearance interval ( AL ) ,leaf elongation duration and ( LED) , tiller number per plant ( TN) , and plant dry weight ( DW) . Plant spacing was such thatthe canopy approximated a closed field sward . For measurement units , see Table １ . Leaf elongation rate ( LER) , tiller weight( TW) , and PI ( here : log１０ TW ＋ １ .５ log１０ TN / pot area) were also calculated for each plant . Data were averaged for clonalreplicates and the data matrix of ８ variables for ２０２ genotypes so obtained , subjected to principal component ( PC ) analysis( using the covariance matrix ) in Minitab version １０ .１ .Results For each of the ２００ genotypes and ２ parents , log ( tiller weight , g ) and log ( tiller population density , m‐２ ) are plottedin Figure １ . The solid line is an arbitrarily placed １ :１ compensation line indicating combinations of tiller weight and densitygiving constant plant DW . The dashed line indicates constant PI ( Matthew et al . , １９９５) . The first ３ PCs ( Table １) accountedfor ８３％ of the data variation . PC１ links high PI , DW and TN with lower LER and long LED . PCs ２ and ３ focus on change inDW and PI associated with TW and TN , respectively , and in both cases linked to high LER .Figure 1 Tiller siz e‐density compensationw ithin the Samson‐Impact F１ population .Table 1 V ariable means and p rincipal component ( PC ) structure f or PCAex p loring inter‐relationships w ith Productiv ity Index ( PI ) . Coe f f icients lessthan ０ .２ are sup p ressed .Mean PC１ 耨PC２ 排PC３ 槝LL ( mm) １７６  ‐ ０ `.５４６ ‐０ N.２１９AL ( days) １３ 忖.３ ０ 寣.３５７ ‐ ‐０ N.５２８LED ( days) １５ 忖.１ ０ 寣.３４１ ‐ ‐０ N.５５７LER ( mm day‐１ ) １１ 忖.９ ‐０ Ё.３４７ ０ `.４０４ ０ 3.２２９DW ( g plant‐１ ) ３ 构.２ ０ 寣.３００ ０ `.４８２ ０ 3.２７０PI ４ 构.４ ０ 寣.４４４ ０ `.３０４ ０ 3.３３８TW ( g ) ０ 构.０９７ ‐０ Ё.３０３ ０ `.４２８ ‐TN ( tillers plant‐１ ) ３５ 忖０ 寣.４９３ ‐ ０ 3.３２０％ v ariance ex p lained ‐ ３６ 档.９ ２６ 墘.９ ２２ \.８Discussion and conclusions Means in Table １ allow the reader to visualise the plant status during the experiment . As is commonin PCA , the structure of PCs changed somewhat , depending on the variables entered into the analysis , but relationshipsbetween variables common to most PCA formulations were identified even so . PC１ has a strong size/ density compensationcomponent with small‐tillered plants having high PI , a phenomenon also noted by Bahmani et al . １９９７ . PC２ picks outgenotypes with an association between LL , LER , DW , and PI , and follow‐up study may be of interest to see if scores for thisPC provide useful information for plant improvement .ReferencesBahmani I , Thom ER , Matthew C . , ( １９９７ ) . Effects of nitrogen fertiliser and irrigation on the productivity of differentryegrass ecotypes when grazed by dairy cows . Proc . New Zealand Grassland A ssociation , ５９ , １１７‐１２３ .Matthew C , Lemaire G , Sackville Hamilton NR . , ( １９９５ ) . A modified size/ density equation to describe size densityrelationships for defoliated swards . A nnals o f Botany , ７６ , ５７９‐５８９ .-0.8 ~ -0.9 Cl ; -1 Cl -1 .2 0 ...J -1.3 -1 .4 3.2 a rent • Impact parent 3.4 3.6 3.8 4 Log tiller density 

Tiller Weight versus Tiller Number in a Perennial Ryegrass Population: A Productivity Index

https://uknowledge.uky.edu/cgi/viewcontent.cgi?article=2283&amp;context=igc

Tiller Weight versus Tiller Number in a Perennial Ryegrass Population: A Productivity Index

Abstract

Similar works

Full text

Available Versions

University of Kentucky