Cao, Z. Z.

Du, W. H.

Humphries, Alan W.

Wang, G.

English

University of Kentucky

University of Kentucky UKnowledge International Grassland Congress Proceedings XXI International Grassland Congress / VIII International Rangeland Congress Alfalfa Growth and Reproduction as Influenced by Plant Growth Regulators W. H. Du Gansu Agricultural University, China G. Wang Lanzhou University, China Z. Z. Cao Gansu Agricultural University, China Alan W. Humphries South Australian Research and Development Institute, Australia 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/21/14-1/26 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 ]574　 瞯 　 Multifunctional Grasslands in a Changing World 　 Volume Ⅱ 　Grasslands/Rangelands Production Systems——— Seed Science and TechnologyAlfalfa growth and reproduction as influenced by plant growth regulatorsW . H . DuA , B , G . W angB , Z . Z . CaoA , and A lan HumphriesCA College o f G rassland Science , Gansu A gricultural University , L anz hou 730070 , China . E‐mail : duwh ＠ gsau .edu .cnB S tate Key L ibrary o f A rid A gro‐ecology , L anz hou University , L anz hou 73000 , China . C South A ustralian Research andDevelopment Institute , A delaide , South A ustralia 5001 .Key words :chlormequat ( CCC) ,ethephon ( EP) ,paclobutrazol ( PP３３３ ) ,alfalfa ,seed yield ,yield componentsIntroduction Plant Grow th Regulators ( PGRs) have been widely evaluated for agricultural production ( Bai １９９２ ; Buck １９９３ ;Pen １９９９) . Although studies on the effect of PGRs on alfalfa seed production began in １９７０s , they mainly have been done incountries such as Australia , New Zealand and Canada but except for China . And all references showed that PGRs couldincrease seed yield of alfalfa . But few studies refered to seed yield components . So , the main aim of this study was to see ifresults about PGRs could work in China under field conditions and to describe in detail how PGRs affect seed yield componentsof alfalfa .Materials and Methods The field experiment was established in Wuwei city of Gansu province , located in northwest of China .Three foliar applications of ０ .３ ％ , ０ .５ ％ and ０ .７ ％ CCC , ０ .１５ ％ and ０ .３５ ％ EP , and ０ .１２ ％ and ０ .２２％ PP３３３ at ７‐daysintervals were applied at the branching stage in ２００３ and ２００４ . Indexes such as above‐and underground biomasses , reproductiveallocation rate ( RAR) , harvest index ( HI ) , harvested seed yield , yield components , seed germination , plant height andlodging percentage were determined in the two years .Results Above ground biomass was decreased with ０ .１２ ％ PP３３３ by ２５ ％ and ０ .２２ ％ PP３３３ by ４８ ％ , and undergroundbiomass was decreased by ４４ ％ . The RAR and HI of alfalfa increased by a factor of ３‐４ with the application of ０ .１２ ％ and０畅２２ ％ PP３３３ in the two years of the study . Harvested seed yield was increased with ０畅１２ ％ PP３３３ by ３１‐４６ ％ and ０畅２２ ％PP３３３ by ４６‐４７ ％ . In ２００３ , the number of racemes per shoot were increased with ０畅２２ ％ PP３３３ by ６５ ％ , ０畅１５ ％ EP by３５ ％ , and ０畅７ ％ CCC by ３０ ％ ; the number of pods per raceme were increased with ０畅２２ ％ PP３３３ by ３４１ ％ , ０畅１２ ％ PP３３３by １８５ ％ , ０畅１５ ％ EP by １７６ ％ , ０畅３ ％ CCC by １６４ ％ , and ０畅３５ ％ EP by ９５ ％ . In ２００４ , ０畅２２ ％ PP３３３ increased numberof racemes per shoot by １２ ％ ; the number of pods per raceme were increased with ０畅２２ ％ PP３３３ by ４４２ ％ , ０畅１２ ％ PP３３３ by２７４ ％ , ０畅１５ ％ EP by ２７２ ％ , ０畅３ ％ CCC by １９２ ％ and ０畅３５ ％ EP by ８５ ％ . In two years , the highest number of seeds perpod was gained under PP３３３ treatment , which increased them by ８４‐８８ ％ in ２００３ and １４１‐１４４ ％ in ２００４ . Among yieldcomponents , the number of pods per raceme and the number of seeds per pod were the most important factors to determinealfalfa seed yield .Conclusions PP３３３ was the best PGR in alfalfa seed production , which increased seed yield by reducing plant heights , increasinglodging resistance ability , the number of racemes per shoot , the number of pods per raceme and the number of seeds per pod .This PGR had no ill effect on seed quality . Of the two rates tested , the highest rate ( ０畅２２ ％ ) had the greatest effect onimproving seed yield . Furhter research is recommended to investigate the effect of different rates of applied PPP３３３ across anumber of environments in China and around the world as a basis for developing recommendations to the alfalfa seed productionindustry .ReferencesBai , B . Z . , １９９２ . Plant physiology . A gricultural Press o f China , Beijing , １８３pp .Buck , D . C . , １９９３ . The effects of various plant grow th regulators on the nutritive value , yield and stand composition of someforage species and forage mixtures . Dissertation Abstracts International B , Sciences and Engineering 53(７) , ９５‐１０１ .Pen , Y . M . , １９９９ . Studies on physiological effect and utilization of PGRs on forage and forage crops . Grassland o f InnerMongolia 4 , ５４‐５７ .

Alfalfa Growth and Reproduction as Influenced by Plant Growth Regulators

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Alfalfa Growth and Reproduction as Influenced by Plant Growth Regulators

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