New Zealand Journal of Agricultural Research abstracts

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Lucerne growth and components of seed yield as influenced by plant growth regulators

Du Wenhua^1,2

Wang Gang^1,*

Tian Xinhui²

Alan Humphries³

¹State Key Library of Arid Agro-ecology
Lanzhou University
Lanzhou 73000, PR China

²College of Grassland Science
Gansu Agricultural University
Lanzhou 730070, PR China

³South Australian Research and Development Institute
Adelaide, South Australia 5001

^*Corresponding author: wangg@lzu.edu.cn

Abstract Effects of 0.3, 0.5, and 0.7% chlormequat, 0.15 and 0.35% ethephon, and 0.12 and 0.22% paclobutrazol on lucerne growth and components of seed yield were investigated in Gansu province, China. The paclobutrazol application decreased above- and below-ground biomass by 25–48 and 44% at concentrations of 0.12–0.22%, and increased seed yield by 31–47%. Applications of ethephon and chlormequat did not affect lucerne biomass, but reduced seed yield in the first year. Plant growth regulators also affected yield components very differently, with paclobutrazolhaving the greatest effect. The 0.22% paclobutrazol application increased the number of racemes per shoot by 38%, the number of pods per raceme by 392% and the number of seeds per pod by 115%. Although ethephon and chlormequat reduced seed yield in the first year and gave no response in the second, these plant growth regulators had some positive affects on some seed yield components. The 0.15% ethephon application increased the number of racemes per shoot by 35% and the number of pods per raceme by 225%. The 0.3% chlormequat application increased the number of fertile shoots per unit area by 24% and number of pods per raceme by 178%. None of the plant growth regulators had ill effects on lucerne seed quality (1000-seed weight and seed germination). Among yield components, the number of pods per raceme and number of seeds per pod were the most important factors to determine lucerne seed yield and yield potential can be estimated with the use of the two factors as a selection criterion. Results from this study will be used to recommend further evaluation of paclobutrazolat multiple sites and to guide lucerne seed production in the north-west region of China.

Keywords chlormequat; ethephon; lucerne; paclobutrazol; plant growth regulators; seed yield; yield components

A07189; Online publication date 14 August 2008; Received 7 December 2007; accepted 3 June 2008

New Zealand Journal of Agricultural Research, 2008, Vol. 51: 341–348
0028–8233/08/5103–0341 © The Royal Society of New Zealand 2008

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