Gibberellin substitution for long day secondary induction of flowering in Poa pratensis |
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Authors: | O. M. Heide C. Blundell R. W. King L. T. Evans |
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Affiliation: | O. M. Heide (corresponding author, e‐mail;), Dept of Biology and Nature Conservation, Agricultural Univ. of Norway, N‐1432 Ås, Norway;C. Blundell, R. W. King and L. T. Evans, CSIRO Division of Plant Industry, P.O. Box 1600, Canberra, ACT 2601, Australia. |
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Abstract: | Plants of Poa pratensis cv. Holt initiate inflorescence primordia when exposed to short days (SD) and low temperature, but require a secondary induction by at least 4 long days (LD) for further inflorescence development and stem elongation. Single or double applications of 10 µg per plant of gibberellins A1, A3, A5 and 16,17‐dihydro A5 (DHGA5) induced inflorescence development in a high proportion of plants in SD, but only if the plants were detillered to a single stem. Exposure to 2 LD cycles did not cause heading and flowering alone but enhanced the effect of exogenous gibberellins (GAs), bringing flowering to 100%. GA5 and DHGA5 were less effective than GA1 and GA3 in SD, especially with double applications, but were more effective than GA1 and GA3 when given together with 2 LD. The GAs had differential effects on vegetative growth and flowering, GA5 and DHGA5 causing much less leaf and stem growth than the other two GAs. Marginal induction, whether by LD or GA application, resulted in a high proportion of spikelets with viviparous proliferation. Thus, whereas GAs are inhibitory to the primary induction by SD, they can replace secondary induction by LD when vegetative growth is limited. |
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Keywords: | Gibberellins growth flowering Kentucky bluegrass photoperiod Poa pratensis smooth meadowgrass vivipary |
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