Assessing photosynthetic performance of fennel (Foeniculum vulgare Mill) influenced by plant growth regulators and drought stress imposed at vegetative and reproductive stages

  • Ghasem Parmoon | ghasem.parmoon@gmail.com Department of Agronomy and Plant Breeding, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran, Islamic Republic of.
  • Ali Ebadi Department of Agronomy and Plant Breeding, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran, Islamic Republic of.
  • Soodabeh Jahanbakhsh Department of Agronomy and Plant Breeding, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran, Islamic Republic of.
  • Masoud Hashemi Stockbridge School of Agriculture, University of Massachusetts, Amherst, United States.
  • Seyed Amir Moosavi Department of Plant Production and Genetics, Faculty of Agriculture, Agricultural Sciences and Natural Resources University of Khuzestan, Iran, Islamic Republic of.

Abstract

Maintaining crop productivity under limited irrigation water requires some new strategies. This study investigated the influence of drought stress and the application of plant growth regulators (PGRs) including jasmonic acid, brassinosteroids, and putrescine on photosynthetic performance of fennel (Foeniculum vulgare Mill). The results indicated that fennel exhibited active osmoregulation which prevented a sharp decrease in relative water content. Fennel successfully maintained high leaf chlorophyll index, Net photosynthesis rate, and transpiration under mild stress, however, severe stress reduced the photosynthetic parameters by 22%, 24%, and 50%, respectively. Drought stress increased chlorophyll a fluorescence when fennel plants exposed to the stress condition. Vk and Wk parameters related to the donor side of photoinhibition of photosystem II (PSII) increased by 44% when severe drought stress imposed at the vegetative stage and 34% when occurred during the flowering. The elevation of Vk and Wk indicated a failure in water splitting in PSII. The VJ and VI parameters of acceptor sides increased by 16% and 22%, respectively when drought stress imposed at the vegetative phase and to 19% and 30%, when drought stress occurred during reproductive phase. Using PGRs resulted in reduced VJ, VI, Vk, and Wk, suggesting that some degree of recovery of damages occurred. All three PGRs stimulated biomass production and on average, plants yielded roughly 1.6 fold higher than the control plants. The influences of PGRs were mainly independent of drought stress level.

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Published
2019-06-05
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Original Articles
Keywords:
Brassinosteroids, fennel, chlorophyll fluorescence, proline.
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How to Cite
Parmoon, G., Ebadi, A., Jahanbakhsh, S., Hashemi, M., & Moosavi, S. A. (2019). Assessing photosynthetic performance of fennel (Foeniculum vulgare Mill) influenced by plant growth regulators and drought stress imposed at vegetative and reproductive stages. Italian Journal of Agronomy, 14(2), 93-100. https://doi.org/10.4081/ija.2019.1319