The Inhibition of Flowering by Water Stress

Abstract

SummaryPlants of Lolium temulentum L., a single.cycle, long.day plant, and Pharbitis nil Ohois. cv. Violet, a single·cycle, short-day plant, were subjected to osmotic stress during the inductive cycle. An osmotic potential of-IS atm (using poly. ethylene glycol, mol. wt. 4000) during the 24·hr exposure to light completely prevented flowering in L. temulentum. Similarly, -6 atm osmotic potential during the 16-hr dark cycle suppressed flowering in P. nil. Water stress during induction, achieved by withholding water to soil-grown plants, also prevented flower induction in Xanthium strumarium L.With L. temulentum and X. strumarium, stress accompanied by defoliation during the period immediately following the inductive cycle also prevented flowering. The data were consistent with a stress-imposed inhibition of translocation of the floral stimulus from the leaf. L. temulentum plants which were stressed but not defoliated during this period formed flowers, suggesting that the floral stimulus itself is relatively stable within the leaf during a period of stress.

Drought and the Evolution of Flowering Time in Desert Annuals

“…A number of techniques have been used to impose water stress. A number of researchers have used hydroponic approaches, imposing drought stress either by manipulating the osmotic properties of the growth medium-usually by adding polyethylene glycol (PEG) (Husain and Aspinall and Husain, 1970;King and Evans, 1977;Frank, Bauer, and Black, 1987)-or by removing plants from the growth medium for varying lengths oftime (Boot, Raynal, and Grime, 1986). Hydroponic techniques are attractive because they allow quantitative control over treatments.…”

“…While growth chambers have been used by some researchers (Nicholls and May, 1963;Husain and Aspinall, 1970;Aspinall and Husain, 1970;Marc and Palmer, 1976;King and Evans, 1977;Frank, Bauer, and Black, 1987), they do not seem to present any particular advantage in most cases, because soil water potentials cannot be controlled by growth chambers. Growth chamber experiments are likely to impose limits on sample sizes.…”

Phenology, leaf gas exchange, growth and seed yield in Medicago polymorpha L. populations affected by water deficit and subsequent recovery

“…Clarkson and Russell (1976) suggested that annual medics have no mechanisms for evading dry season conditions by flowering earlier, but once flowering has begun, phasic development is accelerated in some species by drought stress. The delay in flowering by water deficit has been reported in other plants, and several explanations for it have been advanced (Aspinall and Hussain, 1970;King and Evans, 1977;Vince-Prue, 1985;Sharp et al, 2009). …”

Effect of water stress on the phasic development of annual Medicago species

“…Firstly, since flowering time may be influenced by photoperiod in both annual medics (Aitken 1955) and subterranean clover (Evans 1959), water stress may inhibit floral induction in the leaves and possibly translocation of the stimulus to the apex (Aspinall and Husain 1970). This wpuld delay flower initiation and lead to later flowering.…”