Effect of uniconazole and limited water on growth, water relations, and mineral nutrition of “Lalandei” Pyracantha

Abstract

Pyracantha (Pyracantha coccinea M. J. Roem. “Lalandei”) plants were treated with uniconazole at 0.5 mg ai container−1 as a medium drench, 150 mg ai L−1 as a foliar spray, or left untreated. Plants from all treatments were placed under three water regimes: drought acclimated, nonacclimated and later exposed to drought, or nonstressed. Acclimated plants were conditioned by seven 4-day stress cycles (water withheld), while nonacclimated were well watered prior to a single 4-day stress cycle at the same time as the seventh drought cycle of acclimated plants. Nonstressed plants were well watered throughout the study. Nonstressed plants had higher leaf water potentials and leaf conductances than acclimated and nonacclimated plants, and transpiration rates were higher in nonacclimated than acclimated plants. Uniconazole did not affect leaf water potential, leaf conductance, or transpiration rate. Acclimated plants had smaller leaf areas and leaf, stem, and root dry weights than nonacclimated or nonstressed plants. Plants drenched with uniconazole had the lowest stem and root dry weights. Acclimated plants also contained higher N concentrations than nonacclimated or nonstressed plants, and higher P concentrations than nonacclimated plants. Uniconazole medium drench treatments increased levels of Mn and P. Calcium concentration was increased in plants receiving either medium drench or foliar applications.