José A. Monteiro

Effects of exogenous sucrose on carbohydrate levels, flower respiration and longevity of potted miniature rose (Rosa hybrida) flowers during postproduction

Abstract The effect of continuous injection of exogenous sucrose on single flower postproduction longevity of attached flowers of potted ‘Meijikatar’ miniature roses was studied. At bud showing color, with sepals starting to unfold, plants were moved to interior conditions and started being continuously injected with a solution of 3% sucrose or distilled water. Carbohydrate levels, flower respiration and single flower longevity were assessed. There was some variability in the amounts of solution supplied to the plants. Infusion of exogenous sucrose increased attached miniature rose flower longevity by 1.5 days and also increased flower respiration rates. The higher the uptake rate of sucrose solution the longer the flowers lasted. Exogenously supplied sucrose was consumed by increased respiration and consequently, at day 6 after anthesis, no differences were found in nonstructural carbohydrate levels between water and sucrose treatments. However, percent of soluble sugars in the stem was higher in the sucrose-infused plants, suggesting that exogenous sucrose supply not only served as an extra source of respirable carbohydrates but also released stored carbohydrates to flower respiration. At flower death, leaf soluble sugars and total non-structural carbohydrates were higher in the sucrose infusion treatment and, independently of infusion treatment, flower soluble sugars and total non-structural carbohydrates positively correlated with flower longevity.

Nickel and Nitrogen Phytoremediation by Cyperus involucratus: Nickel Impairs Biomass Production and Nitrogen Removal

Phytoremediation can be defined as the use of plants to remove, degrade, contain, or immobilize pollutants in water or soils and can improve biodiversity, in combination with other restoration or mitigation goals. This study aimed to assess the interaction between nickel (Ni) and macronutrient levels, on nickel and nitrogen removal by Cyperus involucratus from fresh water. A complete, 3 factor factorial experiment was performed, under laboratory conditions, testing: 3 levels of macronutrients (0, 100 and 200 mg of N/L) × two levels of Ni (0 and 5 mg Ni/L) × presence or absence of plants. The experiment lasted for 34 days. Ni had a negative effect on plant growth: plants kept in solutions without Ni increased their fresh weight in average, by 22% but if kept in solutions with 5 mg Ni/L decreased it by 8.9%. Plants were able to decrease ammonia and nitrate levels in the solutions of the treatments without Ni but Ni in the solutions impaired ammonia and nitrate removal by plants. The Ni Bioconcentration Factors obtained were 243 L/Kg in 2012 for plants washed with water and, 61 L/Kg in 2013 for plants washed with EDTA. The Translocation Factor to above ground parts was 0.3352 (plants washed with EDTA). Whether this is an effect with importance for the real world phytoremediation is still to be ascertained but this work provides evidence for the need of further studies on the interaction between metal toxicity and macronutrient removal for the most important plant species used in constructed wetlands.