Nitrogen status and biomass determination of oilseed rape by laser-induced chlorophyll fluorescence

The objective of this study was to quantify the biomass and the macronutrient stock in an experiment of fertilization with Eucalyptus urophylla, planted in arenized soil at 12 months-old, in Rio Grande do Sul, Brazil. The experiment had a completely randomized design with five treatments (T1, T2, T3, T4 and T5) with three replications. The treatments T2, T3, T4 and T5, received increasing doses of triple superphosphate. On the other hand, the T1 treatment was the only one to receive natural phosphate in planting. For the determination of the biomass, fifteen trees were felled and separated in the following components: leaves, branches, stem bark, stem wood and roots. Samples of the components were collected and transported to the laboratory for biomass determination and chemical analysis. The total biomass varied between the treatments, with highest biomass accumulation of 6.83 Mg ha-1 occurring in T5. The T1 presented the highest biomass for roots representing 33.4% of the total biomass. The biomass distribution among the different components in the decreasing order was: roots > stem wood > leaves > branches > stem bark, for all the treatments. The treatment with higher doses of fertilizers (T5) presented the highest amount of nutrient accumulation in the total biomass (131.26 kg ha-1). The concentration and accumulation of nutrients presented the following trend K > N > Ca > Mg > P > S. Analyzing the different components of biomass, the highest amounts of nutrients followed the order: leaves > roots > stem wood > branches > stem bark. Fertilization influenced the biomass production of E. urophylla in arenized soil in the Pampa biome, but without significant differences to date (12 months). The leaves had the highest concentration of macronutrients, with the exception of Ca, which was higher in the bark. The K was the element that presented highest accumulation in whole tree. The plantation of eucalyptus with fertilization management may be an alternative for the economic use of arenized soil.

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Determination of the influence of herbicides on dicotyledons plant transpiration using the sap flow method

Plant Soil and Environment ◽

10.17221/655/2014-pse ◽

2014 ◽

Vol 60 (No. 12) ◽

pp. 562-568 ◽

Cited By ~ 1

Author(s):

V. Brant ◽

J. Pivec ◽

K. Hamouzová ◽

P. Zábranský ◽

J. Satrapová ◽

...

Keyword(s):

Chlorophyll Fluorescence ◽

Transpiration Rate ◽

Sap Flow ◽

Herbicide Application ◽

Plant Transpiration ◽

Flow Method ◽

Infrared Gas Analyser ◽

The Impact ◽

Q Values

Physiological parameters are sensitive and provide information on the toxicity of herbicides in plants. The impact of herbicide application on plant transpiration was evaluated by the sap flow method during 2009–2011. The aim of this work was to verify the sap flow method for determining the effect of herbicides on the basis of continuous measurements of the transpiration flow. Helianthus annuus was used as a model plant species. The two different herbicides tested in this study differed by the effect of active ingredients bromoxynil and clopyralid. The water flow was measured using sap flow meter T4.2. The impact of herbicides was assessed by comparing measured transpiration rate (Q) after herbicide application with an extrapolation of transpiration rate of plants before herbicide treatment (Qcalc). After treatment with bromoxynil the Q values decreased significantly compared to Qcalc. For plants treated by clopyralid, the decline of actual transpiration (Q) compared with the modelled one (Qcalc) was less substantial and the plants continued to transpire after the treatment. The effect of herbicides was also verified using infrared gas analyser and chlorophyll fluorescence meter.

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