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Mineral nutrition regulation, saccharosesynthase and saccharosephosphatsynthase activity and saccharose accumulation by the beet plant

Author: Liulenova Valentina
Degree:doctor of biology
Speciality: 03.00.12 - Plant physiology
Scientific adviser: Toma Simion (decedat)
doctor habilitat, professor, Institute of Genetics, Physiology and Plant Protection of the ASM
Scientific consultant: Boris Boincean
doctor habilitat, professor, Research Institute of Field Crops "Selectia"


The thesis was presented on the 25 January, 2008
Approved by NCAA on the 17 April, 2008


Adobe PDF document0.51 Mb / in romanian
Adobe PDF document0.43 Mb / in russian


CZU . 581.1: 582.998.2: 577.175.1:581.145

Adobe PDF document 3.24 Mb / in romanian
142 pages


enzymes, mineral nutrition, saccharosesynthase, saccharosephosphatsynthase, sugar beet, microelements, macroelements, triangular, matrix, biomass


The work reports the findings of the researches carried out for many years on the influence of various doses and ratios of macro- and microelements on the activity of the key enzymes involved in carbohydrate metabolism, i.e. saccharosesynthase, saccharosephosphatsynthase and the accumulation of biomass and saccharose in the beet plant.

It has been established that the enzyme activity is more dependable on the content of phosphorous and potassium fertilizers at the initial development stage, and on that of nitrogenous fertilizers at the intensive growth stage. Saccharosephosphatsynthase appeared to be more responsive to soil applied nitrogen; the activity remained at a high level at the nitrogen dose equal to 0,65 g. of acting matter per kg of soil during the whole vegetation.

It has been shown that biomass accumulation depends on enzyme activity – the correlation between biomass gain and saccharosesynthase, saccharosephosphatsynthase was high and equal to 0,76 and 0,83, respectively. It was found out that saccharose expenditures to preserve leaf blade structures was almost twise as high that to preserve rootfruit structures.

A triangular matrix method revealed change in the requirement of sugar beet for mineral elements towards a higher nitrogen content in medium during the first vegetation year.

The microelements of B, Mn, Zn, Mo stimulated the activity of both enzymes, which resulted in the increase of the yielding capacity and sugar content of sugar beet rootfruits.

A high activity of saccharosephosphatsynthase in leaves was observed when boron was applied in soil.

Foliar microelement nutrition of leaf surface showed a gain in plant weight to 0,4%, increase in dry matter content and sugar content in rootfruits. The sugar content increase was more significant in the boron and manganese treatments and made 1,3% and 1,2%, respectively.

Saccharose accumulation in a rootfruit is the main function of sugar beet during the first vegetation year. The total sugar output is determined by sugar content and yield and depends on mineral nutrition.

Optimal NPK doses have been established to enhance sugar content in rootfruits that make 0,2 g of acting matter for nitrogen; 0,1 g of acting matter for phosphorus; and 0,2 g of acting matter for potassium per kg of soil However, the following doses are optimal to increase the total sugar content: 0,5 g of acting matter for nitrogen; 0,2 g of acting matter for phosphorus and 0,2 g of acting matter for potassium per kg of soil.

The soil microelement application has resulted to an essential, at a 5% significance level, gain of rootfruit yields in the boron and zinc containing treatments up to 0,3% and to a significant sugar content increase: boron application increased sugar content by 1,8%, and Mo by 1,2%.

The analysis of the experimental data has shown a relationship between the changes in the anatomical structure of rootfruits depending on the degree of plant provision with the main mineral elements (NPK), the activity of saccharosesynthase and saccharosephosphatsynthase and yield formation and sugar accumulation during the first year of sugar beet vegetation.