Summary The thesis deals with the effect of mechanic invasion and top dressing applications on the quality of the lawn's greensward and weight of the root system of the plant. The aim of this thesis was to evaluate the effect of aeration, verticutation and top dressing in terms of support of plant root system, the presence of weeds in the lawn and also effect on the color of the grass and compactness of the lawn. Made mechanization interventions were evaluated without further intervention, verticutation and aeration. Application of top dressing is evaluated with and without step. The experiment was turfed in the Central region, twenty kilometers southeast of Prague. The greatest effect (P<0,05) on the weight of the root system should aeration with verticutation and smallest (P<0,05) the weight of the root system had lawn without mechanization invasion. In evaluating the compactness of the lawn was rated verticutation (P<0,05) as the worst. The best (P<0,05) color had lawn without any mechanized invasion and least (P<0,05) weed species was found out in combination of aeration and verticutation. Application of organic top dressing showed a positive effect on the weight of the root system. It was also found lower incidence of weeds. For top dressing applications has not been demonstrated a positive effect on the colour of the lawn. Application of top dressing had a positive effect on compactness of the lawn.

To determine the optimum nitrogen application level required for the production of good quality ‘Drumhead’ cabbage (Brassica oleracea var. capitata) transplants, a glasshouse experiment was conducted. Depending on water requirements, transplants were fertigated every two days (for the first four weeks) and every day (for the last two weeks) by floating trays in plastic tubs containing nutrient solution at 0, 30, 60, 90 and 120 mg•L-1 N until field capacity was reached. Increasing nitrogen from 0 to 120 mg•L-1 increased shoot and root mass of cabbage transplants with more dry mass being partitioned to the shoot than to the roots. Nitrogen at 120 mg•L-1 N produced greatest fresh and dry shoot mass, plant height, leaf area, leaf tissue nitrogen, net assimilation rate, relative growth rate and leaf mass ratio. Nitrogen at 90 mg•L-1 improved dry root mass, pulling success, specific leaf area and leaf area ratio. Greatest values of root: shoot ratio and root mass ratio were obtained at 0 mg•L-1 N. Nitrogen at 90 mg•L-1 was best as it produced transplants with more vigorous root growth which pulled out easily from the seedling trays. To determine the best combination of spacing and nitrogen top-dressing for improved cabbage production under local conditions, a field experiment was conducted. Cabbage ‘Copenhagen Market’ transplants were spaced at 30 x 50 cm, 40 x 50 cm or 50 x 50 cm and fertilized with nitrogen as top-dressing at 50, 100 or 150 kg•ha-1 N applied in two splits (fourth and eighth week after transplanting). There were no interactions between spacing and nitrogen top-dressing for all measured variables. Nitrogen and spacing did not influence dry matter production and leaf tissue nitrogen. Furthermore, spacing did not affect core height and yield (per unit area) of trimmed cabbage heads. Nitrogen at 100 kg•ha-1 produced the greatest head mass and yield for untrimmed cabbage heads. The 30 x 50 cm spacing produced the highest yield of untrimmed heads while 50 x 50 cm spacing produced heavier heads. For trimmed heads, 100 kg•ha-1 N again produced the greatest head mass, head diameter, head height, core diameter and yield. Spacing did not affect the yield for trimmed heads. However, 40 x 50 cm spacing improved head diameter, head height and head mass while core diameter was larger with 50 x 50 cm spacing. The split application of 100 kg•ha-1 N as top-dressing was best for head mass and yield (per unit area) for trimmed and untrimmed heads. Choice of spacing would depend on whether trimmed or untrimmed heads are targeted. / Dissertation (M Inst Agrar (Horticulture))--University of Pretoria, 2005. / Plant Production and Soil Science / unrestricted