EJPAU, 2000, Volume 3, Issue 2
Horticulture

The subject of studies conducted in the years 1995-1997 was the occurrence of aphids on the shrubs of common juniper and wild rose. The studies were carried out in the city green area in a street site (A) and a park site (B). The presence of four aphid species on wild rose shrubs and one species on common juniper shrubs was established. Aphids appeared in the greatest numbers in 1995, while the lowest number was observed on rose shrubs in 1996 and on juniper shrubs in 1997. It was found out that aphids were more numerous in area A, exceptionally in 1995 the number of Maculolachnus submacula Walk. was slightly higher than in area B. The weather in spring and summer affected the increase of the population of all aphid species. After an early and warm spring with rainfalls within the norm the appearance of aphids was more numerous. A delayed vegetative period, high temperatures (over 30°C), dry periods and stormy rainfalls limited the number of aphids.

The studies conducted in the years 1997-1999 concerned the soil after cultivation of rye, winter wheat, triticale and potato. The purpose of the studies was to determine the composition of bacteria and fungi communities in the soil after the cultivation of these plant species.

The purpose of the studies was to determine the quantity and quality of the yield of aboveground parts (false stem and leaves) of winter garlic in the cultivation for bunch yield. The content of dry weight (10.37-12.10%), total carbohydrates (21.64-24.19%), L-ascorbic acid (7.32-9.17 mg %), chlorophyll (0.025-1.532 mg per one kilo) and raw fibre (0.86-1.10%) was determined. In both years of the studies the plants were gathered 30 and 60 days after emergence.

The subject of studies conducted in the years 1994-1996 were observations on the occurrence of Aphis spiraephaga Müll. on three spirea species: Spiraea vanhouttei Zabel., S. arguta Zabel. and S. salicifolia L. Aphids were most numerous on the examined shrubs in 1995, while their lowest numbers were observed in 1994. It was also found out that these aphids colonised the shrubs of S. vanhouttei in the highest degree, being rare on S. salicifolia. The effect of weather (heat, drought, showers of rain) on the number and dynamics of the aphid population concerning the place and period of feeding was greater on S. vanhouttei and S. arguta as compared with S. salicifolia. The damage caused by the feeding of that aphid was often reduced by the plant itself, because those shrubs grew intensively, after the aphids flew away. Newly appearing leaves were not deformed. Another factor which significantly lowered the ornamental value of the sh

During one year, an average of 150 cut chrysanthemums are obtained from 1 m² of the glasshouse cultivation area, usually from three cultivation cycles together. Determination of optimum lighting conditions and vegetation temperature for chrysanthemums can make it possible to shorten a cultivation cycle, which will have a considerable effect on the improvement of production profitability.