Two experiments were carried out to determine the effect of gibberellic acid on the longevity of cut flowers of two Zantedeschia elliottiana (W. Wats./Engl.) cultivars: ‘Black Magic’ and ‘Florex Gold’. The flowers were conditioned for 2, 4 and 20 hours in water solutions of 8-hydroxyquinoline citrate at concentrations of 200 mg l^-1, and then kept in water and gibberellic acid solutions at concentrations of 50 and 100 mg l^-1. Gibberellic acid enhanced the post-harvest longevity of Z. elliottiana flowers. Those of the ‘Black Magic’ cultivar lasted the longest when not conditioned, but merely stored in gibberellic acid solutions. 8-hydroxyquinoline citrate shortened their longevity by a week. The post-harvest longevity of flowers of the ‘Florex Gold’ cultivar significantly depended on the concentration of gibberellic acid and conditioning time. The longest-lasting flowers were those conditioned in 8-hydroxyquinoline citrate for 2 hours.

The experiments were carried out in 2001–2002. Young plants of Tagetes patula were growed in pots in peat substrate. Plants were sprayed or soil drenched with B-Nine, Cycocel and Topflor. All the retardants were applied 1-3 times with a 2 weeks interval. The plants were planted in the field in May. After-effect of B-Nine and Cycocel applied to leaves was observed to the end of experiment. Cycocel and Topflor used directly to peat-substrate retarded growth of plants the strongest. Cycocel and B-Nine applied twice in 0.2% concentration directly to peat-substrate stimulated flowering of plants.

In 1993–2002 relationship between air temperature and phenology the beginning of vegetation and blooming period was investigated in Wrocław area. Linear correlation coefficient between first leaf appearance and the beginning of blooming was significant. The number of warm days (> 10°C) in the 3^rd decade of March affected the length of blooming period and significantly increased pollination. During flowering the number of days with temperature over 5° and 10°C also prolonged the blooming period, however increased number of warm days (> 15°C) shortend the end of blooming phase.

During the years 1998–2000 the field experiments on microirrigation of squash on the very light soil were carried out in Kruszyn Krajeński near Bydgoszcz. The objective of this study was to recognize the effects of microirrigation in cultivation of winter squash in a very light soil conditions. Both systems of irrigation used, significantly increased mean marketable yields of squash as compared to non-irrigated plots. They amounted 59.4 and 55.4 t·ha^-1 for drip and microsprinkler irrigation, respectively. Among three cultivars tested the highest yields were obtained for ‘Melonowa Żółta’, lower for ‘Bambino’ and the lowest for ‘Ambar’. The calculated water use efficiency (WUE) index for both systems of irrigation was higher for drip irrigation.

The experiment was established at the Fruit Experimental Station Samotwór near Wrocław in 1993–2002. The aim of this study was to estimate the production value of 22 plum cultivars grafted on ‘Myrobalan’ seedlings (Prunus divaricata). Results of the study proved that ‘Čačanska Najbolja’ and ‘Magna Glauca’ cultivars were the most vigorous, while ‘Bluefre’ and ‘Auerbacher’ were characterised by the weakest growth. ‘Bluefre’, ’President’, ‘Ontario’ and ‘Auerbacher’ cvs. were the most productive. Mean fruit weight was significantly dependent on the cultivar, too. Among the tested cultivar, the biggest fruit was obtained from ‘President’, ‘Valor’, ‘Bluefre’ and ‘Ontario’ trees. The most sensitive to plum pox virus (symptoms on fruit and leaves) appeared ‘Węgierka Zwykła’, ’Węgierka Zimmera’, ‘Ortenauer’ and ‘Magna Glauca’.

The study was conducted from 1999 to 2002 in the Pomology Department of the Agricultural University in Lublin. The experimental materials were hazelnut trees of cv. ‘Olbrzymi z Halle’, ‘Kataloński’ i ‘Webba Cenny’ planted in 1989 at the distance 4 × 3 m. The fruit size distribution, mass of single nut and kernel and content of water were evaluated immediately after harvest and after 8 weeks of storage. In addition, in 1999–2001 total content of oil, content of linoleic acid and content of major nutrients (N, P, K, Ca, Mg) were determined. The significant differences in the size nuts and values of examined features between cultivars were found. The content of water in dried kernels varied depending on cultivars from 3,79% to 4,08%. The loss of fruit mass during 8 weeks of drying kernels was from 27,5% to 29,6%. The best quality among studied cultivars had cv. ‘Olbrzymi z Halle’.

In 1998–2001 the studies on one-year-old and two-year-old plantations of St. John’s wort (Hypericum perforatum L.), cultivar Topaz were carried out. The percentages of plants with diseases symptoms as well as indexes of infected plants were examined directly in the field. The fungi were isolated from superficially disinfected plants fragments namely from roots, stem bases and leaves, using in first year mineral culture medium and the next years St. John’s wort glucose extract agar. Necrosis of the roots of one-year-old and two-year-old plants were observed. Morover the disintegration and softening of lower parts of shots occurred. Plant organs with such disease symptoms were colonized by a complex of pathogenic fungi wherefrom Fusarium spp., Rhizoctonia solani, Botrytis cinerea and Phoma exigua var. exigua turned out to be of economic importance. Among the species of Fusarium colonizing the roots of one-year-old and two-year-old plants F. avenaceum, F. culmorum, F. equiseti, F. oxysporum and F. solani most often occurred. This species of Fusarium were isolated from external as well as from internal part of shoots of two-year-old plants. Seimatosporium hypericinum, not yet recorded in Poland, was commonly obtained from the stems showing cracks in the bark of diseased stems as well as from leaves showing red-amber necrotic spots.

In 3-years field experiment metolachlor 1728 g·ha^-1 applied next day after sowing of snap bean seeds controlled more than 90% of weeds and did not injured bean plants. Bentazon 450 g·ha^-1 + 450 g·ha^-1 applied postemergence with adjuvant controlled from 57% to 95% of weeds and caused slight chlorosis of bean leaves. Both herbicides did not influence the yields of green pods nor dry seeds. Three weeks delaying of first weeding caused a significant decrease of these yields but it did not affect the breadth of green pods nor the weight of 1000 dry bean seeds.

The experiment of the additional blow of bushes of 8 cultivars of blackcurrant (Ribes nigrum L.) was conducted in 1995–1997 in Pulawy, Poland. The artificial wind blow generated by the vacuum cleaner fan was used. The additional blow of free-pollinated and isolated bushes did not caused better pollination of flowers and did not have any positive effect on the weight of 100 fruits, the yield structure or the number of seeds per fruit.

A field experiment was carried in central-eastern Poland in the years 2000–2003. The effect of organic fertilization and liming of soil on yielding of celeriac ‘Odrzański’ cv., was analysed. The following types of organic fertilizers were applied: farmyard manure 60 t·ha^-1, rye straw 6 t·ha^-1, and green manures in the form of summer intercrops (phacelia, rye, winter vetch, faba bean). The soil was limed with 2 t·ha^-1 of the common calcium carbonate fertilizer. Celeriac was cultivated just before organic fertilizers were ploughed in. Analysis of the results indicates the dependence of yield on climatic conditions also. The greatest yields of celeriac were obtained after farmyard manure. Faba bean and phacelia were characterized by a very similar yield-forming effect to that of farmyard manure. The highest yields were obtained on limed soil.

In the years 2000–2002 a mycological analysis was made of the corms of Acidanthera bicolor Hochst. meant for setting up experiments, and the roots, corms and leaves of plants at anthesis. The mycological analysis of corms before planting showed that they were infected by Alternaria alternata, Botrytis cinerea, Fusarium spp. and Penicillium spp. In the period of vegetation the roots and corms were mainly infected by F. oxysporum, F. culmorum, F. solani and B. cinerea. On the other hand, the leaves of the studied plant were mostly infected by A. alternata and B. cinerea.

The pathogenicity of Fusarium avenaceum, F. culmorum and F. equiseti to thyme was examined in present work. Isolates of tested fungi originated from various herbs plants. The effect of Fusarium spp. post-culture liquids and water suspensions of Fusarium spp. spores on germination of thyme schizocarps was studied in the laboratory. The effect of Fusarium spp. on the shooting up and healthiness of seedlings was carried out in the climatic chamber conditions using the method with infested soil. It was shown, that harmfulness of F. avenaceum, F. culmorum and F. equiseti to thyme, regardless of the origins of fungi isolates, was expressed by inhibition of schizocarps germination and by limiting of seedlings numbers and their growth. The symptoms of infection were a necrosis of shoots and roots. Each of the three used methods of artificial infection of thyme secured direct contact of with the surface of schizocarps, shoots and roots of seedlings. However the method with Fusarium spp. post-culture liquids should be recommended to the fast estimation of Fusarium spp. pathogenicity to thyme on account of occurrence of toxins, which are produced by fungi.

Two groups of chrysanthemum (Dendranthema grandiflora Tzvelev) representing the five cultivars were analysed to define their content of pigments in the inflorescence with the spectrophotometric method. It was observed that respective cultivars obtained as a result of the ionising radiation differed in their quality and quantity of flavonoids and carotenoids in the inflorescence as compared with original cultivars they originated from. Each of the chrysanthemum cultivars studied showed its own permanent repetitive profile of the occurrence of specific pigments, which gives a possibility of showing the distinctness of the cultivars analysed and their identification.

The experiments were carried out in 1998–2000 in a unheated plastic tunnel. The effects of single plants topping on the quantity and quality of the yield of three cultivars of eggplant (Solanum melongena L.) – ‘Black Beauty’ ‘Solara F₁’ and ‘Epic F₁’ in the experiment was determined. No significant influence of the method on the marketable yield and the number of fruits in marketable yield was found. Plants topping also had no positive effect on mean weight of marketable yield fruit. Results achieved in present experiment point out that fruit size (length and diameter) more depends on cultivar and weather course than plants topping procedures.

Leaf yields from five cultivars of parsley (Festival, Paramount, Karnaval, Titan, Hamburger Schnitt) were compared in the studies conducted in field conditions in the years 2001 – 2003. The cultivars examined during two years yielded at the level of 67.84–96.96 t·ha^-1 total yield and 53.57–74.49 t·ha^-1 marketable yield. The greatest total and marketable yield was recorded, in cultivation of ‘Festival’ (96.96 t·ha^-1; 74.49 t·ha^-1), ‘Karnaval’ (91.05 t·ha^-1; 70.04 t·ha^-1) and ‘Hamburger Schnitt’ (90.20 t·ha^-1; 73.92 t·ha^-1) cultivars.

Greenhouse tomato plants (cv. Cunero F₁) were grown in the NFT units with plastic troughs filled with either rockwool or coconut fiber. The initial concentrations of sulphates in the nutrient solutions were 200, 400 or 600 mg SO₄^-2 dm^-3. The effect of different sulphate levels and type of medium on the yield, mineral composition and quality of tomato were studied. Regardless of the initial sulphate level or type of medium, the accumulation of sulphates in the nutrient solution was observed in the begining growing period. However, the organic medium (coconut fiber) cumulated more sulphates than mineral one. On the other hand, there was a higher concentration of sulphates in the recycling solution in the units with mineral (rockwool) medium compared to coconut fiber. Regardless of the type of medium the accumulation of sulphates in the root zone had no influence on the total and marketable yields as well as on the level of ascorbic acid and sugar in the fruits and its acidity. However, the yield of tomato on rockwool was higher. But the sulphate levels and type of medium did not effect the mineral composition of plants.

In field experiment conducted in 1998–2000 the influence of conservation tillage on primary infestation of carrot was investigated. In experiment four cover crop mulches (Sinapis alba L., Vicia sativa L., Phacelia tanacetifolia B., Avena sativa L.) were applied. No-tillage cultivation system caused the significant increment of primary weed infestation in carrot in comparison with conventional tillage. Cover crop mulches reduced significantly the number of weeds before and after carrot emergence. The most of weeds stepped out on control objects. Among investigated cover crops a profitable effect on decrease of weed infestation had Phacelia tanacetifolia and Avena sativa mulches.