The objective of this study was to find out which effect dill growing in differing environmental conditions might have on biomass yield and essential oil content in the aboveground part.

Field trials were conducted during growing seasons of 1998 and 1999 on three localities: Pančevo (South Banat) at the altitude of 70 m, marsh meadow soil, Gorobilje (West Serbia) at the altitude of 300 m, alluvial soil, and Blagaja (West Serbia) at the altitude of 600 m, brown soil.

Experimental results have shown an immediate effect of the environmental factors on dill biomass yield as well as on its essential oil content. Thus, in both years, the highest dill's dry above-ground mass yield was achieved on the locality of Pančevo, averaging 3750 kg/ha, the lowest one on the locality of Blagaja, averaging 2620 kg/ha, while that attained in Gorobilje averaged 3665 kg/ha, allowing for slight variations between the years.

Quantitative indicators of essential oil content in dill clearly indicate its highest content on the locality of Gorobilje, averaging 80.5 l/ha.

Key words: dill, environmental conditions, locality, yield, essential oil.

In Yugoslavia, dill is being produced nearly in all producing, mainly small-sized areas and in gardens, too. Large-scale production of dill is a rare case and, if so, it is for processing purposes (Lazić et al., 1993). Plantation dill production on larger-sized areas has been preferred in recent years with advancement of canned vegetables industry, and particularly with higher demands of ether oil (Stepanović B, 1998).

Dill has a multipurpose use, most often as a spice in foodstuffs, but none the less as medicinal plant. Due to its medicinal properties, dill has found its use in pharmacy and veterinary (Jovanović, 1987).

The aboveground part is mainly used for essential oil and food concentrates production. Essential oil is used in perfume industry, medicine and food industry (Jevđović et al., 1998 b). Plant residues occurring after essential oil distillation may be used as forages, too.

Considering its paramount importance and usability, dill production on wider and different growing areas with plantation growing type has been attempted recently. Therefore, research goal was to closely study the possibilities of dill cultivation as well as the effects of different environmental factors on the biomass yield and essential oil content in its aboveground part.

Two-year-old studies under various environmental conditions were carried out during growing seasons of 1998 and 1999. Field trials were arranged on three different production areas: two localities in West Serbia (Gorobilje and Blagaja) and one in South Banat (Pančevo). After soil preparation, seeding in continuous rows with inter-row distance of 50 cm was done by means of tractor seeder. Variety "Domaća aromatična" was used in the experiment. Sowing depth was 3 cm, with 7 kg/ha seeds used on all the localities in both years.

Usual cultural practices for dill were applied all through vegetation in both years. Weeds were destroyed mechanically without herbicide use.

On the locality of Gorobilje at the altitude of 300 m, the trials were performed on the alluvial type of soil in both years. Seeding was performed on 20^th of April. Over dill growing season, the mean air daily temperatures on this locality were around 18^oC. Precipitation amounts in 1998 and 1999 amounted to 432 mm and 570 mm, respectively. On this locality, biomass was picked on 27^th July in both years.

On the locality of Blagaja, the experiments were arranged on brown soil, at the altitude of 600 m. Seeding was done in the third decade of April (22^nd and 24^th April) in both years. The mean air daily temperatures over the growing season amounted to around 17^oC. The precipitations recorded during growing season of 1998 were lower (438 mm) than those recorded during that of 1999 (573 mm). The aboveground mass was picked on 25^th July in both years.

On the locality of Pančevo, the experiments were arranged on the marshy humus at the altitude of 70 m. Seeding was done at the beginning of April in both years under way. The mean air daily temperatures over the growing season amounted to 19^oC. Precipitation over the vegetation of 1998 amounted to only 288 mm, which was much less compared to those recorded in 1999 (617 mm). Picking was done on 20^th July (1998) and on 24 th July (1999).

After picking, the mowed biomass was dried up in thermic dryers at temperature of 40^oC, essential oil distilled as usual and yield determined.

Yield of aboveground part of dill

From Table 1. one can see the results on the dill's dry aboveground part yield.

The results on the dry aboveground part yield denote the presence of significant relative variation of this trait, both, per localities and per years.

The highest yield of aboveground part of dill 3960 kg/ha was achieved on the locality of Pančevo in 1999, and the lowest one on that of Blagaja during the vegetation of 1998. This seemed to have depended, among other things, on the impact of seeding time, which was apparently in positive correlation with the yields achieved. The earliest seeding was made on the locality of Pančevo, thus, the highest yield and vice versa, the last seeding made on the locality of Blagaja resulted in the poorest yields.

In their studies on highland production of parsley, which belongs to the same family as dill Pavlović et al. 1998 came to similar results.

On the locality of Pančevo, the highest yield was achieved in both years, averaging 3750 kg/ha, as a result of suitable environmental factors compared to other localities with considerably lower yields recorded.

It could be interesting to mention that the yield achieved in 1999 (average 3563 kg/ha) was higher in all the localities studied than that achieved in 1998 (average 3153 kg/ha). So obtained results may be attributed to fairly suitable environmental conditions, especially rainfalls, which were more abundant in 1999 than those in 1998. The obtained data thus confirm that dill yield is highly influenced by the environmental conditions dominating on the localities under study. That environmental factors have a high influence on dill yield was also supported by the studies of Jevđović et al. 1998(a).

Essential Oil Content in Dill Aboveground Part

From Table 2, one can see percentage of essential oil content in the above-ground part per years and per localities.

The highest content of essential oil of 2.3% in aboveground part of dill was determined on the locality of Gorobilje in 1998, and the lowest one of 1.5% on Blagaja locality in 1999.

In terms of essential oil content, the differences between the localities on which dill was produced were evident. The highest average content of essential oil, averaging 2.2%, was established on the locality of Gorobilje, and the lowest one, averaging 1.55%, on that of Blagaja. On the locality of Pančevo, essential oil averaged 1.95%. Low content of essential oil recorded on the locality of Blagaja may be attributed to its poorest climatic-edaphic factors.

This is confirmed by research results of Pavlović et al., 1998 who emphasized that essential oil content was determined by the environmental factors dominating over the dill production on the locality in question.

On a two-year basis, no significant differences existed in the content of essential oil in the aboveground part of dill (1.8 and 1.9%).

The yield of essential oil

From Table 3, one can see the results on essential oil yield in aboveground part of dill, which manifestly succeeded its content in percentages. On the locality of Gorobilje, the highest yield of essential oil was attained in both years, averaging 80.5 l/ha, with the lowest one, averaging 40.0 l/ha, achieved on the locality of Blagaja. On the locality of Pančevo, essential oil averaged 71.5 l/ha.

In terms of essential oil yield, these findings also stand in direct correlation with the environmental factors existing on the localities concerned, which apparently affect the amount of essential oil in dill.

Stepanović et al., 1998 cited that in so far as dill is provided with better environmental conditions, its quality will also be better since warmer days contribute to a higher essential oil content. This was also proved by present study in which under more suitable temperatures (Gorobilje and Pančevo) considerably higher yields of essential oil were attained. Similar to essential oil content expressed in percentages, no differences in essential oil content in the dill aboveground part were found on a two-year basis.

On the basis of studies on the effects of the environmental factors on yield and quality of dill, conducted over the two growing seasons, the following may be concluded:

Taken on the whole, the factors studied had a significant effect on both, yield of dry aboveground part and on the content and quality of essential oil, as well.

The highest content of essential oil, averaging 2.2%, was established in both years in aboveground part of dill on the locality of Gorobilje.

On the locality of Gorobilje, there has been established the highest yield of essential oil, averaging 80.5 l/ha in both years under study. The content of essential oil is mostly influenced by climatic-edaphic factors and production conditions, thus, this locality seemed to be exceptionally suitable for such production.

In order to achieve high yields of aboveground mass and essential oils, dill producers are highly recommended to produce this crop on the areas that are environmentally similar to the localities of Gorobilje and Pančevo on which dill did best.

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