YIELD AND QUALITY OF SELECTED HERB CULTIVARS IN FINLAND

Cultivars of six leaf herb species were grown during 1999-2000 at South Finland (Piikkio, 60° N, 23 E) and North Finland (Ruukki, 64° N, 41 E). The plants were propagated by seedlings, grown in black plastic mulch, fertilized by 20 t/ha compost. Growth, fresh and dry leaf yield, essential oil content, and composition were studied. The yields obtained from the southern growing site were generally higher by 10-40 % than those from the site 500 km further North. The shorter growing season affected the biomass production, but did not strongly influence the essential oil content and composition which were similar to other European results. The yield differences were very high in the case of Greek oregano and marjoram, but savory and dragonhead showed a better tolerance to the cooler climatic conditions and the yield differences were much smaller. Sage and thyme can be only grown in Finland as annuals and their yields were almost identical from both sites. Using bred cultivars, sufficient quantities of high quality raw material can be produced under Nordic conditions. INTRODUCTION There is increasing interest in the use and cultivation of culinary herbs in Finland, by amateur gardeners and professional growers. Unfortunately, the cultivar name and characteristics of the cultivar are generally not marked on the seed packets, even though in some European countries there exist many cultivated materials. The aim of this experiment was to test several registered cultivars under Finnish climatic conditions and to give recommendations for seed companies and herb growers to improve the quality of domestically grown herb raw material. MATERIALS AND METHODS The cultivar trials were done in two phases. In the first phase from 1997 to 1998, twenty four herb cultivars obtained from European seed companies and Institutes were tested under organic growing conditions. These initial assessment trials were done at the experimental site of the Ecological Production, Karila, Agrifood Research Finland, Mikkeli (61° N, 44 E), situated in the South-East of Finland. The following cultivars were tested: Proc. Int. Conf. on MAP Eds. J. Bernath et al. Acta Hort. 576, ISHS 2002 140 Dracocephalum moldavica: Blue Dragon, Snow Dragon Origanum majorana: Priganum, Quedlinburg standard Origanum heracleuticum: Greek Oregano ( Finland), Pizza Dost (Germany) Salvia officinalis: Extracta, Syn-1 Satureja hortensis: Aromata, Compacta Thymus vulgaris: Varico 1, Deutscher Winter These selected cultivars were grown from 1999 to 2000, in South Finland (60° N, 23 E) at Piikkio, Plant Production Research, Horticulture, and in North Finland (64° N, 41 E) at Ruukki, North Ostrobothnia Research Station. Climatic data of the experimental places are presented in Table 1. The plants were grown in plots covered by black plastic mulch and fertilized with 20 tonnes/ha of compost. The plant density was 4-12 plants/m2 with a plot size of 5 m2 with three replications. Growth, overwintering, fresh and dry herb yield were measured. The essential oil content and composition were determined in Kosice, except for Dracocephalum moldavica, which was analyzed in Scotland. RESULTS The weather conditions of the cultivation areas did not vary much over the two years of the experiment, but there were differences observed between the two different sites. The average cumulative temperature of the growing periods in South Finland was 1482 °C, while in North Finland it was only 1071 °C. The average temperatures in the summer months were 1-3 °C higher in the South compared with the North (Table 1). These climatic differences strongly influenced the growth and biomass potential of the herbs. Dracocephalum moldavica There were no significant differences in the plant growth of the two cultivars of dragonhead. The length of the growing season from sowing to harvest was similar in both places  from 66 to 71 days. Similarly, for both cultivars the dry matter content was 20-23 %, and the leaf:stem ratio, at 63:37. The average plant heights were 55 cm in South Finland and 37 cm in North Finland. The fresh and dry yields, therefore, were higher in the South at 20  38%. Only in South Finland was the marketable dry leaf yield of the white flowered `Snow Dragon` cultivar 40 % higher than that of the cultivar `Blue Dragon` (Fig. 1). According to Table 2, the essential oil content of both cultivars was slightly higher in South Finland, but the composition of the oil was practically similar at both sites. Origanum majorana The growing season for marjoram was longer in South Finland (136 and 108 days) than in North Finland (111 and 101 days) in both 1999 and 2000, respectively. The warmer and longer growing season in the South in 1999, gave better conditions for growth than in the North, therefore two harvests and double yield were obtained (Fig. 2). The plants were also taller in the South (41 cm), than in the North (31-34 cm). The marketable dry leaf yields from the two cultivars were double in the South (215 g/m2, 232 g/m2) compared with those in the North (99 and 106 g/m2) for Priganum Blattmarjoram and Quedlinburg Standard respectively. The essential oil yield from the second harvest was only a bit higher than that of the first harvest (Table 3). Due to calibration problems, we could not detect the quantities of sabinene derivates in the marjoram essential oil as its main component, only the quantities of α and γ-terpinene and terpinen 4-ol. There were no significant differences between the composition of the essential oils of the two cultivars, however, the proportion of terpinene derivatives shows a small rise at the northern growing site.