Maataloustieteellinen Aikakauskirja Vol. 61: 387—394, 1989 The Effect of Nitrogen Fertilization on the Herb Yield of Dragonhead B. GALAMBOS1 1 and Y. HOLM 2 ' Agricultural Research Centre, South Savo Research Station, Karila. 50600 Mikkeli 2 University of Helsinki, Department of Pharmacy, Pharmacognosy Division, Fabianink. 35, SF-00170 Helsinki, Finland Abstract. The influence of a top-dressing of nitrogen fertilizer (calcium nitrate, CaNO,) on the individual plant height and weight, herb yield and nitrate content of dragonhead (Dracocephalum moldavica L.) was studied in 1987 in Puumala, Finland. The nitrogen doses applied ranged from 0 to 270 kg/ha. Nitrogen fertilization increased both the individual plant height and weight, the fresh and dry herb yield and the nitrate content of the plants. However, no optimum nitrogen dose could be found since the maximum was not reached in most of the cases. An exception was the herb yield (d.w.) of transplanted plants, harvested at the flowering stage, where a nitrogen dose of70—80 kg/ha gave the highest yield. If the plants were allowed to grow a few weeks more the yield was four fold compared to the earlier harvesting. Sown plants gave a yield two times higher than the transplanted plants, but this was partly due to the greater plant density on the sown plots. Index words: nitrogen fertilization, dragonhead, herb yield Introduction Dragonhead (Dracocephalum moldavica L., Lamiaceae) is an annual, 30—70 cm high, soft-stemmed plant with a bluish-purple or sometimes white inflorescence. The dried herb has antiseptic, analgesic and anticolic effects (Csedö 1980), and is used against headaches, colds and kidney complaints (spasms). It is also used in the food industry and for manufacturing perfumes (Halasz-Zelnik el al. 1988). Dragonhead is native to south Si- beria and the Himalayan area. It was in- troduced in Europe via Moldavia in the six- teenth century and was earlier also called Melissa turcica (Hegi 1964). Dragonhead has 387 JOURNAL OF AGRICULTURAL SCIENCE IN FINLAND https://www.c-info.fi/en/info/?token=E_QSwZSqXxZydRes.gLDcxdXUj57ts4iVP43u0w.DWkJotcLMi9jrPXtwt2So_28iDqHIUXxIUE6n1vBeZQIm9vY2ARvkElDsU9Y-D-xX0QAOhWaXUvhQLmaEq6GSQme1pztYbZchcU6Zf09ol7O6scIM1Sc7VFNBHslFRxc5mMyVKCYt90xc4MJskNdSWQaAj3iM9ulg7Y6s-SK4M-Y2BznGAg 388 been cultivated in the Soviet Union, Roma- nia and Bulgaria for a long time. Cultivation has recently been started also in Yugoslavia, Czechoslovakia, Poland, Hungary and Fin- land (Halasz-Zelnik et al. 1988, Von Schantz et al. 1987). In spite of its wide- spread cultivation, there are very few data available about the agrotechnical methods used. Factors that have been investigated in- clude: optimal harvesting time, weed control, the raising of seedlings contra field sowing, and mulching of the soil (Halasz-Zelnik et al. 1988, Von Schantz et al. 1987, Holm et al. 1988. Fertilization, and especially nitrogen fertilization, is dealt with in two papers (Cse- do 1980, Galambosi et al. 1989). Since nitro- gen is one of the most important nutrients for plant growth, careful studies are required on this subject. Nitrogen fertilization of other Lamiaceae plants, such as peppermint and basil, has proved to have an increasing effect on the herb yield (Hornok 1974, Hälvä and Puukka 1987, Franz 1971, Wahab and Hor- nok 1981). The effect of nitrogen fertilization on the plant height, weight, herb yield (fresh and dry), the proportion of leaves and the ac- cumulation of nitrogen was studied in this work. Material and methods Plant material Dragonhead seeds were initially obtained from Romania, where it is commonly culti- vated in 1983, and in subsequent years from our own plants. The plants investigated in this study all originated from our own seed. The cultivation site was Pirttimäki, Puumala (61 °4o' N, 28° 15'E), Finland. The plot size was 10 m 2. A randomized block design was used and each treatment was replicated four times. The plant height and weight was meas- ured from 5 plants in each replication and the mean was calculated. The herb yield (both fresh and dry) represents the average of the four replications. Soil and fertilization The soil on the plots was stony till, and soil analysis made before the fertilization tests (1986) gave the following results: pH 5.9 and plant-available Ca 1500,K 95, P 12.6, Mg 130 and N 25 mg/1 (Viljavuuspalvelu Oy, a soil analysis company). The plots were treated with PK fertilizer (phosphor-potassium) 54—84 kg/ha in au- tumn 1986. Nitrogen top-dressing (CaNOj, NOj-N 15.5 %, Ca 20 %) was applied on 24. 5. 1987 (sown plots) and 15. 6. 1987 (planted plots). The nitrogen doses were 0, 15, 30, 45, 75 and 120 kg/ha. The sown plots were treated on 15. 6. 1987 with a further 150 kg N/ha to give the following total nitrogen doses: 150, 165, 180, 195, 225 and 270 kg/ha. Weather conditions The temperature and precipitation were measured at Sorjola meteorological observa- tory (Institute of Meteorology) about 3 km from Pirttimäki, where the experiments were carried out. Propagation Sowing in the open field was done on 28. 5. 1987. The row spacing was 50 cm (5 kg seeds/ha, 80 plants/m 2 ). The seedlings were grown in a plastic greenhouse for 4 weeks (sown 8. 5. 1987)and transplanted in the field on 5. 6. 1987. The planting density was 50x25 cm (8 plants/m 2 ). Harvesting The sown plants were harvested on 13. 9. 1987 in the full-flowering stage. Half of the planted plants were harvested on 30. 7. 1987 (full flowering) and the other half on 21. 8. 1987 (post flowering). The herb material was dried at 40°C for 14 h in an Orakas dryer (Marlemi Ky, Lemi, Fin- Table 1. Regressions of the individual plant height and weight on the amount of nitrogen fertilizer. 1 land), in which the warm air passes through the plant material from beneath. Leaves and stems were separated using a sieve (3 mm 0 holes). The material was weighed in both the fresh and dry condition. Analyses The nitrate content of the plant samples was measured at the Partala Center for Rural De- velopment (Juva) from water extracts using an ionspecific electrode (Orion 93-07, Finland). The dependence between the nitrogen dose and the herb yield, plant height and weight was tested using regression analysis. If the de- pendence was curvilinear, second order equa- tions were used or the data were square-root transformed (nitrogen doses, Table 1). Results and discussion Figs. 1 A and 1 B show the mean tem- perature and precipitation for the growing sea- son 1987 and the long term averages (30 years). Although the summer of 1987 was cooler than normal with quite heavy precipi- tation, the dragonhead plants still grew well. The length of the growing period (counted from the sowing date) was 105 days for the sown plants, and 77 days (counted from the transplanting date) for the planted plants. The seed ripening was considered as the end of the growing period in both cases. Transplanted plants The transplanted plants were treated with nitrogen doses ranging from 0 to 120 kg/ha. Fig. I. A and B. Mean temperature and precipitation in Puumala 1987 and the long time average 1930—1960. Months: 5= May, 6 = June, 7 =July, 8 =August and 9=September. Inter- Slope t-value Proba- Coeff. of cept bility determination Height planted I 2 0.578 35.3 7.621 0.0016 0.967 planted IP 0.308 42.1 2.646 0.0572 0.798 Weight planted I 2 2.738 40.3 5.091 0.0070 0.931 planted IP 11.962 118.5 11.926 0.0003 0.986 1 based on square root transformed data (nitrogen doses) 2 harvested 30. 7. 1987 ■' harvested 21. 8. 1987 389 The average plant height varied from 35 cm to 46 cm at the earlier harvesting (30.7.1987) and from 42 cm to 49 cm at the later harvest- ing (21. 8. 1987). The changes in the plant height as a result of the nitrogen fertilization are presented in Fig. 2. Until the earlier har- vesting an increasing nitrogen dose increases the plant height according to Mitscherlich’s law (asymptotic regression) (Snedecor and Cochran 1973). After that the height in- crease is linear as indicated by the fitted curves in Fig. 2. The goodness of the fit of the curves can be improved by using the square root transformed nitrogen doses (Table 1). The individual plant weight (fresh) response to the nitrogen fertilization was curvilinear at both harvestings (Fig. 3). As mentioned above the goodness of the fit of the curves can also in this case be improved by using the square root transformed nitrogen doses (Table 1). The maximum individual plant weight was reached by the later harvesting. The average plant weight was three times greater at the later harvesting than at the earlier. This inten- sive accumulation of weight is due to the rapid growth of branches following flowering. Nitrogen fertilization explained 80 to 99 % of the increase in plant height and weight (Ta- ble 1). The herb yield (dry weight) response to the nitrogen fertilization is presented in Figs. 4 A and 4 B. Also in this case the response was quadratic. At the later harvesting the coeffi- cient of determination was, however, better (0.966) when the square root transformed nitrogen doses were used. The herb yield at the later harvesting was about four times greater than at the earlier harvesting. Fig. 2. Response of dragonheadplant height to N ferti- lization (transplanted plants). Fig, 3. Response of dragonhead individual plant weight (fresh) to N fertilization (transplanted plants). Fig. 4. A and B. Response of dragonhead yield (trans- planted plants) to N fertilization, harvesting 30. 7. 1987 (A) and 21. 8. 1987 (B). 390 Table 2. The effect of nitrogen fertilization on the herb yield (dry weight) and proportion of leaves of transplanted The proportions of dry weight yield in per- cents are presented in Table 2. The nitrogen fertilization did not have any effect on the proportion of dry weight neither at the earlier nor at the later harvesting. However, the proportion of dry weight was significantly higher (p<0.05) at the later harvesting. The proportion of leaves out of dry mate- rial was constant at the earlier harvesting, being on average 67.3 %. At the later harvest- ing the proportion of leaves decreased signifi- cantly (p<0.05) as the nitrogen dose in- creased. The proportion of leaves at the later harvesting was significantly smaller(p<0.01) than at the earlier harvesting (Table 2). The effect of nitrogen fertilization on the nitrate (NO3 ) content of dragonhead herb in- creased linearily at the earlier harvesting from 2 900 to 16 500 mg/kg d.w. and quadratical- ly at the later harvesting from 1 450 to 10 000 mg/kg d.w. The nitrate content reached its maximum with the highest nitrogen dose. The uptake of nitrate was more effective at the be- ginning and during the middle of the vegeta- tion period, when the temperature was higher and the nitrogenase activity thus also higher (Figs. 1 A and 1 B). According to the dry weight percentages in Table 2, the nitrate con- tent in the fresh material varied between 270 and 2 129 mg/kg. Since no nitrate measure- ments are available for herb spices, these results will be compared to those for vegeta- bles. Fresh Brussels sprouts contain 123—202 mg/kg and beetroot 1 643—2 723 mg/kg ni- trate (Hansen 1978). Carrot has been found to contain 39—744 mg/kg, Chinese cabbage 230—2 126 mg/kg and lettuce 89—3 898 mg/kg nitrate (Ahonen, Kuokkanen and Penttilä 1987). The nitrate content of Fig. 5. The nitrate content of dry dragonheadherb in re- spect to N fertilization (transplanted plants). Fig. 6. Response ofdragonhead plant height to N ferti- lization (sown plants). dragonhead. Nitrogen Earlier harvesting Later harvesting kg/ha Dry weight Proportion Dry weight Proportion ~ TTT " ~ of leaves ~ ~~ ' ~ of leaveskg/10 m! % y kg/10 m % 0 0.42 14.9 69.0 1.70 18.6 60.6 15 0.59 13.9 67.7 2.32 17.7 59.9 30 0.75 15.6 62.7 2.88 14.3 59.4 45 0.64 13.6 68.8 2.83 17.4 59.0 75 0.70 13.4 67.1 3.00 17.0 58.3 120 0.67 12.9 68.7 3.29 16.6 58.4 Mean 14.1 67.3 16.9 59.3 S.d. 1.01 2.39 1.46 0.89 391 dragonhead is quite high compared to these vegetables, but the single dose used for tea or as a spice is very small. Sown plants The sown plants received nitrogen doses ranging from 150 to 270 kg/ha. The average plant height varied from 50 cm to 59 cm. The bigger plant height of the sown plants is part- ly due to the higher plant density of the sown plots. The plant height response to the nitro- gen fertilization is quadratic (Fig. 6) as was the case with the transplanted plants at the earlier harvesting. Both the sown and trans- planted plants were in flowering when the har- vesting was performed. However, the sown and transplanted plants cannot be directly compared since they received different nitro- gen doses. The herb yield obtained from the sown plots varied between 3.84 and 4.42 kg d.w./lO cm 2 (Table 3). The herb yield response to the different nitrogen doses does not differ sig- nificantly, which can be explained by the fact that the plants were not able to utilize all the given nitrogen. The nitrogen fertilization did not affect the proportion of dry weight. The proportion of leaves was constant, being on average 47.2 °7o, determined on the dry weight. This is clearly lower than the proportion of leaves of the transplanted plants (67.3—59.3 %). The lower proportion of leaves can be partly explained by the fact that the plant density was higher on the sown plots, why the plants were forced to grow straight upwards. Thus the stems, which contain hard- ly any volatile oil, grew longer. The nitrate content of the plants increased quadratically as the nitrogen doses were in- creased and varied between 2 250 and 12 000 mg/kg d.w. The response of the nitrate con- tent to the nitrogen fertilization was cur- vilinear and resembles the corresponding re- sponse obtained for the transplanted plants at the later harvesting. The nitrate amounts, on the other hand, are almost the same as those measured from the earlier harvesting of the transplanted plants, although these received smaller nitrogen doses. This indicates that the nitrate is mostly incorporated in the leaves. The results of this study can be summoned up as follows: nitrogen fertilization increased all the studied parameters, i.e. the plant height, weight, herb yield and nitrate content. No optimum nitrogen dose could be found, except for the herb yield (d.w.) of the trans- planted plants at the earlier harvesting, where a nitrogen dose of 70—80 kg/ha gave the max- imum yield. Acknowledgement. The authors wish to thank Mr, J. Derome (Lie.For.) for checking the language of the man- uscript. Fig. 7. The nitrate content of dry dragonheadherb in re- spect to N fertilization (sown plants). Table 3. The effect of nitrogen fertilization on the yield (dry weight) and proportion of leaves of sown dragonhead. Nitrogen kg/10 nT Dry weight Proportion kg/ha % of leaves % 150 3.84 15.9 47.7 165 3.95 15.9 47.3 180 3.93 15.8 46.1 195 3.89 15.1 47.6 235 4.42 15.6 48.6 270 3.76 14.5 45.7 Mean 15.5 47.2 S.d. 0.56 1.08 392 2 References Ahonen, A., Kuokkanen, 1. & Penttilä, P.-L. 1987. The nitrate concentration of domestic vegetables on Hel- sinki market in summer and autumn 1984. J. Agric. Sci. Finland 59: 425—430. Cseoö, K. 1980. Planlele medicinale si condimentare din judetul harghita, Tirgu Mures, 264—266. Franz, C. 1971. Einfluss von Stickstoff und Kali auf Wachstum und Bildung von Ätherishen Öl der Pfef- ferminze, Mentha piperita L., Dissertation, Miinchen. Galambosi, 8., Holm, Y. & Hiltunen, R. 1989. The ef- fect of some agrotechnical factors on the herb yield and essential oil of dragonhead. JEOR (accepted for publication). Halasz-Zelnik, K., Hornok, L. & Domokos, J. 1988. Data on the cultivation of Dracocephalum moldavica L. in Hungary. Herba Hungarica 27: 49—58. Hansen, H. 1978. The influence of nitrogen fertilization on the chemical composition ofvegetables. Qualitas Plantarum 28: 45—63. Heci, G. 1964. Illustrierte Flora von Mittel-Europa, Band V, 4. Teil, 2. Auflage, Carl Hanser Verlag, Miin- chen, 2360—2362. Holm, Y., Galambosi, B. & Hiltunen, R. 1988. Varia- tion of the main terpenes in dragonhead. Flavour and Fragrance Journal 3: 113—116. Hornok, L. 1974. (In Hungarian). Abstract; Effect of nutrition supply on crop as to the quantity of Mentha piperita L. and its essential oil content. Pubi Univ. Horticulturae 38: 75—82. Halva, S. & Puukka, L. 1987. Studies on the fertiliza- tion of dill ( Anethum graveolens L.) and basil (Oci- mum basilicum L.) I Herb yield of dill and basil af- fected by fertilization. J. Agric. Sci. Finland 59: 11 17. Von Schantz, M., Holm, Y., Galambosi, B. & Hiltu- nen, R. 1987. Arznei- und Gewiirzpflanzen, Versuche zum Anbau in Finnland. Dtsch. Apoth. Ztg. 127: 2543—2548. Snedecor, G. & Cochran, W. 1973, Statistical methods, 6 ,h ed. The lowa state university press, 593 p., Ames, lowa. Wahab, A.S.A. & Hornok, L. 1981. (In Hungarian). Abstract: Effect of NPK fertilization on yield and es- sential oil of sweet basil (Ocimum basilicum L.). Pubi. Univ. Horticulturae 46: 67—73. Ms received December 27, 1988 SELOSTUS Typpilannoituksen vaikutus ampiaisyrtin satoon B. Galambosi ja Y. Holm Helsingin yliopisto. Farmasian laitos. Farmakognosian osasto. Fabian ink. 35, 00170 Helsinki Ampiaisyrlli (Dracocephalum moldavica L.) on yksi- vuotinen, 30—70 cm korkea haihtuvaa öljyä sisältävä ruo- hokasvi, jolla on sinipunaiset tai harvemmin valkoiset ku- kinnot. Se on kotoisin Siperiasta ja Himalajan alueelta, mistä se on Moldavian kautta kulkeutunut Eurooppaan 1500-luvulla,Ampiaisyrttiä on viljelty kauan Neuvosto- liitossa, Romaniassa ja Bulgariassa. Viljely on viime ai- koina aloitettu myös Jugoslaviassa, Tsekkoslovakiassa, Puolassa ja Unkarissa. Suomessa ampiaisyrttiä viljeltiin ensimmäisen kerran v. 1945 Maatalouskoelaitoksen puu- tarhaosastolla, Piikkiössä ja käytännön viljelmällä (0.5 — I ha) v. 1984 lähtien Puumalan Pirttimäen koetilalla. Vaikka tämä kasvi on laajalti viljelty, niin siihen liitty- västä viljelytekniikasta on vähän tietoja. Tässä työssä tut- kittiin typpilannoituksen vaikutusta kasvien korkeuteen, painoon, satomäärään, lehtien osuuteen ja nitraaltipitoi- suuleen. Typpilannoitekokeet tehtiin kesällä 1987 Puumalassa. Koepalsloille annettiin syksyllä 1986 PK-peruslannoitusta (54 —84 kg/ha). Typpilannoitus suoritettiin 24.5. 1987 (kylvetyt kasvit) ja 15.6. 1987 (istutetut kasvit). Typpi- lähteenä oli kalkkisalpietari (NO,-N 15.5 %, Ca 20 %) ja annetut typpimäärät olivat 0, 15, 30, 45, 75 ja 120 kg/ha. Kylvetyille kasveille annettiin lisäksi 15.6. 1987 150 kg N, joten lopulliset typpimäärät olivat siinä tapauk- sessa 150, 165, 180, 195, 225 ja 270 kg/ha. Keskimääräi- nen sato vaihteli00.40.752 —0.75 kg/10 m! (kuivapaino) ai- kaisemmassa sadossa. Myöhemmin kerätyssä sadossa määrä oli11.73.290—3.29 kg/m! (istutetut kasvit). Kylvetyis- tä kasveista saatu sato oli33.74.42 kg/10 ml . 393 Typpilannoitus lisäsi selvästi sekä tuore- että kuivasa- toa. Kylvetyt kasvit, jotka saivat suuret typpimäärät, ei- vät kuitenkaan pystyneet hyväksikäyttämään kaikkea typ- peä, koska sadot eivät enää kasvaneet typpimäärän lisään- tyessä. Kasvien nitraattipitoisuus nousee kun typpilannoite- määrää lisätään. Tuoreen kasvimateriaalin nitraattipitoi- suus vaihteli 270—2 129 mg/kg. Typpilannoituksen optimimäärää ei voitu tämän tut- kimuksen avulla selvittää, koska maksimia ei saavutet- tu, paitsi istutettujen kasvien satomäärän kohdalla aikai- semmassa sadossa. Tällöin sato oli suurin kun käytetyt typpimäärät olivat 70—80 kg/ha. 394