Maataloustieteellinen A ikakauskirja Vol. 59: 31—36, 1987 Studies on production techniques of some herb plants I Effect of Agryl PIT mulching on herb yield and volatile oils of basil (Ocimum basilicum L.) and marjoram (Origanum majorana L.) HÄLYÄ S. Dept, of Horticulture, University of Helsinki, SF- 00710 Helsinki, Finland Abstract. Agryl Pl 7 fiber-mulching of cold-sensitive herbal plants, basil (Ocimum basilicum L.) and marjoram (Origanum majorana L.), were studied at three locations in Finland (1984—1985). The growing sites were Helsinki (60° 14' N), Sahalahti (61° 28' N), and Inari (69° 04' N) for both species in 1984, and Helsinki for marjoram in 1985. Agryl Pl 7 mulching increased basil yield at all locations. The uncovered basil yielded ap- proximately 54 kg/100 m J and when grown under the mulch, more than three fold, 191 kg/ 100 m 2. In the north (Inari), however, basil and marjoram did not give practically any yield. Marjoram did not benefit from mulching either in the south: the yield was 96 kg without and 80 kg/100 m 2 with mulching. The vegetation under the mulch was severely affected by fungus- diseases. The volatile oil content in the dried basil herb ranged from 0.46 to 0.93 %. There were no significant differences in the total oil content whether basil was grown with or without Agryl Pl7. The oil content in marjoram ranged from 1.94 to 2.55 % the total content being significantly higher when grown under the cover. Index words: basil, dill, fiber-cover, herb, mulch, volatile oil Introduction There is a lot experience in the efficiency of different mulching materials to protect the vegetable crops against low temperatures. Dif- ferent fiber-covers have been used to achive earlier and larger yields in cool areas. For instance, Agryl Pl 7 fiber has been used to pro- tect strawberry, potato and vegetable plants like lettuce, cabbage, cucumber all of which have given earlierand larger yield when grown under the cover (Hardh 1982, Guttormsen 1986, Pessala 1986, Samuelsen 1986). The fiber is protected against uv-radiation degrega- tion, and it is transparent to 75 —80 % of the light and uv-radiation. Pessala(l9B6) has reported that the maxi- mum temperatures are 10—15°C and the minimum temperatures 2.4—4.5°C higher under fiber-covers than in the open field. The 31 JOURNAL OF AGRICULTURAL SCIENCE IN FINLAND https://www.c-info.fi/en/info/?token=svcEc6LJinJCjibP.X0rqeI5__6RTYvOme3swyg.jB_WWqlVitkwcW-7beI0q8c_srsS1gByEcLxqkgmjaO_fkr-wTprs6OiAaq4_TmcU48zMoedUOBfPWd3Pqtu6tsNPA0XZv5pQle-vWjf96Iu5mb96zjxYkepWlhQW3QrroNJ5kMPIESjqe_VH6f0tCusuT2uNPWJAwsXoV5VMoc differences are smaller at night and on cloudy days than on sunny days. Schales and Shel- drake (1966) and Bohlin (1977), among the others, have reported on higher humidity under cover. Weeds and plant diseases have caused problems in warm and humid condi- tions under the mulch. There is a lack of knowledge on the effects of the vegetation covers used for herb plants. Therefore a study was carried out to determine the effect of mulching of two cold-sensitive species, basil and marjoram. Both the herb yield and content and composition of volatile oils was studied. The cultivation of these plants is most sensitive in the open field in the northern climate. Materials and methods Basil and marjoram were grown under fiber- cover and uncovered at three locations in Fin- land in 1984. The growing sites were Helsinki (60° 14' N), Sahalahti (61° 28' N) and Inari (69° 04 N). The research was also carried out with marjoram in 1985 in Helsinki. The vege- tation was covered by Agryl Pl 7 from trans- planting till harvest. The plants were first grown in a greenhouse because this had, in the preliminary trials, proved superior to direct- sowing. The basil plants were grown using commer- cial seeds which consisted of several chemo- types. Marjoram was of the French type in both years. The plants were grown 40—57 days in a greenhouse before transplanting out- doors to spacings of 20 X 25 centimeters. The soil received a moderate basic fertilization (0.9—0.4—1.4 kg NPK/100 m 2), and the field was irrigated and hand-weeded when neces- sary. The herbs were harvested at the begin- ning of flowering and the amount of the fresh yield was measured. The volatile oil analyses of the dried (at + 35°C for 15 hours) herbs from Helsinki were carried out by the method of head space gas chromatography as described by Hiltu- nen et al. (1985). Marjoram was analysed by this method in 1985, only. In addition, fresh marjoram samples from Sahalahti and Inari and basil from Sahalahti were determined by high resolution gas chromatographic mass spectrometric method in 1984 (Nykänen 1986). The field trials were set up according to the method of completely randomized blocks with plots of 1.5 m 2 in 1984, and 3.8 m 2 in 1985. The data was statistically analysed by the analysis of variance (Steel and Torrie 1980). Results Herb yield The differences in daily temperatures were largest during bright days. The minimum tem- peratures were in an average o—4°C higher and the maximum temperatures s—s.B°C5 —5.8°C higher under the fiber than in the open field. The growth period for basil was 98 days in southernFinland (Table 1). There were no dif- ferences in the growth and development of basil grown with or without the cover. In the south the fresh basil yield was 191 kg under the cover and 54 kg/100 m 2 when grown uncovered. The yields were significant- Table 1. Growth periods (days) of basil (1984) and marjoram (1984 and 1985) grown with and without Agryl Pl7 at three locations. BASIL / -8 4 MARJORAM Helsinki Sahalahti Inari Helsinki Sahalahti Inari -84 -85 -84 -84 No cover 97 98 106 106 89 126 106 Agryl Pl 7 97 98 106 106 82 119 106 Sown 24.4 24.4 7.5 24.4 3.5 24.4 7.5 Planted 20.6 13.6 18.6 20.6 13.6 13.6 18.6 32 3 ly larger under the cover both in Helsinki (p<0.001) and in Sahalahti (p<0.001) (Fig. 1). In the preliminary tests basil gave larger yield (210 kg/100 m 2) in a greenhouse than out-of- doors. In the north basil did not give practi- cally any yield at all. The growing period for marjoram was 106—126 days in 1984, and 82—89 days by the first harvest in 1985 (Table 1). The devel- opment was approximately a week shorter under the cover than when grown uncovered. The marjoram yielded in an average 80 kg/ 100 m 2 when grown under Agryl Pl7, and 96 kg/100 m 2 when grown uncovered (Fig 1). The first harvest yielded significantly (P<0.05) more than the second one. The later crops were severely affected by plant diseases (Alternaria sp. and Botrytis cinered). The yields in Sahalahti in 1984 and in Helsinki in 1985 were significantly (p<0.01) larger when marjoram was grown without the cover. In the preliminary tests carried out in a greenhouse the yield was 130 kg/100 m 2. Volatile oil Basil The total content of volatile oil in basil herb ranged from 0.46 to 0.93 %. There were no significant differences in the amount of the main compounds whether the herb was grown with Agryl Pl 7 or without it (Table 2). Only the content of 1,8-cineol was significantly (p<0.05) higher when grown without mulch- ing. The main components in the oil were methyl chavicol (estragol), linalool, 13- caryophyllene, and unidentified component X 2. The crop stand consisted of several feno- types those with violet (1) or white (2) flowers being the major types. There were significant Fig. I. The fresh herb yield of basil and marjoram grown with and without Agryl Pl7-cover at three locations (1984 and 1985). The stacked bars present the first and second yields. 33 Table 2. Essential oil content in two basil fenotypes grown with and without Agryl Pl 7 (Helsinki, 1984). Oil F-valueTreatment % Treatments F( 1,3) =0.33 Fenotypes No cover 0.89Fenotype 1 F(1,6) =14.68** InteractionFenotype 2 0.46 (1.6) =3.37 Agryl Pl7 0.93Fenotype 1 Fenotype 2 0.65 differences between the oil contents of the two fenotypes. The violet-flowered fenotypes had more j3-caryophyllene and methyl chavicol whereas those with the white flowers had more linalool and eugenol (Table 3). Marjoram The total content of volatile oils in marjo- ram ranged from 1.94 to 2.55 %. The oil con- tent was significantly (p < 0.05) higher in the herb grown under Agryl-cover than without it in both harvests. The main components were Table 3. Main components in the essential oil of basil fenotypes 1 and 2 grown with and without Agryl Pl 7 (Hel- sinki, 1984). Treatment Methyl Lina- j3-caryo- Euge- x 2 Borne- 1,8- chavicol 100 l phyllene nol ol cineol No cover Fenotype 1 70.78 0 6.57 1.38 3.36 1.42 2.48 Fenotype 2 19.83 24.43 3.24 8.02 7.29 0.95 1.92 Agryl Pl 7 Fenotype I 70.91 3.31 5.52 0.82 3.62 1.19 1.20 Fenotype 2 33.25 34.58 4.00 4.83 ■ 3.09 0.77 1.21 Treatment F(1,3) 0.82 0.81 5.20 1.32 0.63 0.58 16.89** Fenotype F(1,6) 88.75*** 257.05*** 29.91** 6.01* 0.79 6.53* 1.29 Interact. F(1,6) 2.00 0.02 4.08 0.37 1.38 0.01 1.41 Table 4. Essential oil content and components in marjoram grown with and without Agryl Pl 7 (Helsinki, 1985). NO COVER AGRYL P 1 7 F(1,3) I Harvest II Harvest I Harvest II Harvest Treatment Component August I. Sept. 9. July 25 Sept. 9. (+ ) Oil content % 1.94 2.11 2.40 2.55 Linalool 34.50 37.77 36.54 30.77 0.39 c/s-Sabinene 12.63 13.15 12.18 10.96 0.34 hydrate Linalyl acetate 7.61 9.31 5.65 6.99 8.85 Sabinene 6.53 6.49 7.47 7.84 7.06 7-terpinene 5.95 4.28 5.44 6.70 1.93 trans-Sabinene 4.49 3.60 4.17 3.59 1.31 hydrate a-terpinene 3.69 2.77 3.40 4.36 2.86 p-cymene 0.07 0 0.04 0 0.13 Terpinen -4-ol 2.71 2.41 2.36 2.93 0.25 a-pinene 2.44 2.11 2.75 2.99 3.39 iB-caryophyllene 2.50 1.70 2.42 2.88 1.35 /3-phellandrene 1.24 1.12 1.28 1.65 6.04 Terpinolene 1.32 1.05 1.22 1.60 3.45 Limonene 0.97 0.96 1.04 1.23 3.82 3-carene 0.77 0.85 0.31 0.51 16.99* Myrsene 0.17 0.16 0.93 1.00 236.84*** Oil content/treatment: F(1,3) I harvest 22.88 + , II harvest 14.72+. 34 linalool, cis-sabinene hydrate, linalyl acetate, sabinene, 7-terpinene and trans-sabinene hydrate. The six major compounds accounted for 75 % of the total oil content (Table 4). Ex- cept for the compounds 3-carene and myrsene, found only in traces, there were no significant differences between the 16 compounds studied whether grown with or without the cover. Discussion Both basil and marjoram reached larger yields when grown in a greenhouse than in the field. Outdoors the effect of Agryl Pl 7 was mainly in increasing the herb yield of basil and the volatile oil content in marjoram herb. The fiber increased also the rate of development of marjoram. The basil types, instead, devel- oped at different rates and no destinct differ- ences were found whether grown with or without the mulching. The differences between the two major basil fenotypes were considerable. Thus a pressure should be placed on herb plant breeding in purpose to receive varieties with high essential oil content. The fiber did not increase the average amount of the volatile oils in the dry basil herb. Nykänen(1986), instead, states that the oil content in fresh basil was significantly higher when grown under Agryl PI7. Specif- ically the amounts of methyl chavicol and eu- genol were higher. The differences in the re- sults are partly due to the analysing methods and heterogenious materials. The composition of oil may have changed also during the drying process, and the results on dry herb sup- posingly resemble that of a typical commercial herb. Using Agryl Pl 7 increased the amount of volatile oils in marjoram. This phenomenon was also found in fresh herb (Nykänen 1986). These results confirm with those of Härdh and Härdh (1972) and Härdh (1978), who found higher oil content in marjoram grown in a greenhouse than outdoors. On the con- trary, Härdh (1978) also states that the total amounts of aromatic compounds of marjoram are often higher under the field conditions than in warmer conditions, in greenhouse. The marketable marjoram yield did not in- crease and the benefit of the mulching was found in the amount of the oil, only. The warm and humid conditions under the fiber led to disease infection. This phenomenon was earlier reported by many scientists. Acknowledgements. I wish to thank Leena Puukka and Heikki Vuorela for the technical assistance. The work was supported by the Ministry of Agriculture and Forestry and the TIURA foundation. References Bohlin, 1977. Marktäckning i köksväxtodling pä friland. konsulentavd. stencilserie, trädgärd 121. Guttormsen, G. 1986. Muligheter med nye dekkemate- rialer. Klimatförbättrande ätgärder i fältmässig grön- saksodling. NJF-seminar 93: 27—30. Hiltunen, R., Vuorela, H. & Laakso, I. 1985. Quanti- tative head space gas chromatography in the analysis of volatile oils in aromatic plants. Edit. Baernheim Svendsen, A. & Scheffer, J.J. Essential oils and aro- matic plants, pp 23—41. Dordrecht. Härdh, J.E. & Härdh, K. 1972. Effects of radiation, day-length and temperature on plant growth and quality: a preliminary report. Hort. Res 12: 25—42. Härdh, J.E. 1978. The aromatic compounds of spice plants in nordic conditions. Acta Hort. 73: 269—271. Härdh, K. 1983. Katteet aikaistavat varhaisperunan sa- toa. (Earlier potato yield with mulching). Puutarha- uutiset 35: 410—411. Nykänen, I. 1986. High resolution gas chromatographic mass-spectrometric determination of the flavorcom- position of basil (Ocimum basilicum L.) cultivated in Finland. Z. Lebensm.-Unters. Forsch. 182: 205—211. Pessala, R. 1986. Kokemuksia peittokatteiden käytöstä avomaan vihannesviljelyssä. (Vegetation covers in growing field vegetables). Puutarha 89: 80—83. Samuelsen, R.T. 1986. Plast og fiberduk til hodekäl og 35 kälrot i nord. Klimatförbättrande ätgärder i fältmässig Hort. Sei. 88: 425—430. grönsaksodling. NJF-seminar 92: 16—21. Steel, R.G.D. & Torrie,Steel, R.G.D. & Torrie, J.H. 1980. Principles and Schales, F.D. & Sheldrake, R. 1966. Mulch effects on procedures of statistics, a biometrical approach. 633 soil conditions and muskmelon response. Proc. Amer. p. New York. SELOSTUS Eräiden maustekasvien viljelyteknisiä kokeita. I Harsokatteen vaikutus basilikan ja meiramin satoon ja haihtuvaan öljyyn. Häivä, S. Helsingin yliopisto, puutarhatieteen laitos, 00710 Helsinki Agryl Pl7 harsokatteen käyttökelpoisuutta tutkittiin vuosina 1984ja 1985 kylmänarkojen maustekasvien, ba- silikan (Ocimum basiticum L.) ja meiramin (Origanum majoram L.), viljelyssä. Kenttäkokeet tehtiin ensimmäi- senä koevuonna kolmella paikkakunnalla: Helsingissä (60° 14’ N), Sahalahdella (61° 28' N) ja Inarissa (69° 04'). Toisena vuonna meiramikoe toistettiin Helsingissä, yli- opiston puutarhatieteen laitoksella. Haihtuvien öljyjen pi- toisuus määritettiin head space-menetelmällä kaasukro- matografisesti. Harsokatteen käyttö lisäsi basilikasatoa. Ilman katet- ta viljeltäessä tuore yrttisato oli keskimäärin 54 kg/ 100 m 2 jakatteen alla yli kolmekertainen, 191 kg/100m2 . Pohjoisimmalla paikkakunnalla, Inarissa, ei saatu juuri lainkaan satoa kummastakaan lajista. Meirami ei hyöty- nyt katteesta eteläisemmilläkään koepaikoilla. Tuore yrt- tisato oli 96 kg kattamattomalla ja 80 kg/100 m 2 kate- tulla alueella. Harsokatteen alla meiramikasvusto oli saas- tunut pahoin sienitauteihin. Haihtuvan öljyn määrä kuivatussa basilikassa oli 0.46— 0.93 %. Kate ei vaikuttanut öljypitoisuuteen. Meiramin haihtuvan öljyn määrä oli 1.94—2.55 %. Harsokatteen alla öljyn määrä oli merkitsevästi suurempi kuin ilman katetta viljeltäessä. Vuorokauden minimilämpötilat olivat katteen alla o—4°C korkeammat jamaksimilämpötilat s—s.B°C5 —5.8°C kor- keammat kuin taivasalla. 36