Calendula officinalis—production potential and crop agronomy in southern England

Industrial Crops and Products 7 (1998) 223 – 229

Calendula officinalis— production potential and crop agronomy in southern England H.T.H. Cromack, J.M. Smith * ADAS Bridgets Research Centre, Martyr Worthy, Winchester, Hampshire SO21 1AP, UK Received 6 August 1996; accepted 11 November 1996

Abstract Interest in Calendula officinalis L. as an industrial oil crop has developed from the discovery that it has a seed-oil content of around 20%, of which up to 60% is calendic acid, a useful industrial feedstock. An EU AIR project ‘vegetable oils with specific fatty acids’, is in progress to further develop this and other species. The first 2 years agronomic evaluations of the crop in north west Europe is reported. Nine accessions representing the range of existing genotypes were compared in field experiments. Significant differences in crop maturity, seed, oil and calendic acid content of the oil were recorded. The results suggest the best of current cultivars should produce field yields in the range 2.0–2.5 t ha − 1. Highest yields were produced by early maturing genotypes. Oil content averaged 16.3%, the best accession produced 19.2%. The effect of plant densities between 10 and 80 plants m − 2 on crop development and seed production was investigated. In 1995 there was a significant effect of plant density on yield, which increased up to a plant density of 40 m − 2. Eleven pre-emergence and one post-emergence herbicide were compared for crop tolerance and efficacy of weed control. Only high rate pendimethalin, of the pre-emergence herbicides and post-emergence phenmedipham at full rate caused any adverse crop effects. Trifluralin and metazachlor gave the most consistent weed control over the spectrum experienced; these and a number of other materials significantly reduced weed density. The application of the majority of herbicides significantly increased crop yield. The lack of a safe post-emergence material limits weed control options in the crop. © 1998 Elsevier Science B.V. Keywords: Calendula officinalis; Accessions; Maturity; Seed yield; Calendic acid; Seed-oil; Plant density; Herbicide; Pre-emergence; Post-emergence; Broad leaved weeds

1. Introduction

* Corresponding author. Present address: ADAS Boxworth Research Centre, Boxworth, Cambridge, CB3 8NN, UK.

Calendula officinalis L. is a native of the Mediterranean area (Earle et al., 1964) but is grown widely across Europe as an ornamental plant. The

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species also has medicinal properties and is used as a herb (Meizer zu Beerentrup and Robbelen, 1987). Industrial interest in the crop has developed from the discovery that its seed has an oil content of around 20% of which up to 60% is calendic acid (Meizer zu Beerentrup and Robbelen, 1987). Potential uses for calendic acid include coatings, paints and cosmetics (Muuse et al., 1992). Robbelen et al. (1994) considered that a second round of developmental activity was required to establish the crop as a new potential crop for non-food uses. To move to this goal the species is one of five included in an European Community AIR project ‘vegetable oils with specific fatty acids’, which commenced in 1994. This paper reports the first 2 years’ progress on the agronomic evaluation of the crop in north west Europe.

2. Materials and methods

2.1. Crop potential Nine accessions (Table 1) were obtained from current European plant breeding programmes and maintainers of ornamental and herb genotypes. Seed was sown in the second half of April, to a target population of 60 plants m − 2 in 27 cm rows using an Oyjord drill. Plot area was 8.1 m2 in 1994 and 16 m2 in 1995. The experiment was laid out as a single treatment factor design in three randomised blocks with one complete set of treatments per block, on a loam soil in south west England. Fifty kilograms per hectare each of nitrogen, phosphate and potash was applied to the seedbed. Weed control was by hand weeding, supplemented in 1995 by the application of chlorthal-dimethyl. In 1994 cypermethrin was applied to control Heliothis peltigera and tebuconazole to contain Coleosporium senecionis; no pesticides were required in 1995. Yield was assessed in 1994 by sequential hand harvesting of the central 1.1 m2 of each plot and in 1995 by combine harvesting, after desiccation, of the whole plot area. Harvested samples were cleaned, accessions bulked and sub-sampled for chemical analysis. Oil was extracted by the method of

Wilson et al. (1962) and methylated (Metcalf and Schmitz, 1992) prior to G.L.C. analysis of individual acids.

2.2. Plant density The number of seeds sown (Table 2) were calculated, using the germination percentage of the seed lot and assuming a 30% establishment loss, to achieve the target plant populations. Target populations were reduced in 1995 in the light of the 1994 results. The accessions used were Pot Marigold in 1994 and Single Wild Type in 1995. Seed was sown in the second half of April by Oyjord drill, in 27 cm rows. Plot area was 8.1 m2 in 1994 and 16 m2 in 1995. The experiment was laid out as a single treatment factor design in three randomised blocks with one complete set of treatments per block, on a loam soil in south west England. Fifty kilograms per hectare each of nitrogen, phosphate and potash was applied to the seedbed. Weed control was by hand weeding in 1994 and supplemented in 1995 by the application of chlorthal-dimethyl. In 1994, cypermethrin was applied to control Heliothis peltigera and tebuconazole to contain Coleosporium senecionis; no pesticides were required in 1995. Crop assessments were carried out on four 0.25 m2 quadrats per plot. Yield was assessed in 1994 by sequential hand harvesting of the central 1.1 m2 of each plot Table 1 Accessions of Calendula officinalis L. evaluated Accession

Source

E 93

Institut fur Planzenbau und Pflanzenzuchtung, Germany C N Seeds Cambridge, UK C N Seeds Cambridge, UK K J King and Son, Essex, UK

Pot Marigold Single Wild type Double Lemon Coronet Russian Hens and Chickens CPRO-DLO 879144 CPRO-DLO 880557 Double Extra

K J King and Son, Essex, UK Kieft, Venhuizen, the Netherlands CPRO-DLO, Wageningen, the Netherlands CPRO-DLO, Wageningen, the Netherlands Bertrand Freres, Angers, France

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Table 2 Target plant density, the number of viable seeds sown and plant establishment of Calendula officinalis L. in 1994 and 1995 Target plant density m−2

No. of viable seeds sown (m−2)

Plant establishment (%)

1994

1995

1994

1995

1994

1995

30 50 60 70 80 100 120

10 20 40 60 80 100

43 71 86 100 114 143 171

14 29 57 86 114 143

51.0 55.6 40.2 54.9 45.9 35.0 47.4

72.6 70.5 83.0 66.7 65.2 62.2

and in 1995 by combine harvesting, after desiccation, of the whole plot area.

2.3. Herbicides— crop tolerance and efficacy of weed control Table 4 shows the herbicide treatments applied by experimental plot sprayer, pre-sowing, immediately after drilling (pre-em) and at crop 2/4 leaves (post-em). The accessions used were Pot Marigold in 1994 and Single Wild Type in 1995. They were sown in the second half of April, to a target population of 60 plants m − 2 in 24 or 27 cm rows. Plot area was 13.4 m2 in 1994 and 16 m2 in 1995. The experiment was laid out as a single treatment factor design in three randomised blocks with one complete set of treatments per block, except for the untreated control, which was replicated three times in each block. Fifty kilograms per hectare each of nitrogen, phosphate and potash was applied to the seedbed. Crop and weed assessments were carried out on four 0.25 m2 quadrats per plot. Yield was assessed by combine harvesting, after desiccation, of the whole plot area.

3. Results and discussion

3.1. Crop potential There were significant differences between accessions in their speed of maturity (Table 3); Pot Marigold and Double Extra were consistently the latest and Hens and Chickens and CPRO-DLO

879144 the earliest to mature. These differences were more marked in 1994, due to a wet early August which extended vegetative growth and the flowering period. Crop height did not differ significantly between accessions but Single Wild Type and CPRO-DLO 880557 were consistently the shortest; this effect was most marked under the dry conditions of 1995. The average yield was 1.80 (range, 0.92–2.99) t ha − 1 in 1994 and 2.10 (range, 1.39–2.56) t ha − 1 in 1995. The yield range was wider in 1994 because the extended maturity period had a greater adverse effect on later maturing accessions. The yield range is similar to that reported by Robbelen et al. (1994), Muuse et al. (1993) and Borm and van Dijk (1994) from combined plots by Breemhaar and Bouman (1995) and better than obtained in previous UK experiments (Cromack et al., 1993). Accession had a significant effect on seed yield (Table 3) and an interaction with years (PB0.05). Overall Single Wild Type produced the highest yield, but this was largely due to an exceptionally high yield in 1994 and an average yield in 1995. E93 and CPRO-DLO 879144 produced the most consistent yields. The performance of Double Extra and Pot Marigold was poor in both years. Robbelen et al. (1994) also reported differences in yield between years which appeared to effect accessions differentially. Seed of Calendula officinalis is composed of a mixture of winged, hooked and larval types. The seed of the majority of accessions contained a reasonably equal distribution of each type, but there were extreme types,

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Table 3 Days to first flower, plant height, seed yield, oil and calendic acid content of nine accessions of Calendula officinalis L. — mean 1994 and 1995 Accession

Days to first flower

Plant height at matu- Seed yield (t ha−1 at rity (cm) 91% DM)

Seed oil content Calendic acid content of (%) oil (%)

IPP E 93 Pot Marigold Single Wild type Double Lemon Coronet Russian Hens and Chickens CPRO-DLO 879144 CPRO-DLO 880557 Double Extra

66 72 69 65

47.3 45.5 41.8 45.5

2.17 1.60 2.41 2.03

17.2 17.4 14.2 16.1

43.6 44.1 50.8 50.3

67 64

47.8 47.8

2.06 1.96

15.5 19.2

44.4 48.3

63

46.5

2.18

16.4

49.0

69

40.5

1.99

16.1

47.0

75

42.7

1.16

14.3

43.4

3.91 15.0

0.111 14.1

S.E.M. 9 (32 df) CV (%)

1.35 3.4

df, degrees of freedom.

seed of the low yielding Double Extra was composed almost entirely of larval types, while the seed of the Single Wild Type contained no hooked seed. A high proportion of larval seed would be desirable for seed handling and cleaning but does not seem compatible with high yield and oil content, a view confirmed by Robbelen et al. (1994). Oil contents were disappointingly low, ranging from 13 to 21% in 1994 and 13.4 to 18.1% in 1995. However these values are similar to those reported by Muuse et al. (1993) and Cromack et al. (1993), but the range is wider than that reported by Robbelen et al. (1994). Within accession there was reasonable consistency in oil content, with Hen and Chickens producing the highest and Single Wild Type and Double Extra the lowest values. Calendic acid content of the oil ranged between 42 and 52% with Single Wild Type and Double Lemon Coronet averaging over 50%. This range is lower than that reported by Muuse et al. (1992) As a result of the yield and oil content effects, the highest yield of oil (0.37 t ha − 1) was produced by Hen and Chickens and E93. Oil yields were generally lower than those reported by Robbelen et al. (1994).

3.2. Plant density In 1994 plant establishment of Pot Marigold was poor and patchy as a result of a loose seedbed which caused deep drilling, in addition, some drill blockages occurred. Establishment ranged from 35 to 56% of viable seeds (Table 2). As a result plant densities were lower than the target and were concentrated between 50 and 55 m − 2. Seedbed conditions in 1995 were excellent and some of the larger winged seeds were removed from the seed sample of Single Wild Type. As a result establishment was good ranging between 62 and 83% of viable seeds enabling the achievement of all but the highest target population. Robbelen et al. (1994) also reported establishment problems in some years, which they suggested were caused by the factors encountered plus the effect of drought after germination. Plant establishment was generally inferior at higher seed densities. In 1994 all plant densities produced full ground cover before flowering, but under the dry conditions of 1995 densities below 40 m − 2 failed to achieve full ground cover. No differences in crop height or crop development were recorded.

df, degrees of freedom.

Isoxaben Isoxaben Isoxaben + pendimethalin Isoxaben+trifluralin Trifluralin Pendimethalin Pendimethalin Chlorthal-dimethyl Chlorthal-dimethyl Propachlor Metazachlor Phenmedipham Phenmedipham Chlorpropham Chlorpropham Propyzamide Propyzamide Metamitron Hand weeded control Untreated control S.E.M. 9(76 df) CV (%)

Active Ingredient

18.75+960 1104 1000 1320 5600 6750 4320 1250 570 1140 1120 2240 500 1000 1750

18.75 31.25 18.75+1000

Rate (g a.i. ha−1)

Pre-em Pre-sowing Pre-em Pre-em Pre-em Pre-em Pre-em Pre-em Post-em Post-em Pre-em Pre-em Pre-em Pre-em Pre-em

Pre-em Pre-em Pre-em

Timing

6.5 7.2 6.0 5.2 6.2 6.8 6.2 6.3 6.3 5.0 6.0 6.8 6.8 6.3 6.7 7.0 6.0 0.548 14.9

6.3 7.0 6.7

Plant vigour score (0 – 9)

44.1 51.1 43.0 37.0 42.3 47.9 46.2 40.8 48.4 39.5 1.6 46.6 44.6 39.7 42.3 47.4 43.2 5.86 23.1

39.7 50.0 45.2

Plant density (m−2)

13.8 5.3 9.5 10.7 10.8 12.5 20.0 6.2 15.3 13.2 18.2 14.5 19.3 12.2 14.0 6.7 28.2 5.056 60.8

24.7 23.8 9.7

Weed density (m−2)

1.26 1.39 1.28 1.29 1.31 1.17 1.19 1.29 1.36 1.37 1.23 1.40 1.24 1.24 1.35 1.28 1.13 0.090 12.2

1.25 1.30 1.35

Seed yield (t ha−1 at 91% DM)

Table 4 The effect of herbicides on the vigour, density and seed yield of Calendula officinalis L. and density of broad leaved weeds—mean 1994 and 1995

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The relationship between seed yield and plant density is plotted in Fig. 1. Yields in 1994 were low due to the use of the late maturing accession Pot Marigold and the wet early August, which extended crop maturity. Analysis of variance showed that there was no significant effect of plant density on seed yield. In 1995, using the accession Single Wild Type and, under favourable weather conditions, there was a significant effect of plant density (P B0.05). Yield increased up to a plant density of 40 m − 2. Borm and van Dijk (1994) reported similar results but Robbelen et al. (1994) suggested that the crop was more responsive to increasing plant density and had a higher optimum, 60 m − 2. Their results do suggest some interaction between cultivar and optimum density, which may help to explain some of the differences in results between experiments. However both sets of data suggest that the optimum plant density is between 40 and 60 m − 2. Plant density had no effect on seed oil content which was contrary to the results of Borm and van Dijk (1994), who reported a positive relationship between plant density and oil content.

3.3. Herbicide— crop tolerance and efficacy of weed control The main broad leaved weed species were Chenopodium album, Polygonum con6ol6ulus, Polygonum a6iculare, Atriplex patula and Galium aparine. Total numbers averaged 28 m − 2. Overall herbicide treatments had no significant effect on crop vigour or plant density. However in 1994 pendimethalin at 1320 g a.i. ha − 1 tended to re-

Fig. 1. Effect of plant density on seed yield in 1994 and 1995.

duce crop vigour and significantly reduce crop ground cover. In 1995, no adverse effect from this treatment was recorded, but in a preliminary observation in 1993 some crop damage was noted (Smith, 1993). In 1995, post-emergence phenmedipham at 1140 g a.i. ha − 1 significantly reduced crop vigour. No damage was recorded in 1994, but in the preliminary observation Smith (1993) reported a transient effect. It is postulated that the hot dry conditions put the crop under greater stress in 1995, thereby predisposing it to greater herbicide damage. Robbelen et al. (1994) also reported crop damage from high application rates of phenmedipham. They also reported some crop damage from propyzamide and metamitron which were not duplicated in this experiment. Most herbicide treatments increased yield in comparison to the untreated control, but yield differences between herbicide treatments were not statistically significant. Overall weed density was significantly (PB 0.05) reduced by pre-emergence application of isoxaben plus pendimethalin, isoxaben plus trifluralin, trifluralin, pendimethalin, chlorthaldimethyl, metazachlor and propyzamide at 1000 g a.i. ha − 1. Trifluralin and metazachlor gave the most consistent control of the weed spectrum found in this experiment and would be the recommended treatments. The relatively poor performance of metamitron is at variance with the results of Robbelen et al. (1994). The only postemergence herbicide investigated, phenmedipham, cannot be recommended because of its adverse effect on the crop. 4. Conclusions The experiments reported suggest that the best of current cultivars should produce field yields in the range 2.0–2.5 t ha − 1. Early maturing genotypes appear to be most suitable for climatic conditions of north west Europe, allowing a more concentrated flowering period and easier harvesting. Oil content was disappointing, averaging only 16.3%, with the best accession achieving 19.2%. There would appear to be scope for further improvement in crop yield, agronomic characteristics and oil content.

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Plant density of 40 m − 2 or more had little effect on crop development and yield. Lower densities, particularly of early maturing types, did not produce full ground cover or yield potential. It would therefore seem desirable, because of the uncertainty over establishment, to set the field target population slightly in excess of 40 plants m2. A number of pre-emergence residual herbicides were shown to be crop safe. Post-emergence phenmedipham at full rate caused some adverse crop effects. Trifluralin and metazachlor gave the most consistent weed control over the spectrum experienced and would be the recommended materials. The use of a herbicide significantly increased crop yield. The lack of a safe post-emergence material limits weed control options in the crop.

Acknowledgements These studies form part of the European Community AIR VOSFA programme. Financial support from the European Community and the UK Ministry of Agriculture and Food is gratefully acknowledged. Thanks are due to Institut fur Planzenbau und Pflanzenzuchtung, Germany, CPRO-DLO, the Netherlands and K.J. King and Son, UK for the supply of seed.

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and row distance on Calendula officinalis L. grown for seed. In: Alternative Oilseed and Fibre Crops for Cool and Wet Regions of Europe. Proceedings of a Workshop, 7-8 April 1994 at Wageningen, CPRO-DLO, Netherlands, pp. 203. Breemhaar, H.G., Bouman, A., 1995. Harvesting and cleaning Calendula officinalis a new arable oilseed crop for industrial application. Ind. Crops Prod. 4, 255 – 260. Cromack, H.T.H., Freer, J.B.S., Smith, J.M., 1993. The performance of a range of novel crops in southern England. In: Proceedings of Second European Symposium on Industrial Crops and Products, 22 – 24 November 1993 at Pisa, Italy, Elsevier, Amsterdam. Earle, F.R., Miklojajczak, K.L., Wolf, I.A., 1964. Search for new industrial oils: X Seed-oils of the Calendulae. J. Am. Oil Chem. Soc. 41, 345 – 347. Meizer zu Beerentrup, H., Robbelen, G., 1987. Calendula and Coriandrum — New potential oil crops for industrial uses. Fat Sci. Technol. 6, 227 – 230. Metcalf, L.D., Schmitz, A.A., 1992. Lipid analysis — A practical approach. In: Hamilton, R.J., Hamilton, S. (Eds.). Lipid analysis IRL Press, Oxford, pp. 47 – 48. Muuse, B.G., Cuperus, F.P., Derksen, J.T.P., 1992. Composition and physical properties of oils from new oilseed crops. Ind. Crops Prod. 1, 57 – 65. Muuse, B., Borm, G., VanDijk, N., Derksen, J., 1993. Effects of harvest date on yield of seed and target fatty acids of new oil crops in the Netherlands. In: Proceedings of Second European Symposium on Industrial Crops and Products, 22 – 24 November 1993 at Pisa, Italy. Smith, J.M., 1993. Evaluation of herbicides for use in Calendula officinalis. ADAS Experimental Report D103/005 (unpublished report), pp. 6. Robbelen, G.D., Theobald, D., Pascual-Villalobos, M.J., 1994. Variability, selection and performance of Calendula officinalis and Euphorbia lagascae for industrial seed-oil uses. In: Alternative Oilseed and Fibre Crops for Cool and Wet Regions of Europe. Proceedings of a Workshop, 7 – 8 April 1994 at Wageningen, the Netherlands, pp. 60 – 73. Wilson, T.L., Smith, C.R., Wolff, T.A., 1962. Lunaria seedoil — a rich source of C24 fatty acids. J. Am. Oil Chem. Soc. 39, 104 – 105.