Influence of the sulfur nutritional status on color and scent of flowers Silvia Haneklaus Elke Bloem Ewald Schnug Institute for Crop and Soil Science Julius Kühn-Institut (JKI) Braunschweig, Germany www.jki.bund.de
The sulfur nutritional status of agricultural crops is closely linked to the emission of volatiles during growth, pungency and aroma of the end product. (Bloem et al. 2010; Lacroux et al. 2008; Paterson 1979) Photo: http://www.spiegel.de/gesundheit/ernaehrung/bild-854300-398084.html
Nectar-feeding bat (Glossophaga soricina) Cabbage white butterfly (Pieris brassicae) Volatile sulfur compounds act as attractants for pests and foraging bats, and repellents for microbes and insects. (Finch 2011; von Helversen et al. 2000; Knudsen et al. 2006; Mann et al. 2011) Photo: http://idw-online.de/pages/de/news418473
Severe sulfur deficiency causes characteristic symptoms in Brassica crops during flowering
Timing and magnitude of macroscopic sulfur deficiency form changes in color and shape of petals during flowering of oilseed rape. (Bloem et al. 2010; Schnug & Haneklaus 2005)
D L S status Mean diameter (D) (mm) Mean length (L) (mm) Mean D:L ratio Extreme S deficiency 5.2 12.5 0.41 Severe S deficiency 6.0 13.5 0.45 Sufficient S supply 10.0 16.4 0.61 LSD 5% 0.29 0.40 0.015 Severe sulfur deficiency significantly reduced the diameter of petals from 10.4 to 7.1 mm and the length from 17.0 to 13.7 mm.
Deformations and lucency are strongest when severe sulfur deficiency sets in during vegetative growth.
Ultraviolet spectra of oilseed rape petals with and without S deficiency. ASD-Fieldspec R Pro JR Spectrometer with Plant probe top. Severe sulfur deficiency changes the spectral signature of flowering oilseed rape. (Lilienthal & Schnug 2005)
Influence of graded N and S rates on flower yield and color intensity of petals of oilseed rape (Brassica napus) and marigold (Calendula officinalis) Treatment Reps No. of flowers per Petal colour intensity at plant 440 nm 470 nm (within 10-11 weeks) [Ext. unit g -1 fresh weight] Oilseed rape S-0 n=8 216.1 7.2 6.5 S-50 n=8 262.9 8.0 7.4 S-250 n=8 260.9 8.3 7.7 LSD 5% 81.5 1.0 0.9 N-250 n=12 143.4 9.4 8.6 N-1000 n=12 349.8 6.3 5.8 LSD 5% 66.6 2.3 0.8 N x S ns ** * 423 nm 446 nm Marigold [Ext. unit g -1 fresh weight] S-0 n=8 2.6 21.3 23.0 S-50 n=8 3.7 22.0 23.5 S-250 n=8 3.9 21.0 22.3 LSD 5% 1.4 2.0 2.7 N-250 n=12 2.1 23.4 25.5 N-1000 n=12 4.7 19.5 20.3 LSD 5% 1.1 1.7 2.2 N x S ns ns ns Two factorial ANOVA was used to analyse the results and the means were compared by the Tukey test at 5% probability level; bold letters indicate statistically significant differences between treatments. Significance levels were given for the interaction between N and S (N x S) and coded in the following way: ns not significant; * significant, p<0.05; ** highly significant, p<0.01; *** very highly significant, p<0.001. (Bloem et al. 2011)
Sulfur and color & shape of flowers Under conditions of severe sulfur deficiency the following metabolic changes (presumably) take place: - photosynthesis is inhibted (Schnug & Haneklaus 1994) - carbohydrates accumulate (van Schaewen at al 1990) - GSH content decreases (Schnug et al. 1995; Salac 2005) - cytoplasmatic decrease of ph enhances synthesis of secondary metabolites (Sakano 2001) - ph is a signal and messenger (Felle 2001) - flavonoids are metabolized increasingly as antioxidants (Lunde et al. 2008) -changes in color are reversible, not that of shape (Haneklaus et al. 2006) - color of flavonoids may vary ph-dependently from white to colorless (ph <8) (Alkema & Seager 1982) - cell shape influences color expression (Grotewold 2008) - the deformation of petals affects cell morphology (Schnug and Haneklaus 1994)
1719 chemical compounds were found in the headspace of 991 plant species at flowering. 7 major compound classes can be distinguished based on their chemical structure of major pathways of secondary metabilsm: Aliphatics, benzoids and phenylpropanoids, C5-branched compounds, terpenoids, N-containibg compounds, S-containing compounds, other cyclic compounds. (Knudsen et al. 2006)
3-Hydroxy-2-butanone 28% 22% 2,3-Butanedione Formaldehyde 17% 7% 18% 3-Methyl-2-butanone 2-Butanone Organic sulphides 4% 4% 56 different compounds In total 62 volatile organic compounds (VOCs) were found in the headspace of oilseed rape during flowering; hereof 17 % were S- containing metabolites. (Robertson et al. 1993)
Two-dimensional PCA plot for headspace volatiles from flowers with and without S deficiency symptoms collected at different experimental sites and analyzed by AromaScan A32/50S: 32-conducting polymer sensor E-nose. Severe sulfur deficiency significantly changed the bouquet of volatiles in flowering oilseed rape.
Severe S-deficiency coinicides with a reduced number of visiting honeybees and the major attractants scent, color and petal morphology alter significantly, but it is the fact that bees mistake S-deficient for pollinated flowers which precludes adapatation of behavior. (Schnug & Haneklaus 2005)
Field experiments All crops were sufficiently supplied with sulfur. S fertilization significantly increased the S content in flowers of mustard, oil radish, chamomile and field beans. (Bloem et al. 2010)
S fertilization significantly changed the floral scent of flowering oil radish and chamomile (PCA plot for headspace volatiles). (Bloem et al., 2010)
Sulfur fertilization influences the floral scent of crops. Climatic conditions affect the composition of volatiles. (Bloem et al. 2010)
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