Tomáš Lošák, Rostislav Richter, Petr Škarpa
Mendel University of Agriculture and Forestry Brno, Czech Republic Department of Agrochemistry, Soil Science, Microbiology and Plant Nutrition
Foliar application of elementary sulphur
in the nutrition of poppy (Papaver somniferum L.)
*Nalistne nawożenie maku (Papaver somniferum L.) siarką elementarną
Key words: poppy, elementary sulphur, nitrogen application, yield seed, capsules per plant,morphine
A vegetation pot trial with poppy (Papaver somniferum L.) variety Opál, was conducted at constant nitrogen nutrition (0.9 g N per pot). Foliar application of a 2% solution of elementary sulphur at the stage of elongation growth (one application) and elongation growth + shedding of blossoms (two applications) had a positive effect on seed yields, which increased by 8.5% after one application and by 5.1% after two applications compared to the variant not fertilised with sulphur. There increase were statistically significant. The number of capsules dropped to 1.7 capsules per plant in both sulphur-fertilised variants compared to 2 capsules per plant in the variant fertilised with nitrogen only. The post-harvest content of morphine in poppy straw (= empty capsule + 15 cm of stem) after one foliar application of S increased to 0.80%, while after two applications of S it dropped to 0.72% compared to the variant not fertilised with S (0.76%). All the same, crucial for yield formation was nitrogen because the control variant without N and S application showed the lowest level of all the studied indicators.
Słowa kluczowe: mak, siarka elementarna, nawożenie azotem, plon nasion, makówki na roślinie, morfina
Doświadczenie wazonowe z odmianą maku Opal zostało założone przy stałym poziomie nawożenia azotem (0,9 g N·wazon-1). Nalistne nawożenie 2% roztworem siarki elementarnej w fazie wydłużania pędu (jednokrotne) oraz w fazach wydłużania pędu i opadania płatków (dwukrotne) wpływało korzystnie na plon nasion. W porównaniu z kombinacją bez siarki jednokrotne zastosowanie siarki przyczyniło się do wzrostu plonu o 8,5%, a dwukrotne o 5,1%. Liczba makówek na roślinie obniżyła się średnio do 1,7 na poletkach obu wariantów nawożenia siarką. Na poletkach, na których zastosowano tylko nawożenie azotem rośliny wytworzyły średnio 2 makówki. Zawartość morfiny w słomie makowej po zbiorze (pusta makówka + 15 cm łodygi) zebranej z poletek jednokrotnie nawożonych siarką wzrosła do 0,80%, a z poletek nawożonych dwukrotnie zmalała do 0,72% w porównaniu z kombinacją, na której nie zastosowano siarki (0,76%). Niemniej jednak istotniejszy wpływ na plon miało nawożenie azotem, ponieważ najniższe wartości wszystkich badanych wskaźników odnotowano na poletkach kontrolnych, na których nie zastosowano nawożenia azotem i siarką.
Introduction
The tradition of poppy (Papaver somniferum, L.) cultivation in Central Europe is very long. In the Czech Republic at the present time poppy is grown for food production (seed) and for the pharmaceutical industry (alkaloids). Characteristic for poppy is a short vegetation period and weak root system, due to which the plants require a good supply of all biogenic elements in the soil and which is then reflected both in seed yields and quality of poppy straw (Lošák, Richter 2004).
The main problem in poppy nutrition is the optimal content of macro and micro biogenic elements in the soil, or in the plant, which has a positive effect on yields as well as on the quality of harvested products. Nitrogen fertilisation plays a crucial role in poppy cultivation and imperative is the appropriate dose, form and date of application (Yadav et al. 1984, Jain 1990). Tomar et al. (1993) and Subrahmanyam et al. (1992) studied the use of sulphur in poppy nutrition in terms of growth, seed yields, oil and protein content in seeds, and content of the alkaloid morphine in poppy straw.
Sulphur aroused the interest of producers, especially in the past 15 years when the amount of sulphur in the soil was substantially reduced, mainly because the applications of mineral and organic fertilisers, fungicides and also limited SO2
emissions reduced to less than 10 kg S·ha-1 (Lošák 2003). The plant takes up
sulphur from the soil solution particularly in the form of sulphates (SO42-) (Marschner 1995). Apart from that sulphur can be taken up also via the leaves in the form of foliar applications. For this it can be also suitable to apply elementary sulphur (Jolivet 1993). Sulphur as a macro element plays an important role in plant metabolism, it is a component of the amino acids cysteine and methionine. It is also contained in glutathione, which is very important in the process of detoxification of free radicals and inactivation of heavy metals (Briat, Lebrun 1999; De Kok, Stulen 1993). Moreover elementary sulphur shows also fungistatical effects (Haneklaus et al. 2002, Schnug et al. 1995). If the supply of sulphur is sufficient the plants are capable themselves to release hydrogen sulphide through the leaf surface, which prevents pathogen attacks (Salac et al. 2003).
In present practice we apply fertilisers containing sulphur in the form of sulphate or elementary sulphur. The sulphate form is readily soluble and mobile in the soil profile. On the other hand the elementary form of sulphur is insoluble in water and so unavailable for plants until microbial oxidation into sulphates takes place. This makes it suitable for application on leached soils and for reserve fertilising (Boswell 1997). If foliar application is used, the slow process of oxidation allows a much smoother and continuous supply of sulphur for the plants than with foliar applications of sulphate solutions (Pedersenet al. 1998).
The objective of the presented study was to establish a vegetation pot experiment with poppy to explore the effect of single and double foliar applications of elementary sulphur on the state of health of poppy plants, on seed yields, number of capsules per plant and the content of morphine in poppy straw.
Material and methods
The vegetation pot experiment with poppy was established on 3 April 2005 and included 4 combinations (Tab. 1).
Table 1 Pattern of experiment — Schemat eksperymentu
Foliar application of S
Nalistne nawożenie siarki
Treatment Kombinacja Pattern Schemat Doses of N [g·pot-1]
[g·wazon-1] stem elongation wydłużanie pędu after flowering opadanie płatków 1 control – – – 2 N 0.9 – – 3 N + S 0.9 2% solution – 4 N + S + S 0.9 2% solution 2% solution
Plastic pots were filled with 9.5 kg of medium heavy soil characterised as fluvisol; at the same time in variants 2–4 nitrogen was applied in the form of ammonium nitrate to a uniform level of 0.9 g N per pot. Table 2 gives the agrochemical characteristics of the soil prior to the establishment of the experiment.
Table 2 Agrochemical properties of the soil in Mehlich III (mg·kg-1)
Agrochemiczna charakterystyka gleby
pH/CaCl2 P K Ca Mg S
5.7 108 251 3716 342 21
mildly acid good good high very high good
słabo kwaśny dobry dobry wysoki bardzo wysoki dobry
The soil was extracted for analyses using the method according to Mehlich III
(CH3COOH, NH4NO3, NH4F, HNO3 and EDTA). The colorimetric method was
used to determine the content of available phosphorus in the extract. The content of available potassium, magnesium and calcium was determined by atomic absorption spectrophotometry (AAS). The quantification of sulphate sulphur was preceded by extraction with demineralised water in a 1 : 5 ratio and capillary zone electro-phoresis was applied for measurements of sulphur. The activity of hydrogen ions (soil pH) was measured in a 0.01 mol·dm-3 CaCl
Five days after filling the pots and natural settling of the soil, poppy seeds of the variety Opál were shallowly sown into the pots. After the stage of 2 leaves the plants were thinned to 7 plants per pot. During vegetation the plants were watered on a regular basis with demineralised water. The plants were sampled for chemical analyses. The pots were weeded and protected against the beet aphid (Aphis fabae) with Sumithion (0.05%). Since the supply of P, K, Ca and Mg in the soil was good to very high, the plants were not fertilised with these nutrients.
The foliar application of 2% fertiliser solution (containing 20% of elementary sulphur) was done in combination 3 and 4 at the stage of elongation growth and in combination 4 also in the stage of blossom shedding (green poppy heads). The plants were harvested on 17 August, i.e. 4 plants from each pot. Each combination subsumed 4 pots. The content of morphine in the straw was estimated by means of polarography in the Research Institute of Oil Plants in Opava. The yield and the number of capsules per plant were elaborated statistically using the method of variance analysis and Tukey’s test with the minimal significant differences of DT0.05 and DT0.01.
Results and discussion
During vegetation visible infection with diseases was not observed and any combination showed visual symptoms of attack by fungous diseases on the plants.
The results of yield presented in Table 3 show that the differences in yields of seeds per pot were statistically significant. There were higher after one application of sulphur, i.e. by 8.5% (var. 3) and after two applications of sulphur by 5.1% (var. 4) compared to the similar variant where no sulphur was applied (var. 2). Tomar et al. (1993) compared four levels of sulphur fertilisation in the form of elementary S and simple super phosphate and discovered that seed yields were the highest after application of the highest sulphur dose.
Subrahmanyam et al. (1992) assumed that the sulphate form of sulphur (SO42-) was more effective, and after the application of 60 kg S·ha-1 they discovered that yields of poppy seeds increased by 18.6%. The seed yields of all the nitrogen-fertilised variants (var. 2–4) showed a statistically highly significant increase, i.e. by 56.9–65.4% as compared with the unfertilised control (var. 1). These results correspond with data of Yadav et al. (1984), when increasing nitrogen doses by 50 – 100 – 150 – 200 kg N·ha-1 the seed yields increased compared to the control. Likewise Jain et al. (1990) stated that yields increased by 37.5% after applying nitrogen doses increasing from 30 to 90 kg N·ha-1. Kharwara et al. (1988) discovered that seed yields were significantly stimulated when nitrogen doses increased from 75 kg N·ha-1 to 150 kg N discovered that seed yields were significantly stimulated when nitrogen doses increased from 75 to 150 kg N·ha-1.
Table 3 Seed yields, number of poppy heads per plant and morphine content (%)
Plon nasion, liczba makówek na roślinie, zawartość morfiny (%) Seed yield — Plon nasion
Treatment Kombinacja Pattern Schemat g·pot-1 g·wazon-1 rel. % Number of capsules per plant Liczba makówek na roślinie Content of morphine Zawartość morfiny [%] 1 Control 5.57 43.1 1.0 0.61 2 N 12.90 100.0 2.0 0.76 3 N + S 14.00 108.5 1.7 0.80 4 N + S + S 13.56 105.1 1.7 0.72 Dt0.05 0.63 0.11 Dt0.01 0.92 0.19
In the control variant (var. 1) there was only one poppy head per plant (Tab. 3); in variants were nitrogen and sulphur were applied their number increased highly significantly to 1.7 (var. 3 and 4). The application of N without S (var. 2) resulted in a further significant increase in the number of poppy heads per plant. Lošák and Páleníček (2005) reported that the number of poppy heads per plant increased with increasing doses of nitrogen to 1.75–2.2, while the number of poppy heads per plant decreased to 1.50–2.11 after the application of sulphur to the soil.
The content of morphine in the straw (empty poppy head + 15 cm of stalk) decreased considerably to 0.61% in the variant not fertilised with nitrogen (Tab. 3). This finding corresponds with a number of literary sources, which reported that the increased concentration of morphine is dependent on increasing levels of N-fertilisation (Yadav et al. 1984). Kharwara et al. (1988) observed that the concentration of morphine increased when nitrogen doses increased from 75 kg N·ha-1 to double this dose. The content of morphine increased in all the fertilised variants to 0.72–0.80%, and the highest concentration corresponded to the variant where sulphur was applied as a foliar application in the stage of elongation growth (var. 3). Subrahmanyam et al. (1992) also reported that the content of alkaloids, incl. morphine, increased after fertilisation with higher doses of sulphur.
Conclusions
In the vegetation pot experiment with poppy the positive effect of foliar applications of elementary sulphur in the stage of elongation growth on seed yields and on the concentration of the alkaloid morphine in the straw was proved. Although nitrogen plays the crucial role in yield formation, joint application with sulphur seems to be a suitable nutritional measure in poppy production.
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