EFFECT OF USING COVERS IN EARLY CROP POTATO CULTURE ON THE CONTENT OF PHOSPHPRUS AND MAGNESIUM IN TUBERS

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J. Elementol. 2008, 13(2): 275 280 275 EFFECT OF USING COVERS IN EARLY CROP POTATO CULTURE ON THE CONTENT OF PHOSPHPRUS AND MAGNESIUM IN TUBERS Wanda Wadas, Romualda Jab³oñska-Ceglarek, Agnieszka Kurowska Department of Vegetable Crops University of Podlasie Abstract Potassium is the main mineral component of potato tubers. With a high level of potato consumption, the crop also supplies the human organism with magnesium and phosphorus. The content of mineral components in potato tubers may change as an effect of agro technical factors. The aim of the study was to determine the effect of the type of cover (perforated polyethylene film, polypropylene fibre) and date of its removal (2 and 3 weeks after plant emergence) on phosphorus and magnesium in tubers of early potato cultivars (, ). The potatoes were harvested 60 days after planting. Accelerated plant growth under covering resulted in the phosphorus content in tubers of cv. being 0.088 g kg 1 d.m. higher in comparison with thecontrol, but did not affect the content of magnesium. With perforated film used to cover potato plants, an average content of phosphorus in tubers was by 0.217 g kg 1 d.m than when polypropylene fibre cover was applied. The content of magnesium in tubers was on average 0.067 g kg 1 d.m. higher under polypropylene fibre cover. Duration of the period when potato plants grew under cover did not significantly affect the phosphorus and magnesium accumulation in tubers. Key words: early potato, perforated film, polypropylene fibre, phosphorus, magnesium. prof. dr hab. Wanda Wadas, Department of Vegetable Crops, University of Podlasie, Prusa 14, 08 110 Siedlce, Poland, wwadas@ap.siedlce.pl

276 WP YW STOSOWANIA OS ON W UPRAWIE ZIEMNIAKA NA WCZESNY ZBIÓR NA ZAWARTOŒÆ FOSFORU I MAGNEZU W BULWACH Abstrakt G³ównym sk³adnikiem mineralnym bulw ziemniaka jest potas. Spo ywanie ziemniaków pokrywa równie czêœciowo zapotrzebowanie organizmu cz³owieka na fosfor i magnez. Zawartoœæ sk³adników mineralnych w bulwach ziemniaka mo e ulegaæ zmianom pod wp³ywem czynników agrotechnicznych. Celem badañ by³o okreœlenie wp³ywu rodzaju os³ony (folii perforowanej, w³ókniny polipropylenowej) i terminu jej zdjêcia (2 i 3 tygodnie po wschodach roœlin) na zawartoœæ fosforu i magnezu w bulwach wczesnych odmian ziemniaka (, ). Ziemniaki zbierano po 60 dniach od sadzenia. Przyspieszenie wegetacji roœlin przez stosowanie os³on spowodowa³o zwiêkszenie zawartoœci fosforu w bulwach odmiany œrednio o 0,088 g kg 1 s.m. w porównaniu z upraw¹ bez os³aniania roœlin, ale nie mia³o wp³ywu na gromadzenie w bulwach magnezu. W przypadku stosowania folii perforowanej zawartoœæ fosforu w bulwach by³a wiêksza, œrednio o 0,217 g kg 1 s.m., ni przy stosowaniu w³ókniny. Wiêksz¹ zawartoœæ magnezu, œrednio o 0,067 g kg 1 s.m., stwierdzono po zastosowaniu w³ókniny. D³ugoœæ okresu okrycia roœlin nie mia³a wp³ywu na zawartoœæ obu pierwiastków w bulwach ziemniaka. S³owa kluczowe: ziemniak wczesny, folia perforowana, w³óknina polipropylenowa, fosfor, magnez. INTRODUCTION Potato tubers contain over 1% mineral compounds, mainly potassium, in fresh mass. With a high potato consumption in some countries, this crop can also supply the human organism with magnesium and phosphorus. Twohundred grams of potatoes provide 8 15% recommended daily amount of magnesium and 8 12% of phosphorus (KOLASA 1993, LESZCZYÑSKI 2000). The content of mineral components in potato tubers depends on the genetic characters of a cultivar, but may change under climatic and agro technical factors (CZEKA A, G ADYSIAK 1995, KLIKOCKA 2001, KO ODZIEJCZYK, SZMIGIEL 2005). Until now, studies on the effect of covers used in early crop potato culture on the chemical composition of tubers have focused mostly on organic compounds (LACHMAN et al. 2003, WADAS et al. 2003, 2007, DVOØÁK et al. 2006). The aim of the present study was to determine the effect of potato plants being covered, for various lengths of time, on phosphorus and magnesium in immature potato tubers. MATERIAL AND METHODS The effect of the type of cover (perforated polyethylene foil, polypropylene fibre) and the date of its removal (I 2 weeks after plant emergence, II

3 weeks after plant emergence) on phosphorus and magnesium in tubers of early potato cultivars (, ) was investigated. The study was carried out in the years 2002 2004 at the Department of Vegetable Crops, University of Podlasie in Siedlce. The field experiment was established in a split block split plot design with the control object not covered, on soil characterised by a low to moderate content of available potassium and moderate to high content of phosphorus and magnesium, ph KCl 6.1 6.7. In each year of the study spring triticale was grown as a potato forecrop. Farmyard manure was applied in autumn, at a rate of 30 t ha 1. Mineral fertilizers were applied in spring at the recommended rates of 60 kg N (ammonium nitrate 34%), 26 kg P (60 kg P 2 O 5, granular superphosphate 19%) and 75 kg K (90 kg K 2 O, potassium sulphate 60%) per 1 ha. In the successive years 8 week pre sprouted seed potatoes were planted on 9, 16 and 13 April. The potatoes were harvested 60 days after planting. The content of phosphorus with vanadium molibdenum colorimetric method and magnesium with atomic absorption spectrometry (AAS) method were determined. The analysis of the results was conducted using the orthogonal contrast to compare the control with the test objects. The most favourable weather conditions for early crop potatoes were in a very warm and wet vegetation period of 2002 (Table 1). The year 2003 was warm but with the whole potato growth season was marked by seasonal drought. In contrast, the year 2004 was the coldest one with the least rainfall from mid May to mid June. 277 2002 2003 2004 air temperature and precipitation sums in the vegetation period of potato Years April 9.0 7.1 8.0 T emperature ( C) Precipitation (mm) May 17.0 15.6 11.7 June 17.2 18.4 15.4 April 12.9 13.6 35.9 May 51.3 37.2 97.0 Table 1 June 61.1 26.6 52.8 1981 2000 8. 1 11. 2 16. 7 49. 6 48. 2 67. 7 RESULTS AND DISCUSSION The content of phosphorus in potato tubers ranged from 2.730 to 3.733 g kg 1 d.m.; that of magnesium varied from 1.267 to 1.670 g kg 1 d.m. (Tables 2 and 3). Irrespective of the potato culture method, most phosphorus and magnesium was accumulated by potato tubers in 2003 and 2004, when drought occurred in the period of tuber formation and growth, which was in contrast to a very warm and wet year 2002. According to CZEKA A and

278 Years 2002 2003 2004 Cultivar P hosphorus content in potato tubers Control object no covering 2.967 3.033 I 2.967 (g kg - 1 d.m. ) Kind and date of cover removal perforated film II 3.000 3.100 polypropylene fibre I II 2.983 2.933 2.933 2.730 2.850 2.750 Table 2 for covers 2.917 2.842 3.000 3.050 2.958 2.832 2.800 2.879 3.067 3.100 3.133 3.267 3.300 3.130 3.217 3.200 2.900 2.833 2.870 2.883 2.850 3.050 3.025 3.083 3.200 3.215 3.208 2.868 3.038 3.133 3.267 3.633 3.733 3.267 3.567 3.450 3.333 3.467 3.230 3.367 3.350 3.467 3.200 3.516 3.500 3.508 3.320 3.358 3.433 3.094 3.194 3.255 3.225 3.011 3.010 3.008 3.117 LSD0.05 : years = 0.146 comparison the control object with remaining (contrast) contrast x cultivar = 0.068 kind of cover = 0.159 date of cover removal = n.s. = n.s. G ADYSIAK (1995), phosphorus in potato tubers was negatively correlated with the air temperature prevailing from plant emergence to flowering, while magnesium was reversely correlated with the field water capacity from flowering to the early canopy drying time, the finding which was confirmed in the present study. According to other authors, potato tubers harvested in a wet year contain more magnesium, whereas the accumulation of phosphorus does not depend on meteorological conditions (KO ODZIEJCZYK, SZMI GIEL 2005). Stimulating plant growth by using plant covers resulted in increased phosphorus content in tubers of cv. (by 0.088 g kg 1 d.m., on average) in a three year period in comparison with the cultivation without plant covering, but did not significantly affect the content of this element in tubers of cv.. The use of covers in the early crop potato culture slightly affected the accumulation of magnesium in tubers. The present study showed a significant affect of the type of cover on phosphorus and magnesium content in tubers. Phosphorus content was higher by an average of 0.217 g kg 1 d.m. over a three year period when perforated film cover was applied. The content of magnesium content rose by 0.067 g kg 1 d.m. when polypropylene fibre cover was used. Polypropylene fibre plant cover proved to be most effective in enhancing magnesium concentration in tu

279 Years 2002 2003 2004 Cultivar M agnesium content in potato tubers Control object no covering 1.267 1.333 I 1.267 (g kg - 1 d.m. ) Kind and date of cover removal perforated film II 1.167 1.170 polypropylene fibre I II 1.233 1.217 1.367 1.333 1.367 1.367 1.317 Table 3 for covers 1.267 1.283 1.168 1.225 1.350 1.334 1,342 1.283 1.633 1.670 1.617 1.550 1.534 1.558 1.635 1.608 1.400 1.467 1.467 1.570 1.508 1.492 1.450 1.483 1.483 1.552 1.450 1.461 1.384 1.422 1.472 1.507 1.489 1.456 LSD0.05 : years = 0.081 comparison the control object with remaining (contrast) = n.s. kind of cover = 0.028 years x kind of covers = 0.048 date of cover removal = n.s. bers in the warm and moderately wet vegetation period of the year 2002. With this type of cover, the average magnesium content in tubers was higher by 0.117 g kg 1 d.m. compared to that in tubers grown under perforated film. Polypropylene fibre plant cover also created more favourable conditions for potassium accumulation in tubers (WADAS et al. 2007). The length of time when potato plants were covered did not significantly affect phosphorus and magnesium accumulation in tubers (Tables 2, 3). Prolongation of the perforated film cover period to 3 weeks after plant emergence raised the phosphorus concentration in tubers but depressed their magnesium content. However, the interaction between the type of cover material and the date when the cover was removed was not statistically confirmed. The content of phosphorus and magnesium in tubers of very early potato cultivars and was similar.

280 CONCLUSIONS 1. Phosphorus and magnesium content in tubers was higher in years with less rainfall in the potato growth season. 2. Plant vegetation being accelerated by application of covering resulted in higher phosphorus content in the tubers of cv., but had only very weak effect on magnesium. 3. Phosphorus content was higher when perforated film cover was applied; magnesium accumulated best under polypropylene fibre cover. 4. Duration of the period when potato plants grew under cover did not significantly affect the phosphorus and magnesium accumulation in tubers. REFERENCES CZEKA A J., G ADYSIAK S. 1995. Dzia³anie niektórych czynników na zawartoœæ makrosk³adników w bulwach ziemniaka. Zesz. Probl. Post. Nauk Rol., 421a: 55 58. DVOØÁK P., HAMOUZ K., JÙZL M., ERHARTOVÁ D. 2006. Influence of row covering with non woven textile on tubers quality in early potato. Zesz. Probl. Post. Nauk Rol., 511: 225 231. KLIKOCKA H. 2001. Wp³yw ró nych sposobów uprawy roli i pielêgnowania ziemniaków na zawartoœæ makroelementów w ich bulwach. Biul. IHAR, 217: 197 203. KOLASA K.M. 1993. The potato and human nutrition. Am. Potato J., 70: 375 384. KO ODZIEJCZYK M., SZMIGIEL A. 2005. Zawartoœæ makroelementów w bulwach ziemniaka jadalnego w zale noœci od kompleksu glebowego, odmiany oraz nawo enia. Fragm. Agron., 1(85): 436 445. LACHMAN J., HAMOUZ K., HEJTMÁNKOVÁ A., DUDJAK J., ORSÁK M., PIVEC V. 2003. Effect of white fleece on the selected quality parameters of early potato (Solanium tuberosum L.) tubers. Plant Soil Environ., 49(8): 370 377. LESZCZYÑSKI W. 2000. Jakoœæ ziemniaka konsumpcyjnego. ywnoœæ, 7, Supl. 4(25): 5 27. WADAS W., JAB OÑSKA CEGLAREK R., KOSTERNA E. 2003. Wp³yw stosowania w³ókniny w uprawie bardzo wczesnych odmian ziemniaka na zawartoœæ wybranych sk³adników w bulwach. ywnoœæ, 3(36): 110 118. WADAS W., JAB OÑSKA CEGLAREK R., KOSTERNA E., ÊCZYCKA T. 2007. Zawartoœæ potasu w m³odych bulwach ziemniaka w zale noœci od sposobu uprawy. Rocz. AR Pozn. CCCLXXIII, Ogrodn., 41: 643 647.