The after-effect of microelement contamination (0, 30, 90 and 270 kg·ha-1) on sunflower was examined in the 4th year on a calcareous sandy soil. The microelements were applied in the form of Cr2(SO4)3, K2Cr2O 7, CuSO4, Pb(NO3)2, Na 2SeO3 and ZnSO4 on a single occasion when the experiment was set up in spring. The four rates of six elements (24 treatments) were added to the soil in three replications on a total of 72 plots (each 7×5 = 35 m2). Like sandy soils in general, the soil had poor water management, was prone to drought and was poorly supplied with N, P and K. The ploughed layer contained 0.7-1.0% humus and 2-3% CaCO3, and the groundwater depth was 5-10 m. A basic fertilizer rate of 100 kg·ha -1 each of N, P2O5 and K2O was applied to the whole experiment every year. The crop sequence was carrot, pea, winter wheat and sunflower. The main results were as follows: - The favourable rainfall conditions resulted in a 2.3 t·ha-1 sunflower seed yield on the uncontaminated plot, with 7.1 t·ha-1 total air-dry aboveground biomass. The oil content and oil yield of the seeds was 51% and 1.2 t·ha-1. The Se loading was still toxic in the 4 th experimental year, leading to a significant yield decrease even at the 30 kg·ha-1 rate, while the 270 kg·ha-1 rate destroyed the crop almost completely. The by-product /main product ratio at harvest rose from 2.1 in the control to 5.0. Toxicity was more pronounced in the generative phase. - The Cr content of the sunflower organs rose by an order of magnitude compared with the control. On average the increase was twice as high in the Cr(VI) treatment as on the Cr(III) plots. The concentrations declined in the order shoot, stem, leaf, inflorescence, seed. The Pb concentration decreased in a similar order and was below the 0.1 mg·kg-1 detection limit in the seed. The Cu content exhibited a moderate increase on contaminated soil, but the change in the seed was insignificant. The Zn concentration rose by at most 2-3 times. Se exhibited hyperaccumulation in all the plant organs, with an approximately 1000-fold increase. The seed of sunflower grown on Se-polluted soil became unsuitable for human consumption, and the stems for feeding purposes. - Due to the yield reduction, the maximum Se uptake was recorded at rates of 30 and 90 kg·ha-1, and amounted to 450 g·ha-1. Assuming constant conditions, phytoremediation would require 66 years for the 30 kg·ha-1 rate and around 200 years for the 90 kg·ha-1 rate. The aboveground yield of sunflower extracted a maximum of around 10 g Pb, 24 g Cr, 100 g Cu and 330 g Zn per hectare from the contaminated soil. The cleansing of soil contaminated with 270 kg·ha -1 would thus take 27,000 years for Pb, 11,000 years for Cr in the Cr(VI) treatment, 2700 years for Cu and 818 years for Zn. - Leaf diagnostic data indicated excessive quantities of Ca and Mg, a mild deficiency of N, K, P and Cu and a severe deficiency of Zn. The absolute Zn deficiency did not lead to yield losses, however, as the P/Zn ratio remained close to the optimum 50-150 range. The specific element contents of 1 t seeds + the relevant inflorescence and stem were as follows: 34 kg N, 7 kg P (16 kg P2O5), 32 kg K (38 kg K2O), 66 kg Ca (92 kg CaO), 15 kg Mg (25 kg MgO) and 4-5 kg S. These data can serve as guidelines when estimating plant nutrient requirements. The 30 kg specific P2O5 content recommended by the Hungarian extension service is exaggerated and could lead to over-fertilization. - After the 4th year of the experiment, an average 0.5% of the Cr from the Cr(III) treatment, 1% of that from the Cr(VI) treatment and 1.5% of the Se could be found in NH4-acetate+EDTA- soluble form in the ploughed layer of the soil. Cr(VI) and Se may have leached into the subsoil or have become partially bound. On average, 1/3 of the Cu, Pb and Zn quantities added to the soil was detected in soluble form. Table 1. Crop sequence and rainfall sums between 1995 and 1998 in the experiment set up on calcareous sandy soil in Orbottyán. (1) Year. (2) Crop species. a) Carrot; b) Pea; c) Winter wheat; d) Sunflower. (3) Vegetation period (months). (4) Sowing. (5) Harvesting. (6) Rainfall quantity, mm. (7) Apr.-Sep. (8) Oct.-June. (9) Annual sum. A. 45-year mean rainfall sum at the experimental location. Table 2. Effect of the toxic Se treatment on sunflower in the microelement pollution experiment in 1998. (1) Measured parameters. a) Green mass; b) Air-dry mass; c) Air-dry matter; d) Scoring; e) Inflorescence; f) 1000-seed weight; g) Seed; h) Stem; i) Together; j) Inflorescence/seed; k) Stem/seed; l) By-product/seed; m) Seed soil; n) Oil yield. (2) Se rates in spring 1995. (3) LSD5%. (4) Mean. A. 4-6-leaf shoots on 5 July. B. Leaf below the inflorescence on 5 Aug. (at the beginning of flowering). C. Yield components at harvest (on 8 Oct.). D. Yield at harvest (on 8 Oct.). E. Mass ratios at harvest (on 8 Oct.). F. Oil content and oil yield (on 8 Oct.). Note: Scoring: 1 = Dying, poorly developed, 5 = well-developed stand. (-): The plant stand was destroyed. Table 3. Effect of the treatments in the microelement load experiment on the composition of air-dry sunflower in 1998, mg·kg- 1. (1) Plant organs. a) Shoot; b) Stem; c) Leaf; d) Inflorescence; e) Seed. (2)-(4): see Table 2. Note: Shoot in the 4-6-leaf stage; leaf at the beginning of flowering; stem, inflorescence and seed at harvest. Table 4. Effect of the toxic Se treatment on the estimated Se uptake in the microelement load experiment in 1998, g·ha-1. (1) Measured parameters. a) Stem; b) Inflorescence; c) Seed; d) Together. (2)-(4): see Table 2. Note: Quantity taken up by the above-ground harvested mass of sunflower on contaminated soil. Table 5. Mean element composition of air-dry sunflower grown in the microelement load experiment on uncontaminated soil in 1998. (1) Element symbol, units. (2) 4-6-leaf shoots. (3) Leaf at flowering. (4) At harvest. (5) Stem. (6) Inflorescence. (7) Seed. Note: Hg remained below the detection limit. Table 6. Composition of the 4-6-leaf air-dry shoots of sunflower (A) and of the leaf below the inflorescence at the beginning of flowering (B) according to data from the literature. (1) Element symbol and units. Table 7. Mean and specific element uptake of sunflower at harvest on uncontaminated soil in 1998. (1) Element symbol and units. (2) Stem. (3) Inflorescence. (4) Seed. (5) Together. (6) Specific. Note: - Not detectable. Hg remained below the detection limit. Table 8. Effect of treatments on the NH4-acetate + EDTA-soluble element contents in the ploughed layer of a calcareous sandy soil in Orbottyán in 1998 (after the 4th year). (1)-(4): see Table 2. Note: Mean content of other elements.
|Translated title of the contribution||Effect of microelement pollution on sunflower (Helianthus annuus L.) grown on a calcareous sandy soil|
|Number of pages||16|
|Journal||Agrokemia es Talajtan|
|Publication status||Published - Dec 1 2010|
ASJC Scopus subject areas
- Agronomy and Crop Science
- Soil Science