Determination of optimum nitrogen rate and the regulation of nitrate accumulation in Beijing cabbage plants
2008
Belyaeva, I.S. | Salyaev, R.K. | Sabirova, R.N. | Lapteva, T.I., Russian Academy of Sciences. Siberian Branch, Irkutsk (Russian Federation). Siberian Inst. of Plant Physiology and Biochemistry
Plants of the Beijing cabbage (Brassica pekinensis) known as the strongest nitrate accumulator were grown in a climatic chamber. The conditions promoting intensive nitrate accumulation were simulated during experiment. It was maintained the low (11 deg C) temperature in the root zone and low irradiance (110 W/square meter). The plants were grown in water culture (WC) or in quartz sand (SC) using nutrient solutions. In the control variant a ratio nitrate:sulphate:phosphates anions was equal 75:10:15 and ratio of potassium:calcium:magnesium cations was equal 33:56:11. In the so-called optimized nutrition variant corresponding ratios were equal 46:21:33 and 43:35:22 respectively. The minimal dose of nutrient corresponded to 90 milligram-equivalent/plant in a WC and 30 milligram-equivalent/plant in the SC. The experiment proceeded during 45 days. The optimization of nutrition has allowed increasing of plants productivity in 1.4-3.3 times in comparison with the control and in 2-15 times to reduce the content of nitrates in the crop. The optimum doses of nitrogen estimated for the maximal yield are 0.7 g/plant in WC and 1.0 g/plant in SC. The crop yield are 5.7 and 9.1 kg/square meter respectively, the content of nitrates are 2290 and 1170 mg of nitrates-ions in 1 kg of crude production. The reduced doses of nitrogen were recommended for producing crop with a minimum percentage of nitrates. It is necessary to apply 0.3 and 0.5 g/plant in WC and SC respectively. The crop yield decrease to 3.0-4.8 kg/square meter, but the content of nitrates decreases to level in 2.4 and more times lower than maximum permissible concentration. It is possible to recommend such production for a children and dietary food. Optimum ratio of mineral elements and a nitrogen dose have been developed for notheated greenhouses and for conditions without additional illumination, therefore their application can essentially reduce a net cost of production.
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