Physiological and agrochemical characteristics of different varieties of potato under cultivation on meadow-chernozem soil

Among all highyield crops, the potato has a high nutrient conditions demand. The article is devoted to the responsiveness of different potato varieties (Alaya Zarya, Svitanok, Kormilets, Zekura and Rosara) to the natural soil fertility in order to develop effective fertilizer system for different varieties of potatoes cultivation to obtain crop expected. Field experiments were carried out in 2008-2010 on the experimental meadow-chernozem field of a heavy loamy soil with a very little level of fertility situated at the premises of Omsk State Agrarian University. Two-factor experiment. Three-times repeated. The scheme of potato plant was the following: 70 x 30 cm tubers weighing 80-100 g. The experimental plot size was 9.6 m2. The total test plot territory was 510 m2. Responsiveness of potato varieties to the natural fertility of the soil was determined by the yield increase compared to Alaya Zarya variety. On the average over the last three years of experiments with its various weather conditions and changing level of nutritional content in the soil, Alaya Zarya (variety of local selection) was high yielding. The rest varieties of potato formed the yield of potato tubers, to the check variety (taken as 100%) within: Zekura varieties and Rosara - 82.7 % and 83.1 %; Svitanok and Kormilec - 89.8-92.1 % respectively. Variety features of plants and their cultivation conditions determine chemical content and export of nutrients that the crop contents. According to the estimations that have been made for the three years of experiment the first place by the export of nutrients, particularly nitrogen, was taken by Alaya Zarya - 106.8 kg/ha, the second place - by Svitanok - 99.3kg/ha. As for Zekura, Rosara and Kormilets' export of nitrogen, it was varying from 76.3 to 88 kg/ha. The results concerning phosphorus export from soil let us arrange the varieties in the following decreasing order: Alaya Zarya (39.5 kg/ha) > Kormilets(31.6 kg/ha) > Svitanok (29.7 kg/ha) > Zekura (25.1 kg/ha) > Rosara (23.1 kg/ha). The experiment showed that potassium was being exported more in terms of quantity than other nutrients. Results are in descending order: Alaya Zarya > Svitanok > Kormilets > Zekura > Rosara. For one ton of potato to be produced a lot of nitrogen was required especially under cultivation of the following varieties: Alaya Zarya, Svitanok, Zekura. Varieties Alaya Zarya, Svitanok and Kormilets had a great demand for phosphorus. Potassium was highly demanded by Svitanok, Alaya Zarya and Zekura to form tubers. Rozara required less phosphorus per crop unit formationkg), in comparison to Alaya Zarya by 36.4% and Zekura by 25.0%. Researches have shown that the responsiveness of different varieties of potatoes to the natural fertility of the soil is different, so working on physiologi- cal and agrochemical aspects of potato nutrition it is highly important to consider two basic principles: 1) the ability of soil to meet the needs of each potato variety in nutrients; 2) needs of potato varieties and their ability to absorb nutrients and soil under specific conditions of agricultural output.