INFLUENCE OF PRECIPITATION AND THERMAL CONDITIONS ON STARCH CONTENT IN POTATO TUBERS FROM MEDIUM-EARLY CULTIVARS GROUP

The basis of this elaboration constituted data concerning mean starch content in nine medium-early cultivars of potato grown in six experimental stations belonging to COBORU (Research Centre for Cultivar Testing) in years 2010-2013. Using stepwise regression analysis the influence of thermal and precipitation conditions on starch content in potato cultivars was examined. Such analysis was performed for locations, years and particular cultivars. The analysis showed that starch content in tubers of medium-early potato cultivars depends more on precipitation than on thermal conditions. The relationship between starch content in tubers and precipitation and thermal conditions varied in different stations. In four stations (Karzniczka, Sulejow, Uhnin, Wegrzce) it depended on precipitation noted in August, in two (Uhnin and Slupia) - in July and in other two (Naroczyce and Slupia) - in June. Positive influence of temperature on starch content was noted only in August in Karzniczka. Starch content in tubers of Ametyst and Gawin cultivars depended on precipitation sum in August, Satina cultivar - in July, Oberon cultivar - in June and July, and Cekin, Finezja, Jurek, Stasia and Tajfun cultivars - on precipitation in July and August.