YIELDING OF DIFFERENT MATURITY GROUPS POTATOES AT THREE SITES AND TUBER QUALITY DURING STORAGE

Two-year field trials (2001-2002) were conducted with aim to investigate the effect of growing site and maturity group of ten potato cultivars on yielding and changing of tuber quality during long-term storage. The biggest number of tubers per plant and highest mean tuber weight were obtained in Čačak, what gave the highest yields in both seasons; the lowest values were obtained in Guča. Favourable soil characteristics had more important role than weather conditions on potato field performance. Early cultivars gave the smallest number of tubers per plant and highest mean tuber weight, while opposite to this was recorded in mid-late to late cultivars (ML-L). The share of tubers >55 mm was consistently high in early cultivars. ML-L maturity group gave the highest yields at all sites and the highest initial tubers dry matter (DM), >20% in 2001 and >21% in 2002, while it was <20% in early cultivars overall experiment. Constant increase in DM content and decrease in starch content in tubers DM was recorded after two-month and seven-month storage under conditions with ventilation system without control of humidity. The effect of site on tuber DM was significant at mid-early to mid-late (ME-ML) and ML-L in 2002, when it was the highest in tubers originated from Sombre; there was no effect on starch content. Presented study showed that high yields can be achieved by growing potato cultivars of different maturity groups and Čačak has been shown to be the site with good agro ecological conditions; ME-ML (with exemption of cv. Condor) and ML-L groups gave the highest yields of tubers with DM content sufficient for processing for French fry and chips.