Sodininkystė ir daržininkystė - Sodininkystės ir daržininkystės institutas

differed (Table 5). Vitamin C accumulation in the tubers mostly depends onthe variety, and fertilizers not always increase the amount of vitamin C(Lazauskas, Raþukas, 2001). The amount of vitamin C in potato tubers variedfrom 12.4 to 13.6 mg kg -1 on average. Fertilizing with wood ash decreased theamount of vitamin C in tubers, but significant differences among the treatmentsweren’t observed. Higher (13.5-17.2 mg kg -1 ) vitamin C amounts weredetermined in wet 2004. Nitrate amounts in potato tubers depend on thecharacteristics of variety, meteorological conditions, fertilizing, potato ripenessand yield size. When yield increases less nitrates accumulate under uniformfertilizing (Lazauskas, Simanavièienë, 1995). The permissible nitrate amountsin early potato tubers is 200 mg kg -1 and in other – 160 mg kg -1 (Lazauskas,Raþukas, 2001). When analysing research data it was determined, that thehighest, but permissible nitrate amount (98.7 mg kg -1 ) accumulated in notfertilized with wood ash treatment. Fertilizing with wood ash, independentlyon the rate, less nitrates accumulated.Table 5. The influence of fertilizing with wood ash on the quality ofpotato tubers5 lentelë. Træšimo pelenais átaka bulviø gumbø kokybiniams rodikliamsVëþaièiai, average data of 2003-2004 / Vidutiniai duomenysTreatmentsVariantaiThe amount ofvitamin CVitaminas C,mg kg -1The amount ofNO 3NO 3 kiekis,mg kg -1StarchcontentKrakmolas, %Dry matterSausosiosmedžiagos, %Without wood ash / be pelenø 13.6 98.7 13.6 19.62 t ha -1 wood ash / pelenø 13.4 67.5 13.4 19.84 t ha -1 wood ash / pelenø 12.5 63.2 13.3 19.66 t ha -1 wood ash / pelenø 12.4 86.0 13.2 19.7R 05 / LSD 05 6.02 29.50 0.18 0.76Used wood ash rates didn’t have significant influence on potato dry matter.Similar amounts (19.6-19.8%) were determined in all treatments. It dependedon meteorological conditions more than on fertilizing. According to the averagedata, potato tubers accumulate 13.2-13.6% of starch. Different wood ash rateshad significant influence on the accumulation of the starch. The higher woodash rate was applied, the smaller amounts of starch were determined. Accordingto the references, potato accumulated less starch when were grown in fertilizedby phosphorus and potassium soil (Lazauskas, Raþukas, 2001). Changes ofstarch amount in potato tubers were insignificant, when increasing ash ratesfrom 2 to 4 and from 4 to 6 t ha -1 .Generalizing first not numerous research data, it became clear, that woodash had a positive influence not only on red beet and potato yields, but alsoon their quality. Therefore, wood ash is suitable for red beet and potatofertilizing. Increasing wood ash rates, red beet and potato tuber yields also212