Scientific Papers Series B Horticulture

from SCDVV Murfatlar (Columna andMamaia) from the 2012 harvest.The data regarding climate were recorded usingthe weather station of the research station,model Weather Master 2000.The dynamics of grape maturation for thestudied varieties was monitored by followingthe accumulation of sugars and the decrease ofacidity. At the same time, the evolution of theweight of the berries was also monitored.The determinations were made every 7 days, ondates established in advance. A number of 5berries were harvested from each grape, asfollows: one berry from the left side, one fromthe right side, one from center-front, one fromcenter-back and one from the basis of thegrape. The 5 berries each were harvested from60 grapes (thus giving a total of 300 berries toanalyze). The 60 grapes were made of 10grapes chosen from each of the 6 rows selectedat random, and the location of each grape onthe rows was chosen in zig-zag. The harvestedberries were put in labeled plastic bags andtransported to the laboratory in a cooler box,avoiding their crushing and heating.The determination of sugars was done using aSmart electronic refractometer, on the basis ofthe percentage of dry matter in the grapes. Theread values were adjusted for temperature andthe value of the sugar content of the must wasderived using data tables.The acidity of the must was measured bytitrimetry by neutralizing the acids in adetermined amount of must using a solution ofNaOH of known factor. Based on the amountof base solution used during the titration, thetotal acidity of the must can be calculated.The total acidity was expressed in g/l H 2 SO 4 .The determination of the weight of the berrieswas done using a laboratory technical scale,taking data on the weight of 100 berries.RESULTS AND DISCUSSIONSThe climatic conditions of the year, namely themain three factors (heat, light, humidity)exercise an important influence on the processof grape maturation. This influence can actuallydecide the yield and the quality of that year’scrop. In Table 1, the data on the three climatefactors of 2012 are compared to the multi-yearaverages recorded during the last 50 years inthe viticultural center of Murfatlar, which areconsidered “normal”.The sum of temperature degrees in the periodof vegetation of 2012 was 4100.8°C, comparedto the average value of 3449°C. That is 651.8°Cmore than what is considered the normal value.The maximum temperature recorded in thisperiod was 39.8ºC (in August), and the lowesttemperature recorded was-2ºC (in April).Regarding the precipitations, the sum of rainfallwas 246.4 mm, compared to the average valueof 245.7 mm. So the difference was very small,but the distribution in time of the rainfall wasnot uniform.The total sunshine time was 1780.6 hours,compared to the average of 1587.2 hours (seeTable 1).Table 1. Evolution of air temperature, precipitations and sunshine time during the growth season 2012, compared to themulti-year averagesAir temperature Precipitations Duration of sunshineMonth T avg (50 years T avg Average T min Average T max Multi-year Multi-yearaverage) ( o C) ( o C)( o (mm)C) averageaveragehoursApril 10.2 14.5 -2.0 28.6 33.5 44.5 160.7 210.1May 16.2 19.8 8.4 31.0 50.2 145 261.8 281.1June 20.4 21.2 12.6 37.2 53.2 7.4 314.5 314.0July 22.6 28.0 13.1 38.2 35.6 33.2 323.7 341.6August 22.6 26.1 10.7 39.8 31.6 8.8 305.5 345.6September 17.6 20.7 7.8 36.0 41.6 5.6 221.0 288.2The accumulation of sugars in the berries,between the beginning of ripening and fullmaturity, happens quickly and in largeconcentrations. The increase is faster in thefirst 2-4 weeks at the beginning of the process,and later slows down and even stagnates for aperiod of 3-5 days (Cotea, 1985).The concentration of accumulated sugars in thewhite varieties at full maturity (Figure 1) was394