PHENOLOGICAL OBSERVATION OF WHITE GRAPE VARIETIES IN THE GRAPE GROWING AREA OF GROCKA

Phenological stages of white wine varieties grown in the “Radmilovac” collection vineyard were recorded during a threeyear period. The included stages were: time of bud burst shoot growth, flowering, véraison and full ripening. The number of days, sum of active and sum of effective temperatures were established for each phenological stage, 12 features in total. The features such as the length of vegetative period from bud burst to full ripening and sum of active temperatures for the same period were of crucial importance for the classification of varieties. Based on climate characteristics and phenological observations of plant organ growth and development in some cultivars, the total of 66 cultivars, of 71 investigated, can be grown at Radmilovac. Late-maturing varieties cannot be successfully grown.


I n t r o d u c t i o n
The knowledge of the phenological changes during the vegetation of vine, on one hand, and the meteorological parameters on the other, are important factors in choosing the sorts in a vineyard region.Mesoclimate conditions, sun radiation, precipitation, evaporation etc., reflect themselves throughout the phenological process during the period of vegetation, the ability of grape growing on a certain site (H o p p h m a n , 1988).According to the results of T o d o r o v i ć and P e t r o v i ć (1986), the analysis of precipitation, sum of temperature, and hydrotermical coefficient effect on the grape quality, reflected by the index of ripeness, points out the existence of the linear correlation between the hydrothermical coefficient during the ripening period and the index of grape ripeness (R=-0.51).According to V e r e s h et al. (1984), the sum of active temperatures during the period of vegetation was of primary importance for classifying the cultivars in Czechoslovakia.
The aim of this work was to select and recommend the white grape varieties for growing in the growing area of Grocka, according to the phenological observations and more important meteorological parameters.

Materials and Methods
The phenological observations of 71 cultivars assigned for white wine production were carried out at "Radmilovac" ampelographic collection during the period 1991-1993.The plantation is situated to the south-east of Belgrade, in the grape growing area of Grocka.According to the results by P e t r o v i ć and T o d o r o v i ć (1991), the Belgrade subregion is in the second climate zone, with the sum of effective temperatures of 1470 o C .The normal precipitation sum during the period of vegetation is 413.2 mm, which makes 61.76% of the entire precipitation sum.The hydrothermical coefficient is HTC=1.24,which characterizes the area with insufficient humidity.According to the Branac hydrothermical diagramm, "strong drought" appears on average in this grape growing region at the beginning of grape ripening (S i v č e v , 1996).
Phenological observations include: bud burst, shoot growth, flowering, veraison and full ripeness.For each cultivar one day during the investigation year cycles were marked.The period in-between the shoot growth and flowering was designated as phenophase 1, the period in-between flowering and veraison as phenophase 2; the period in-between veraison and full ripeness is phenophase 3, and the period which includes all three phenophases is designated as phenophase 4. The number of days, sum of active and sum of effective temperatures were established for each of phenological stages (phenophase) -12 features in total.
The data were processed using factor and discriminant analyses.The starting basis of discriminant analysis was the classifying of cultivars into the I, II, III and IV ripening epoch.The calculated values ranged between 10 1 and 10 3 , so they had to be transformed into log(x) for the sake of easier data processing.

Results and Discussion
The adaptability of a cultivar is based on its genetical variability and phenotype adaptability.It is a general rule that the grape variety of wide adaptability has a high genetical potential and that it gives very high yields in favourable ecological conditions, and lower yield and grape quality in unfavourable conditious.Therefore, the survey of the influence of climate on the grown culture -vine, is very significant (S i v č e v , 1996, C v e t k o v i ć et al., 1999).
Observing the features in multidimensional area, our aim was to decrease the original group of data and to investigate a part of variations which is common to all variables.The phenological features having the primary significance for all the investigated cultivars are defined in our case.On the correlative matrix in the column that refers to the phenological observations from bud-burst to flowering, it is noticed that there is greater correlative relation between this phase and the sum of active temperatures than between the phase and the sum of effective temperatures.At this time of the year, daily air temperature is seldom higher than 10 °C, so greater sum of active temperatures is achieved by increasing the number of days, i.e. by extension of this phenophase.
In the second phase, i.e. from flowering to varaison, all three features: sum of active temperatures, sum of effective temperatures and number of days are in the high correlative relation in-between the same period.This period has primary significance for the length of variason-full ripeness period, and stands in the negative correlative relation for all the surveyed cultivars.The relation between sum of active temperatures and number of days for the same period is somewhat faintly expressed.
In the fourth column that refers to the period from the bud-burst to full ripeness, the positive correlative relation is observed only between sum of active temperatures and number of days for the same period.
The differences between cultivars are the greatest in the field of sum of active air temperatures for the flowering to variason period (activ 2) and in the negative correlation with the sums of active temperatures which refer to the period from variason to grape ripeness (activ 3).The greatest deviations have come about in the sum of effective temperatures correlated to the period from bud-burst to vintage, to what also point the results of F o r l a n i et al., (1988), S i v č e v (1998a).
The cultivars are classified into four groups: early, middle-late, late and very late.Using the descriminant analysis, based on the features: the length of period of vegetation from bud-burst to full ripeness (pheno 4), sum of active temperatures for the same period (activ 4) and the length of period from bud-burst to flowering (pheno 1), we succeeded in separating the cultivars in 80.56%.Additional division of 13.47% was provided by the following features: sum of effective temperatures from bud-burst to flowering (effect 1), sum of active temperatures for the same period (activ 1) and by sum of effective temperatures from bud-burst to full ripeness (effect 4).The features referring to the periods from flowering to varaison (pheno 2) and from varaison to full ripeness (pheno 3) have contributed less compared to the previous one -5.96%.Such a small contribution to separating the cultivars during the summer is, by W o l f a r t t et.al. (1988), ascribed to a physiological condition of vine.B o u b a l s and T r u e l (1980) explain the appearance of varaison on grape by the polygenic character of this feature, with cumulating effect.Calculated discriminant scores are based on the first two canonic discriminant functions, and they represent a diagram i.e. disposition of cultivars by ripening epoch in disriminant space (tab.2).It is noticed that the cultivars of I

C o n c l u s i o n
Grape growing area of Grocka lies in the area of the Danube region and belongs to zone C 1 .The average sum of active temperatures from bud-burst to full ripeness is 3311ºC, and sum of effective temperatures for the same period is -1470ºC.The average length of the period of vegetation during a 183-day survey varied between 167 days (year 1992) and 207 days (year 1991).
The normal height of rainfall during the period of vegetation is 413.2 mm, which makes 61.76% of the year rainfall amount.
Heliothermic coefficient has a value of 1.24 which speaks of insufficient humidity in the region.The deficit of humidity appears in August, at the beginning of grape ripening phenophase.
Heliothermic conditions are favourable for growing and developing of the most of white grape vine varieties.
According to the time of ripening, the cultivars are classified into four groups: there are 2 cultivars of the I epoch, 30 of the II epoch, 34 of the III epoch and 5 of the IV epoch.
In the conditions of Radmilovac site, the cultivars of the I, II, and the III epoch could be successfully grown, all together 66 cultivars.

Fig
Fig. 1. -Meteorological conditions in the period of investigation 1. B o u b a l s , D., T r u e l , P. (1980): Influence of fruit-ripening time in the vinifera grape.IV International Symposium of Grape Breeding.Abstracts.Devise.2. C v e t k o v i ć , D., Branislava S i v č e v , Snežana S t a n k o v i ć , J o k s i m o v i ć , J. (1999): Effects of altitude on grape yield and quality in the cultivar Muscat Hamburg grown under the conditions of the Toplica grape growing subregion.Journal of Agricultural Sciences.Belgrade, Vol.44, No 2, 145-151.
T a b. 1. -Correlative factor analysis matrix structure of the phenological features