The impact of thermal regime on picking dates of plum trees in serbia

Abstract

The impact of thermal regime on picking dates of plum trees is examined in this study. Spatial distribution of harvesting time in Serbia is obtaineded using phenological observations from 40 stations. Thermal regime is determined using Kerner's coefficient of continental climate. Picking dates of plum trees in Serbia vary over the 35-day time interva. The earliest date of ripening is August 24, i.e. 26 in Negotin, i.e. Zaječar, respectively while the latest dates were September 27, i.e. in on the mountain Zlatibor respectively. Extreme values of Kerner's coefficient of -3.1 and 9.2 were found at the same locations: Negotin and Zlatibor, respectively. The Value of correlation coefficient (R2 = 0,8023) points out to the significant dependence of picking dates on the thermal regime type. A severe continental type of the thermal regime (April warmer than October and large annual range of air temperature) causes earlier ripening of plum trees, while a mountain type of thermal regime (October much warmer than April and small annual range of air temperature) delays fruit ripening comparing to a moderate continental type of the thermal regime (October warmer than April and medium annual range of air temperature). It was found that same correlation between the thermal regime type and harvesting time existed over different locations for the same time period and one location for different years.

U radu je analiziran uticaj toplotnog režima na vreme berbe šljive požegače. Prostorna raspodela vremena berbe požegače u Srbiji je određena na osnovu srednjeg datuma berbe na 40 lokacija za period od 1961. do 1995. godine, a tip toplotnog režima posmatranih lokacija izračunavanjem vrednosti Kernerovog koeficijenta kontinentalnosti na osnovu srednjih mesečnih temperatura za isti vremenski period. Uporednom analizom klimatoloških i fenoloških osmatranja utvrđeno je da u odnosu na umereno kontinentalni klimatski tip pojačano kontinentalni tip toplotnog režima uslovljava ranije, a planisnki tip toplotnog režima kasnije sazrevanje šljive požegače.