Sezonske promene sadržaja ukupne vode u lišću oraha

Abstract

Having in mind importance and dependence of physiologic functions upon water, the investigations of its dynamics in the leaves of walnut trees cv. were carried out. The following standard cultivars of walnut trees, belonging to the collection plantation located in the surroundings of the town of Zaječar (Eastern Serbia). Toward the end of each month of the vegetation period, the leaves were sampled and the total content of water was determined by drying samples at 105 oC to its constant weight. The study shows the average results of the total water content in leaves per years of investigation (1999-2003). The results point to a high dependency of the total water content in leaves on available precipitations and air temperatures, which is proved by the coefficient of correlations (r=0.418; r=-0.494). The greatest total water content in leaves was, on the average, at the beginning of the vegetation and ranged from 77.3% (in April) to 70.51% (in May), while it was the lowest in the second part of the vegetation, amounting to 61.8% (in August and September), and 59.6% (in October). Averagely for all cultivars, the total water content was 66.2%. Depending on all conditions, the greatest total water content was in 1999 (67.5%), while the lowest one was in the year of 2002 (63.6%). The greatest average content of total water was found in the leaves of the cv. Šampion (68.4%), and the lowest in the cv. Elit (65.0%).

Imajući na umu značaj i zavisnost fizioloških funkcija od vode sprovedena su izučavanja njene dinamike u lišću kultivara oraha. Za istraživanje su odabrane standardne sorte oraha iz kolekcionog zasada koji se nalazi u okolini Zaječara (istočna Srbija). Krajem svakog meseca u vegetaciji uzorkovano je lišće i određivan sadržaj ukupne vode sušenjem uzoraka na 105 0C do konstantne težine. U radu su prikazani prosečni rezultati sadržaja ukupne vode u lišću po godinama ispitivanja (1999-2003). Rezultati ukazuju na visoku zavisnost sadržaja ukupne vode u lišću od raspoloživih padavina i temperatura vazduha, što dokumentuje i koeficijent korelacije (r= 0.418; r=-0,494). Prosečno, najveći sadržaj ukupne vode u lišću bio je na početku vegetacije od 77,3% (april) do 70,51% (maj), a najmanji u drugom delu vegetacije 61,8% (avgust, septembar), odnosno 59,6% (oktobar). Prosečno za sve sorte sadržaj ukupne vode bio je 66,2%. U zavisnosti od svih uslova, najveći sadržaj ukupne vode bio je u 1999. godini (67,5%), a najmanji 2002. godine (63,6%). Najveći prosečni sadržaj ukupne vode bio je u lišću sorte Šampion (68,4%), a najmanji kod sorte Elit (65,0%).