Results of testing of four in vitro propagated Bulgarian goji berry (Lycium barbarum L.) cultivars in the region of Plovdiv, Bulgaria

The study was conducted during the period 2014-2018 at the experimental field of the Department of Fruit Growing at Agricultural University - Plovdiv, Bulgaria. In vitro propagated plants of four Bulgarian cultivars ('JB 1', 'JB 2', 'JB 4' and 'JB 10') were planted in the orchard on June 12, 2014 at spacing 3x2 m. The plants were grown under drip irrigation. The plants were formed as trees with 70-90 cm trunk height. Despite of late planting in the permanent place the plants of all cultivars started to bloom and bear fruits (although single fruits) in the same year. During the next vegetations flowering of tested cultivars started in the last ten days of April or in May for the cultivars 'JB 1'and 'JB 4' and about a week later for the other two cultivars and finished in the autumn. Fruit bearing period began 42-47 days after the beginning of flowering, first in 'JB 1' and about a week later in the other cultivars and continued until the first frost. The highest cumulative yield for the period 2nd-5th vegetation was obtained on 'JB 1' with 2.26 kg tree-1. The highest fruit weight was recorded in ' JB 4', followed by 'JB 2', and the smallest were the fruits of 'JB 1' and 'JB 10'. The tested cultivars were attacked by powdery mildew (Arthrocladiella mougeotii (Lev.) Vassilkov), and the cultivar 'JB 2' visibly was the most susceptible to this disease.