Major properties and yield of 'Boranka' and 'Timočanka' plum cvs. as influenced by planting density

Abstract

Aiming at the development of the technology of growing plum cvs 'Boranka' and 'Timočanka', newly bred at Fruit Research Institute- Čačak, we studied major pomo-technological properties of fruits as influenced by planting density. Plants with well-developed sylleptic shoots, grafted on 'Myrobalan' rootstock (Prunus cerasifera Ehrh.) were planted in spring 2007. Spacing varied among variants, viz. 4.0 x 1.0 m (variant I 2,500 tree ha-1), 4.0 x 1.5 m (variant II 1,666.6 tree ha-1), 4.0 x 2.0 m (variant III 1,250 tree ha-1) and 5.0 x 4.0 m (variant IV as control, 500 tree ha-1). In high density planting variants, modified spindle-bush trained trees were formed by applying specific pomo-technical practices, whereas the improved conventional pyramidal crown was formed in control trees. The paper presents the average results over the period of initial cropping from 2008 to 2010. Fruit size and weight in 'Boranka' depended on planting density however the identified statistical differences were not significant. In contrast, the differences were significant in 'Timočanka' where fruits were larger and had higher fruit weight. The highest yield per tree and unit land area as well as cumulative yield over the period of study was observed in the variant involving greater number of trees, whereas it was lowest in control. As for 'Boranka', the average yield per tree in all the variants was as follows: 2,292 kg (5.73 t ha -1, var. I), 1,639 kg (2.73 t ha-1, var. II), 0.996 kg (1.24 t ha-1, var. III), and 0.503 kg (0.25 t ha-1, var. IV). In 'Timočanka', the obtained yield was as follows: 4,675 kg (11.687 t ha-1), 5,352 kg (8.97 t ha-1), 2,867 kg (3.584 t ha -1) and 2,557 kg (1.288 t ha-1). Cumulative yield per tree and unit land area over the period of study was as follows: 'Boranka' - 6,877 kg (11.7 t, var. I), 4,917 kg (8.19 t, var. I), 1,992 kg (2.49 t, var. III) and 1,006 kg (0.50 t, var. IV); 'Timočanka' - 16,056 kg (35.06 t, var. I), 14,025 kg (26.759 t, var. II), 8,603 kg (10.755 t, var. III) and 7,732 kg (3.866 t, var. IV). Total soluble solids content varied among the variants, ranging from 11.8% to 14.6% and 11.2 to 15.5% in 'Boranka' and 'Timočanka' respectively.