Turkish Journal of Agriculture and Forestry




The aim of this tudy was to determined the effects of stand loss applied at different growth stages on the yield and yield components of sunflower. The research was conducted during two-years (1994-1995) under dry conditions in Bursa. In this tudy, plant populations were reduced to 25 % and 50 % compared to check ( 60.000 pants/ha) at the 4-, 8-, 16- leaf and bud stages of sunflower. According to the results, no significant reduictions in seed yield occurred when plant populations were reduced by 25 % (45.000 plants/ha) compared to check. However, it was determined that significant reductions in seed yield obtained when stands were reduced 50 % (30.000 plants/ha) from the check. 22 %, 17 %, 29 % and 33 % yield loss occurred when populations were reduced 50 % at the 4-, 8-, 16 leaf and bud stages, respectively. Especially, stand reduction of 50 % at later growth stages (16- leaf and bud stages) resulted in significant yield loss. Significant yield losses were arisen with decrease at head diameter and seeds per head. This observation is substantiated by the high correlations between of both head diameter and seeds per head with yield within 30.000 plants/ha (50 % stand loss) treatments. Because, positive correlations were noted between head diameter and seeds per head with yield at the lowest plant population.

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