Seed Distribution Mechanisms and Sowing Speed on Plantability and Agronomic Characteristics of Sunflower

Precision in sowing is an important strategy for increasing agricultural yield. The objective of this study was to evaluate the influence of seed distribution mechanisms and sowing speeds on characteristics of sunflower. The experiment was set in March 2015 in São José do Rio Claro, state of Mato Grosso (Brazil). The experimental design was a completely randomized block design, in a 2 × 5 factorial arrangement, with two seed distribution mechanisms (perforated and pneumatic disc) and five sowing speeds (4; 6; 8; 10 and 12 km h-1) with four repetitions. The vegetative and reproductive characteristics of the sunflower were evaluated and also the double, faulty and acceptable spacing were evaluated to observe the homogeneity of seed distribution through the sowers. Regardless of the seed distribution mechanism, the rise in the sowing speed caused a reduction in plant population by changing plant height, head height, head mass, achene mass per head, mass of one thousand achenes and head diameter. The perforated disk distribution mechanism showed the best performance in acceptable spacings and the pneumatic one provided a greater guarantee of the desired plant population. The different distribution mechanisms, as well as different sowing speeds, did not influence achenes yield. The farmer should be aware of the speed of sowing adopted in his sunflower crop, as increasing speeds may affect uniform seed distribution as well as plant development.