G. Delchev1*, T. Barakova2
1Department of Plant Production, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria 2Field Crops Institute, 6200 Chirpan, Bulgaria
(Manuscript received 16 May 2016; accepted for publication 11 August 2016)
Abstract. The research was conducted during 2012 – 2014 on pellic vertisol soil type. Under investigation were 4 sunflower hybrids (Helianthus annuus L.): hybrid Bacardy (an imitolerant hybrid by ClearField plus technology), hybrid Estiva (an imitolerant hybrid by ClearField technology), hybrid Sumico (a tribenuron-methyl tolerant hybrid by ExpessSun technology) and hybrid Arizona (a hybrid by conventional technology). Factor A included the years of investigation. Factor B, herbicides and tank mixtures, included 20 rates. It includes 3 variants by ClearField plus technology, 5 variants by ClearField technology, 5 variants by ExpessSun technology and 7 variants by conventional technology. All variants are on herbicide Gardoprim plus gold 500 SC (S- metolachlor + terbuthylazine) – 3.5 l/ha, which treated after sowing before emergence of the sunflower. It is found that the highest seed yield is obtained at herbicide tank mixture Pulsar plus + Stomp aqua by ClearField plus technology. Tank mixture Listego + Dash + Sharpen by ClearField technology and Express + Trend + Select super by ExpressSun technology also lead to obtaining high seed yields. The most unstable are secondary weed infested checks by the fourth technologies for sunflower growing which are treated with soil-applied herbicide Gardoprim plus gold only. Technologically the most valuable are herbicide combination Pulsar plus + Stomp aqua and herbicide Pulsar by ClearField plus technology, tank mixtures Listego + Dash + Sharpen and Listego + Dash by ClearField technology and Express + Trend + Select super and Express + Lactofol B + Select super by ExpressSun technology. Tank mixtures of herbicides Smerch, Pendigan, Wing, Raft, Pledge and Modown with Amalgerol premium by conventional technology have low estimates due to insufficient control of some weeds in sunflower crops.