Impact of some herbicides, herbicide combinations and herbicide tank mixtures on sowing characteristics of winter forage pea (Pisum sativum L.)

Abstract

The research was conducted during 2015 - 2017 on pellic vertisol soil type. Under investigation was Bulgarian winter forage pea cultivar Mir (Pisum sativum var. arvense). Factor A included 3 rates: untreated control and 2 soil-applied herbicides – Dual gold 960 EC (S-metolachlor) - 1.5 l.ha-1, Stomp aqua (pendimethalin) - 5 l.ha-1. Factor B included 8 rates: untreated control, 5 foliar-applied herbicides – Basagran 480 CL (bentazone) - 2 l.ha-1, Pulsar 40 (imazamox) - 1.2 l.ha-1, Korum (bentazone + imazamox) - 1.25 l.ha-1, Zencor 70 WG (metribuzine) - 500 g.ha-1, Maton 600 EK (2.4-D ethylhexyl ester) – 1 l.ha-1 and 2 herbicide tank mixtures – Zencor 70 WG (metribuzine) – 500 g.ha-1 + Targa super 5 EC (quizalofop-P-ethyl) - 2 l.ha-1, Maton 600 EK (2.4-D ethylhexyl ester) – 1 l.ha-1 + Targa super 5 EC (quizalofop-P-ethyl) – 1 l.ha-1. Soil- applied herbicides were applied during the period after sowing before emergence. Foliar-applied herbicides were applied during 2 - 3 real leaf stage of the pea. All of herbicides, herbicide combinations and herbicide tank-mixtures were applied in a working solution of 200 l.ha-1. Mixing of foliar-applied herbicides was done in the tank on the sprayer. Foliar-applied herbicides Zencor and Maton and herbicide tank mixtures Zencor + Targa super and Maton + Targa super were proven to decrease germination energy of the winter forage pea seeds. Laboratory seed germination was proven to decrease by herbicide Maton and herbicide tank mixture Maton + Targa super only. Lengths of primary germ and primary root are decreased by herbicides Zencor and Maton and herbicide tank mixtures Zencor + Targa super and Maton + Targa super. Foliar-applied herbicides Basagran, Pulsar and Korum as well as their combinations with soil-applied herbicides Dual gold and Stomp aqua, were proven to decrease waste grain quantities. The highest yields of winter forage pea seeds were obtained by treatment with foliar-applied herbicide Korum after soil-applied herbicides Stomp aqua and Dual gold. High yields were obtained also by treatment with foliar-applied herbicide Pulsar after soil-applied herbicides Stomp aqua and Dual gold, as well as by foliar treatment with herbicide tank-mixture Zencor + Targa super after soil-applied herbicides Stomp aqua and Dual gold.