After-effect of foliar-applied herbicides for broad-leaved weeds on the primary germ weight of cotton seeds (Gossypium hirsutum L.)

  1. Barakova, St. Georgiev

 

Field Crops Institute, 6200, Chirpan, Bulgaria

 

(Manuscript received 25 June 2019; accepted for publication 15 August 2019)

 

Abstract. The trial was carried out during 2013-2015, with twelve cotton cultivars (Gossypium hirsutum L.). Influence of herbicides Bazagran 480 SL (bentazone)- 1.5 L/ha, Pulsar 40 (imazamox) – 1.2 L/ha and Express 50 VG (tribenuron-methyl) – 50 g/ha was studied. These herbicides were used during the budding stage of cotton. From the viewpoint of cotton growing technology, technologically the most valuable are cultivars Helius, Trakia, Viki, Filipopolis, Boyana, Avangard, Natalia, Darmi, Dorina and Nelina, in foliar treatment with herbicide Bazagran 480 SL. Technologically the most valuable are cultivars Chirpan-539, Helius, Viki, Boyana and Natalia in foliar treatment with herbicide Pulsar 40. Technologically the most valuable are cultivars Helius, Trakia, Viki and Nelina in foliar treatment with herbicide Express 50 VG. These variants combine high primary germ weight and high stability of this index during the different years.

Problems and achievements of cotton (Gossypium Hirsutum L.) weeds control

T. Barakova1*, G. Delchev2
1Field Crops Institute, 6200 Chirpan, Bulgaria
2Department of Plant Production, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria
(Manuscript received 2 June 2017; accepted for publication 17 August 2017) Abstract. Weed control in the cultivation of cotton is critical to the yield and quality of production. The influence of economically important weeds was studied. Chemical control is the most effective method of weed control in cotton but much of the information on it relates to primary weed infestation. Problems with primary weed infestation in cotton have been solved to a significant extent. The question of secondary weed infestation with annual and perennial graminaceous weeds during the period of cotton vegetation is also determined largely by the use of antigraminaceous herbicides. The data related to herbicides to effectively control secondary germinated broadleaf weeds in conventional technology for cotton growing are quite scarce, even globally. We are still seeking effective herbicides for control of these weeds in cotton crops. Studies on their influence on the sowing characteristics of cotton seed and the quality of cotton fiber are still insufficient. In the scientific literature there is not enough information on these questions. The combinations of herbicides, as well as their tank mixtures with fertilizers or plant growth regulators are more efficient than autonomous application. Often during their combined application higher synergistic effect on yield is produced. There is information about cotton cultivars resistant to glyphosate. These cultivars are GMO and they are banned within the European Union, including Bulgaria.

Selectivity and stability of vegetation-applied herbicides in cotton (Gossypium hirsutum L.)

T. Barakova1*, G. Delchev2

1Field Crops Institute, 6200 Chirpan, Bulgaria
2Department of Plant Production, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria
(Manuscript received 16 May 2016; accepted for publication 26 May 2016)

Abstract. An experiment was carried out during 2013 – 2015 in the experimental field of the Field Crops Institute, Chirpan, with two cotton cultivars − Helius and Darmi (Gossypium hirsutum L.). Herbicides: Goal 2 E, oxyfluorfen (80 ml/da); Linuron 45 SC, linuron (200 ml/da); Wing-P, pendimethalin + dimethenamid (400 ml/da); Merlin 750 WG, isoxaflutol (5 g/da); Bazagran 480 SL, bentazone (150 ml/da) were investigated. They were treated separately or combined with growth regulator Amalgerol (500 ml/da) or foliar fertilizer Lactofol O (500 ml/da) in the budding stage of the cotton. It was established that selectivity is the lowest in the two cotton cultivars with herbicides Linuron 45 CK and Merlin 750 WG. The purpose of this investigation was to establish the selectivity and stability of some herbicides and their tank mixtures on the cotton by influence of different meteorological conditions. It has been found that the highest phytotoxicity on cotton is given the vegetation-applied herbicides Merlin and Linuron. Foliar fertilizer Laktofol O reduces phytotoxicity of herbicides Goal, Wing, Merlin and Bazagran in two cotton cultivars. Herbicides Wing and Bazagran have excellent selectivity for the two cotton cultivars – Helius and Darmi. The highest yield was obtained by vegetation treatment with herbicide Bazagran, followed by herbicides Wing and Goal. Tank mixtures of Goal, Bazagran and Wing with Laktofol, followed by those with Amalgerol are technologically the most valuable. They combine high yield with high stability over the years. Аlone application of herbicides Linuron and Merlin and their tank mixtures with Amalgerol and Laktofol have low estimate.

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Productivity of irrigation cotton cultivated under different inter-row spaces

I. Saldzhiev, A. Muhova
Abstract. Field trial on cotton (Vega cultivar) was carried out during 2007–2011 on leached vertisols under irrigation regime of sprinkling – 75 % of the field moisture capacity (FMC) for the soil layer of 0 – 40 cm. The trial included the following variants: factor A) Irrigation with lower rates:1). Single irrigation of 600 mm/ha at the interphase period blooming-boll formations; 2). Two irrigations of 450 mm/ha – the first one at the blooming stage and the second – in the boll formations period; 3).Two irrigations of 600 mm/ha – the first one at the blooming and the second – in the boll formations period; 4). Non-irrigated variant – for standard. Factor B) Width of inter-row space: 1). 60 cm. 2).80 cm. It was established that the best results were obtained for the variant where cotton cultivated at 80 cm of inter-row space and with second irrigation with 600 mm – 939 kg/ha more than the non-irrigated control and 11.9 % more than the variant with irrigated norm 600 mm/ha. In reference of net profit of 1000 m3 irrigated water the best results were achieved after single irrigation norm of 600 mm/ha. In respect to width of inter-row space the yield from a unit of area with inter-row space 0.80 cm we receive 4.6 % more than sowing at 0.60 cm inter-row space.
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Rumi and IPK Nelina – new cotton varieties

A. Stoilova, Hr. Meluca
Abstract. The new cotton varieties Rumi and IPK Nelina were tested in 2005–2010. Rumi variety resulted from the crossing of the Bulgarian breeding line 268 (Garant X Progress) to the American variety Deltapine 20. The Progress variety was obtained after the interspecific hybridization G. hirsutum L. G. barbadense L. IPK Nelina variety resulted from the crossing of the Bulgarian variety Perla-267 (Garant X Progress) to the Romanian line T-073. Rumi variety had higher productivity than the standard cultivars – Chirpan-539 (for earliness and productivity) and Avangard-264 (for fiber quality) and other valuable properties such as finer and longer fiber than that of Chirpan-539, also lower content of short fibers and nep. In fiber quality it was closer to Avangard-264. In the state variety testing, Rumi variety exceeded both standards in seed cotton yield by 8.3 %, it exceeded Avangard-264 in fiber yield by 12 % due to higher lint percentage. IPK Nelina variety had high productivity and high lint percentage of the fiber. In the state variety testing, in seed cotton yield it was aligned with the standard cultivars, but in fiber yield was superior to Chirpan-539 by 2.6 % and to Avangard-264 by 8.8 %. These new varieties were approved by the IASAS (Executive Agency for Variety Trials, Approbation and Seed Control) in 2011 (Rumi) and 2012 (Nelina) and protected with certificates.

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Potassium fertilization on cotton

Research studies on cotton potassium fertilization in the last years at the Cotton and Durum Wheat Research Institute – Chirpan, Bulgaria have been reviewed. The soil Eutric vertisols was well supplied with available potassium (31-43 mg/100 g soil). The effect of K application was not clearly established. At K the seed-cotton yield increased with 6.4 % compared to the unfertilized. K O use efficiency was 0.18-0.61 kg of seed-cotton. For 100 kg seed-cotton yield it 160 2 was necessary to apply 3.36-4.94 kg K O. Production of dry matter was 5.0 % higher at 160 kg K O/ha. The concentration in the seeds was considerably higher 2 2 (1.3-1.4 %) in comparison with the lint (0.5-0.98 %). The total annual potassium uptake was 55-115 kg/ha. The changes of quality indexes were not essential. The difference between KNO , KCL and NaKNO with respect to yield and quality was insignificant. The optimum balance was created at applied 70 kg K O/ha.

Potassium fertilization on cotton

G. Panayotova, N. Valkova