Seleção massal e porcentagem de fibra em cultivar de algodoeiro colorido

Abstract

Resumo -Algodoeiros de fibras coloridas apresentam qualidade inferior em relação aos de fibra branca, além de menor potencial de rendimento, porque, comparados aos brancos, os coloridos foram pouco explorados em termos de melhoramento genético. Este trabalho teve como objetivo avaliar o efeito da seleção massal para porcentagem de fibra alta, média e baixa, dentro de uma população da cultivar BRS Verde, lançada em 2003. Quinhentas plantas da cultivar BRS Verde foram colhidas ao acaso e estratificadas em quatro classes quanto à porcentagem de fibra. As sementes de cada classe foram misturadas e participaram de um ensaio em blocos ao acaso com quatro tratamentos, mais a população original e quatro repetições. Ficou evidenciada a eficiência da seleção massal em alterar a média das populações selecionadas e o ganho de seleção foi de 11% quanto à porcentagem de fibra.Termos para indexação: algodão, melhoramento, fibra verde, variabilidade genética. Mass selection for lint percentage in a colored cotton cultivarAbstract -The colored fiber cotton presents inferior quality in relation to the white one due to the fact that the colored was poorly studied as far as genetic breeding is concerned. The objective of this work was to verify the effect of mass selection for high, medium and low lint percentage in a population of the cotton cultivar BRS Verde. Five hundred plants were randomly harvested and after ginning, they were separated into four groups, based on lint percentage. Seeds within each class were mixed up to compose the treatments of a trial, ran as a complete randomized block design with four replicates. Treatments comprised four classes plus a sample of original population. Mass selection was efficient in changing the populations means and the overall genetic gain, concerning high lint percentage, was 11%.

Genetic diversity among cotton cultivars in two environments in the State of Mato Grosso

“…Plant height is the most important trait affecting the cotton harvest (Silva et al, 2011) because the harvester platform has a fixed size and plants of cultivars with plant height higher than 130 cm, such as BRS CEDRO, can be tipped and kneaded by machine, reducing the quality and quantity of harvested fiber. Average boll weight is one of the main components of cotton plume production, relating linearly with lint percentage (Carvalho et al, 2005). Despite GxE interaction was detected for this trait, the cultivars IPR JATAI, LD CV 05, LD CV 02, and BRS 293 deserve mention because they presented the highest averages in both environments.…”

“…Lint percent is estimated by the ratio between the weight of cotton in lint and the weight of cotton in seed and indicates how much of the total weight can be attributed to the fiber. This trait is fundamental to the farmer, because it is the part of commercialized production with higher economic value (Carvalho et al, 2005). There is a negative correlation between percentage of fibers and fiber length in long fiber materials (Carvalho et al, 2015a).…”

Weed control via intercropping with gliricidia: I. cotton crop

“…These cultivars cover the majority of the cotton-grown area. Most cotton grown commercially in the world has white lint, but recently there is a growing interest in colored lint cotton in several countries (Dutt et al, 2004, Punitha & Raveendran, 2004, including Brazil (Carvalho et al, 2005).…”

Divergência genética entre genitores de algodoeiro de fibras brancas e coloridas

“…Entre estas a FIB% é a característica mais importante para o produtor, pois é o componente da produção comercializado com maior valor econômico (Carvalho et al, 2005). Assim, entre as características estudadas, a %FIB, a PAC, a PAP, a CSP e a STR são as mais eficientes para explicar a dissimilaridade entre as cultivares.…”