Resumo -O objetivo deste trabalho foi avaliar as relações entre os caracteres tecnológicos (variáveis independentes explicativas) e a produtividade de fibra do algodão (variável dependente) e identificar seus efeitos diretos e indiretos pela análise de trilha. Os caracteres tecnológicos foram: finura, resistência, comprimento, uniformidade de comprimento, alongamento e índice de fiabilidade do fio. Avaliaram-se 12 cultivares de algodoeiro herbáceo, no Estado do Mato Grosso, no ano agrícola 2000/2001. Estimaram-se as correlações, e fez-se a análise de trilha pelo método proposto por Wright. O caráter finura apresenta o maior efeito direto sobre a produtividade da fibra. A resistência, o comprimento e o alongamento têm efeito secundário. A uniformidade de comprimento e a fiabilidade apresentaram efeito indireto via finura. Um esquema de seleção restrito é necessário, para se eliminarem os efeitos indiretos negativos do índice de fiabilidade sobre a finura.Termos para indexação: Gossypium hirsutum, seleção, finura. Correlations and path analysis of technological properties and the lint yield of cottonAbstract -The purpose of this work was to study the relations between technological properties (independent variables) and the lint yield of cotton (dependent variable). The technological properties analyze were: micronaire, strength, length, uniformity of length, elongation and index of thread spinning. Twelve cotton cultivars were evaluated, in Mato Grosso State, during the 2000/2001 crop season. Correlations and other parameters for path analysis were estimated, according to Wright. The trait micronaire showed the highest direct effect on lint yield; in addition, strength, length and elongation were secondary effects. The uniformity of length and the spinning inder showed indirect effect on micronaire. A restricted selection is necessary to eliminate the negative indirect effect of the spinning index on micronaire.

MELHORAMENTO GENÉTICO VEGETAL -ArtigoUso da metodologia REML/BLUP para seleção de genótipos de algodoeiro com maior adaptabilidade e estabilidade produtiva Use of REML/BLUP methodology for selecting cotton genotypes with higher adaptability and productive stability those tested, since they present high adaptability and productive stability of cotton. There was agreement among the statistics used in discrimination of the most productive genotypes with high adaptability and stability, indicating that they can be part of selective criteria in the routine of cotton breeding programs.

ABSTRACT. Seed cotton yield is a trait governed by multiple genes that cause changes in the performance of genotypes depending on the cultivation environment. Breeding programs examine the genotype x environment interaction (GE) using precise statistical methods, such as AMMI (additive main effects and multiplicative interaction) and GGE biplot (genotype main effects + genotype x environment interaction). The AMMI method combines the analysis of variance and principal components, to adjust the main effects (genotypes and environments) and the effects of GE interaction, respectively. The GGE biplot groups the genotype additive effect together with the multiplicative effect of the GE interaction, and submits both of these to the principal components analysis. The aim of this study was to investigate the association between the AMMI and GGE biplot methods and select cotton genotypes that simultaneously showed high productivity of seed cotton and stability in Mato Grosso environments. cotton productivity were analyzed by AMMI and GGE biplot methods. Both methods were concordant in the discrimination of environments and genotypes for phenotypic stability. The genotypes BRS ARAÇÁ and LD 05 CV had high seed cotton productivity and phenotypic stability, and could be grown in all environments across Mato Grosso State.

RESUMO -Objetivou-se avaliar a produtividade, o rendimento e a qualidade de fibras de cultivares de algodoeiro herbáceo submetidas a diferentes lâminas de irrigação. Durante dois anos consecutivos foi conduzido um experimento de campo na região de Apodi (RN) disposto em parcelas subdivididas com quatro lâminas de irrigação (130, 100, 70 e 40% da evapotranspiração da cultura -ETc) e quatro cultivares de algodoeiro (FiberMax 993, BRS 286, BRS 336 e BRS 335), em delineamento de blocos casualizados com quatro repetições. Foram avaliadas a produtividade, a percentagem e a qualidade das fibras do algodoeiro. Houve diferença significativa para as características avaliadas entre as cultivares e as lâminas de irrigação. A rega com déficit (70 e 40% ETc) ocasionou declínio na produtividade de algodão em caroço, na percentagem e qualidade das fibras. As cultivares FiberMax 993 e BRS 286 apresentaram as maiores produtividades e percentagem de fibras entre as cultivares avaliadas. Com a lâmina de 40% da ETc as cultivares de fibra média (FiberMax 993, BRS 286 e BRS 335) apresentaram fibras curtas, e a cultivar de fibra longa (BRS 336) apresentou fibra média. De forma geral, a redução na qualidade da fibra não foi severa, haja vista a fibra produzida está dentro da faixa de qualidade aceitável pela indústria têxtil nacional, mesmo em condições de déficit hídrico. Dessa forma, a decisão em irrigar o algodoeiro com ou sem déficit hídrico dependerá dos custos da irrigação e do valor de mercado do produto.Palavras-chave: Déficit hídrico. Algodão. Semiárido. EFFECT OF IRRIGATION ON YIELD AND FIBER QUALITY IN COTTON CULTIVARSABSTRACT -This study was conducted to evaluate seed cotton yield, fiber yield, and fiber quality traits of cotton cultivars grown under different irrigation levels in Brazil. The experiment was conducted over two years in the region of Apodi -RN, with sprinkler irrigation. Treatments comprised of 4 irrigation levels i.e., 130, 100, 70 and 40 % of the crop evapotranspiration (ETc) and 4 cotton cultivars i.e., FiberMax 993, BRS 286, BRS 336 and BRS 335. The experimental design was factorial with randomized complete block design and four replicates. Yield, lint percent and fiber quality traits determined were evaluated. Different responses were observed for cultivars at various irrigation levels. Cultivars grown under limited irrigation exhibited a decline in the seed cotton yield, lint percent, and fiber quality. Cultivars with the highest yield and lint percent were FiberMax 993 and BRS 286. Within irrigation level of 40 % ETc, the medium fiber cultivars produced short fibers whereas the long fiber cultivar, BRS 336, produced medium fiber length. Overall, the different levels of water deficits did not significantly affect fiber quality of the four cultivars tested as all fiber quality traits remained acceptable for the domestic textile industry.

Information about combining ability is important in determining breed