Valéria Carpentieri Pípolo

CORRELAÇÃO ENTRE HETEROSE E DIVERGÊNCIA GENÉTICA ESTIMADAS POR CRUZAMENTOS DIALÉLICOS E MARCADORES MOLECULARES RAPD EM POPULAÇÕES DE MILHO-PIPOCA ( 1 )

Com o objetivo de correlacionar a heterose, estimada atraves de cruzamentos dialelicos, com a divergencia genetica obtida pelo uso de marcadores moleculares RAPD, oito populacoes de milho-pipoca (1-PASHA, 2-PAPA, 3-PAAPC, 4-PO, 5-ZL, 6-CMS 042, 7-RS 20 e 8-CMS 43) foram intercruzadas em esquema dialelico completo, sem reciprocos, no ano agricola de 2002/2003, gerando 28 hibridos. A avaliacao dos hibridos foi realizada no ano agricola de 2003/2004, em Londrina e Ponta Grossa, PR, em um ensaio com trinta e oito tratamentos, constituidos de vinte e oito combinacoes hibridas, oito parentais e duas testemunhas (IAC 112 e IAC TC01). O delineamento experimental utilizado foi o de blocos casualizados com tres repeticoes. Foram avaliados seis caracteres: massa de graos, capacidade de expansao, altura de planta, altura de espiga, prolificidade e florescimento feminino. Foi utilizada a tecnica de RAPD para a obtencao das estimativas de distâncias geneticas entre as populacoes. Os resultados inferem em correlacoes positivas e significativas entre a divergencia genetica detectada pelos marcadores RAPD e massa de graos, altura de plantas, altura de espiga e prolificidade, dos vinte e oito hibridos avaliados no dialelo em estudo. Para capacidade de expansao, florescimento e heterose percentual nao foi detectada correlacao significativa com a divergencia genetica.

Identification of promising wheat genotypes for crossing

ABSTRACT - The objective of this study was to identify pr omising wheat genotypes fr om the IAP AR br eeding pr ogram for cr ossesby multivariate techniques. Measur es of dissimilarity between genotypes wer e obtained fr om multicategoric variables. T o identifyclusters, Tocher optimization and UPGMA were used. The genotypes were divided into five diverging groups, indicating a widegenetic base of the wheat br eeding pr ogram of the Agricultural Resear ch Institute of Parana (IAP AR). As indicated by the geneticdistance, cr osses involving the cultivars IPR 85 and IPR 1 18 seem to be the most pr omising to incr ease genetic gains in both grainand flour quality as well as for agronomic parameters.Key words : Triticum aestivum L., genetic improvement, multivariate analysis. INTRODUCTIONIn recent years, the development of more productivewheat varieties with higher industrial quality hassignificantly increased. Due to selection by farmers andmore recently with scientific research work, both wheatarea and yield have increased in Brazil (Bacaltchuck andSilva 2001).Since wheat production in Brazil was 5.02 milliontons in 2009 (Conab 2010), covering only part of thenational demand, efforts should be made to develop newcultivars to supply the domestic market in coming years.In breeding programs using hybridization, as in thecase of wheat, the parental selection is the first stage of abreeding program. According to Harlan (1992), thevariability within and between species is closely relatedto their evolution.In the Wheat Breeding Program of the AgriculturalResearch Institute of Parana (IAP AR) hundreds of crossesare performed each year between adapted varieties andsources of characteristics required for cultivation andindustrialization of new cultivars for high yield potential,resistance to biotic and abiotic stresses and technologicalquality (Riede 2001).Since the beginning of the domestication process,wheat was subjected to intensive human manipulation,altering the genetic basis (Bered et al. 2000). Wheat is ayoung species, derived from few plants, limiting the geneticdiversity . To overcome a series of biotic and abiotic barriers,an expansion of the genetic diversity in wheat has becomeimperative (Cunha et al. 2008).Knowledge on the differences in genetic constitutionswithin or between groups of genotypes is highly importantfor any breeding program. The importance is given by the

Avaliação de cultivares de milho crioulo em sistema de baixo nível tecnológico - DOI: 10.4025/actasciagron.v32i2.430

With the advent of modern agriculture, landrace seeds were replaced by hybrid cultivars, which feature high grain yield potential – though more dependent on intensive technologies. The objective of this work was to evaluate maize landraces, in order to identify more productive materials that can lead a sustainable process in which the grains themselves in which can be used as seed. Fifteen maize varieties were evaluated, with commercial cultivars BR 106 and IPR 114 as controls. The experiments were carried out in Arapongas and Imbau (Parana State), during the 2004/2005 agricultural year, without external input. The design used was randomized blocks with four replications. The plots were two 4-m rows, spaced 90 cm apart, with 20 plants/row. The landrace varieties P-13, P-15 and P-05 showed high productive potential in low technological level systems, at each location, as well as in the average of both locales. The varieties P-19 and P-10 have their recommendation restricted to Imbau, while P-16 and P-17 will be indicated for Arapongas.