As cultivares de café IPR 99 ("Sarchimor") e IPR 107 ('IAPAR 59' x 'Mundo Novo IAC 376-4') eram no passado resistentes à ferrugem (Hemileia vastatrix). Os objetivos deste estudo foram: a) Identificar progênies dessas duas cultivares com resistência à ferrugem; b) Identificar progênies com resistência incompleta; c) Verificar a eficiência dos cruzamentos testes na seleção dessas cultivares. A avaliação da resistência em campo foi realizada em cafeeiros adultos expostos à população local de raças presentes no IAPAR. Foram avaliados 23 cruzamentos testes com progênies F3 de 'IPR 107' e 5 com progênies F4 de 'IPR 99'. Além disso, foram avaliadas 11 progênies F4 de 'IPR 107' e 5 progênies F5 de 'IPR 99', provenientes de autofecundação. Várias progênies das cultivares IPR 99 e 107 apresentaram alta freqüência de plantas com resistência completa e são portadoras de mais genes de resistência não quebrados pelas raças de ferrugem. Progênies das cultivares IPR 99 e IPR 107 com a resistência quebrada apresentaram resistência incompleta à população local de raças. Cruzamentos testes foram eficientes na seleção de progênies de café com mais genes de resistência não quebrados.
All plants of the coffee cultivars IPR 99 ("Sarchimor") and IPR 107 ('IAPAR 59' x 'Mundo Novo IAC 376-4') were resistant to rust (Hemileia vastatrix) in the past. Currently, susceptible plants were observed in the two cultivars due to the breakdown of resistance by new rust races. The aims of this study were: a) to identify coffee (Coffea arabica L.) progenies of the two cultivars with resistance to rust; b) to identify progenies with incomplete resistance; c) to investigate the efficiency of test-crosses for selection from these cultivars. Evaluation for field resistance was carried out in adult plants subjected to natural infection by the local leaf rust population at IAPAR. Twenty-three test-crosses with F3 progenies of 'IPR 107' and five with F4 progenies of 'IPR 99' were evaluated. Moreover, 11 F4 progenies of 'IPR 107' and five F5 progenies of 'IPR 99' derived from self pollinations were evaluated. Several progenies of the IPR 99 and 107 cultivars presented high frequency of resistant plants and thus should carry additional SH genes not defeated by specific rust races found at IAPAR. However, susceptible progenies of 'IPR 99' and 'IPR 107' presented incomplete resistance to the local race population. Test-crosses were efficient for selecting coffee progenies more resistant to rust.
