Avaliações preliminares da resistência à cochonilha-da-raiz Dysmicoccus texensis em clones de Coffea canephora resistentes a Meloidogyne spp

The purpose of this paper was to investigate the coffee plants variability to the resistance to root-mealybugs,Dysmicoccus texensis, and the root-knot nematodes Meloidogyne. These species are considered important threats to coffeeplantations, especially in the main producing regions of São Paulo, as Alta Mogiana and Alta Paulista. The interaction among D.texensis and seven selected C. canephora clones that express resistance to different Meloidogyne species were evaluated inexperiments under greenhouse, regarding the differences in the infestation standards presented by clones. Mealybugs reproductionin roots of clones IAC 5, EH 5, EH 7, EH 101 and EH 199 was significantly reduced, suggesting the possibility of finding multipleresistance to the biotic stress.Investigou-se, neste trabalho, a variabilidade de cafeeiros quanto à resistência apresentada à cochonilha-da-raiz, Dysmicoccustexensis e a nematoides do gênero Meloidogyne. Ambas as espécies configuram problemas fitossanitários importantes para a cafeicultura,sobretudo nas regiões da Alta Mogiana e Alta Paulista no Estado de São Paulo. A interação entre D. texensis e sete clones de C.canephora resistentes à diferentes espécies do gênero Meloidogyne foi avaliada em experimento realizado em casa de vegetação,observando-se as diferenças nos padrões de infestação apresentados pelos clones. A reprodução de cochonilhas no sistema radiculardos clones IAC 5, EH 5, EH 7, EH 101 e EH 199 foi bastante reduzida, sugerindo a possibilidade de reunir nos mesmos resistênciamúltipla aos dois agentes bióticos

Clonal Arabica coffee resistant to Meloidogyne paranaensis and damage threshold on plants development

Plants of Coffea arabica Icatu IAC 925 germplasm show resistance to Meloidogyne paranaensis under field conditions, but with variable rates of segregation. One mother plant, IAC 3, of Icatu IAC 925 was evaluated under controlled conditions through the reaction of its clones, obtained by somatic embryogenesis. Reproduction of nematodes in clones were compared with an open-pollinated progeny from the same mother plant, C. arabica cultivar Mundo Novo IAC 515-20, susceptible to nematodes, and Clone IAC 1, also susceptible and obtained by somatic embryogenesis. Open-pollinated progeny showed segregation to resistance and was classified as susceptible according to the reproduction factor. The average number of nematodes (eggs and J2) per gram of roots in clones was eight fold lower than that of open-pollinated progeny, and 51 fold lower than Mundo Novo IAC 515-20. Based on Seinhorst model, IAC 3 clone showed a tolerance limit of 7.7 nematodes per cm3 of soil, while in Mundo Novo the tolerance limit was 3.9 nematodes per cm3 of soil. These results revealed that clonal Arabica coffee nematoderesistant trees represent an alternative to the time consuming and expensive process inherent to conventional breeding strategies

Clonal Arabica coffee resistant to Meloidogyne paranaensis and damage threshold on plants development

ABSTRACT: Plants of Coffea arabica Icatu IAC 925 germplasm show resistance to Meloidogyne paranaensis under field conditions, but with variable rates of segregation. One mother plant, IAC 3, of Icatu IAC 925 was evaluated under controlled conditions through the reaction of its clones, obtained by somatic embryogenesis. Reproduction of nematodes in clones were compared with an open-pollinated progeny from the same mother plant, C. arabica cultivar Mundo Novo IAC 515-20, susceptible to nematodes, and Clone IAC 1, also susceptible and obtained by somatic embryogenesis. Open-pollinated progeny showed segregation to resistance and was classified as susceptible according to the reproduction factor. The average number of nematodes (eggs and J2) per gram of roots in clones was eight fold lower than that of open-pollinated progeny, and 51 fold lower than Mundo Novo IAC 515-20. Based on Seinhorst model, IAC 3 clone showed a tolerance limit of 7.7 nematodes per cm3 of soil, while in Mundo Novo the tolerance limit was 3.9 nematodes per cm3 of soil. These results revealed that clonal Arabica coffee nematode-resistant trees represent an alternative to the time consuming and expensive process inherent to conventional breeding strategies

Coffea arabica clones resistant to coffee leaf miner

Brazilian arabica coffee production is based on a set of highly productive cultivars sexually propagated. All of them are susceptible to coffee leaf miner, Leucoptera coffeella, and most of them are also susceptible to coffee leaf rust, Hemileia vastatrix. Aiming to reduce the selection process of cultivars with multiple resistances to both biotic constraints, the Coffea arabica clones 760, 1059, 1064 and 1215 were evaluated under field conditions. The mean yield of four C. arabica clones was not statistically different from the experimental controls; however, the yield of clone 1059 was 21% higher than the control cultivar Obatã IAC 1669-20. Leaf miner resistance level in all the evaluated clones remained the same as the mother plant’s. However, the same did not occur for resistance to H. vastatrix, due to the emergence of new pathogen races. In summary, it is potentially feasible the adoption of clone 1059 as a new clonal cultivar resistant to coffee leaf miner