Coffea arabica lines with resistance to nematode Meloidogyne paranaensis derived from crossings with IPR 100

Abstract

The aim of this work was to evaluate the reaction of IPR 100 derived Arabica coffee lines to the nematode Meloidogyne paranaensis and to investigate the association between the parameters used to select resistant genotypes. The experiment was carried out in a greenhouse at IAPAR in Londrina -PR, Brazil. The resistance to M. paranaensis of nineteen Coffea arabica F 3 lines derived from the cross "PRFB E9705-9" × 'IPR 100' and three from the cross 'IPR 100' × "Sarchimor E9601 III-19-1" were assessed. Plants with three to four pairs of leaves were inoculated with 5000 M. paranaensis eggs and J 2 juveniles. After 90 days of inoculation, the variables reproduction factor (RF), fresh weight of roots (FWR) and number of eggs and J 2 juveniles per gram of roots (Nematodes.g -1 ) were assessed. Reduction in the reproduction factor (RRF) and host susceptibility index (HSI) were used to classify the resistant levels. Resistant lines were identified and the use of RRF, HSI and RF indices together helped to identify genotypes with resistance to nematodes. In the present study, statistical difference between the FWR of the genotypes was observed. Thus, if the indices are used alone, it is likely that HSI is better, since it can minimize possible interference in the classifications due to differences between the root volumes of the assessed genotypes. The percentage of plants with different resistance levels based on the classification of RRF and HSI and percentage of resistant plants based on RF are useful to identify homozygous and heterozygous genotypes.

Methodological aspects of the quantification of dispersible clay and their relations with soil properties along a catena under no-till system

“…The study was carried out at an experimental site of Ponta Grossa State University (UEPG), Paraná State, Brazil (25° 05′ 52″ S and 50° 02′ 43″ W). The predominant climate in the region, according to the classification of Köppen, is humid subtropical mesothermal (Cfb), with an annual rainfall and temperature averages of 1,545 mm and 18°C, respectively (IAPAR, 2000). The soil in the study area is classified as a Rhodic Hapludox (Soil Survey Staff, 2010) and had been cultivated under a no-till system for 25 consecutive years at the time of the experiment, with the following crop rotation over the years: maize (Zea mays L.) soybean (Glycine max L.) and bean (Phaseolus vulgaris L.) in spring/summer and wheat (Triticum aestivum L.) intercropped with black oat (Avena strigosa Schreb) + vetch (Vicia sativa L.) in autumn/winter.…”

August 2020

“…To classify genotypes resistance levels (RL) the reduction of reproduction factor was used (RRF), calculated by the formula: RRF = [(RF of susceptible control -RF of treatment) / RF of susceptible control] x 100 (Moura and Regis, 1987). Based on RRF the genotypes were classified according a scale: < 25.00% = highly susceptible (HS); 25.00 to 49.99% = susceptible (S); 50.00 to 74.99% = moderately susceptible (MS); 75.00 to 89.99% = moderately resistant (MR); 90.00 to 94.99% = resistant (R); 95.00 to 100% = highly resistant (HR) (Shigueoka et al, 2017). For each genotype, we calculated the mean RF and RRF based on the data of the mean plots.…”

“…For each genotype, we calculated the mean RF and RRF based on the data of the mean plots. Since the mean values of RRF is based on the values of RF of the susceptible control, RRF values of this control were 0.00 (Shigueoka et al, 2017).…”

Coffea arabica cultivars with resistance to nematode Meloidogyne exigua originated from Costa Rica

“…To classify the resistance levels, the reduction in the reproduction factor (RRF) of M. exigua of each cultivar was used in relation to the susceptible control Caturra, with the formula RRF = RF of the susceptible control -RF of the cultivar / RF of the susceptible control x 100 (Moura and Regis, 1987). Based on the RRF values, the cultivars were classified according to the criteria of Shigueoka et al (2017), being: < 25.00% = highly susceptible (HS); 25.00 to 49.99% = susceptible (S); 50.00 to 74.99% = moderately susceptible (MS); 75.00 to 89.99% = moderately resistant (MR); 90.00 to 94.99% = resistant (R); 95.00 to 100% = highly resistant (HR).…”