IPR 100 – Rustic dwarf Arabica coffee cultivar with resistance to nematodes Meloidogyne paranaensis and M. incognita

‘IPR 100’ was derived from a crossing between “Catuaí” and a hybrid (“Catuaí” x BA-10 coffee). ‘IPR 100’ is a medium size dwarf cultivar with high rusticity, with late ripening cycle, and with resistance to Meloidogyne paranaensis and to some M. incognita populations.

IPR 100 -Rustic dwarf Arabica coffee cultivar with resistance to nematodes Meloidogyne paranaensis and M. incognita

INTRODUCTION
Brazilian coffee growers have nematodes as main constraints, since they reduce the production, besides being a limiting factor for the implementation of new coffee plantations in these infested areas.Many Brazilian regions with great potential for coffee cultivation cannot be exploited due to the presence of these pathogens.
Several species have been found in association with coffee plant roots in Brazil.However, Meloidogyne and Pratylenchus genera are the most important.The most damaging nematodes to coffee crops in Brazil are M. exigua, M. incognita and M. paranaensis (Gonçalves and Silvarolla 2007).
The use of resistant coffee cultivars is a viable alternative for infested areas, since it represents an efficient, economically viable and environmentally correct management method to control nematodes.However, currently, there are few coffee cultivars available with resistance to nematodes.Hypocotyledonary grafting, using the rootstock cultivar Apoatã IAC 2258 (C.canephora) resistant to M. exigua (Salgado et al. 2005, Fonseca et al. 2008), M. incognita (Sera et al. 2006, Fonseca et al. 2008), and M. paranaensis (Sera et al. 2006, Fonseca et al. 2008) has been the widely recommended strategy for nematode management in coffee-growing infested areas since 1987.Nevertheless, there are some problems in using rootstock cultivars compared to ungrafted, such as: a) segregation for susceptibility to nematodes (10 to 15%) due to the crosspollinated reproductive system of C. canephora; b) breakage in the grafting region; and c) need of replanting (about 10 to 15%) (Gonçalves and Silvarolla 2007), due to susceptible segregating plants.Besides, grafted seedlings are more expensive than ungrafted ones.T Sera et al. is recommended for semi-dense and dense planting systems in lower and higher temperature areas with annual average between 19 ºC and 23 ºC in the state of Paraná.

PEDIGREE AND IMPROVEMENT METHOD
'IPR 100' was developed using the genealogical method.'IPR 100' was originated from a crossing between "Catuaí" and a hybrid ("Catuaí" x BA-10 coffee).It was introduced by the Instituto Agronômico de Campinas (IAC) and named H8721-8 C1420 EP166.In 1977, seeds of this plant in F 2 RC 1 generation were introduced by IAPAR and named PR 77041.Three selection generations were carried out, and selected plants were .F 4 and F 5 plants that originated 'IPR 100' were selected in areas highly infested with nematodes.In these areas, these F 4 and F 5 plants presented high yield, whereas susceptible genotypes died or almost died in few years.F 6 genetic seeds field was originated using a composite sample of seeds of the F 5 plants IAPAR 77041-62-6-10-3 and IAPAR 77041-62-6-10-4.F 7 basic seeds field was planted at IAPAR (Londrina-PR-Brazil) with a composite sample of seeds of the F 6 plants originated from genetic seeds field.'IPR 100' was released in 2012.
'IPR 100' is a medium size dwarf plant (~ "Catuaí") recommended in the spacing between plants varying from 0.50m to 0.80m, depending on the annual average temperature of the cultivation site and on the technologies adopted, such as fertilization, irrigation and pruning.In hot regions without irrigation, spacing should be narrower, since usually, canopy diameter and branching are smaller.In farms with fertirrigation, spacing between rows and between plants can be wider.In farms where pruning are frequently used, these spacings can be narrower.Using wider spacing between plants, yield per plant will be higher, and adequate nutrition is necessary.Spacing between rows can vary from 2.5 to 3.0 m, according to the coffee crop area and to the level of mechanization.

RESISTANCE TO NEMATODES
IPR 100 was evaluated for resistance to Meloidogyne paranaensis and M. incognita under greenhouse conditions, in the Instituto Agronômico do Paraná (IAPAR) (lat 23° 21' 20" S, long 51° 09' 50" W, alt 574 m asl), in Londrina, state of Paraná, Brazil.Two experiments were carried out between January to May, 2014, with temperatures ranging from 31.1 ºC to 19.2 ºC.Cultivar Mundo Novo IAC 376-4 was used as susceptible control in all experiments.Experiments were arranged in a completely randomized design, with one plant per plot, and 15 replications (experiment with M. paranaensis), or 20 replications (experiment with M. incognita).
Nematode populations collected from coffees in Apucarana, PR (M.paranaensis) and Altônia, PR (M.incognita) were identified, and each species was cultured from a single egg mass (isolates).Species identification was carried out with α-esterase phenotypes (Carneiro et al. 2000) and morphological approaches (Hartman and Sasser 1985).Both isolates were routinely multiplied in coffee cv.Mundo Novo IAC 376-4 under greenhouse conditions.Approximately 60 days before inoculation, nematodes were extracted from coffee roots (Boneti and Ferraz 1981) and inoculated in tomato cv.Santa Clara for inocula multiplication.
After extracting eggs using the NaCl method (Boneti and Ferraz 1981) from tomato roots, a suspension (2 ml) containing 2,000 eggs was poured in each pot (Pi = initial population) into two small 3.5-4.5 cm deep holes beside the root system of the coffee seedlings.
After the experimental period, 121 and 130 days after inoculation of M. paranaensis and M. incognita, respectively, roots were washed, and dried on absorbent paper.Fresh weight was determined and nematode extraction was carried out according to Boneti and Ferraz (1981).Nematode final population (Pf) was estimated by counting the eggs and the second-stage juveniles (J2) on the suspension obtained after nematode extraction from the entire root systems only, not from the soil.Reproduction factor (RF = Pf/Pi) values were subsequently determined (Oostenbrink 1966).After that, number of nematodes per gram of roots (Nematodes g -1 ) was calculated for each replication.
Data of Nematodes g -1 were submitted to the Lilliefors (Kolmogorov-Smirnov) test for normality of errors, and to the Levene's test, for homogeneity of variances at 5% of probability.Log (x + 1) transformation was used for Nematodes g -1 data.Analysis of variance (ANOVA) and Tukey test at 5% of probability were used.Cultivars were classified as resistant when RF ≤ 1.0, and as susceptible, when RF > 1.0.
High RF values (29.85 and 30.81) obtained from the control (cultivar Mundo Novo IAC 376-4) confirm the viability of the inocula and the appropriate experimental conditions.On the basis of RF values, IPR 100 was classified as resistant to M. paranaensis (0.40) and M. incognita (0.24) (Table 2).In general, Nematodes.g - data on both experiments are in agreement with RF values.IPR 100 resistance observed in the present study for both nematodes confirmed previous results, in which 'IPR 100' showed resistance to nematodes M. paranaensis (Sera et al. 2007b, Ito et al. 2008, Andreazi et al. 2015) and to M. incognita races 1 (Kanayama et al. 2009) and 2 (Ito et al. 2008).Besides, 'IPR 100' presents good agronomic performance in comparison with susceptible controls Catuaí IAC 64 and Mundo Novo IAC 379/19 in areas infested with M. paranaensis in the state of Minas Gerais, Brazil (Salgado et al. 2014).IPR 100 has not been tested for all races of M. incognita yet.Thus, this cultivar is resistant to some M. incognita populations.IPR 100 has not been evaluated to M. exigua yet.However, detailed studies are in progress in order to know the host reaction of IPR 100 to M. exigua.

OTHER TRAITS
Ripening is late, similar to "Catuaí".At lower temperatures, with annual average between 19 ºC and 21 ºC, ripening usually occurs in August.At higher temperatures, with annual average between 22 ºC and 23 ºC, ripening usually occurs in June.
'IPR 100' shows rusticity and better adaptation to high temperatures and poor soils than other compact cultivars, such as "Catuaí".'IPR 100' was selected in coffee regions with poor and sandy soils, low altitudes and higher temperatures (1) M. Novo = susceptible control.
(2) Means followed by the same letter did not differ by the Tukey test at 5% significance.Data were transformed by log (x + 1).

Table 1 .
Annual mean yield per hectare (bags of 60 kg ha -1 ) of 'IPR 100' in comparison with other cultivars (state ofParaná, Brazil)

Table 2 .
Means of the number of eggs and second-stage juveniles per gram of roots (Nematodes g -1 ) of Meloidogyne paranaensis and M. incognita, reproduction factor (RF), and resistance reaction (RR) of IPR 100 and Mundo Novo IAC 376-4 (M.Novo) coffee cultivars