The faba bean (
Vicia faba L.), is a Fabaceae native to Central Asia, domesticated for 10,000 years (
Duc, 1997;
Kumar et al., 2019) and it is practiced in about 58 countries
(Singh et al., 2012). It is the fourth most important grain legume in the world behind peas, chickpeas and beans
(Yahia et al., 2012; Luo et al., 2014). This crop has been part of our agricultural systems for a long time; its global area is more than 2,5 million hectares of which more than 50% is located in China, 20% in North Africa and less than 10% in Europe (
Abu Amer et al., 2011). World production has reached up to 4.92 MT (
FaoStat, 2020).
In Algeria, the faba bean remains the most important food crop, covering an area of 40222 hectares with a total production of 54878 tonnes (
FaoStat, 2020). Unlike in the world, the faba bean in Algeria is the first place among other grain legumes
(Maatougui et al., 1994).
Chocolate spot, caused by the fungus
Botrytis fabae Sard., is the major disease of faba bean (
Vicia faba L.) in Algeria
(Maatougui et al., 1994; Ranjana et al., 2019). The chemical control against this disease is possible but is not environmentally friendly
(Bouhassan et al., 2003). An effective control is a research of resistance sources in faba bean germplasm collection and transferred to commercial cultivars via breeding
(Villegas-Fernandez et al., 2012; Gautam et al., 2013). In this case, this mode of control based on plant screening tests like cut-twig, detached leaves, greenhouse and field screenings
(Boumaaza et al., 2018; Bouhassan et al., 2004a).
The present study has the objective to evaluate the resistance sources in seven faba bean gemplasm accessions against two
Botrytis fabae isolates using detached leaves screening method.
Plant material
Seven (07) varieties of different origins were used in the inoculation test: Giza 02, Giza 40, Sakha 01, Sakha 02, Sakha 03, Ziban and Precoce de Seville (Table 1).
Fungal material
Two different strains (BF1 and BF2) of Botrytis fabae were used in this screening test, with BF1 from the Mascara region and BF2 from Relizane. The two strains used in this study were obtained by isolation from faba bean leaves with typical chocolate spot symptoms. The Botrytis fabae strains were identified by macroscopic (colony color, sclerotia size, etc.) and microscopic (size of conidia, etc.) characteristics, to distinguish it from the other species Botrytis cinerea which can causes the same symptoms of chocolate spot disease (Table 2). The BF strains were cultivated on the PDA culture medium (Potato Dextrose Agar, Fischer Ltd., France), at temperature of 22 ± 2°C (Bouhassan et al., 2003; 2004a, b).
Test of artificial inoculation
The faba bean seeds used were sterilized with sodium hypochlorite (2%) for 3 minutes and then rinsed 3 times with sterile distilled water. Then, they had sown in 10 cm × 5 cm pots, containing a sterile peat, at the rate of 2 seeds / pot. After 15 days, leaflets can be removed to do the inoculation test at the rate of 2 leaflets for each repetition. To prepare the inoculum of two BF isolates, the colonies of isolates were immersed in sterile distilled water taken and then scraped off with a sterile glass spatula. The suspension is adjusted to 3 × 106 conidia/ml using Malassez-cell
(Bouhassan et al., 2004b). Symptoms were assessed 15 days after inoculation of the bean leaflets. The severity of the disease is scored according to the rating scale of
Bouhassan et al., (2004b), (1, 2, 3, 4 and 5), which respectively represent 0%, 10%, 20%, 50% and 100% of the surface of the necrosis on leaflet. This scale is based on the percentage of the area of the infection relative to the entire area of the leaflet. With faba bean leaflets inoculated, we are classified into interval classes, the leaflets of seedlings of varieties marked from 1.0 to 2.9 are considered resistant and those which are coded from 3.0 to 5 are sensitive
(Bouhassan et al., 2004b).
Statistical analysis
Thevariances (σ
2), averages (
x) and standard deviation (σ) of manyrepetitionswere analyzed by the software XLStat (Addin Soft, USA). The no parametric testof K samplesof Kruskal-Wallis (
P0.05 et
P0.01), was used in this statistical analysis.
All symptom ratings were collected only after 7 days of inoculation. A significant difference (P <0.05) was observed in the reaction of the varieties to two strains of
Botrytis fabae (BF1 and BF2), (Table 3). According to the results of the screening test based on the rating of symptoms from the percentage of symptom intensity, the results are as follows: Total sensitivity was observed in the four (4) varieties Giza02, Sakha 01, Sakha 02 and Sakha 03, followed by total death of the leaflets after 12 days of inoculation; Two (2) varieties (Giza 40 and Ziban) showed tolerance towards strains of
Botrytis fabae (Fig 1). The standard variety ‘Precoce de Seville’ showed significant resistance to both strains of
Botrytis fabae (Fig 1, Table 3).
In comparison between two BF isolates (BF1 and BF2), no difference was observed in their pathogenicity on all seven faba bean varieties. All these varieties showed the same reaction of resistance/sensitivity to chocolate spot disease caused by these two isolates.
The importance of genetic control through the use of resistant varieties against pest pests has been reported by several authors worldwide
(Bouhassan et al., 2004a, b;
Ahmed et al., 2016; Wolde and Mitiku, 2018;
Rubiales et al., 2012; Sheikh et al., 2015).
Our essay is the first research work carried out in Algeria on this topic, that it is based on the research of the sources of resistance of seven (07) varieties of faba bean (Giza 02, Giza 40, Sakha 01, Sakha 02, Sakha 03, Ziban and Precoce of Seville), against the chocolate spot disease caused by
Botrytis fabae Sard. A similar study was carried out in Spain by
Madeira et al., (1993) and
Sillero and Rubiales (2014), in Poland by Goral and Walentyn-Goral, 2012 and in Morocco by
Bouhassan et al., 2004b.
A significant difference was observed in the reaction of faba bean varieties against two strains of
Botrytis fabae, by 04 susceptible varieties (Giza02, Sakha01, Sakha02 and Sakha03), two tolerant varieties (Giza40 and Ziban) and only one resistant variety (Precoce de Seville). This difference has been reported in some studies around the world with other faba bean cultivars
(Villegas-Fernandez et al., 2012; Wolde and Mitiku, 2018;
Abd-Rabh et al., 2013; Bouhassan et al., 2004a,b; Terefe et al., 2015). El-Komy et al., (2015) reported in their work the total sensitivity to
Botrytis fabae of two varieties of faba bean that we used in our essay (Giza 02 and Sakha 02).These results are very close to those obtained in our test. In Tunisia,
Rhaeim et al., (2013) noted the limited number of resistant varieties to
Botrytis fabae despite the large number of varieties tested (67 varieties). The same remark was observed in our results and in other authors
(Abd-Rabh et al., 2013; Wolde and Mitiku, 2018).
Although the majority of the authors in the bibliography have chosen the field screening test, but certain authors such as
El-Komy et al., (2015), Bouhassan et al., (2004a, b) and
Madeira et al., (1993), confirmed the similarity of results of this type of screening with other tests like cut-twig, greenhouse and detached leaves.
