Effect of Weather Conditions on Yield and Health Status of Faba Bean Seeds in Poland

Faba beans are considered to be one of the most important leguminous crops. The species is characterized by high nutritional value, in terms of both energy and protein content, which makes it suitable for food and feed production. Fungal diseases are among the key biotic factors responsible for a decline in faba bean yields. In this study, the yield and health status of faba bean seeds from the region of Warmia and Mazury (WM) and the region of Lower Silesia (LS), in Poland, were determined. Correlations between weather conditions vs. the yield of faba bean seeds and the occurrence of saprophytic and pathogenic fungi were analyzed. The study revealed that temperature and precipitation influenced the development and yield of faba beans in successive growth stages. Temperature exerted the greatest effect on the yield of faba beans during inflorescence emergence (BBCH 55-Biologische Bundesanstalt, Bundessortenamt and CHemical Industry), whereas the effect of precipitation was the maximum at the 4–5 leaves unfolded stage (BBCH 34–35) and at the end of flowering (BBCH 69). The occurrence of saprophytic, pathogenic, and toxin-producing fungi was influenced by temperature and precipitation in the flowering stage (BBCH 61–64).

The yield and quality of faba bean seeds are affected by soil type, climatic conditions, and agronomic factors [1,5,6]. Fungal diseases are among the key biotic factors responsible for yield loss in faba beans. Crop losses due to diseases in species of the family Fabaceae can reach 15% or even 80% [7,8]. Fungal pathogens cause major losses to economically important legume crops, including faba beans, by suppressing the growth and development of plants and, in extreme cases, by causing wilting and plant death. Some fungal pathogens can cause epidemic outbreaks, thus contributing to the closure of seed plantations [7,9]. The colonization of legumes by pathogens and the severity of fungal diseases are determined by various factors such as agricultural treatments, cultivar, soil-related infections, environmental conditions, and seed health [9][10][11][12]. The major fungal diseases affecting faba beans, which may cause significant crop losses, include ascochyta blight (Ascochyta fabae Speg.), chocolate spot (Botrytis fabae Sardina), Fusarium wilt and rot (Fusarium spp.), and faba bean rust (Uromyces fabae (Pers). J. Schröt.). The latter disease is more dangerous for late-maturing varieties [7,9,13]. Elwakil [11] demonstrated that many faba bean pathogens were seed-borne and seed transmitted. In their study,

Materials and Methods
Faba bean (cv. Olga with indeterminate growth habit and cv. Granit with determinate growth habit) were grown in 2011, 2012, and 2013, in the regions of Warmia and Mazury (Bałcyny, 19 • 51 E, 53 • 35 N) and Lower Silesia (Pawłowice, 17 • 02 E, 51 • 31 N), Poland. Spring wheat was used as the preceding crop of faba bean. Studies were conducted on experimental plots, with four replications. The experimental plots had an area of 125 m 2 each. Nitrogen fertilization was carried out by using ammonium nitrate (34% N) and 30 kg of N/ha before sowing. Phosphorus and potassium fertilizers were applied before sowing, at 26.16 kg P/ha (superphosphate-17.4% P) and 83 kg K/ha (potassium salt KCl-49.8% K). Before sowing, faba bean seeds were inoculated with Rhizobium bacteria and treated with Vitavax 200 FS-300 mL/100 kg. Seeds of faba bean were sown on 31 [20] and health status of faba bean seeds were determined. The grain yield from the plot at 15% humidity was converted into dt/ha. Faba bean seeds were subjected to mycological analyses. Batches of 200 seeds from each sample were analyzed, and the morphological characteristics of fungi isolated from seeds were determined. Seeds were surface disinfected with 1% sodium hypochlorite for 5 min and 70% ethanol for 5 min, and 8-9 seeds were plated in each 9 cm diameter sterile Petri dishes with PDA (potato dextrose agar) medium. After 10-14 days, fungal cultures were transferred to sterile dishes with the PDA medium and incubated at a temperature of 20-22 • C, with cycles of 12 h light/12 h darkness. After 14-20 days, fungal colonies were identified to the genus and species level (morphological structures: conidia and mycelium), under a microscope, based on the available monographs [21][22][23]). The number and percentage of the incidence of each fungal species recovered were calculated. The phenological phases of plant growth were determined, and BBCH codes were assigned (Table 1). Weather conditions were monitored in two locations in Poland (Bałcyny in the region of Warmia and Mazury, and Pawłowice-a district of Wroclaw in the region of Lower Silesia). Mean monthly temperature and total precipitation between April and July were recorded in all years of the study (Table 2).
Faba bean yields were analyzed statistically. The least significant difference was calculated at α ≤ 0.05, with the use of Tukey's test. All calculations were performed in Dell Statistica (ver. 13) software (www.software.dell.com). Correlations between weather conditions (temperature and precipitation) vs. faba bean yield and seed colonization by saprotrophic and pathogenic fungi in the analyzed regions were processed with the use of Pearson's correlation coefficients.

Results
The seed yield of both faba bean cultivars varied across years and locations (Table 3), and it was considerably higher in the region of Warmia and Mazury (Northeastern Poland) than in the region of Lowers Silesia (Southwestern Poland). The determinate-growth cv. Granit yielded higher than the indeterminate-growth cv. Olga in the region of Warmia and Mazury in all years of the study, and its yield ranged from 52.0 to 62.7 dt/ha. In the region of Lower Silesia, cv. Granit yielded higher only in 2011, whereas cv. Olga was characterized by higher seed yields in 2012 and 2013. An interaction between weather conditions in different growth stages of faba bean and seed yield was analyzed in the present study. The analysis revealed that favorable moisture conditions in the emergence stage (BBCH10) exerted a minor inhibitory effect on germination and had no significant influence on seed yield (Table 2, Figure 1). In the 3 leaves unfolded stage, total precipitation reached 70 mm/m 2 and considerably exceeded the long-term mean monthly precipitation (31.7 mm/m 2 ), which negatively affected seed yield. The temperatures recorded in this growth stage exceeded the long-term average by 2.2 • C (Warmia and Mazury) and over 4 • C (Lower Silesia). A linear correlation analysis revealed that seed yield was negatively affected by temperature in the 3 leaves unfolded stage, but the noted effect was not statistically significant ( Figure 1). In the 4-5 leaves unfolded stage (BBCH 14-15/34-35), temperature exerted a similar, nonsignificant effect on faba bean yield (R = −0.24) (Figure 1). An analysis of the effect of precipitation on seed yield indicated that rainfall total of approximately 30 mm/m 2 (80% of the long-term average) in BBCH stages 14-15/34-35 was most conducive to yield formation ( Figure 2). In the 6-7 leaves unfolded stage (BBCH 16-17/36-37), temperature had no significant effect on faba bean yield, which tended to decrease slightly (R = −0.42), in response to precipitation total exceeding 40 mm/m 2 (Figure 3). In the inflorescence emergence stage, mean daily temperature had a minor effect on faba bean yield, and the noted tendency (R = 0.44) suggests that temperatures oscillating around 16 • C were optimal to yield formation. In the above growth stage, high precipitation had a significant negative influence on seed yield (R = −0.87), and such a relationship was also observed at the beginning of flowering (BBCH 61) (R = −0.77). Until the end of flowering (BBCH 63-69), the optimal rainfall and temperature ranged from 20 to 25 mm/m 2 and from 16 to 18 • C, respectively (Figures 1 and 2 Faba bean seeds were colonized by both pathogenic and saprotrophic fungi. Pathogens were represented by three genera, Ascochyta, Botrytis, and Fusarium, whereas saprotrophs belonged to the genera Alternaria, Aspergillus, Acremonium, Cladosporium, Epicoccum, Mucor, Penicillium, and Rhizopus ( Figure 4). Antagonistic fungi of the genus Trichoderma were encountered sporadically ( Table 4). The predominant pathogenic species were Botrytis fabae-the causative agent of chocolate spot-and Botrytis cinerea-the causative agent of gray mold. Ascochyta fabae-the causative agent of ascochyta blight and fungi of the genus Fusarium-were less prevalent (Table 4). saprotrophic fungi (R = 0.65 and R = 0.59, respectively), pathogenic fungi (R = 0.45 and R = 0.64, respectively), and toxin-producing fungi (R = 0.48 and R = 0.61, respectively) ( Figure 3). In the above growth stage, high temperatures (18-20 °C) contributed to the occurrence of saprotrophic fungi, whereas precipitation in the range of 10-20 mm/m 2 promoted seed colonization by pathogenic and toxin-producing fungi (Figure 3).  Faba bean seeds were colonized by both pathogenic and saprotrophic fungi. Pathogens were represented by three genera, Ascochyta, Botrytis, and Fusarium, whereas saprotrophs belonged to the genera Alternaria, Aspergillus, Acremonium, Cladosporium, Epicoccum, Mucor, Penicillium, and Rhizopus ( Figure 4). Antagonistic fungi of the genus Trichoderma were encountered sporadically ( Table 4). The predominant pathogenic species were Botrytis fabae-the causative agent of chocolate spot-and Botrytis cinerea-the causative agent of gray mold. Ascochyta fabae-the causative agent of ascochyta blight and fungi of the genus Fusarium-were less prevalent (Table 4).  In both locations, seeds of the determinate-growth cv. Granit were more severely infected by fungi than seeds of the indeterminate-growth cv. Olga (Table 4). The levels of seed colonization by pathogenic and saprotrophic fungi were higher in faba beans grown in the region of Warmia and Mazury (Table 4). Seeds of both cultivars were abundantly colonized by Botrytis cinerea and B. fabae, particularly in 2011. Seeds harvested in Lower Silesia were less severely infected by pathogenic fungi represented by B. cinerea and Fusarium spp., which were isolated only from cv. Olga (Table 4).

Discussion
Faba bean cultivation is influenced by agronomic factors, climate, and local environmental conditions [24]. In Poland, faba beans are grown mostly in the region of Warmia and Mazury and in the region of Lower Silesia [1], which is why these two regions were analyzed in the current study. Throughout the experiment, the average yield of faba bean seeds was higher in the region of Warmia and Mazury (5.40-5.63 t·ha −1 ) than in the region of Lower Silesia (3.81-3.92 t·ha −1 ). In both faba bean cultivars and locations, the highest seed yield was attained in 2012, when temperature and humidity conditions were conducive to the growth and yielding of faba beans. Kulig [6] demonstrated that the

Discussion
Faba bean cultivation is influenced by agronomic factors, climate, and local environmental conditions [24]. In Poland, faba beans are grown mostly in the region of Warmia and Mazury and in the region of Lower Silesia [1], which is why these two regions were analyzed in the current study. Throughout the experiment, the average yield of faba bean seeds was higher in the region of Warmia and Mazury (5.40-5.63 t·ha −1 ) than in the region of Lower Silesia (3.81-3.92 t·ha −1 ). In both faba bean cultivars and locations, the highest seed yield was attained in 2012, when temperature and humidity conditions were conducive to the growth and yielding of faba beans. Kulig [6] demonstrated that the seed yield of faba beans ranged from 2.11 to 5.20 Mg ha -1 depending on weather conditions in a 13-year experiment. In a study by Barłóg [5], the growing season was the main determinant of green seed yield (BBCH 85-87). The highest faba bean yield (8 t/ha of fresh matter) was attained in 2012, a year characterized by the highest precipitation, whereas in the dry years, 2010 and 2011, seed yield reached 4.18 and 4.02 t/ha, respectively. Another important factor affecting seed yield was the content of plant-available potassium in soil [5].
Podleśny [25] analyzed the influence of weather conditions on faba bean yield and concluded that the greatest effect was exerted by rainfall in June, i.e., in the flowering stage. The cited author also demonstrated that faba bean cultivars differed in their sensitivity to weather conditions. The traditional cv. Nadwiślański was less sensitive to periodic drought than the determinate-growth cv. Tim. The decline in faba bean yields under the least favorable weather conditions in 2001 (water deficit during flowering) reached 21.8% in cv. Nadwiślański and 35.4% in cv. Tim compared with their respective yields in 2002 which was most conducive to faba bean cultivation [25]. In the present study, weather conditions also exerted a significant effect on faba bean yields. In the flowering stage (BBCH 63-69), seed yield was considerably affected by precipitation total of 20-25 mm/m 2 and temperature of 16-18 • C. According to Fahad [18], suboptimal water supply and temperatures exert adverse effects on plant growth and yields. Karkanis [26] reported that climate change is also gradually affecting many European regions, so it is imperative to breed elite cultivars that feature a higher abiotic and biotic stress resistance and nutritional value.
Seeds of the analyzed faba bean cultivars (Olga and Granit) were infected by pathogenic and saprotrophic fungi. Pathogenic fungi were represented by Botrytis fabae, Botrytis cinerea, Ascochyta fabae, and members of the genus Fusarium. According to numerous authors [9,27,28], chocolate spot caused by Botrytis fabae and Botrytis cinerea is the most common and economically important fungal disease of faba beans around the world. Its symptoms can be observed mostly on leaves, but also on stems, flowers, and pods. The disease can spread rapidly under supportive conditions, causing substantial yield losses [29]. Gleń [15] reported that faba bean seeds harvested from plants treated with Polyversum WP, Bioczos BR, and Biosept 33 SL were also colonized by fungi. Regardless of the applied plant protection agents, the following fungi were isolated most frequently: Alternaria alternata-21.7%, genus Fusarium-19.6%, genus Penicillium-14.4%, Botrytis cinerea-10.4%, and Epicoccum purpurascens-9.4% of all isolates. In a study by Saeed [30], faba bean seeds were infected mostly by members of the genus Fusarium and the fungus Ascochyta fabae. The above findings are consistent with the results of the present study, where fungi of the following genera were isolated from faba bean seeds: Acremonium, Alternaria, Ascochyta, Aspergillus, Botrytis, Cladosporium, Epicoccum, Fusarium, Mucor, Penicillium, and Rhizopus. Fungal infection rates were higher on seeds of cv. Granit with determinate growth habit. According to Elwakil [11] demonstrated that faba bean seeds were inhabited by 13 different fungal genera, among which were also Aspergillus, Penicillium, Alternaria, Botrytis, Cladosporium, Epicoccum, Fusarium, and Rhizopus. However, Marcenaro and Valkonen [31] reported that the most damaging and common fungi found in common bean seeds were Fusarium spp. (F. chlamydosporum, F. equiseti, F. incarnatum), Lasiodiplodia theobromae, Macrophomina phaseolina, and Penicillium citrinum. Furthermore, other species were also identified, e.g., Corynespora cassiicola, Colletotrichum capsisi, Colletotrichum gloeosporioides, Aspergillus flavus, and Diaporthe spp.
In the current study, weather conditions at the beginning of flowering and during full-flowering stage promoted seed colonization by saprotrophic, pathogenic, and toxin-producing fungi.
Podleśny [12] also demonstrated that disease incidence in faba beans was related to weather conditions. It should be stressed, however, that in many cases, the rapid spread of pathogens was determined by the distribution pattern rather than the total amount of rainfall. In some locations, the rate of fungal infections remained low despite heavy rainfall because rainfall frequency was low. Moreover, in some cases, a close correlation between weather condition and disease incidence was not found, which indicates that fungal colonization of faba beans was also determined by other factors [12]. Marcinkowska [32] also found that the occurrence of fungi on pea seeds was affected not only by weather conditions during the growing season, but also by cultivar and local environmental conditions. Environmental conditions were related to local weather conditions, as well as the microclimate in pea fields. Rainfall particularly contributed to the prevalence of fungal infections in peas. Our previous studies also revealed a significant effect of precipitation total and average temperatures during the growing season on seed colonization by pathogenic and saprotrophic fungi in three lupine species and field peas [33,34].

Conclusions
The results of this study indicate that weather conditions exert significant effects on the yield and quality of faba bean seeds. Temperature and precipitation in different growth stages affect the development of vegetative and generative part plants, which is directly associated with faba bean yields. The present findings showed that temperature during inflorescence emergence (BBCH 55) and rainfall at the 4-5 leaves unfolded stage (BBCH [34][35] and at the end of flowering (BBCH 69) had the greatest influence on faba bean yields. Weather conditions directly affected seed colonization by various fungal species, which is associated with the presence of undesirable secondary fungal metabolites-mycotoxins. Temperature at the beginning of flowering (BBCH 61) and precipitation during full flowering stage (BBCH 63-64) were the key determinants of the growth of saprotrophic, pathogenic, and toxin-producing fungi in faba beans.