Assessment of the Suitability of 10 Winter Triticale Cultivars (x Triticosecale Wittm. ex A. Camus) for Organic Agriculture: Polish Case Study

: The aim of the study was to compare 10 winter triticale varieties according to their traits useful for cultivation in organic farming. The study was carried out in the years 2014–2017 in the experimental organic farm of the Institute of Soil Science and Plant Cultivation–State Research Institute in Pulawy (Poland). The highest-yielding varieties under organic conditions were Pizarro and Subito. Borowik cultivar showed the highest competitive ability against weeds. The highest number of weeds was found in the Leontyno cultivar, which was connected to the lowest plant density, the lowest weight of the above-ground parts of the canopy and smaller value of tillering coe ﬃ cient. The most a ﬀ ected by the fungal pathogens Drechslera tritici-repentis (Died.) Shoem. and Puccinia striiformis Schwein. were Fredro and Algoso. Cluster analyses indicated that the most useful cultivars for cultivation in the organic system were: Borowik, Subito, and Tomko, which all showed higher yielding potential, bigger competitiveness against weeds, and average resistance against fungal pathogens. Pizarro, Tulus, and Twingo, which showed high resistance to fungal pathogens with lower competitiveness to weeds, were classiﬁed to the second group of usefulness. The least useful for the organic system were: Algoso, Fredro, Grenado, and Leontyno.


Introduction
Triticale (x Triticosecale Wittm. ex A. Camus) is a hybrid resulting from the crossing of a species of the genus Triticum and a species of the genus Secale [1]. Currently, the area of this cereal in the world is about 3.5 million hectares [2]. In Poland in 2018 triticale was cultivated on the area of 1 million 188 thousand ha, 93% of which was taken by winter triticale [3]. Currently there are 334 triticale varieties in the EU Common Catalogue [4]. The Polish National Register of Cultivars kept by the Research Centre for Cultivar Testing (COBORU) includes 63 cultivars of triticale in total, including 47 cultivars of winter triticale and 16 cultivars of spring triticale [5]. According to Łysoń and Biel [6], Polish triticale cultivars are among the most efficient in the world and occupy 70-80% of the world's triticale cultivation area. They also exhibit high adaptation to environmental conditions [6]. This cereal species is becoming more and more popular among farmers, also with those operating in the organic system. This is due to its beneficial traits, such as relatively low soil requirements [7,8], a higher resistance to diseases and soil acidification than wheat [6], significant yield potential [9][10][11][12], high fodder value [7,[13][14][15][16][17], and resistance to abiotic stresses, such as drought and frost [1,12,18]. Winter triticale is more sensitive to a forecrop cultivars included in the Common Catalogue of varieties of agricultural plant species [4] that differed in their features were cultivated: Algoso, Borowik, Fredro, Grenado, Leontyno, Pizarro, Subito, Tomko, Tulus, Twingo. The cultivars were selected on the basis of criteria developed in previous studies with other cereal species and took into account: wintering stability, susceptibility to fungal diseases, morphological differentiation, and yields obtained in conventional farms [34,37,[39][40][41][42][43]. The field experiment was established in a system of random blocks in four replications for each cultivar. The area of each plot of replication for sowing and harvest was 30 m 2 . Pre-sowing treatments were performed in accordance with good agricultural practice, and sowing was at the optimum time for the region (first half of September). The sowing rates were the same for each cultivar-450 grains·m −2 . The row spacing was 12 cm and the planting depth 3.5 cm. According to organic agriculture rules, mineral fertilizers and other agrochemicals were not used [30]. Final harvests were carried out in the first decade of August. Habitat conditions prevailing in the years of the study are presented in Table 1.

Meteorological Conditions
The experimental site belongs to a moderately continental climate zone. Average annual precipitation is 655 mm with a mean air temperature of 7.6 • C (data from the years 1951-2013). The meteorological data for the research period is presented in Table 2. In autumn 2014 temperatures were higher than the long-term average, while rainfall, especially in September, was one quarter of the average. In May 2015 precipitation was significantly higher than the long-term average, which resulted in increased weeds and fungal pathogens. In the period from June to August 2015 a deepening drought was observed. In October precipitation was about one quarter of the average for that month. November, on the other hand, was the warmest, and the rainfall was the highest of all the years of the research. In the 2016 growing season temperatures were above average, and May saw a shortage of precipitation. In October and November, the temperatures were slightly below the average, while the precipitation in October was higher than the average for that month. In 2017 there was a deficiency of rainfall from May to the end of June, which negatively affected the triticale yields.

Weed Infestation Analyses
The number of weeds and their dry matter were assessed at the dough stage of triticale (BBCH 85-87) [44], using the weight-counting method, on an area of 1 m 2 in each plot of replication. To avoid the edge effect the frames were placed two meters from the edges of the plots. Weeds were cut at the soil level, sorted by hand and indicated to species according to Rutkowski [45]. The dry matter of weeds and wheat was determined after drying at 40 • C for 7 days.

Assessment of Plant Infestation by Pathogens
Assessments of the condition of plant infestation by pathogens were performed in 2016-2017 at the stage of milky wax maturity (BBCH 77-83) on the three uppermost leaves. For phytopathological analysis these three leaves were taken from 10 plants in each of the 4 repetitions. The percentage of leaf-blade surface damaged by individual pathogens was determined. The method of disease assessment on leaves were in accordance with European and Mediterranean Plant Protection Organization (EPPO) recommendations [46].

Biometric Analyses and Grain Yield
Biometric analyses of triticale height and number of tillers per plant (tillering coefficient) were performed on 30 plants, in 4 repetitions for each cultivar, at the dough stage of triticale. The plant density and dry matter of the above-ground parts were determined from 1 m 2 , in 4 repetitions, for each cultivar. Harvest was done using a special small harvester for the entire plot area. Grain yield was evaluated after harvest and calculated as t·ha −1 at 15% moisture content.

Statistical Analyses
Analysis of variation (ANOVA) was done, where cultivars and years were the factors of the experiment (10 cultivars × 3 years). Since the number and weight of weeds did not have a normal distribution, a logarithmic transformation log (x + 1) of the data was carried out before the analysis of variance. The significance of differences between treatments was verified by Tukey's test at p ≤ 0.05. To estimate how the features of the triticale cultivars influence the parameters of weed infestation, Spearman's correlation coefficients between the number of weeds and their dry matter and the morphological features, and the canopy parameters were assessed for all tested cultivars. Cluster analysis using the furthest neighbor method was done to divide the samples into groups with similar characteristics. The following variables were used in cluster analysis: number of weeds, dry matter of weeds, infestation by pathogens, and grain yield. Calculations were performed using Statistica 10 software (Stat. Soft. Inc., Tulsa, OK, USA).

Competitiveness against Weeds
The level of weed infestation of the triticale cultivars depended on the morphological traits of the cultivars and the structure of the canopy. The highest competitive capacity, measured both by the number (91.2 plants·m −2 ) and dry weight of weeds (39.4 g·m −2 ), was shown by the winter triticale cultivar Borowik (Table 3). This was due to the large height of this cultivar (Table 4) and the large plant density and weight of the above-ground parts ( Table 5). The highest weed weight was found under the canopy of the low height cultivar Grenado (80.0 g·m −2 ) (Tables 3 and 4). On the other hand, the highest number of weeds (120.0 plants·m −2 ) was recorded in the stand of the Leontyno cultivar (Table 3), which was associated with the small tillering of this cultivar (Table 4) as well as the smallest plant density and the lowest weight of the above-ground parts (Table 5). Table 3. Number and dry matter of weeds in triticale cultivars grown in the organic system at the dough stage.
Among the cultivars studied, Twingo (1.6 on average) and Grenado and Subito (1.5 on average) exhibited the largest, while Leontyno (1.3) showed the smallest overall tillering ( Table 4). The tallest cultivars were Borowik (108 cm on average) and Pizarro (107 cm), while the shortest were Twingo (82 cm) and Grenado (84 cm). In 2017, the cultivars were significantly lower in height and less tillered than in the previous years, which was due to weather conditions (low temperatures during emergence and in spring, and low and uneven precipitation during the growing season) (Tables 2 and 4). The Leontyno cultivar was characterized by significantly the lowest crop plant density and weight of the above-ground parts of the canopy in 2015 and 2016 (Table 5), which had a negative effect on its competitiveness against weeds (Table 3). Pizarro was characterized by the highest plant density and the biggest weight of the above-ground parts of the canopy in 2015 (Table 5). Correlation analysis showed that the number of weeds was significantly negatively correlated with the number of tillers per plant and plant height, as well as with triticale plant density and dry weight of the above-ground parts of triticale plants (Table 6). On the other hand, weed weight was only slightly affected by the triticale plant density. Table 6. Spearman's correlation coefficients for weed infestation indices and morphological and structure parameters of the canopy of winter triticale (total for all cultivars and years of study, n = 120 observations). In the study of Mahayan et al. [47], conducted on different barley genotypes, yield losses caused by weeds ranged from 43% to 78%. The level of weed infestation of cereals is influenced by the mechanical measures, fertilization, crop rotation, the species of the crop, and the selection of cultivars [48]. Triticale is less competitive against weeds than rye [49]. This is related to the slow growth rate of this plant at the initial developmental stages until the moment of canopy closure.

Dry
Studies by other authors confirm that the competitive ability of cereals against weeds depends primarily on the morphological traits of each cultivar such as: number of tillers per plant, stem length, leaf angle, leaf surface, relative growth rate [34,39,42], early canopy closure and plant height [40,50,51]. According to Wolfe et al. [51], even slight differences in the shading capacity of cultivars of cultivated plants affect the degree of light available to weeds and that can significantly influence their growth. On the other hand, the study by Kronberga et al. [24], conducted under Latvian conditions, showed that triticale height did not significantly influence competitiveness against weeds or yields.
The date of sowing, seed quality, plant density, field levelling and field architecture are also of great importance for the competitiveness of cereal crops against weeds [37,39]. Due to the scarcity of research on triticale some features were related to other cereals [41,43,49]. In the study carried out by Starczewski andŻołądek [49], at the highest crop density, 600 plants·m −2 , the air-dry weight of weeds decreased by almost 38% and the yield of winter triticale grain increased by 15.3% in comparison to a crop density of 400 plants·m −2 . The research conducted by Feledyn-Szewczyk and Jończyk [43] on oat cultivars grown in the organic system showed a negative correlation between weed infestation and the weight of the above-ground parts of oats and its tillering and height. Similarly, research carried out on winter wheat in the organic system showed that low weed infestation of wheat cultivars that showed the highest competitiveness against weeds was related to their morphological traits, such as: leaf area, stand structure, plant density, penetration of photosynthetic active radiation under the canopy and the weight of the above-ground parts of wheat [39].

Infestation by Fungal Pathogens
The leaf infestation of winter triticale cultivated in the organic system varied from 12.5% for the Twingo cultivar to 31.6% for the Algoso cultivar (average from 2016-2017) ( Table 7). In 2016, the biggest infestation was caused by the fungus Drechslera tritici-repentis (Died.) Shoem. and was especially found in the cultivars: Subito, Fredro, and Algoso. The smallest infestations were recorded for the cultivars: Grenado, Twingo, and Tulus. In 2017, the triticale was most infested by Puccinia striiformis Schwein.  Table 2). The cultivars most susceptible to fungal infections were Algoso and Borowik, while the least susceptible were Twingo, similarly as in 2016, and Pizarro. Paluch et al. [10] examined the occurrence of brown rust on the leaves of winter triticale and recorded a 24.1% higher occurrence of brown rust (Puccinia recondita) under triticale monoculture as compared with its cultivation under a three-field crop rotation system. Diseases of cereals caused by fungal pathogens may significantly reduce grain yields and deteriorate their quality parameters [17]. The degree of cereal infestation by pathogens depends on weather conditions during the growing season [52], sensitivity of varieties to pathogens, crop rotation, nitrogen fertilization level [51,52], and the method of weed control [53]. According to Grądzielewska et al. [1], the following are threats to triticale crops: powdery mildew, various species of rust, Rhinchosporium secalis, stem base diseases, leaf and ear spotting, as well as snow mold and ergot. Triticale infestation by pathogens can lead to a 5-20% yield reduction, and in extreme cases even to 60% [52]. According to Bielski [11], the frequency of diseases of the stem base, leaves and ears in triticale is increasing and the losses caused by these diseases may reach one third of the yield. Czajkowski and Czembor [54] state that from an economic and ecological point of view, breeding resistant varieties and seeking new effective sources of resistance among wheat and triticale genotypes are the only right way to protect cereals from the powdery mildew of cereals and grasses. According to Kramek and Kociuba [55], triticale shows an intermediate response to leaf and ear diseases compared to the parent species (wheat and rye), with the exception of resistance to mildew, which is significantly higher than it is in wheat and rye. According to Korbas and Mrówczyński [56], the date of sowing is an important factor that can significantly control plant infestation by pathogens. According to Kuś et al. [33], the complex influence of such factors as tillage, crop rotation, selection of varieties, sowing of mixtures, and fertilization with organic and natural fertilizers reduces disease pressure and influences the formation of a specific balance between pathogenic factors and saprophytic microflora and pathogen antagonists.

Yield
In the years 2015-2017 the mean yield of winter triticale grain, regardless of cultivar, ranged from 3.56 to 6.10 t·ha −1 ( Table 8). The highest yield was recorded for triticale varieties in 2015 while the lowest yield was obtained in 2017 when unfavorable weather conditions occurred, and at the same time a higher intensity of fungal diseases, mainly brown and yellow rust, and weed infestation was recorded. The highest mean yields were noted for Pizarro (5.52 t·ha −1 ) and Subito (5.49 t·ha −1 ). The characteristic trait of the Subito and Tomko varieties was the ability to produce a grain of high weight, while the Pizarro cultivar was more resistant to fungal pathogens. The lowest yields under the conditions of organic production were obtained by the Leontino cultivar, which was characterized by small plant density (Table 5) and low tillering coefficient ( Table 4). The low plant density of the Leontino cultivar contributed to weed infestation, which was one of the highest among the evaluated cultivarss ( Table 3). The Grenado cultivar was characterized by the lowest 1000 kernel weight (TKW) (39.0 g on average), which translated into the low yield of this cultivar ( Table 8). The highest 1000 kernel weight was recorded for the Borowik cultivar (50.2 g on average).
Observations from other studies indicate that cereal yields in the organic system are on average 25 to 50% lower than in the conventional system, depending on the species, year, type of soil, and intensity of use of chemical means of production in the conventional system [8,41,43] (Table 9).  In the studies of Tratwal et al. [8], conducted in the years 2013-2016 in the conventional system, in very good soil conditions and high level of crop management, the Borowik cultivar achieved the highest yields among the tested cultivars (10.6-11.8 t·ha −1 depending on the input of agrochemicals) ( Table 9). In our research, under the conditions of the organic system, this cultivar also had a high yield (5.31 t·ha −1 average from 3 years of research) and was the second best-yielding cultivar after Pizarro, it also had the highest 1000 kernel weight among the tested cultivars (Tables 8 and 9). In the mentioned above study by Tratwal et al. [8] the lowest yielding cultivar was Twingo, while in the current research under the conditions of organic farming it yielded at an average level. The significant differences between our results and those of Tratwal et al. [8] are due to the possibilities offered by conventional production that are not available in organic farming (mineral nitrogen fertilization, fungicide protection, foliar feeding of micro-nutrients, and use of growth regulators). In the second year (2014/2015) of the study by Tratwal et al. [8] very high yields of triticale were obtained and those were significantly different from the other 2 years of the research, and this greatly increased the average yield for the 3 years. For comparison, in 2015 in own experiment the Tulus cultivar yielded in the organic system 6.07 t·ha −1 , while in the conventional experiment of Tratwal et al. [8] the yield was more than twice bigger (Table 9). In 2016 the yield differences between the experiments in the organic and conventional systems were much smaller (5.78 t·ha −1 in our study and 5.76-6.59 t·ha −1 in Tratwal et al. [8] research). This indicates a higher yield stability over years in the organic system compared to the conventional one. Other studies confirm that the yields of cereals in the organic system are mostly lower than in the conventional system, but more stable over the years [41]. Our results and Jaśkiewicz et al. [58] and Jaśkiewicz and Jasińska [59] study suggest that it is possible in organic agriculture to obtain a yield of cereals that is similar or even higher than that obtained from the conventional system (Table 9).
In our research the 1000 kernel weight (TKW) of the tested triticale was on average from 39.0 g (Grenado) to 50.2 g (Borowik), similarly to Kronberga [9] results (Table 9). In the studies of Tratwal et al. [8], under conditions of high-input conventional agriculture, the variety with the highest TKW was also Borowik (49.42 g). This indicates that this cultivar responds similarly under conventional and organic farming conditions, and can therefore be recommended for organic agriculture.

Suitability for Organic Farming
Cluster analysis showed that the cultivars most useful for organic farming, exhibiting the highest grain yields and the least weed infestation, were Borowik, Subito and Tomko (Table 10, Figure 1). Pizarro, Tulus, and Twingo were also distinguished by favorable parameters in terms of fungal disease and weed infestation, as well as giving high yields. Algoso, Fredro, Grenado, and Leontyno were the least useful for the organic farming system. They produced low yields and they were suffering from the highest number and weight of weeds and a high leaf infestation by fungal pathogens.  Triticale is suitable for growing in organic farming due to its stable yield, tolerance to marginal conditions, resistance to diseases, and high competitive ability against weeds [24,32]. According to Wenda-Piesik and Wasilewski [60], triticale performs much better in less favorable habitat conditions, such as dry soils with nutrient deficiencies, unfavorable temperature distribution, or organic farming conditions, compared to wheat. Triticale yields are influenced by cultivar, local climate, agroecological conditions, mineral fertilization, protection against diseases, weeds and pests [61]. In turn, Le Campion et al. [31] state that the availability of nitrogen at the period of stem formation is the main factor limiting the yield of winter cereals grown in the organic system.
When selecting cultivars that perform best in organic conditions a given cultivar should be assessed in terms of its characteristics important from the point of view of farmers and organic processors [50]. In our research it was found that both higher resistance to pathogens and Triticale is suitable for growing in organic farming due to its stable yield, tolerance to marginal conditions, resistance to diseases, and high competitive ability against weeds [24,32]. According to Wenda-Piesik and Wasilewski [60], triticale performs much better in less favorable habitat conditions, such as dry soils with nutrient deficiencies, unfavorable temperature distribution, or organic farming conditions, compared to wheat. Triticale yields are influenced by cultivar, local climate, agro-ecological conditions, mineral fertilization, protection against diseases, weeds and pests [61]. In turn, Le Campion et al. [31] state that the availability of nitrogen at the period of stem formation is the main factor limiting the yield of winter cereals grown in the organic system. When selecting cultivars that perform best in organic conditions a given cultivar should be assessed in terms of its characteristics important from the point of view of farmers and organic processors [50]. In our research it was found that both higher resistance to pathogens and competitiveness against weeds were important features of a cultivar and that they influenced its grain yield. Furthermore, the level of weed infestation was correlated with the tillering and height of plants, the density of triticale plants and the dry mass of the above-ground parts of the canopy. Kronberga's study [32], conducted in Latvian conditions, confirmed that important traits for organic crop ideotype of triticale are: good winter hardiness, resistance to snow mold, good weed competitiveness, early maturity, prostrate growth habit, and greater leaf size. According to Koziara et al. [62], primarily genetic conditions, and to a lesser extent habitat conditions and the applied agrotechnology determine the achievement of satisfactory yields and that is why it is so important to look for and select suitable cultivars for organic farming.

Conclusions
It can be concluded that under the conditions of the organic system the Borowik cultivar of triticale showed the highest competitive ability against weeds, while the Leontyno cultivar showed the smallest. The number of weeds was significantly negatively correlated with the tillering and height of plants, as well as with the density of triticale plants and the dry matter of the above-ground parts of the canopy. The pathogens most infesting the triticale cultivated in the organic system were Drechslera tritici-repentis (Died.) Shoem. and Puccinia striiformis Schwein. The least infested cultivars were Twingo and Pizarro. The highest-yielding cultivars in the organic system were Pizarro and Subito. The Borowik cultivar had the highest 1000 grain weight. Two groups of triticale cultivars with features that identify them as suitable for cultivation under conditions of organic production were distinguished. The first group consisted of the cultivars: Borowik, Subito, Tomko, and they have the highest yielding potential, higher competitiveness against weeds, and average resistance to fungal pathogens occurring on leaves. The second group consisted of the cultivars: Pizarro, Tulus, Twingo, which showed higher resistance to fungal pathogens than the first group, but lower competitiveness against weeds. The least useful cultivars for the organic system turned out to be: Algoso, Fredro, Grenado, and Leontyno. Our results showed also that it is possible in organic agriculture to obtain a yield of cereals that is similar or even higher than that obtained from the conventional system.