EFFECT OF SELECTED AGROTECHNICAL FACTORS ON WINTER DURUM WHEAT YIELDING

Barbara Chrzanowska-Drożdż¹, Andrzej Kotecki¹, Jarosław Bojarczuk^2
1 Department of Plant Cultivation, Wrocław University of Environmental and Life Sciences, Poland
² Smolice Plant Breeding, IHAR Group

ABSTRACT

Over 2005-2008 at the Agricultural Experiment Station Pawłowice, in the vicinity of Wrocław, there was investigated an effect of sowing rate (Experiment 1) and plant protection method (Experiment 2) on the components and grain yield size of durum winter wheat, Komnata cultivar. Overwintering of Komnata plants in each research year over mild winters were evaluated to be very good. In Experiment 1, 400, 500, 600 and 700 grains·m^-2 were sown. Komnata demonstrated very low productive tillering capacity over the research years. The highest Komnata grain yield (4.66 t·ha^-1) was observed under semi-drought conditions in 2006. Increasing the sowing rate increased the number of productive spikes per area unit, decreased the number of grains per spike and 1000 grain weight, which resulted in a decrease in productivity per spike. Komnata did not react with an increase in the grain yield when the higher sowing rate of 600 and 700 grains·m^-2 was applied, as compared with the yield recorded for the sowing rate of 500 grains·m^-2. Experiment 2 investigated the effect of the chemical plant protection method: (0) – without protection – control; (Z) – seed dressing; (1x) – seed dressing + 1x fungicides; (2x) – seed dressing + 2x fungicides on the durum wheat yielding. Dressed sowing seed and a single fungicide treatment decreased the plant infection with fungal pathogens. The chemical plant protection methods applied, as compared with the control (with no protection) increased the number of spikes per area unit, number of grains per spike and 1000 grain weight, which enhanced the productivity per spike. Wheat grain yield for the seed dressing treatments (Z) was significantly higher than the no-protection yields (0). The plant protection method which involved dressed sowing seed and 2-time fungicide treatment (2x) was more favourable to the grain yield than seed dressing and a single fungicide treatment.

Key words: winter durum wheat, sowing rate, chemical protection method, yield structure components, grain and straw yield.

INTRODUCTION

Durum wheat (Triticum durum Desf.), besides common wheat (Triticum aestivum L.), enjoys the greatest economic importance globally. Due to unique grain quality characters; a high content of protein and gluten, high glassiness and hardness as well as the content of yellow pigments, it is considered the best raw material for pasta production [4,6,16]. In 2007 the total world production was 34.8 m tonnes of durum wheat grain, mostly in the EU (8.4 m tonnes); Canada – 3.7; the US – 2.0; Turkey – 2.7; Algeria 2.5; Tunisia – 1.4; Morocco – 0.5; and the other countries: 13.6 m tonnes [8]. Most of the global production comes from the plantations of spring cultivars, showing a good quality, however, yielding low.

The highest-quality semolina is produced from the continental dry climate regions. Durum wheat is resistant to drought; its transpiration coefficient is, on average, 300 dm³ of water per 1 kg d.m. produced and it is much lower than in common wheat. The semolina quality is mostly deteriorated by excessive rainfall over formation, ripening and harvest, while for the highest grain yield, it needs most precipitation over the shooting phase, tillering and flowering [10,16,19].

In 2003, the breeders of the first Polish cultivar, Komnata, of Smolice Plant Breeding acquired a temporary exclusive right to this cultivar. In 2009 it was entered into the Domestic Cultivar Register. In Poland so far no research has been performed which would cover the agronomic practises of winter durum wheat. The results reported by some authors [17,18,19,21] concern the research into spring durum wheat, most frequently foreign lines and cultivars.

The agronomic requirements of Komnata cultivar are scarcely known and so it seems justifiable to investigate a further development of agronomic components, including the sowing rate and chemical protection against pathogens, especially their effect on the grain yield.

The working hypothesis formulates a question why winter durum wheat cultivar would react differently to the experimental factors that the common wheat.

MATERIAL AND METHODS

Two independent single-factor Komnata durum wheat field experiments were carried out over 2005-2008 at the Agricultural Experiment Station Pawłowice, of the Wrocław University of Environmental and Life Sciences. The experiments were set up following the randomised split-plot design, in 4 reps, on the good wheat complex soil, III b class, on the stand after winter rape. Experiment 1 investigated the effect of four sowing rates: 400, 500, 600 and 700 grains·m^-2 on the yield structure components and yielding in Komnata. Nitrogen fertilisation in a form of ammonium nitrate was applied at the dose of 90 kg·ha^-1 (60 + 30) in early spring (BBCH 29) and at the shooting phase (BBCH 32).

Experiment 2 investigated the chemical control against fungal diseases on the yield structure components and the grain yield: (0) control – no protection applied; (Z) – seed dressing with Panoctine 350 SL in 2005 and in 2006 and with Maxim 025 FS in 2007; (1x) – seed dressing and a combined fungicide application (Alert 375 SC and Talius 200 EC); (2x) seed dressing and a combined fungicide application (Alert 375 SC and Talius 200 EC + (Charisma 250 SC and Acanto 250 SC). The preparations were applied following IOR guidelines for common wheat. The sowing rate was 500 grains·m^-2, while nitrogen fertilisation: 60 + 30 kg N·ha^-1.

The content of phosphorus in soil in 2005 and in 2006 was high (66 and 69 mg·kg^-1), in the last year, 2007, it was average (49 mg·kg^-1). In all the research years, the richness with potassium was average (124 mg·kg^-1), whereas with magnesium – average (58 and 60 mg·kg^-1) in 2006 and in 2008 and high (72 mg·kg^-1) in 2007. Reaction pH_KCL of soils was slightly acid in the first and the second year (5.7) and acid (5.2) in 2007.

The tillage applied was typical, usual as for winter cereals: skimming, pre-sowing plough, pre-sowing tillage with the cultivation unit. Phosphorus-potassium fertilisers at the dose of 18 kg P·ha^-1 and 58 kg K·ha^-1 were used pre-sowing. Wheat was sown on September 26, 2005, Setember 23, 2006 and September 26, 2007 at the row-spacing of 12.5 cm, 3 cm deep. The plot for harvest was 16.5 m² in size. In the autumn of 2005 and 2006 Cougar 600 S.C. was applied to control the weed infestation, and in 2007 – Maraton SC 375 herbicide. In the spring of 2007 and 2008, Aminopielik D 450 was applied. Experiment 1 involved the use of the fungicide mixture: Alert 375 SC at the dose of 0.8 dm³·ha^-1 + Talius 200 EC at the dose of 0.15 dm³·ha^-1. The plant density was counted 12 days after emergence and after over-wintering on the plot 1 m² in size and, based on that, the percentage of plants after wintering was calculated. Prior to harvest, there was determined the number of productive spikes per 1 m². For 20 spikes biometrical measurements were made. The grain yield was investigated maintaining constant moisture of 13% and the straw yield – for the water content of 15%. Wheat was harvested using the plot combine-harvester on July 24, 9 and 22 in successive years.

The results were statistically verified applying the analysis of variance; the significance of differences was verified with the Student's t-test at a = 0.05.

Temperature conditions over the research period are given in a form of temperature deviations from the many-year mean, while precipitation was a percentage of the average total precipitation for 1975–2005. The pattern of weather conditions over research differed a lot (Table 1). In the first research year there was noted a higher temperature, except for November, January, February and March, than in the many-year period (deviation of +0.8°C – warm period). In the second year of the vegetation period, in all the months temperature exceeded the multi-year mean and the temperature deviation was highest (+2.6°C – very warm period). In the third vegetation period, except for September, October and November, the mean air temperature exceeded the many-year mean (deviation +1.0°C – warm period). At the same time the total precipitation in the first year of vegetation accounted for 89% of the many-year mean total for the years 1975–2005. This period recorded very dry autumn, wet winter and very dry spring (except for April) and precipitation deficit at the beginning of summer vegetation period.

The 2006-2007 growing season, unlike the previous one, included a very wet autumn and winter, very dry spring and abundant precipitation in June and July. The total precipitation exceeded the mean many-year total by 25%. The third growing season, 2007-2008, recorded very wet autumn and winter, exceptionally high rainfall was noted in April, while May through July were dry. The total precipitation of the vegetation period was 12% higher than the mean many-year total.

RESULTS

In Experiment 1, the number of plants after emergence at the sowing rate of 400 and 500 grains·m^-2 accounted for 98 and 93% of the planned sowing rate, and when the sowing rate was increased from 600 to 700 grains·m^-2, it decreased by 15 and 13%, respectively. The least favourable conditions over plant emergence were recorded in the third vegetation period, in 2007. In the initial growth period rainfall was excessive and distributed unevenly, which resulted in poor and delayed plant emergence. Plant losses after emergence accounted for, on average, 13% and the losses were highest in the case of high sowing densities. Due to mild winters, Komnata overwintering must be considered satisfactory in each research year. Irrespective of the research years and the sowing rates applied, overwintering was almost full and, on average, it accounted for 95%. Due to very good plant overwintering, the plant number after winter was similar as the number of plants after emergence. Tillering of durum wheat in three vegetation periods was poor; a single plant developed, on average, 1 stem with the spike. With the increasing sowing rate from 400 to 500 grains·m^-2, the productive tillering coefficient decreased slightly, yet significantly, from 1.13 to 1.05, at a high sowing rate of 600 grains·m² it did not change, while at a very high sowing rate of 700 grains·m^-2, it decreased significantly, reaching the value of 0.87 (Table 2). When exposed to such a high sowing rate, 600 and 700 grains·m^-2, as compared with the control, the values of most morphological characters of plants, such as: stem length, spike length and the number of spikelets per spike were getting lower. Significant differences occurred between extreme sowing rates (Table 2).

The number of productive spikes differed over the research years (Table 3). In the first and third year it was similar, while in the second year – it was highest (505 pcs·m^-2), which was determined by slightly, yet significantly, higher productive tillering. The number of spikes per area unit increased significantly up to the sowing rate of 600 grains·m^-2, while increasing the number of the grain sown to 700 pcs·m^-2 did not differentiate that character since it was increasing non-proportional to the amount of grains sown per 1 m². The number of grains per spike depended on the weather conditions over years. In the second research year plants produced the highest number of spikes, which showed the lowest number of grains per spike (18.8). The number of grains per spike in low-rate sowing, 400, and in medium-rate sowing, 500 grains·m^-2, was stable from 21.6 to 20.0, while at high sowing rates, 600 and 700 grains·m^-2, the number of grains per spike decreased, respectively, to 18.6. In the first and third research years, durum wheat grain demonstrated very high 1000 grain weight; 63.4 and 62.9 g. In the second year, 1000 grain weight was lowest (57.6 g). As for low sowing rates, the grain plumpness was highest and showed little differences, whereas an increase in the sowing rate to 600 and 700 grains·m² resulted in a significant decrease in 1000 grain weight. There was identified no interaction between the research years and the sowing rate in numerical values of this important yield component. In the second research year, the grain weight per spike was lowest and differed significantly from the average value of the character in the other years. As compared with the lowest sowing rate, 400 grains·m^-2, each increase by another 100 grains·m² up to 700 resulted in a decrease in the productivity of 1 spike.

Durum wheat grain yield (Table 4) differed significantly between research years and the sowing rates. The lowest grain yield (4.05 t·ha^-1) was recorded for a low sowing rate. An increase in the sowing rate to 500 grains·m^-2 triggered a significant 7% increase in the yield. A further increase in the sowing rate to 600 and 700 grains·m^-2 did not differentiate Komnata yielding. Under a varied sowing rate, the net grain yield (grain yield per 1ha decreased by the grain weight for sowing) did not differ significantly. The wheat straw yield did not differ for the sowing rate from 400 to 600 grains·m^-2, however, as a result of an increase in non-productive tillering (stems without spikes), it increased significantly for the highest sowing rate.

In Experiment 2, the number of plants after emergence ranged from 454 to 464 pcs·m^-2, which, on average, accounted for 90% of the real sowing rate (Table 5). The number of plants after over-wintering was, on average, 443 pcs·m^-2 and accounted for 96% of the total number of plants after emergence. The highest number of plants after over-wintering was recorded in 2006, slightly fewer in 2007 and 2008. Productive tillering in all the research years was very poor, similarly as in experiment 1; a single plant produced, on average, 1 stem with a spike. Morphological characters of plants expressed as the stem length, the spike length and the number of spikelets per spike depended on the weather pattern and the plant protection methods applied. In 2007 wheat demonstrated the shortest spike and the lowest number of spikelets per spike and the longest stem. The plant protection method differentiated neither the stem length nor the number of spikelets per spike. Single and 2-time fungicide treatments (1x and 2x) increased the spike length.

The number of productive spikes in wheat varied and differed significantly between extreme plant protection methods; it was 434 pcs·m^-2 with no protection applied and 457 pcs·m² when fungicides were applied twice (2x), respectively (Table 6). A slight, yet significant, increase in the number of grains per spike (3 pcs) was identified as compared with the control as a result of 2-time protection treatments (2x). The lowest number of grains per spike was observed in 2007, significantly more in 2008 and most in 2006. The 1000 grain weight in wheat depended on the research years and the plant protection method. As compared with the control, seed dressing resulted in a significant increase in the 1000 grain weight by 1.5 g. As far as seed dressing is concerned, a two-time application of fungicides increased the 1000 grain weight by another 0.9 g. In the unfavourable year 2007, the 1000 grain weight was lowest and it was 55.8 g. In the more favourable years, 2006 and 2008, it was much higher, 66.0 and 65.2 g, respectively. Low 1000 grain weight and low number of grains per spike in 2007 resulted in the lowest grain weight per spike (1.22g). This character varied depending on the extreme protection methods; it was, respectively, 1.32g when no protection was applied and 1.43 g when fungicides were used twice (2x).

Over the research period, there were observed differences in the occurrence of powdery mildew of cereals and grasses (Blumeria gramins (DC.) Speer), brown rust (Puccinia recondita Rob.ex Desm) and take-all diseases. The research results on the occurrence of diseases and the degree of their harmfulness have been published earlier [12].

Despite a low intensity of fungal diseases, there was recorded a favourable yield-protecting effect of the protection methods applied against fungi. The grain yield in wheat differed between research years and the chemical control method (Table 7). In 2007 it was significantly lower than the yield recorded in 2006 and in 2008, between which no variation was shown. The protection method in a form of seed dressing (Z) secured 0.38 t·ha^-1 of the yield significantly. Seed dressing with a single fungicide treatment (1x) was no longer effective, despite a slight yield increase by 0.09 t·ha^-1. An intensive plant protection which involved seed dressing and 2-time fungicide treatment, as compared with dressing and a single use of fungicides protected 0.07 t·ha^-1 of the yield (non-significant difference). The durum wheat straw yield over years was double the grain yield. In 2007, the lowest grain yield coincided with the highest straw yield (6.40 t·ha^-1). Under intensive plant protection (2x), there was reported the highest straw yield (5.92 t·ha^-1) which did not differ significantly from the yield of the (1x) treatment.

DISCUSSION

Variable weather conditions throughout the research years had an essential effect on the development, morphological characters of plants prior to harvest, the occurrence of fungal pathogens, yield structure components and the durum wheat grain and straw yield size. Komnata grain yield for three research years ranged from 3.58 to 4.66 t·ha^-1 and it was lower than the potential yield reported by the breeders of that cultivar [2].

According to the Komnata breeders, its winter-hardiness is comparable to the average winter-hardiness of common wheat cultivars (4-5°). In the present research, overwintering was satisfactory and it accounted for, on average in the research years, in both experiments, 95% (score 9 on the COBORU scale).

The sowing rate is a very important component of agronomic practises for wheat, not only due to its essential effect on the grain yield, occurrence and harmfulness of pathogens but also due to high sowing material prices. Winter wheat shows spontaneous control of plant density per area unit [9,13,14,15]. An excessively high sowing rate can decrease the survival rate of plants and their fall-out and decrease the productivity of the remaining ones, with no effect on the grain yield size. Defining optimal values of the yield structure components which would condition high wheat yields is difficult since, depending on the genotype, environmental conditions and the weather pattern, there are considerable compensation possibilities. The productivity of a single plant does not stand for the optimal level of characters of the high-production field structure. The field productivity is connected with the number of spikes per area unit, the number of grains per spike and the kernel weight (1000 grain weight). The productivity of a single plant is connected with its productive tillering, the number of grains per spike and 1000 grain weight. The number of grains per spike depends on the number of spikelets per spike and the number of grains per spikelet; most frequently, the higher the sowing rate, the lower the number of grains per spike [9,14]. An essential cause of a decrease in the yield for higher sowing rates is non-productive tillering, decreasing the possibility of a high spike density per area unit. From tillering to ear-formation, the tillers compete with the main stem for light, water and nutrients, and wither later but, at the same time, as a result of a strong growth during the vegetation period, limit the production potential of the main stem. The present results coincide with that thesis. The tillering of durum wheat was very poor, most often the plant consisted of a single stem with a spike. Similarly as the number of spikes per area unit, also the number of grains per spike depended on the sowing rate. In the present research the number of grains per spike for low sowing rates, 400 grains·m^-2, and average sowing rates, 500 grains·m^-2, was getting stable, while high sowing rates, 600, and very high sowing rates, 700 grains·m^-2, decreased that value from 20.0 to 18.6 kernels per spike. The 1000 grain weight most frequently depends on the genotype, namely the cultivar and weather condition pattern over ripening [9,13,14]. Similar observations were made in the present research; a higher 1000 grain weight (63.4 and 62.9 g in 2006 and 2008) was reported in 2007 (57.6 g). The spring and summer of 2007 recorded a higher mean temperature than the many-year mean and scarce rainfall, the deficit of which shortened respective developmental phases, and thus resulted in poorer kernel filling.

In the present research the Komnata grain yield was increasing up to the sowing rate of 500 grains·m^-2, and then got stable. As for the sowing rate of 700 grains·m^-2, in the first and the second research year it got slightly lower (non-significant difference). There was identified no effect of the interaction between the years and the sowing rate on the grain yield. Irrespective of the weather conditions over years, high sowing rates turned out to be unjustifiable, which was seen from no significance of the differences in the net grain yield. Dubis and Budzyński [5] pay attention to the effect of the weather pattern during the spring and summer vegetation of wheat; according to the authors, low sowing rates of common wheat, 120 and 240 grains·m^-2, guarantee high grain yields provided that the wheat growth and development in spring coincides with good humidity conditions, whereas under semi-drought conditions in spring, the high sowing rates of 480 and 600 grains·m^-2 are more favourable. Similarly Śniady and Sobkowicz [20], sowing 250 grains per m² at the early and optimal date, recorded a higher grain yield than in the case of high sowing rates (450 and 650 grains per m²). The reports by Sulewska [18] show that the optimal sowing rate for spring durum wheat forms is 500-600 grains per m², while Rachoń [17] recommends 600 grains·m^-2. No differences in the common wheat yield as a result of varied sowing rates are reported by Podolska [14].

The common occurrence of pathogens and their high pathogenicity caused by fungi towards winter wheat plants are demonstrated by Balsom et al. [2], Jańczak et al. [7] and Pląskowska et al. [12]. In the present research the lowest durum wheat grain yield was reported for the control – with no protection applied (3.52 t·ha^-1). As for the chemical control treatments (Z, 1x and 2x), there was reported the highest yield as a result of intensive protection which involved seed dressing and 2-time use of fungicides (4.06 t·ha^-1). The application of such a plant protection method resulted in a significant increase in yield, as compared with seed dressing, and similar (non-significant) – as compared with dressing and a single use of fungicides. The number of productive spikes and the number of grains per spike were slightly modified by the plant protection method; significant differences were found between the extreme plant protection methods (Z and 2x). Seed dressing and 2-time application of fungicides, as compared with the control, resulted in the highest increase in 1000 grain weight. Earlier reports by Pląskowska and Chrzanowska-Drożdż [12] showed that the seed dressing itself considerably enhanced the plant health status, protecting the plants against infection with Blumeria graminis and Puccinia recondita. Jańczak et al. [7] claim that wheat grain dressing, as a pre-sowing plant protection treatment, does not always guarantee a high yield increase, however, it enhances the health status of plants and constitutes the first stage of further control of fungi. Rachoń et al. [17] report on a higher spring durum wheat grain yield as a result of intensive control than in the case of minimal protection which involved seed dressing only. Similarly, Balmos et al. [1], Cavelier et al. [3] and Ciołek and Makarska [4] report on higher durum wheat yields due to comprehensive plant protection. However, there are reports in which intensive protection did not increase the spring durum wheat yield, Woźniak [21]. Panasiewicz et al. [11] showed that growing Komnata durum wheat with no fungicides applied can provide satisfactory results and, therefore, they recommend organic farming for this cultivar.

In domestic literature one can find fragmentary and scare coverage on agronomic factors, including the sowing rate and chemical control of durum wheat, and so foreign reports can be considered of little relevance and only of little reference for domestic conditions. Further research on optimizing agronomic factors for this cultivar is needed.

CONCLUSIONS

1. Under the climatic and soil conditions of the Lower Silesia, Komnata durum wheat overwintering was satisfactory.

2. On good wheat soil, the stand after winter oilseed rape and under semi-drought conditions recorded the top yielding (4.66 t·ha^-1) in Komnata cultivar.

3. Komnata did not show any differences in yielding depending on the sowing rate from 400 to 700 grains·m^-2, and thus lower sowing rates are possible for this cultivar.

4. Increasing the sowing rate from 400 to 700 grains·m^-2 increased the number of productive spikes per area unit; the number of spikes did not compensate for the low productivity of a single spike, caused by a decrease in the number of grains per spike and decreased 1000 grain weight.

5. Wheat field protection against fungal pathogens, as compared with the control, with no protection applied, which involved seed dressing and the application of a single fungicide treatment ensured a favourable pattern of the values of the yield structure components and, finally, resulted in a significant increase in the grain yield.

6. In order to determine the agronomic requirements, including the sowing rate and chemical plant protection, further research in this field is indispensable.

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Research work financed from the science funds over 2006–2009 as research project no 2 P06R 032 30

Accepted for print: 23.06.2009

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