EFFECT OF THE SOWING DIRECTION ON THE YIELDING OF SUGAR AND FODDER BEET

Aleksander Szmigiel, Marek Kołodziejczyk
Department of Plant Production, Agricultural University of Cracow, Poland

ABSTRACT

The paper presents the results of field studies conducted over 2001-2003 at the Experimental Unit located at Prusy near Krakow to determine the effect of the sowing direction on yielding of sugar and fodder beet and the contents of dry matter, sugar and protein in roots. The experiment was set up on a degraded chernozem developed from loess and classified as very good wheat complex. The factors investigated comprised sowing directions (north-south and east-west) and beet root cultivars: Arosa and Vectra (sugar beet) and Goliat and Krakus (fodder beet). The average root yield of the sugar beet cultivars studied was 77 t per ha, whereas fodder beet – 105 t per ha. The investigations revealed no significant effect of the sowing direction on the beet root yield. However, such relationship was registered for the yield of leaves and the contents of dry matter and sugar in roots. A bigger yield of leaves, by an average of 4.7% and higher concentrations of dry matter and sugar in roots, by 0.8 and 1.0%, respectively, were registered when sowing was performed in the north-southern direction. The average content of dry matter in sugar beet roots was 23% and sugar 17.8%, whereas for fodder beets – 13.9% and 10.6%, respectively.

Key words: sugar beet, fodder beet, sowing direction, root yield, sugar content .

INTRODUCTION

The plant productivity or the amount of biomass produced during the process of photosynthesis depends on the interaction between the genotype, weather and agronomic conditions over the vegetation period. In order to produce a potential yield, i.e. the one which can be actually obtained, plants need an adequate supply of  water and minerals, eliminating all negative factors, such as diseases, pests or weeds, but, above all, a  definite amount of solar energy. Therefore the proper plant habit, plant density and the spatial leaf positioning to ensure the maximum utilization of solar energy are very important. The direction of sowing is a non-agronomic factor unconnected with the outlays but significantly determining the amount of solar radiation absorbed by the crop stand and thus affecting the quality and quantity of yield. Baker and Meyer [1] revealed that the north-south oriented rows are better insolated than those of east-west orientation. The results of investigations into the effect of the direction of sowing on crop yields are not unanimous. Clarke et al. [2] obtained a higher level of wheat yield with east-west row orientation. On the other hand, Szmigiel [7,8] demonstrated that north-south is a more advantageous direction of sowing. Cereals sown in this direction yield better than those from the east-west row orientation and the grain is more abundant in protein. Also in sugar beet cultivation a larger yield of roots and leaves, higher dry matter and sucrose content were found in the roots of plants sown in the north-southern direction [11]. In spite of their characteristic large area, the beet root leaves develop relatively late, which especially in dry years cause higher soil heating and unproductive water evaporation, which, in turn, may affect the amount and quality of the root yield.

The investigations aimed at determining the effect of north-southern and east-western directions of sowing on the amount of root yield, leaf mass and the contents of dry matter, sugar and protein in sugar and fodder beet roots. It was assumed that the level of yielding and the chemical composition of roots would diversify the positioning of beet rows with reference to the quarters of the world.

MATERIAL AND METHODS

The field experiments were conducted over 2001–2003 at an experimental unit at Prusy near Krakow on a degraded chernozem classified as very good wheat complex. The soil was characterized as medium-to-high phosphorus content, low-to-medium abundance in potassium and slightly acid reaction. The experiment was set up following the split plot method and the plot area was 15 m². The factors analyzed comprised: sowing directions (north-south and east-west) and beet root cultivars: two sugar beet cultivars (Arosa and Vectra) and two fodder beets (Goliat and  Krakus). Winter wheat constituted the forecrop. Mineral fertilization was applied at the following doses: 120 kg N·ha^-1 (80 + 40), 80 kg P₂O₅·ha^-1 and 120 kg K₂O·ha^-1. Beet seeds were sown each year in the third decade of April. Single-grained sowing was used to sow sugar beet and fodder beet, Krakus at 45 x 18 cm spacing, whereas seeds of fodder beet, Goliat, at the amount of 18 kg·ha^-1 were sown by means of seed drilling. The destined plant density was 80000 plants. Weeds were controlled using Betanal Progress 274 OF chemical preparation at the dose divided into 1.3 and 1.6 l·ha^-1. The plants were harvested in the second decade of October. The yield of roots and fresh leaf weight were assessed. Subsequently root samples were collected from each plot to determine their chemical composition. The contents of dry weight were defined (applying the gravimetric method), sugar (the polarimetric method) and protein (total N – following the modified Kjeldahl method and converted into total protein with the use of 6.25 coefficient value). The results were statistically verified using the analysis of variance. The significance of differences was assessed with Tukey's test at the significance level α = 0.05.

Climatic conditions during the period of investigations were diversified. The growing season in 2001 was marked by a particularly great amount of rainfall in April, July and September, but relatively small amount in October. The average air temperature in April and September was slightly lower and in October slightly higher than the average for the last decade (1994–2003). The total precipitation measured during the period of April-October 2002  approximated to the multi-annual average. The mean air temperature during this period was also at the level of the average temperature for the last decade, however May was warmer but September and October were cooler. The growing period in 2003 belonged to the dry ones (with rainfall amount almost 200 mm lower than the average) and warm (particularly in summer months). Over the three-year period of the investigations the least average value of daily solar radiation 15.2 MJ·m^-2 was recorded in the beet vegetation period in 2001. In the other years of the studies, i.e. 2002 and 2003, the quantity of total solar radiation was on average 16.1 MJ·m^-2·d^-1.

RESULTS AND DISCUSSION

The effect of precipitation, temperature and insolation on the root yield and sugar content in the roots has been relatively well recognized, however the present results are not always in agreement. As reported by Nowak [4], sugar beet and fodder beet cultivated in very good wheat complex conditions produced the largest yields when exposed to the precipitation between 400 and 500 mm. On the other hand, Rudnicki et al. [6] claim that the highest root yields may be obtained at the total precipitation of 340 mm and the mean daily temperature of 14.5°C, whereas the leaf yields at the precipitation over 400 mm and the temperature of 13.6°C, which suggests that the effect of precipitation and temperature on the root yield is different than on the leaf yield. The present results only partially confirm the above dependence since the largest root and leaf weight was produced by beet root plants in the 2001 growing season characterized by the highest total precipitation and the lowest mean air temperature during the three year period of investigations. On the other hand, the lowest beet root and leaf yield (particularly in fodder beets) was recorded in 2003, which was warmer and drier than the average.

The present experiments revealed no significant effect of the sowing direction on the beetroot yield (Table 1). Such significance was found for the leaf yield. The plants produced as a result of the north-southern sowing developed, on average, 4.7% higher weight (Table 2). The increase in the yield of both beet leaves and roots (respectively by 2.0 and 3.4 t·ha^-1) between the north-southern and east-western sowing directions were reported by Ziółek [11]. On the other hand, Szmigiel [7,8] and Śniady and Ziobrowski [10], who investigated the effect of the sowing direction upon winter and spring cereal yielding, demonstrated  no significant effect but only a tendency for increased grain yields for the north-southern sowing, as compared with the east-western direction.

The fresh weight yield of beet roots and leaves were significantly diversified by the cultivar factor. Of the sugar beet cultivars, a larger root yield, on average 79.4 t·ha^-1, was produced by Vectra than by Arosa, which yielded at the level of 75 t. As reported by Malec [3], the quantity of sugar beet root yield only to a slight degree, i.e. in 5%, depends on the cultivar factor. In the fodder beet group, Goliat plants produced a higher yield, on average 105.6 t·ha^-1, whereas Krakus beets yielded by 2 t lower. The yield of sugar beet leaves was at the level of 32 t per ha, while in fodder beets – on average 31.3 t for Goliat and 33.9 t·ha^-1 for Krakus. The foliage coefficient of sugar beets was on average 0.41, whereas in fodder beets – 0.31 (Fig. 1). Beetroot sowing in the north-southern direction caused a slight increase in the coefficient value.

The direction of sowing had a significant influence on the dry weight and sugar content in beet roots (Tables 3 and 4). A higher content of dry matter and sugar in roots, respectively by 0.8 and 1.0%, were found in sowing in the north-southern direction. Ziółek [11] reported on  similar results and provided an explanation of the increase in the dry matter and sugar contents in sugar beet roots for the north-south rows arrangement thanks to a more intensive photosynthesis due to a higher plant insolation.

The present research did not demonstrate any significant dependency between the direction of sowing and the protein content in beet root, however a tendency for higher content of this component was recorded for the east-west rows arrangement (Table 5). Szmigiel [7,8,9] investigated  the effect of the sowing direction on the protein content in cereal grain and found its significantly higher content for sowing in the north-southern direction, whereas Ziółek [11] did not reveal any significant relationship between the nitrogen content in sugar beet roots and the direction of sowing.

The contents of dry matter, sugar and protein in the beet roots were also markedly modified by the cultivar factor and weather conditions pattern during the plant growing season. The average content of dry matter in the roots of the sugar beet cultivars researched was at the level of 23.5% and sugar – 17.8%, while in fodder beets the values were, respectively, 13.9% and 10.6%. In sugar beets group Arosa revealed higher contents of both dry matter and sugar, while Krakus among fodder beets. According to Malec [3], of the natural and agronomic factors, the effect of the cultivar factor on the sugar content in beet roots is small (3%). Weather conditions have a greater influence (10%) on its content. Under conditions of low or moderate temperature (to 14.5°C), usually combined with a considerable amount of precipitation, the sugar content in beet roots clearly diminishes, whereas at higher temperature and moderate precipitation its content increases [6]. A significant technological dependence of the root quality on air temperature, particularly in the final period of sugar beet development, was reported also by Pačuta et al. [5]. In the present investigations the growing season in 2003 proved the most beneficial for sugar accumulation, irrespective of the beetroot usable form or cultivar as it was characterized by a moderate amount of rainfall and mean air temperature higher than the average. The year 2001 was the least favorable because it was cooler, with total precipitation from April to October over 650 mm. The average protein content in the dry matter of sugar beet root for cultivars was 4.68%, while in fodder beet it was, respectively, 7.38%. During the three-year period of research the highest protein content in beet roots, on average, 6.76% was recorded in 2002 and the lowest, 5.43%, in 2003.

CONCLUSIONS

1. The sowing direction did not determine the beet root yield but affected the leaf yield. Beetroot plants from the north-south oriented rows formed a greater leaf weight than those sown in the east-western direction.

2. The dry matter content in sugar beet and fodder beet roots sown in the north-southern direction was, on average, 0.8% higher and the sugar content 1.0% higher than in the plants in the east-west oriented rows.

3. The row orientation did not significantly affect the protein content in roots. On the other hand, a tendency for its higher content was observed in beet roots cultivated in the east-west orientation.

REFERENCES

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Accepted for print: 10.04.2009

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