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Photosynthetic capacity and productivity of hybrids of sugar beet
Section 7. Agricultural sciences
Zheryakov Evgenie Viktorovich, candidate of agricultural sciences, assistant professor, FSBEE HPT «Penza State Agricultural Academy» E- mail: sher20063@rambler.ru
Photosynthetic capacity and productivity of hybrids of sugar beet
Abstract: The research has shown that the largest area of leaves which provides high photosynthetic potential of plants is observed in hybrids Nero, Spartacus and Hercules. On the basis of the conclusion which has been drawed sugar-beet hybrids with high productivity are singled out. Their productivity was determined on the basis of sugar content of roots and collection of them per hectare.
Keywords: sugar-beet, photosynthesis, photosynthetic potential, leafarea, productivity, sugar content, cercosporosis.
In Russia growing area of sugar beet considerably decreased over the last three years — from 1 million to 292 thousand hectares in 2011 to 905,8 thousand hectares in 2013, and in the Penza region from 61.2 thousand hectares to 46.8 thousand hectares. One of the main reasons for this is not only the problem of implementation of harvest, but the critical situation of the spreading of root rot, lesion of leaf surface with various diseases, which caused significant losses with keeping. At present there is an increase of merchandise of breeds, at the same time the proportion of hybrids of foreign selection is increasing. There are 332 varieties and hybrids of sugar beet in the state registry of selection achievements approved for use on the territory of the Russian Federation on 1st February 2013, among them there is only 24 % of domestic breeding. Foreign breeding hybrids have various degrees of adaptation to specific soil and climatic conditions of Russia, and it can be confirmed by the fact that yield and sugar content are not always high, and there is often a high percentage of diseases [2; 4]. This causes the need for competitive variety trial. The variety is a leading element of the technology, as not only the level ofyield and quality ofroots, but sugar yield per hectare of sowing and tons of raw materials also are dependent on it. Thus along with the improvement of agrotechnics, application of new hybrids and varieties (that are resistant to diseases and unfavourable environmental factors and show high stable yield of root crops) to production plays an important role in the complex of measures aimed at solving the problems of increasing of production of sugar beet [1; 3; 6].
Field-work in the second agro-soil area of the Penza region was conducted to identify such hybrids. The scheme of the experiment included 8 options: 1 — HM 1820; 2 — Nero; 3 — Hercules; 4 — Triada; 5 — Spartacus; 6 — Volga; 7 — Compact; 8 — RMS 120. The experiment must be conducted for three times, the accommodation of options is randomized. The total area of the plot is 0.4 hectares, the discount area of the plot is 0.3 hectares. During the years of the research conditions of vegetation were diversified. In 2012 the weather conditions
were established as follows: during the 1st and 2nd decades of May the average temperature was 12.9-19.0 °C, during the 3rd decade — 18.2 °C. The conditions of vegetation in June, 2012 were characterized with the optimal indicator of the temperature — 18.6 °C and sufficient moistening — 82.1 mm. In July the average daily temperature was 21.5 °C, the rainfall was less than the average annual quantity by more than 40 % — by
35,3 mm. The third decade was characterized by high average daily temperature of 20.6 °C, low moistening — 0,7 mm. Meteorological conditions of August also had a pronounced contrast. Precipitation in the 1st decade was 31.8 mm., and the medium temperature was 24.1 °C. In the second and third decades the monthly precipitation was 62.3 and 55.7 mm. respectively. The average temperature in August was also higher than the average long-term one — 25.6 °C. In 2013 weather conditions were as follows: during the 1st and 2nd decades of May the average temperature was 14.8-19,8 °C, for the 3rd decade — 18.0 °C. The rainfall was less than average one by 5 mm.; and 28 mm. were in the first and second decades of May. The conditions of vegetation in June, 2013 were characterized by an optimal indicator ofthe temperature — 19.1 °C and overmoistening (the number of precipitations exceeded at over 1.8 times and amounted to 106.0 mm). In July the average temperature was 19.1 °C, the rainfall was more than the average annual one by 12.8 % — 78 mm. The meteorological conditions ofAugust also had a pronounced contrast. The rainfaill in the 1st decade was 25 mm., and the average daily temperature was 19.3 °C. In the second and third decades there were only 19 mm. of rainfall. The average temperature in August was also higher than the average long-term one and amounted to 19 °C. In September, in the first and second decades the temperature was about 13-14 °C, and in the third decade the temperature fell sharply to 7 °C. September was on average long-term level according to the temperature indicators, and the amount of precipitation is more than average amount by 58 %. In the first decade of August there were 51.4 mm. of precipitation, in the second
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Section 7. Agricultural sciences
decade — 40.5 mm., in the third decade — 50.3 mm. From May till September there were 408.5 mm. of rainfall, and it is more than average long-term rainfall by 130.5 mm. during this period. The leaf area was determined by the method of cutting.
The basic process in determining plant productivity is photosyntesis. It is carried out in leaves. Photosynthesis can occur in other green parts of plants — stems, chides, green fruits and the like, however, the contribution of these parts to photosynthesis is usually small. It is accepted to compare the crops among themselves, and also different states of one sowing by the leaf area, identifying it with the notion of “as-similatory surface”, the major portion of which are leaves. In general form the optimal scheme for use of assimilants for growth processes can be presented as follows: in early growth period the majority of assimilants of a small photosynthetic apparatus is used for root growth. For further growth it is necessary for plants to provide themselves with the opportunity to obtain enough water and mineral nutrients. After this begins the increased use of assimilants for the growth of the photosynthetic apparatus itself — the leaf area. This is one of the most important periods of plant growth.
The research has shown that for 2 years on average the highest growth of assimilatory surface of leaves occurred from 1st July to the mid-August, and during the period of closing of row widths and intensive Saccharum accumulation it reaches the peak value. During this period exactly the formation of the future harvest occurs. Depending on the studied hybrids the leaf surface changed significantly. In 2012 among all studied hybrids the largest area of leaves was observed with Nero and Spartacus on 17 August — 62.45 and 61.99 thousand m 2/ha, respectively. The smallest assimilatory surface of leaves at the same day was determinated with hybrids RMS 120 and Compact, and it was 40.34 and 41.66 thousand m 2/ha, re-
spectively. In 2013 among all studied hybrids the largest area of leaves was observed on 13th August with Nero and Spartacus — 59.48 and 59.04 thousand m 2/ha, respectively. At the same day the assimilatory surface of leaves from 50 to 55 thousand m 2 was observed with hybrids Heracles (54.57), Triada (51.58) and SY Badia (51.10); about 45 thousand m 2 with hybrids Volga (46.71) and HM 1820 (44.34). The hybrids Compact and RMS 120 had leaf surface of less than 40 thousand m 2, 39.68 and 38.42 respectively.
According to A. Nichiporovich (1970), rapid growth of foliage up to 40-50 thousand m 2/ha is optimal. The most favourable growth development for the formation of yield of tubers is such growth development when after reaching the optimal size for such conditions leaves stunt. Probably they actively work longer in this state for the formation of important reproductive and storage organs, and then they die off, giving them a significant part of the stored plastic and energy substances [5]. The formation of a crop depends not only on the size of leaf area, but also on the time of its functioning. Photosynthetic potential (PP) combines these indicators. PP can be defined for any period of time, for example for decade or interphase periods, or for the vegetation period in general. Large area of leaves provides high photosynthetic potential of plants (table 1). According to the results of the research hybrid Nero had the highest value of PP for the vegetation period, it was 4.08 million m 2 • day/ha, it is less than the peak value of hybrid Nero by 1.96 % in 2012. PP from 3 to 4 million m 2 • day/ha was observed with hybrids HM 1820, Hercules, Triada and SY Badia. The rest of the studied hybrids had the meaning of PP of about 2.5-3.0 million m 2 • day/ha. The regularity discovered in 2013 confirms the ranking of hybrids by PP in 2012, with the only difference that the PP of all hybrids was higher by 1.02-1.96 % during the first year of research.
Table 1. - Value of the photosynthetic potential, million m2 • day/ha, 2013
Hybrid Periods
01.05- 02.06 03.06- 03.07 04.07- 14.07 15.07- 29.07 30.07- 13.08 14.08- 01.09 02.09- cleaning for the period vegetation
RMS 120 0.037 0.29 0.22 0.41 0.48 0.65 0.45 2.549
Compact 0.052 0.33 0.24 0.43 0.54 0.64 0.47 2.702
HM 1820 0.053 0.36 0.29 0.48 0.60 0.72 0.53 3.033
Nero 0.042 0.45 0.39 0.64 0.81 0.98 0.77 4.082
Hercules 0.052 0.46 0.37 0.59 0.74 0.89 0.69 3.792
Spartacus 0.051 0.42 0.36 0.63 0.79 0.98 0.77 4.001
Triada 0.059 0.44 0.35 0.56 0.70 0.85 0.65 3.609
SY Badia 0.053 0.45 0.36 0.56 0.69 0.84 0.65 3.603
Volga 0.033 0.28 0.26 0.48 0.63 0.75 0.55 2.983
At the beginning of vegetation the process of growing of biomass is slow, and then the pace of growth increases. At the end of vegetation when leaf area is small, the daily growth of biomass is also slow. At this time the process of redistribution of accumulated assimilants from leaves, stems and roots into the generative organs takes place.
The integral indicator of the activity of the assimilative apparatus is net photosynthesis productivity (NPP). It is
established that during the years of research its value depended both on determination period and studied hybrids. NPP varies during the process of vegetation. In the first month of the vegetation NPP is higher than in the next one, as in the beginning of the vegetation plants do not shade each other; all leaves are well lit. Later on with the increase of leaf area NPP begins to decrease due to shading of lower leaves (table. 2).
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Photosynthetic capacity and productivity of hybrids of sugar beet
Table 2. - Net photosynthesis productivity in interphase periods, average value for 2012-2013, g/m2 ■ day.
Hybrid Periods
shoots - three pairs of genuine leaves three pairs of genuine leaves - closing of leaves in row widths closing of leaves in row widths- cleaning three pairs of genuine leaves - harvesting
RMS 120 4.20 7.21 1.64 2.09
Compact 3.85 7.08 1.61 2.12
HM 1820 4.06 6.63 1.51 2.16
Nero 4.04 6.55 1.52 2.49
Hercules 3.88 6.20 1.59 2.35
Spartacus 3.76 6.09 1.63 2.55
Triada 4.52 5.73 1.65 2.36
SY Badia 4.39 6.29 1.56 2.11
Volga 4.74 8.10 1.62 2.19
The largest increase (5.73-8.10 g/m 2 • day) was noticed for period of three pairs of genuine leaves before closing of leaves in row widths, and the lowest one — from closing of leaves in row widths to harvesting of sugar beet. On average during the period of vegetation of plants of sugar beet the meaning of NPP was 2.09 is 2.55 g/m 2 • day. Hybrids Spartacus and Nero had the largest value of NPP, it was 2.55 and 2.49, hybrid RMS 120 had the least value of NPP — 2.09 g/m 2 • day. The leaves of plants of sugar beet produce energy-rich carbohydrates during the process of photosynthesis — Saccharum that accumulates in root
Hybrids Triada and SY Badia (which are related to the type of «normally sugary») lost hybrid Spartacus 5,88 and 5,1 t/ha, respectively.
Volga is a hybrid of “sugary” type and its yield was 62.62 t/ha, but by sugar content of root crops this hybrid was superior to all other hybrids — the average sugar content was 19.6 %, while in other years the sugar content of this hybrid was higher than 22 %. The main reason for the decline in this indicator in 2012-2013 is a strong infection of plants by cercosporosis, regrowth of new leaves and consumption of accumulated Saccharum. On average during two years of research cercosporosis affected all studied hybrids of plants of sugar beet. The first signs of infestation of plants of sugar beet by the fungus cercospora beticola were observed in the first
crops. Well-developed and healthy foliage is a prerequisite for high yield and quality of root crops. The number of leaves and the area of leaf surface are the criteria for determining the productivity of plants of sugar beet and accumulation of Saccharum in root crops [7]. The highest yield of root crops during 2 years on average was obtained by harvesting of hybrids of “normal” type of Spartacus (75.42 t/ha), and Hercules (72.66 t/ha) and “normally fruitful” Nero (74.91 t/ha). Other hybrids from the group of normal ones — Compact and RMS 120 provided the yield of 57.91 and 53.87 tons per hectare (table. 3).
decade of August. In 2012 the prevalence was 3.2 % at the intensity of development of the disease 0.07 %. Then the disease continued to develop and affect new plants. High rainfall and high temperatures contributed to it. The final number of infected plants was 23.3 %, the intensity of development was 15.9 %. In July of 2013 the amount of precipitation was more than normal by 15 %, and that was the main reason for lesion of more than 5 % of the plants, the average area of lesion of lamina was 0.09 %. Warm and humid weather (average temperature of the month was 19 °C, the amount of precipitation was 44 mm.) led to increase of number of infected plants to 27.2 % and the intensity of its development to 10.3 %. On average during two years of research among the studied hybrids the most susceptible to cercosporosis were: Volga (P = 56.8 %,
Table 3. — Productivity of sugar beet hybrids
Hybrid 2012 2013
yield, t/ha sugar content, % collection of Saccharum, t/ha yield, t/ha sugar content, % collection of Saccharum, t/ha
RMS 120 55.87 18.5 10.33 51.87 18.8 9.75
Compact 59.45 18.3 10.88 56.37 17.8 10.03
HM 1820 70.08 17.4 12.19 64.58 18.0 11.62
Nero 75.10 18.1 13.59 74.71 18.0 13.45
Hercules 73.26 17.9 13.11 72.05 18.7 13.47
Spartacus 76.18 18.2 13.86 74.66 18.6 13.89
Triada 70.23 19.4 13.62 68.84 19.1 13.15
SY Badia 71.54 18.9 13.52 69.09 19.0 13.13
Volga 63.64 19.7 12.54 61.59 19.5 12.01
Average value 68.37 18.5 - 65.97 18.61 -
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Section 7. Agricultural sciences
R = 19.7 %), Compact (P = 29.7 %, R = 16.1 %) and HM 1820 (P = 31.8 % with R = 17.4 per cent). It was noticed that these hybrids are capable of re-growing of new leaves.
We may distinguish normally sugary hybrids by sugar content of the root crops. They are Triada and SY Badia, their sugar content was 19.25 % and 18.9 %, respectively. The sugar content of root crops of other hybrids was from
17.7 to 18.6 %. The final productivity of sugar beets is collection of Saccharum per unit of area, which is directly dependent on the magnitude of the yield of root crops and
their sugar content. The greatest collection of Saccharum was obtained by the cultivation of hybrid Spartacus, both in 2012 and 2013 and it amounted to 13.86 and 13.89 t/ha, respectively. The collection of Saccharum of the rest of the hybrids was about 12-13.5 t/ha, except RMS 120 and Compact — 10.04 and 10.45 t/ha, respectively.
Thus, the results of our research allow us to recommend the beet-growing economies to use hybrids of foreign breeding (Nero, Spartacus and Hercules) in the cultivation of sugar beet. They allow to obtain 13-14 tons of sugar per hectare.
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3. Zheryakov E. The influence of complex mineral fertilizer “Aquarinum-5” on productivity of variety and hybrid of sugar beet/E. Zheryakov//Young scientist. - 2010. - No. 10 (21). - P. 374-377.
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