David Bečka, Jan Vašák, Přemysl Štranc, Perla Kuchtová Czech University of Agriculture, Prague
Growing technologies for genetically modified
varieties of winter oilseed rape in Czech Republic
*Technologia uprawy rzepaku ozimego
dla odmian zmodyfikowanych genetycznie w Czechach
Key words: winter oilseed rape, hybrid, growing systems, reduction of generative organs, yieldYield indices and the yield itself were examined in three different variety types of winter oilseed rape (line, hybrid and genetically modified hybrid) in three growing technology systems (intensive, standard and low input). The growing systems differed mainly in soil preparation before sowing, seed rate, chemical protection level, growth regulation and fertilization (mainly nitrogen). The weakness of low input technology without ploughing was in the weak root system, which negatively influenced the yield. The advantage of intensive technology is the strong root system, longer assimilation period. The yield of hybrid varieties (modified and not modified) was higher in comparison with the line variety. Genetically modified hybrid was comparable in all studied characteristics with the unmodified one.
Słowa kluczowe: rzepak ozimy, mieszaniec, systemy uprawy, redukcja organów generatywnych, plon W pracy oceniano plon i wskaźniki plonu trzech różnych typów odmian rzepaku ozimego (linia, mieszaniec i mieszaniec genetycznie zmodyfikowany) uprawianych w trzech różnych systemach (intensywny, standardowy i niskonakładowy). Systemy uprawy różniły się głównie przygotowaniem gleby przed siewem, ilością wysiewu nasion, ochroną chemiczną, stosowaniem regulatorów wzrostu i dojrzewania oraz nawożeniem (głównie azotowym). Wadą technologii niskonakładowej (bez orki) był słaby system korzeniowy roślin, co wpływało negatywnie na plon. Zaletą technologii intensywnej był silny system korzeniowy roślin oraz dłuższy okres asymilacji.
Stwierdzono, że jesienią produkcja biomasy części nadziemnej rośliny i biomasy korzenia silnie zależała od pogody w okresie siewów. W warunkach suszy (tworzenie się grud ziemi) bez względu na sposób przygotowania gleby do siewu (tj. technologii) wschody roślin rzepaku były słabe. Przy późnym siewie i w warunkach wilgotnych różnice między technologiami w produkcji biomasy części nadziemnej rośliny i korzenia zwiększyły się.
Sucha masa części nadziemnej rośliny i biomasa korzenia była największa w technologii intensywnej, następnie standardowej, a najmniejsza w technologii niskonakładowej. Jesienią odmiany nie różniły się biomasą części nadziemnej i biomasą korzenia.
Rozwój organów generatywnych (pąków) u rzepaku ozimego był uwarunkowany przebiegiem pogody wiosną (temperatura, opady), intensywnością uprawy i typem odmiany (odmiana mieszań-cowa, odmiana liniowa).
Formowanie i redukowanie organów generatywnych było większe u odmian mieszańcowych (modyfikowanych i niemodyfikowanych) niż u odmian liniowych.
Technologia uprawy rzepaku ozimego decydowała o wysokości plonu: technologia intensywna — 4,1 t/ha, standardowa – 4,0 t/ha, niskonakładowa — 3,3 t/ha. W wariancie niskonakładowym można otrzymać 3 t/ha jeśli plantacja jest dobrze założona i pielęgnowana. Należy jednak wziąć pod uwagę wysokie ryzyko niestabilności plonów spowodowane deszczami po wschodach i nalotem szkodników.
Zarówno odmiany mieszańcowe genetycznie zmodyfikowane (tolerancyjne na glufosynat), jak i nie modyfikowane osiągnęły plon wyższy o 14% od odmian liniowych.
Introduction
The area of GM crops has been increasing since 1996 (1.7 mil. ha). GM crops were grown in 16 countries in the world (mostly in USA — 39 mil. ha, Argentina — 13.5 mil. ha, Canada — 3.5 mil. ha and China — 2.1 mil. ha) on the area 58.7 mil. ha (i.e. the increase since the year 2001 by 12%). Oilseed rape (canola) was the fourth most grown GM crop (after soya bean, cotton and maize) on the area of 3 mil. ha (the increase since 1996 — 97%, since 2001 — 10% resp.) (ISAAA 2003).
The necessary condition for a good overwintering and high yields is the autumn growth and the development of rapeseed plants. Before the winter period, rapeseed plants should create a sufficient above-ground and root mass and reduce water content in tissues. Other important characteristics are: root-neck diameter, height of growth apex, number and length of leaves, length of root (Vašák et al. 1997; Diepenbrok 2000). The reduction of rapeseed generative organs is one of the main causes of low yields in comparison with their growth potential, which ranges (according to many authors) from 7 to 8 t/ha (Diepenbrock, Grosse 1995; Vašák et al. 1997; Kňákal 1999).
Materials and methods
Experiments with three different variety types of winter oilseed rape were established in the Research Station of Czech University of Agriculture in Červený Újezd (405 m above sea level, mean annual temperature 7.7°C; sum of precipitations 549 mm, during the vegetation period (April–September) 13.9°C and 361 mm) line variety — Lirajet (in 2001/2002 — Navajo), hybrid variety — Pronto (in 2001/2002 — Embleme) and genetically modified (GM) hybrid — tolerant to glufosinate (Liberty Link). Experiments were established with three different growing technologies: intensive with expected yield 4 t/ha, standard with yield 3 t/ha and low input with yield 2.5 t/ha. The technologies differ mainly in the soil preparation before sowing, sowing rate, fertilization (mainly nitrogen) and chemical treatments (Table 1).
In the autumn period the plants were sampled at the end of autumn vegetation, i.e. before frost (8.11.1999, 8.11.2000 and 12.11.2001) from 1 m row in each replicate. After washing up of the plants the fresh above ground biomass and
root-mass was were estimated. After drying at 105oC dry mass of above ground biomass and roots was determined. The area of one replicate was 79.2 m2 (harvesting plot 22 m2).
Table 1 Comparison of three growing technologies
Porównanie trzech systemów technologii uprawy
Production technology — Technologia produkcji intensive
intensywna standardowa standard niskonakładowa low input
Autumn — Jesień Soil preparation Przygotowanie gleby ploughing orka (20–22 cm) ploughing orka (18–20 cm) stubble ploughing zaoranie ścierni
Fertilization — Nawożenie P, K, Mg yes — tak yes — tak no — brak
Sowing rate — Siew [seeds/m2] 60 80 80
Fertilization — Nawożenie N
before sowing + during vegetation period przed siewem + w czasie wegetacji
30 + 20 0 + 20 no — brak
Herbicide — Herbicydy * Butisan Star Lasso Microtech
+ Command 4EC + Command 4EC Lasso Microtech Insecticide + fungicide
Insektycydy + fungicydy
yes — tak no — nie no — nie
Growth regulator — Regulator wzrostu Horizon 250EW +
Retacel Extra R68 Extra R68 Retacel
no — nie Spring — Wiosna
Nitrogen total / number of doses
Azot sumarycznie / liczba dawek 210 / 4 150 / 3 150 / 2
Growth regulator — Regulator wzrostu Caramba no — nie no — nie
Stimulation TSM — Stymulacja Atonik Relan (Rexan) no — nie Foliar fertilizer — Nawożenie dolistne Campofort B no — nie no — nie
Fungicide — Fungicydy yes — tak no — nie no — nie
Insecticide against pod pests
Insektycydy na szkodniki łuszczynowe
yes — tak no — nie no — nie
Ripening regulation — Regulacja dojrzewania yes — tak yes — tak no — nie
* at GM variety – application of Liberty herbicide — odmiana GM – stosowano herbicyd Liberty
After generative organ creation 10 plants of each variety were selected (2 weak, 2 above average and 6 average) for the determination of the number of generative organs (twice in a vegetation period): first – at the butonisation (3.5.2000, resp. 8.5.2001) and second–at the time of green ripening (23.5.2000, resp. 4.6. 2001). The analysis of variance of multiple classification was used for evaluation of results and LSD at 95% was estimated. The results were processed with the programme Statgraphics Plus version 4.
All the environmental conditions requested at CR and EU by investigations with GMO were complied. The whole experimental area was sown all around with 8 m wide protective strips (early and late flowering varieties) which were completely destroyed after flowering. Space isolation was assured with the distance of 400 m from other plantations of Brassica crops. All the seeds harvested from the fields surrounding GMO plots were processed as bio-fuel and the meal was burnt or composted. In 2001/2002 the GM variety was destroyed according to request (23.4.2002) of the firm and only the varieties Navajo (line) and Embleme (hybrid) were harvested.
Results and discussion
Development of above ground and root mass in autumn
The three-year experiments (1999–2002) show that the development of leaf and root biomass in autumn was influenced by the technology of growing year (moisture conditions in soil) and partly by a variety (Table 2). In vegetation year
Table 2 Comparison of mass of above ground and root biomass (g/m2) field trial in Červený Újezd
1999–2002 — Porównanie biomasy części naziemnej i korzenia w doświadczeniach
przeprowadzonych w miejscowości Červený Újezd w latach 1999–2002 Technology Technologia Year Rok Number of plants per m2 Liczba roślin na m2 Above ground dry mass
Sucha masa naziemna
[g/m2]
Root dry mass
Sucha masa korzenia [g/m2] 1999/2000 45 21.6 3.4 2000/2001 36 180.3 46.7 2001/2002 54 104.0 11.1 Intensive Intensywna mean – średnia 45 102.0 A 20.4 A 1999/2000 49 14.7 2.5 2000/2001 54 197.2 45.4 2001/2002 97 85.1 10.0 Standard Standardowa mean – średnia 67 99.0 A 19.3 A 1999/2000 38 16.7 3.1 2000/2001 45 178.3 35.9 2001/2002 55 22.6 2.5 Low input Niskonakładowa mean – średnia 46 72.5 B 13.9 B
The different letters in column show significant differences (95% probability)
1999/2000 limiting factors were the clods (greater than 4 cm) per m2. It was: 30.5 clods at the intensive, 23.8 at the standard and 8.6 at the low input variant in this year. The differences between intensive and low input systems were in the weight of dry mass: above ground biomass 4.9 g/m2 (i.e. 23%) and root mass 0.3 g/m2 (i.e. 9%). In 2001/2002 the emergence was again insufficient due to late sowing (one day after agronomic term i.e. 6th September) and excessive soil moisture. The differences in the dry matter between intensive and low input variants were substantially higher in this year, in above ground biomass the difference was 81.4 g/m2 (78%) and in the root biomass 8.6 g/m2 (i.e. 77%). Summarising: the clods
on the surface influenced the above ground and root biomass in a negative way in all the variants (1999/2000), i.e. regardless of soil preparation (ploughing or minimal stubble ploughing). The variant without ploughing gave results substantially different than intensive and standard variants in case of the excessive soil moisture (2001/2002).
Number of plants per m2 was in 2001/2002 higher because of better soil
moisture conditions during emergence.
Growing technologies (variants)
The mean above ground dry mass (1999–2002) was in the intensive variant (102.0 g/m2) and standard variant (99.0 g/m2) statistically different from the low
input variant (72.5 g/m2) (Table 2), but it did not reach the optimum of 200–250
g/m2 above ground biomass in autumn (Diepenbrock and Grosse 1995; Vincenc
and Vašák 2000). Sova (1999) published similar differences among technologies. The intensive variant created 142 g/m2, standard 112 g/m2 and low input 60 g/m2
of dry above ground biomass.
The mean dry root mass (1999–2002) was 20.4 g/m2 at the intensive variant,
19.3 g/m2 at standard both significantly different as compared with low input variant
(13.9 g/m2) (Table 2). Vincenc and Vašák (2000) presented the development of optimum root biomass 30 g/m2 in autumn. Sova (1999) shows the same differences – intensive 24 g/m2, standard 18 g/m2 and low input 10 g/m2.
Varieties
There were no significant differences among varieties in the above ground biomass (Table 3). The mean of hybrid varieties (modified and unmodified) was due to the heterosis by 7.3 g (i.e. 78%) higher as compared with the line variety. Grosse et al. (1992) cit. in Diepenbrock (2000) compared dry above ground biomass of hybrids and their parental lines. Hybrids developed more of above ground dry biomass than parental lines — 11% in autumn, 8% in flowering period and 25% after flowering.
Also no significant differences among types of varieties were determined in dry root biomass (Table 3).
Table 3 Statistical analysis of above ground and roots dry mass (g/m2) depending on the variety
(three years means 1999/2000, 2000/2001, 2001/2002) — Ocena statystyczna suchej masy
naziemnej i korzeni (g/m2) w zależności od typu odmiany
Variety
Odmiana Dry above ground mass Sucha masa naziemna Masa korzenia Dry roots
Hybrid — Mieszaniec 92.3 A 16.6 A
GM hybrid — Mieszaniec GM 94.9 A 19.5 A
Line — Linia 86.3 A 17.4 A
The same letters in column show that differences are not significant (95% probability)
Te same litery w kolumnie wskazują, że różnice nie są istotne (95% prawdopodobieństwa)
0 250 500 750 1000 1250 1500
intensive standard low input
number of buds
liczba p
ąków kwiatowych
1999/2000 2000/2001
Graph 1. Number of buds per plant (n = 30) according to the growing technologies — Liczba pąków
kwiatowych na roślinie (n = 30) w zależności od technologii uprawy (Červený Újezd, 1999/2000
and 2000/2001)
Reduction of generative organs
In 1999/2000 the formation of generative organs (buds) was significantly higher in intensive variant (791 buds per average plant) than in other variants (standard — 535, low input — 547 buds per plant). In 2000/2001 there were no significant differences among variants. The intensive variant had the lowest number of generative organs. But the total number of generative organs was higher by 25% (intensive variant) up to 114% (standard) in comparison with the previous year 1999/2000 (Graph 1). This higher pod creation could be explained by different development of weather conditions during spring periods in both years. In 2000, May and April were warm and dry. This caused fast finishing of flowering of oilseed rape and the assimilates were used for the growth and development of young seeds and pods, and not for the growth and development of additional buds. In 2001 the spring was cooler and damper and caused longer flowering
period of oilseed rape. Even the buds, which would die away in normal weather conditions, were alive. The inter-year difference in bud formation was lower in the intensive variant (199 buds) as compared with standard (609 buds) and low input (464 buds). According to Kuchtová (2002) the most significant factors influencing formation of generative organs were: time of sowing, stand density and N fertilization.
Table 4 Statistical analysis of the creation of generative organs (buds) depending on growing technology (1999/2000 and 2000/2001) — Ocena statystyczna tworzenia organów
genera-tywnych (pąków) w zależności od technologii produkcji
Technology — Technologia Count 1999/2000 2000/2001
Intensive — Intensywna 30 791.167 B 989.667 A
Standard — Standardowa 30 534.667 A 1144.07 A
Low input — Niskonakładowa 30 547.167 A 1010.97 A The same letters in column show that differences are not significant (95% probability)
Te same litery w kolumnie wskazują, że różnice nie są istotne (95% prawdopodobieństwa)
The reduction of generative organs was not statistically different among variants in both years. The number of pods per plant was higher after reduction in 2000/2001 compared with the year 1999/2000 (Graph 2). The number of pods was higher 59% at the intensive technology, by 82% at the standard and by 66% at the low input higher than in 1999/2000. The differences in pod number were not significant among technologies (Table 5). In spite of this, the seed yield in the intensive variant was higher compared with the standard and low input (Graph 3) probably due to the higher number of seeds in a pod.
0 100 200 300 400 500
intensive standard low input
number of pods per plant liczba
łuszczyn na ro
ślinie
1999/2000 2000/2001
Graph 2. Number of pods per plant (n = 30) depending on the growing technologies — Liczba
łuszczyn na roślinie (n= 30) w zależności od technologii uprawy (Červený Újezd, 1999/2000
Table 5 Statistical analysis of the creation of generative organs (pods) depending on the growing technology (1999/2000 and 2000/2001) — Ocena statystyczna tworzenia organów
genera-tywnych (łuszczyn) w zależności od technologii produkcji
Technology — Technologia Count 1999/2000 2000/2001
Intensive — Intensywna 30 213.367 A 339.433 A
Standard — Standardowa 30 204.433 A 371.633 A
Low input — Niskonakładowa 30 209.067 A 347.933 A The same letters in column show that differences are not significant (95% probability)
Te same litery w kolumnie wskazują, że różnice nie są istotne (95% prawdopodobieństwa)
In both years (1999/2000 and 2000/2001) a higher reduction of generative organs was found out in all technologies in hybrid varieties (modified and non-modified) in comparison with the line variety (Table 6). Hybrid varieties create more generative organs (influenced by heterosis) but on the other hand they have
Table 6 Number of generative organs (buds and pod) per plant and their reduction (%) in three variety types at three types of growing technology — Liczba organów generatywnych
pączków i łuszczyn) na roślinie i ich redukcja [%] w trzech typach odmian przy trzech różnych technologiach produkcji (Červený Újezd, 1999/2000 and 2000/2001)
1999/2000 2000/2001 Technology
Technologia OdmianaVariety buds pączki pods łuszczyny reduction straty [%] buds pączki pods łuszczyny reduction straty [%] Pronto (hybrid) 923.5 242.1 74 1167.6 356.8 69 Lirajet (line) 825.5 238.6 71 704.9 317.2 55 Liberty Linky (hybrid) 624.5 159.4 74 1096.5 344.3 69 Intensive
Intensywna
mean — średnia 791.2 213.4 73 989.7 339.4 64 Pronto (hybrid) 491.2 187.2 62 1077.8 330.1 69 Lirajet (line) 666.1 271.2 59 1080.8 424.6 61 Liberty Linky (hybrid) 446.7 154.9 65 1273.6 360.2 72 Standard
Standardowa
mean — średnia 534.7 204.4 62 1144.1 371.6 67 Pronto (hybrid) 537.5 198.8 63 1091.2 345.8 68 Lirajet (line) 485.6 216.5 55 1113.7 455.7 59 Liberty Linky (hybrid) 618.4 211.9 66 828.0 242.3 71 Low input
Niskonakładowa
a higher reduction (e.g. the final number of pods in hybrid varieties is comparable with the number in line varieties). The higher reduction of generative organs in hybrid varieties proves the existing reserves in rapeseed technology (varietal agrotechnique, optimal nutrition, improvement of pod pests and mycotic diseases etc. In the variants with the highest generative organs (in 1999/2000 — intensive, in 2000/2001 — standard) the reduction was also higher. Kuchtová (2002) presents similar results: the higher reduction of generative organs has been usually observed at the higher generative organs creation.
Seed yield
The three year experiments (2000–2002) show evident differences in yields among different growing technologies (Graph 3). The highest mean yield was harvested from the intensive variant (4.1 t/ha) following standard variant (4.0 t/ha). The low input variant with the lowest yield (3.3 t/ha) was substantially different in statistical analysis. Comparing individual varieties (2000–2001) evident differences in the yield of hybrid (genetically modified and unmodified varieties) and line varieties can be observed. The mean yield of hybrid varieties was 4.4 t/ha against 3.8 t/ha of the line variety. This difference was substantially significant and was 0.6 t/ha, i.e. 13,6%. According to Schuster et al. (1999) cit. in Diepenbrock (2000), the results showed the increase in yields of hybrid varieties by 20% in comparison
2 3 4 5
Intensive Standard Low input
yi e ld (t. h a -1) ---Method: 95,0 percent LSD
Variant Count LS Mean Homogeneous Groups ---3 - low input ---32 ---3.---30069 X
2 - standard 32 4.00382 X 1 - intensive 32 4.11632 X
---Graph 3. Comparison of winter rapeseed yield (mean of 3 varieties) depending on the growing technology (t/ha), field trial in Červený Újezd — Porównanie plonów rzepaku ozimego (średnie
with line varieties. The authors proved comparable results in the yields of genetically modified and unmodified varieties and in some cases the yields of GM oilseed rape were higher by 15% compared with the unmodified varieties (Sauermann and Schuster 2000). In our experiments the hybrid variety Liberty Link was by 0,02 t/ha yielding higher in comparison with the unmodified hybrid (i.e. 0,5%).
2 3 4 5
Hybrid Linie GM hybrid
y ie ld ( t. ha -1) ---Method: 95,0 percent LSD
Variety Count LS Mean Homogeneous Groups ---2 - line ---24 3.8375 X
1 - hybrid 24 4.42083 X 3 - GM hybrid 24 4.44167 X
---Graph 4. Comparison of winter rapeseed yield (mean of 3 growing technologies) depending on varieties (t/ha), field trial Červený Újezd — Porównanie plonów rzepaku ozimego (średnie z trzech technologii
produkcji) w zależności od typu odmiany w doświadczeniu polowym
Conclusion
• The production of above ground and root biomass in autumn was strongly influenced by the year (weather in the time of sowing). In dry conditions (when the clods created) regardless of the soil preparation (i.e. technology) the rapeseed plants emergence was low. At the late sowing and in moisture conditions the differences among technologies increased for the benefit of the low input variant.
• The dry mass of above ground and root biomass was the highest with the intensive technology and after that with the standard and the lowest with the low input technology. There were no significant differences in the production of above ground and root biomass in autumn.
• The development of generative organs (buds) at winter rapeseed was influenced by weather conditions in spring (temperature, precipitation) by the growing technology and variety type (hybrid, line).
• The formation and reduction of generative organs were higher in hybrid varieties (modified and unmodified) than in the line variety.
• Intensity of growing of winter rapeseed determined the yield: intensive variant 4.1 t/ha, standard 4.0 t/ha and low input 3.3 t/ha. In the low input variant the yield of 3 t/ha can be obtained if the stand is well established and treated. But we have to consider high risks in the yield stability after precipitation, after emergence and high pest invasion.
• Hybrid varieties reached 14% higher yield whether the variety was genetically modified (tolerant to gluphosinate) or not modified.
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