Biostimulators IN MODERN AGRICULTURE. Field Crops. E D I T O R : Zbigniew T. Dąbrowski

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1 Biostimulators IN MODERN AGRICULTURE Field Crops E D I T O R : Zbigniew T. Dąbrowski W a r s a w

2 1 Biostimulators IN MODERN AGRICULTURE Field crops EDITOR: Zbigniew T. Dabrowski Warsaw 2008

3 2 The series of monographs under a common name BIOSTIMULATORS IN MODERN AGRICULTURE contains a review of recent research related to this subject and consists of the following parts: GENERAL ASPECTS FIELD CROPS SOLANACEOUS CROPS VEGETABLE CROPS FRUIT CROPS ORNAMENTAL AND SPECIAL PLANTS EDITORIAL BOARD: Andrzej Sadowski, Department of Pomology,Warsaw University of Life Sciences (WULS) chairman Zbigniew T. D¹browski, Department of Applied Entomology, WULS Helena Gawroñska, Laboratory of Basic Natural Sciences in Horticulture, WULS Aleksandra ukaszewska, Department of Ornamental Plants, WULS Adam S³owiñski, Arysta LifeScience Poland PRODUCTION EDITORS: Zbigniew T. D¹browski, Warsaw University of Life Sciences (WULS) Anna Karbowniczek, Arysta LifeScience Poland Ada Krzeczkowska, Wieœ Jutra Halina Skrobacka, Wieœ Jutra REVIEWERS: Zbigniew T. D¹browski, Department of Applied Entomology, Warsaw University of Life Sciences (WULS) Ma³gorzata Kie³kiewicz-Szaniawska, Department of Applied Entomology, WULS Marian Saniewski, Institute of Pomology and Floriculture, Skierniewice Anna Tomczyk, Department of Applied Entomology, WULS This edition was supported by Arysta LifeScience Cover: Plantpress ISBN Published by the Editorial House Wieœ Jutra, Limited Janowskiego Warszawa phone: (0 22) wies.jutra@adres.pl Printed by Ryko Copies 300, publishing sheets: 10.0

4 3 CONTENS PREFACE... 5 THE EFFECT OF ASAHI SL ON GROWTH, EFFICIENCY OF PHOTOSYNTHETIC APPARATUS AND YIELD OF FIELD GROWN OILSEED RAPE... 7 Arkadiusz Przybysz, Monika Ma³ecka-Przybysz, Adam S³owiñski, Helena Gawroñska RESPONSE OF WINTER OILSEED RAPE TO THE BIOSTIMULATOR ASAHI SL APPLIED IN SPRING Wojciech Budzyñski, Bogdan Dubis, Krzysztof Jankowski THE USE OF ASAHI SL BIOSTIMULATOR IN SPRING RAPE GROWING W³adys³aw Malarz, Marcin Kozak, Andrzej Kotecki WINTER SURVIVAL AND YIELD OF OILSEED RAPE DEPENDING ON SOWING DATE AND APPLICATION OF MICRONUTRIENT PREPARATION ROUTE ACTING AS A GROWTH STIMULATOR...33 Roman Krawczyk, Jaros³aw Skoczyñski ASAHI SL BIOSTIMULATOR IN PROTECTION OF SUGAR BEET FROM HERBICIDE STRESS...41 Jolanta Kositorna, Marek Smoliñski EFFICIENCY OF ASAHI SL IN PROTECTION OF BARLEY AND WHEAT MIXTURE IN COMPARISON WITH PURE SOWING Tadeusz Michalski, Joanna Horoszkiewicz-Janka, Monika Bartos-Spycha³a EFFECT OF BIOSTIMULATOR ASAHI SL ON YIELD OF MAIZE GRAIN Jerzy Ksiê ak EFFECT OF BIOSTIMULATOR ASAHI SL ON CROPPING OF MAIZE GROWN FOR GRAIN...66 Tadeusz Michalski, Monika Bartos-Spycha³a, Tomasz Maciejewski, Andrzej Jarosz

5 4 THE EFFECTS OF SOWING RATE AND ASAHI SL BIOSTIMULATOR ON SOYBEAN GROWTH AND YIELD Marcin Kozak, W³adys³aw Malarz, Magdalena Serafin-Andrzejewska, Andrzej Kotecki THE EFFECTS OF DIFFERENT SOWING RATE AND ASAHI SL TREATMENTS ON SOYBEAN SEED SOWING VALUE...85 Marcin Kozak, W³adys³aw Malarz, Magdalena Serafin-Andrzejewska, Andrzej Kotecki RESPONSE OF SOME SOYBEAN CULTIVARS TO FOLIAR FERTILIZATION WITH INSOL W UNDER CONDITIONS OF HERBICIDE STRESS S³awomir Micha³ek POTENTIAL ADVANTAGES OF KELPAK BIOREGULATOR APPLIED TO SOME FIELD CROPS Kinga Matysiak, Sylwia Kaczmarek POLISH SUMMARIES

6 5 PREFACE The high yield potential of modern cultivars is often restrained by various environmental stresses both of biotic and abiotic nature, affecting the crop status. The present approach in pro-ecological plant protection from such biotic stresses as weeds, diseases and pests emphasises enhancement of naturally occurring compounds, organisms or plant defence mechanisms. These compounds should fill the gap resulting from the regulatory decisions of national authorities in many countries, leading to restrictions in use of a number of synthetic pesticides. Extensive research carried out in the last two decades has shown that some natural products may be efficiently used in enhancing the plant s endogenous resistance or tolerance to the biotic and abiotic stresses. A group of such active products is presently classified as biostimulators. When reduction of the chemical input is expected, the use of biostimulators becomes a particularly promising option. Biostimulators are defined as compounds of biological origin and should act by increasing natural capabilities of plants to cope with stresses. Biostimulators do not act neither as nutrients nor affect directly the stress factors making them less harmful for plants. The efficacy of biostimulators is not limited to reducing effects of biotic and abiotic stresses. They stimulate growth and development of plants under unfavourable soil and climatic conditions. Although the effects of biostimulators are not so spectacular and not always stable over the years due to interaction with other used chemicals and/or environmental factors the interest of farmers in using biostimulators is successively increasing over time. According to the national legislation, biostimulators are related to the category of plant protection products. Therefore they must comply with all rules for registration and hence prior to formal approval for use they must be tested for safety to humans and the environment. The dynamic increase of research projects on biostimulators and of farmers interest in their use in agriculture and horticulture production provoked an idea of the international conference on Biostimulators in Modern Agriculture. It was organized by the Laboratory of Basic Sciences in Horticulture, at the Faculty of Horticulture and Landscape Architecture at the Warsaw University of Life Sciences. The conference has attracted a large group of scientists and graduate students from universities and research institutions involved in basic and applied research

7 6 in agriculture as well from the industry. About three hundred sixty participants included also representatives of farmers and distributors of agricultural supplies. The extensive and creative discussions during the conference and interest in conference materials as well as suggestions from participants indicated the urgent need for dissemination of the state of knowledge on biostimulators. This inspired the organizers of the Conference to co-ordinate preparing reviews on recent scientific achievements in the field of biostimulators, including the practical aspects of their application on various crops. Following suggestions appearing at the Conference, the organisers invited scientists having experience and achievements in work on biostimulators to prepare relevant reviews related to particular products and crops. Based on the submitted manuscripts the Editorial Board decided to publish a series of monographs entitled: BIOSTIMULATORS IN MODERN AGRICULTU- RE comprising the following six volumes: General Aspects, Field Crops, Solanaceous Crops, Vegetable Crops, Fruit Crops and Ornamental and Special Plants. The Editors hope that this publication would fill the gap in knowledge on the mechanisms of action of various biostimulators and on the conditions for their high efficacy. We are very grateful to the authors who willingly agreed to contribute to these books. EDITORS

8 7 THE EFFECT OF ASAHI SL ON GROWTH, EFFICIENCY OF PHOTOSYNTHETIC APPARATUS AND YIELD OF FIELD GROWN OILSEED RAPE Arkadiusz Przybysz 1, Monika Ma³ecka-Przybysz 1, Adam S³owiñski 2, Helena Gawroñska 1 1 Warsaw University of Life Sciences, Warsaw, Poland, 2 Arysta LifeScience Sp. z o.o., Warsaw, Poland INTRODUCTION Oilseed rape (Brassica napus L. var. oleifera) is the most widely cultivated crop species in the Brassicaceae family today and has now become the world s 3 rd leading source of vegetable oil and oil meal. The acreage of cultivated oilseed rape plants is increasing yearly, mainly due to interest in its cultivation for bio-fuel. In Poland, oilseed rape is the most important crop grown for industrial purposes, and there is potential for increasing the cultivation area of this crop. Nowadays, to obtain the highest possible yield, it is important to ensure near optimal growth conditions. In the field, plants are often exposed to several stressful conditions. For instance, frost during the winter and early spring might damage oilseed rape plants and consequently reduce the yield. Using biostimulators in order to improve plant status and repair damage when plants are/were exposed to stressful conditions has become quite common practice among farmers. Asahi SL, a Japanese product (Asahi Chemical MFG. Co. LTD) internationally known as Atonik, is listed among the most often used biostimulators. It is a composition of three simple phenolic compounds, which easily penetrate into the plant cells, become metabolised and participate in a number of basic metabolic processes. These include promotion of germination, more vigorous growth, stimulation of generative development, nutrient uptake, photosynthetic activity, assimilates transport and plant yield [Gruszczyk, Berbeæ 2004, Djanaguiraman et al. 2004, 2005a,b, Gawroñska et al. 2008a,b, Oosterhuis 2008, Sas-Paszt et al. 2008, Wróbel, WoŸniak 2008a and others]. There is a common opinion that the positive effects of biostimulators are not spectacular, ranging from several to 20% or so of the values recorded for untreated control, but Gruszczyk and Berbeæ [2004] recorded an increase of the yield of feverfew (Chrysanthemum parthenium L.) over 50% due to biostimulator applications. On the other hand, however, it should be pointed out that these effects are often not significant, not stable over the years or not recorded at all, and sometimes even negative effects are observed. In light of the above controversy, a project on the physiological and molecular basis of the Asahi SL mode of action has been realised in our laboratory with experiments conducted under field and controlled (growth chambers) conditions. In this work, an attempt was made to evaluate the effect of Asahi SL on: (i) growth and development, (ii) efficiency of photosynthetic apparatus (intensity of photosynthesis, chlorophyll content and fluorescence of Chl a), (iii) biomass accumulation and (iv) yield of oilseed rape.

9 8 MATERIAL AND METHODS Oilseed rape (Brassica napus L. var. oleifera) cv Lisek plants were cultivated in the 2006/2007 growing season on soil class: IIB/IV at the Chylice Experimental Field of the Warsaw University of Life Sciences. Seeds were sown on in a spacing of 30 cm x 6.5 cm. Asahi SL was applied in spring as a single ( ) or double ( and ) foliar spray in a concentration of 0.2% v/v in 300 l. ha -1. Routine agricultural practices, recommended for this species, were employed. The following parameters were measured and observations were taken on: height of plants was measured and number of leaves counted (at harvest), plant gas exchange: intensity of photosynthesis, stomatal resistance and intensity of transpiration were measured by a an infra-red gas analyser method using the Photosynthesis System LICOR 6200 (Lincoln, Nebraska, USA) 1,2,3,4,5,6,7 and 8 weeks after first Asahi SL application, chlorophyll a fluorescence was measured as above in weekly intervals (Hansatech, Handy PEA, UK), total chlorophyll content was measured 7 and 8 weeks after first Asahi SL treatment (Chlorophyll Content Meter CL-01, Hansatech, UK), at harvest, the plants were divided into main stem, primary laterals, siliques with seeds and seeds separately and fresh weights of these organs were recorded. Plant material was then dried in an air circulated dryer at 105 o C for 2 h and then for 24 h at 70 o C followed by dry matter recording. In separate sub-samples, the number of seeds in siliques was counted. The field experiment was conducted in complete randomised blocks in four replications (plots of 18 m 2, 10 m x 1.8 m). Five plants from each plot were selected for measurements. Depending on the parameter, measurements were performed in between 20 and 36 replications. This is indicated in a particular tables or figures. Data, where appropriate, were subjected to the statistical analysis of one or two factorial ANOVA of the Statgraphics Plus 4.1. Differences between combinations were evaluated by LSD of the t-student test at a = Presented data are mean ±SE (where indicated). RESULTS Generally, application of Asahi SL had positive effects on the most measured parameters and processes. Asahi SL treated plants, as compare to respective controls, were more vigorous and taller by 9% and 2% (in single and double spray respectively) (Tab. 1). These plants were also more advanced in development, especially generative organs and produced more siliques per plant (up to 4.1%) and seeds per silique (2.8%) when compare with untreated plants (Tab. 1). On the other hand, however, Asahi SL sprayed plants produced less leaves than control plants (between 25% and 28%) (Tab. 1). These values might be to some extent overestimated as the possibility of runoff of some of the leaves by wind and/or decomposing of detached leaves between measurements cannot be ruled out. The amount of biomass accumulated by Asahi SL treated plants was greater than by untreated plants. The fresh weight of single and double sprayed plants was greater by

10 9 TABLE 1. EFFECT OF ASAHI SL ON SELECTED PARAMETERS OF OILSEED RAPE ( BRASSICA NAPUS L. VAR. OLEIFERA) CV LISEK PLANTS MEASURED AT HARVEST. PRESENTED DATA ARE MEAN ±SE, n = 20 Tabela 1. Wp³yw Asahi SL na wybrane parametry roœlin rzepaku ozimego (Br assica napus L. v ar. oleifera ) odmiany Lisek mierzone podczas zbioru. Dane przedstawiaj¹ œrednie ±SE, n = 20 COMBINATION Kombinacja CONTROL Kontrola PLANT HEIGHT Wysokoœæ roœlin 1 [ cm - ] LEAVES/ PLANT Liœci/roœlina LATERALS/ PLANT Rozga³êzieñ/ roœlina NUMBER OF Liczba SILIQUES/ PLANT uszczyn/roœlina SEEDS/ SILIQUE Nasion/ ³uszczyna ( ± 1.38) ( ± 1.07) 5.55 ( ± 0.27) ( ± 5.50) ( ± 0.14) A sahi SL 1x * ( ± 1.81) 14.37* ( ± 0.30) 5.42 ( ± 0.21) ( ± 5.17) ( ± 0.13) A sahi SL 2x (±1.43) 13.67* ( ± 0. 27) 5.22 ( ± 0.24) ( ± 7.27) ( ± 0.15) * VALUES DIFFERING SIGNIFICANTLY AT a = 0.05 AS DETERMINED BY LSD OF t -STUDENT TEST, SOURCE: OWN STUDY. * wartoœci istotnie ró ni¹ce siê przy poziomie istotnoœci a =0.05 oszacowane za pomoc¹ NIR testu t-studenta. ród³o: badania w³asne. TABLE 2. FRESH WEIGHT OF ABOVE GROUND PART AND VARIOUS ORGANS OF OILSEED RAPE ( B RASSICA NAPUS L. V AR. OLEIFERA) CV LISEK PLANTS. PRESENTED DATA ARE MEAN ±SE, n = 20. Tabela 2. Œwie a masa czêœci nadziemnej i poszczególnych organów roœlin rzepaku ozimego (Brassica n apus L. var. oleifera) odmiany Lisek. Dane przedstawiaj¹ œrednie ± SE, n = 20 COMBINATION Kombinacja CONTROL Kontrola ABOVE GROUND PART Czêœæ nadziemna FRESH WEIGHT [ g /PLANT] Œ wie a masa [ g /roœlina] SILIQUES WITH SEEDS uszczyny z nasionami MAIN STEM Pêd g³ówny LATERALS Pêdy boczne (±1.96) (±0.85) (±1.02) 3.74 (±0.37) A sahi SL 1x (±2.79) (±1.17) (±1.36) 3.59 (±0.34) A sahi SL 2x (±2.78) (±1.97) (±1.43) 5.02 (±0.50) SOURCE: OWN STUDY. ród³o: badania w³asne. FIGURE 1. THE EFFECT OF THE BIOSTIMULATOR ASAHI SL ON THE YIELD OF SEEDS OF OILSE- ED RAPE (BRASSICA NAPUS L. VAR. OLEIFERA) CV LISEK PLANTS GROWN IN FIELD CON- DITIONS. PRESENTED DATA ARE MEAN ±SE, n = 20. * LINE IS SHOWING LEVEL OF CONTROL SOURCE: OWN STUDY. Rysunek 1. Wp³yw Asahi SL na plon nasion roœlin rzepaku ozimego (Brassica napus L. var. oleifera) odm. Lisek rosn¹cych w warunkach polowych. Dane przedstawiaj¹ œrednie ±SE, n = 20. * linia pokazuje poziom w kontroli ródlo: badania w³asne., YIELD OF SEEDS []/PLANTS/Plon nasion [g/roœliny] /6' à LSD 1, = 1.12 Ãà NIR 0.05 = 1.12 * CONTROL/Kontrola Asahi SL 1x Asahi SL 2x

11 % and 12.7% respectively (Tab. 2). The values for dry matter were 23.6% and 11.9% (Tab. 3). Also, the fresh weight and dry matter of siliques with seeds were greater in Asahi SL treated plants, both being greater in single sprayed plants (Tab. 2 and 3). Asahi SL positively affected seed yield. As seen in Figure 1, the yield of the seeds of plants sprayed once with Asahi SL exceed the yield of control plants by 35%. Contrary to this, when Asahi SL was applied twice, no positive effect was recorded as the yield of double sprayed plants was at the same level as the control plants (Fig. 1). From comparison of biomass distribution, it is seen that the amount of biomass partitioned to seeds also slightly increased in single sprayed plants compared to non-sprayed plants (Tab. 4). The recorded increase of fresh weight and especially of dry matter of the above ground parts of plants corresponded well with the higher efficiency of photosynthetic apparatus of Asahi SL treated plants. As seen in Figure 2A, Asahi SL increased the intensity of photosynthesis both in single and double sprayed plants, and this effect lasted up to 7 weeks after first biostimulator application. The differences between control and Asahi SL treated plants ranged from 1% to 22%. Asahi SL treated plants also often had a higher intensity of transpiration (Fig. 2B). The changes in the intensity of photosynthesis and of transpiration to some extent reflect the changes in stomatal resistance, which TABLE 3. DRY MATTER OF ABOVE GROUND PART AND VARIOUS ORGANS OF OILSEED RAPE ( B RASSICA NAPUS L. V AR. OLEIFERA) CV LISEK PLANTS. PRESENTED DATA ARE MEAN ±SE, n = 20 Tabela 3. Sucha masa czêœci nadziemnej i poszczególnych organów roœlin rzepaku ozimego ( B rassica napus L. var. oleifera) o dmiany Lisek. Dane przedstawiaj¹ œredni e ± SE, n = 20 COMBINATION Kombinacja CONTROL Kontrola ABOVE GROUND PART Czêœæ nadziemna DRY MATTER [ g /PLANT] S ucha masa [g/roœlina] SILIQUES WITH SEEDS uszczyny z nasionami MAIN STEM Pêd g³ówny LATERALS Pêdy boczne 9.60 ( ± 0.51) 4.35 ( ± 0.27) 4.21 ( ± 0.20) 1.03 ( ± 0.10) A sahi SL 1x ( ± 0.66) 5.52 ( ± 0.36) 5.33 ( ± 0.26) 1.02 ( ± 0.08) A sahi SL 2x ( ± 0.67) 4.60 ( ± 0.39) 4.93 ( ± 0.26) 1.21 ( ± 0.10) SOURCE: OWN STUDY. ród³o: badania w³asne. TABLE 4. DISTRIBUTION OF DRY MATTER INTO PARTICULAR ORGANS OF THE ABOVE GROUND PART OF OILSEED RAPE (BR ASSICA NAPUS L. VAR. OLEIFERA) CV LISEK PLANTS. PRESENTED DATA ARE MEAN, n = 20 Tabela 4. Dystrybucja suchej masy pomiêdzy organami czêœci nadziemnej roœlin rzepaku ozimego ( Brassica n apus L. var. oleifera ) odmainy Lisek. Dane przedstawiaj¹ œrednie z 20 powtórze ñ COMBINATION Kombinacja CONTROL Kontrola ABOVE GROUND PART Czêœæ nadziemna % DRY MATTER OF ABOVE GROUND PART % suchej masy w czêœciach nadziemych [% ] SEEDS Nasiona SILIQUES uszczyny MAIN STEM Pêd g³ówny LATERALS Pêdy boczne Asahi SL 1x Asahi SL 2x SOURCE: OWN STUDY. ród³o: badania w³asne.

12 11 FIGURE 2. INTENSITY OF PHOTOSYNTHE- SIS (A), TRANSPIRATION (B) AND STO- MATAL RESISTANCE (C) OF OILSEED RAPE (BRASSICA NAPUS L. VAR. OLE- IFERA) CV LISEK PLANTS GROWN IN FIELD CONDITIONS DURING 8 WEEKS AFTER FIRST ASAHI SL APPLICATION. PRESENTED DATA ARE MEAN ±SE, n = 28. * LINE IS SHOWING LEVEL OF CONTROL SOURCE: OWN STUDY. Rysunek 2. Intensywnoœæ fotosyntezy (A) i transpiracji (B) oraz opory dyfuzyjne aparatów szparkowych (C) roœlin rzepaku ozimego (Brassica napus L. var. oleifera) odm. Lisek w ci¹gu 8 tygodni po pierwszym oprysku roœlin biostymulatorem Asahi SL. Dane przedstawiaj¹ œrednie ±SE, n = 28. * linia pokazuje poziom w kontroli ródlo: badania w³asne. was often lowered by Asahi SL treatment (Fig. 2C). Chlorophyll content, measured 7 and 8 (Fig. 3) weeks after the first Asahi SL application, was higher (5-7%) in treated plants when compared to respective controls, except for double sprayed plants 7 weeks after application. Measurements of chlorophyll a fluorescence showed that Asahi SL played a protective role in oilseed rape plants during spring frost ( C), which in Chylice occurred between 36 th and 39 th day after biommol CO 2 m -2 s -1 mmol H 2 O m -2 s -1 s. cm -1 A B LSD 0.05 = 0.05 FOR TREATMENT NIR 0.05 = 0.05 dla traktowania LSD 0.05 = 0.08 FOR TERM NIR 0.05 = 0.08 dla terminu CONTROL/Kontrola &RQWUROÃ.RQWUROD Asahi $VDKLÃ6/Ã[ SL 1x $VDKLÃ6/Ã[ Asahi SL 2x * DAYS AFTER SPRAY/dni po oprysku CONTROL/Kontrola &RQWUROÃ.RQWUROD Asahi $VDKLÃ6/Ã[ SL 1x $VDKLÃ6/Ã[ Asahi SL 2x LSD 0.05 = 0.31 FOR TREATMENT LSD 0.05 = 0.51 FOR TERM NIR 0.05 = 0.31 dla traktowania = 0.51 dla terminu 2.5 * DAYS AFTER SPRAY/dni po oprysku C NIR 0.05 &RQWUROÃ.RQWUROD CONTROL/Kontrola $VDKLÃ6/Ã[ Asahi SL 1x $VDKLÃ6/Ã[ Asahi SL 2x * LSD 0.05 = 0.20 FOR TREATMENT LSD 0.05 = 0.33 FOR TERM NIR 0.05 = 0.20 dla traktowania = 0.33 dla terminu NIR FIGURE 3. CHLOROPHYLL CONTENT IN THE LEAVES OF OILSEED RAPE (BRASSI- CA NAPUS L. VAR. OLEIFERA) CV LI- SEK PLANTS GROWN IN FIELD CONDI- TIONS 7 AND 8 WEEKS AFTER FIRST ASA- HI SL APPLICATION. PRESENTED DATA ARE MEAN ±SE, n = 36. * LINE IS SHOWING LEVEL OF CONTROL SOURCE: OWN STUDY. Rysunek 3. Zawartoœæ chlorofilu w liœciach roœlin rzepaku ozimego (Brassica napus L. var. oleifera) odm. Lisek w 7 i 8 tygodniu po pierwszym oprysku roœlin biostymulatorem Asahi SL. Dane przedstawiaj¹ œrednie ±SE, n = 36. * linia pokazuje poziom w kontroli ród³o: badania w³asne. RELATIVES VALUE/wartoœci wzglêdne DAYS AFTER SPRAY/dni po oprysku &RQWUROÃ.RQWUROD CONTROL/Kontrola $VDKLÃ6/Ã[ Asahi SL 1x $VDKLÃ6/Ã[ Asahi SL 2x LSD 0.05 = 5.78 for 54 DAYS LSD 0.05 = 3.36 FOR 61 DAYS NIR 0.05 = 5.78 dla 54 dni NIR 0.05 = 3.36 dla 61 dni DAYS AFTER SPRAY/dni po oprysku *

13 ÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃà à ÃÃÃÃÃÃÃÃÃÃÃÃÃÃÃà à 12 A FV/FM B P.I. PERFORMANCE INDEX indeks witalnoœci LSD 0.05 LSD 0.05 NIR 0.05 NIR 0.05 CONTROL/Kontrola &RQWUROÃ.RQWUROD $VDKLÃ6/Ã[ Asahi SL 1x $VDKLÃ6/Ã[ Asahi SL 2x FROST )URVWà przymrozek 3U]\PUR]HNà /6' ÃÃÃIRUÃWUHDWPHQWà LSD 0.05 ÃÃIRUÃWHUP LSD 1,5 Ãà ÃÃGODÃWUDNWRZDQLDà 0.05 NIR ÃÃGODÃWHUPLQX 0.05 NIR 0.05 = 0.22 FOR TREATMENT = 0.47 FOR TERM = 0.22 dla traktowania = 0.47 dla terminu /6' ÃÃIRUÃWUHDWP HQWà ÃÃÃÃÃÃÃÃÃÃÃÃÃÃà à ÃÃIRUÃWHUP 1,5 ÃÃÃGODÃWUDNWRZDQLDà ÃÃÃÃÃÃÃÃÃÃÃÃÃÃà à ÃÃGODÃWHUP LQX FROST przymrozek DAYS AFTER SPRAY/dni po oprysku = FOR TREATMENT = FOR TERM = dla traktowania = dla terminu FIGURE 4. MAXIMUM QUAN- TUM EFFICIENCY OF PHOTO- SYSTEM II (FV/FM, A) AND PERFORMANCE INDEX (P.I., B) IN LEAVES OF OILSEED RAPE (BRASSICA NAPUS L. VAR. OLEIFERA) CV LISEK PLANTS GROWN IN FIELD CONDITIONS DURING 8 WE- EKS AFTER FIRST ASAHI SL APPLICATION. PRESENTED DATA ARE MEAN ±SE, n = 24. SOURCE: OWN STUDY. Rysunek 4. Maksymalna wydajnoœæ kwantowa fotosystemu II (Fv/Fm, A) oraz indeks witalnoœci (P.I., B) w liœciach rzepaku ozimego (Brassica napus L. var. oleifera) odm. Lisek rosn¹cych w warunkach polowych podczas 8-œmiu tygodni po pierwszym oprysku roœlin Asahi SL. Dane przedstawiaj¹ œrednie ±SE, n = 24. ródlo: badania w³asne. stimulator application (in spring of 2007). The maximum quantum efficiency of photosystem II (Fv/Fm, parameter used to express stress conditions of plants), up to 39 days after first Asahi SL application, did not differ between control and treated plants. Following the frost mentioned above, a lowering of the Fv/Fm value in control plants was recorded, while in Asahi SL treated plants, it did not change (Fig. 4A). Performance Index (P.I.), a parameter characterising the relative vitality of plants, was higher after the frost in Asahi SL treated plants. Moreover, it remained at a higher level comparable to control plants in all 4 measurements following the frost (Fig. 4B). DISCUSSION The results of our study proved earlier findings that Asahi SL/Atonik (international trade name for Asahi SL) has positive effect on the growth, development and yield of oilseed rape plants cultivated under field conditions. Asahi SL treated plants were taller, more vigorous and advanced in generative development. Similar effects of growth promotion were also recorded when Asahi SL was applied on cotton [Djanaguiraman et al. 2005a, b, Oosterhuis 2008], tomato [Djanaguiraman et al. 2004, 2005a] and Arabidopsis thaliana L. [Gawroñska et al. 2008b]. Contrary to this, Vavrina [1998a,b,c] did not notice any changes in the growth of bell pepper, cucumber and tomato between Atonik treated and non-treated plants.

14 The mechanism of stimulation of the elongative growth by Asahi SL might be attributed to the increased concentration of endogenous auxin caused by Asahi SL [Djanaguiraman et al. 2004, 2005a]. The results of this study clearly showed that Asahi SL improved the efficiency of the photosynthetic apparatus, which manifested itself through an increase of chlorophyll content and the intensity of photosynthesis and improved some of the parameters of chlorophyll a fluorescence. As previously mentioned, the chlorophyll content in plants treated with Asahi SL was higher, and this is in agreement with the results of a study conducted with A. thaliana [Gawroñska et al. 2008a,b], Hosta and Bergenia plants treated with Siapton and Asahi SL [Krajewska, Latkowska 2008] and with maize plants grown under nitrogen deficiency and treated with Asahi SL [Grzyœ et al. 2008]. Wróbel and WoŸniak [2008b] also reported an increase of both chlorophyll a, b and total chlorophyll and of carotenoids in common osier plants after biostimulator application. The results of our study also showed that in Asahi SL sprayed oilseed rape plants, the intensity of photosynthesis was higher. Although in some instance, the differences in intensity of photosynthesis were not very spectacular (ranging from 1-22% over control), but it is worthwhile to mention that through the 7 weeks of measurements, the intensity of photosynthesis was always higher in plants sprayed with biostimulators. Such long-term positive effects of Asahi SL, to the best of our knowledge, is a new discovery, because according to the information of the Asahi SL producer, its working time lasts up to three weeks from application [Zraly, personal communication]. The increased intensity of photosynthesis in plants treated with Asahi SL is in line with the data of Wróbel and WoŸniak [2008a] on common osier and of Gawroñska et al. [2008a,b] on A. thaliana plants. Zhao and Oosterhuis [1997] also observed an significant (by 13.5%) increase of leaf photosynthesis rate in cotton plants grown under drought stress when they were treated with another biostimulator (PGR-IV). The authors reported that these plants also had a higher stomatal conductance, which corresponds well with our results on oilseed rape and A. thaliana plants, which after Asahi SL treatment, often had lower stomatal resistance (a parameter opposite to stomatal conductance). Lowered stomatal resistance (or increased stomatal conductance) ensures greater CO 2 flow to chloroplast, which, at least partially, explains the previously discussed higher intensity of photosynthesis. On the other hand, however, lowered stomatal resistance allows more H 2 O to be lost by plants via transpiration. Indeed, the transpiration rate recorded in this study was often also higher in Asahi SL treated oilseed rape plants grown in the field and in A. thaliana plants grown both in a hydroponic culture and in a substrate under controlled conditions (growth chambers). Therefore, in consequence, it can be expected that the relative water content (RWC) should be also lower. Contrary to this expectation, the RWC was either almost unchanged or even slightly higher in plants treated with biostimulators. This suggests that Asahi SL also probably improves the plant water status, most probably via stimulation of water uptake. Improved RWC due to Asahi SL treatment was also reported by Wróbel and WoŸniak [2008b] in common osier plants. The greater efficiency of photosynthetic apparatus corresponded well with increased biological yield and economical yield (seed yield), as shown in this research. Both the fresh weight and dry matter of whole above ground parts, siliques with seeds and seeds were higher in Asahi SL sprayed plants when compared to control plants. S³owiñski 13

15 14 [2004] and S³owiñski and Jarosz [2008] also reported a positive effect of Asahi SL on the yield of oilseed rape plants in field experiments conducted in and respectively. In these studies, Asahi SL was tested in several locations in Poland (varying in soil and climate conditions), using three oilseed rape cultivars, and the results showed that the average seed yield of treated plants exceeded that of non-treated plants by 11.7% with a range of %. Positive effects of Asahi SL on the yield of oilseed rape was also reported by other authors [Babuška 2004, Harasimowicz-Herman, Borowska 2006, Budzyñski, Dubis 2008, Cieœlicki et al. 2008, Malarz et al. 2008], but, as pointed out by Harasimowicz-Herman and Borowska [2006], this strongly depends on weather conditions. An increase in yield as a result of biostimulator application has been observed in other plant species such as sugar beet [S³owiñski 2004, Jarosz et al. 2008, Kositorna, Smoliñski 2008], maize [Michalski 2008], celery, leek, potato and tomato (but not always for dry matter) [Czeczko, Mikos-Bielak 2004], feverfew [Gruszczyk, Berbeæ 2004], cotton [Zhao, Oosterhuis 1997, Oosterhuis 2008] and cotton and tomato [Djanaguiraman et al. 2005b]. The increase in yield is usually not very high and ranges from several to 20%, but much higher values are also reported, e.g. in the case of the Gruszczyk and Berbeæ [2004] study, which showed an increase in the biomass of feverfew plants by 54% and 63% in response to treatment with extract from great nettle and Atonik respectively. Contrary to the above, Anyszka et al. [2008] showed that the carrot yield of Asahi SL treated plants was higher only by %. Vavrina [1998 a,b,c] did not recorded any positive effects of Atonik on the yield, fruit number and fruit size of bell pepper, cucumber and tomato. Moreover, in some cases, treatment with a stimulator might even have a negative effect, as has been shown for dry matter accumulation and vitamin C concentration in some vegetables after biostimulator application [Czeczko, Mikos-Bielak 2004]. Studies of this work on components of oilseed rape yield revealed that a higher yield was a consequence of the greater numbers of laterals, siliques per plant and seeds per silique. These results are in agreement with those of S³owiñski [2004], Harasimowicz- Herman and Borowska [2006], Harasimowicz-Herman [2008], Budzyñski and Dubis [2008], Malarz and others [2008], S³owiñski and Jarosz [2008], who, similarly to us, observed a positive effect of Asahi SL on the above listed parameters of yield components. In addition, they often underline that the weight of 1000 seeds is greater due to Asahi SL/ Atonik application, which, together with the higher portion of biomass partitioned to the seeds, as shown in our research, additionally contributes to higher crop yield. An increased number of laterals/branches, fruit set and seeds after biostimulator application has been reported for other species, too [Djanaguiraman et al. 2005b, Gawroñska et al. 2008b, Oosterhuis 2008]. In our study, Asahi SL was applied either as a single or double spray, and in most evaluated processes/parameters, the single spray was more effective, which, though not always, was also reported by other authors [Oosterhuis 2008, Budzyñski, Dubis 2008]. Asahi SL is usually applied in early spring shortly after spring vegetation starts. However, according to Babuška [2004], application of Atonik about 3 weeks before harvest can also be beneficial as it increased the yield and reduced the harvest loss of oilseed rape.

16 It is commonly believed that the positive effects of Asahi SL are more evident and that its potential can be fully realised when plants are under stressful conditions, as under optimal conditions, the positive effects are sometimes very small or not even seen. Vavrina [1998 a,b,c] claimed that the lack of a positive effect on bell pepper, cucumber and tomato is probably due to fact that these plants were grown under favourable conditions. The results of this study on Chl a fluorescence confirmed this opinion. Between 36 and 39 days after Asahi SL was applied, the plants experienced a spring frost ( 4.2 O C). The value of Fv/Fm (maximal quantum efficiency of Photosystem II) of plants not treated with Asahi SL, measured on the 39 th day, was lower when compared with the previous and following terms of measurements, while in the case of treated plants, this parameter did not change. Also, the vitality index (Performance Index) in plants sprayed with a biostimulator right after the frost occurred was higher, and moreover, higher values of P.I. lasted until the end of measurements. These results demonstrate the protective role of a Asahi SL biostimulator against spring frost weather conditions and suggest that Asahi SL treated plants were able to recover from frost injury faster. Harasimowicz-Herman and Borowska [2006] tested the effect of Asahi SL on winter oilseed rape in relation to weather conditions. During the 2003/2004 growing season, winter oilseed rape plants were not exposed to the stress of low temperatures or moisture deficiency during the vegetation period and showed no reactions to Asahi SL. In the next season (2004/2005), when there was a strong frost in the budding period followed by precipitation shortage, application of Asahi SL caused an increase of seed yield up to 11% in biostimulator treated plants. The authors pinpointed that Asahi SL applied just after the start of vegetation resulted in better plant regeneration after winter. The protective role of biostimulators against stress was also reported for cotton, A. thaliana, maize grown under drought, heavy metal and nitrogen deficiency stresses [Zhao, Oosterhuis 1997, Gawroñska et al. 2008b, Grzyœ et al. 2008] as well as other stress, especially biotic stress [Book of abstracts ]. When comparing the positive effect of a biostimulator, the changes in a single parameter, most often, are not spectacular. However, when taking into consideration: length of the working time, for example, of the increased intensity of photosynthesis (in this experiment, lasting up to 7 weeks), which takes place on the most parts of sunny days, together with increased chlorophyll content, positive effects on development of generative organs (higher number of silliques, seeds in sillique) and higher biomass distribution to seeds plus protective effects against spring frost stress altogether they explain the 35% higher seed yield per plant, due to biostimulator treatment, recorded in this experiment. Of course, as previously discussed, the positive effects might be low or not seen at all when plants are grown under optimal conditions. 15

17 16 CONCLUSION 1. The biostimulator Asahi SL stimulates growth and development of oilseed rape plants, especially generative organs development. 2. Oils seed rape plants, due to biostimulator application, produced greater biomass and higher seed yield. 3. Higher seed yield resulted from a higher number of laterals, silliques, seeds per plant and a higher biomass partitioning to seeds and greater seed weights. 4. Efficiency of photosynthetic apparatus increased in response to Asahi SL application, and this manifested itself through the increased content of chlorophyll and higher intensity of photosynthesis. 5. The application of the biostimulator played a protective role against spring frost. 6. Single Asahi SL application gave better results than double treatments. REFERENCES Anyszka Z., Dobrzañski A., Pa³czyñski J. 2008: Response of onions and carrots to the biostimulator Asahi SL applied with herbicides. Book of abstracts of Conference: Biostimulators in modern agriculture, 7-8 February, Warsaw, Poland, 38. Babuška P. 2004: Uplatneni rostlinnìho stimulãtoru Atonik v øepce ozimì. Sbornik Øepka a Mãk, Book of abstracts of Conference: Biostimulators in modern agriculture, 7-8 February, 2008, Warsaw, Poland, 98. Budzyñski W., Dubis B. 2008: Response of winter rape to Asahi SL applied in spring. Book of abstracts of Conference: Biostimulators in modern agriculture, 7-8 February, Warsaw, Poland, 94. Cieœlicki W., Maciejewski T., Bartos-Spycha³a M., Jarosz A. 2008: Effect of biostimulator Asahi SL on yield of winter rape and its quality. Book of abstracts of Conference: Biostimulators in modern agriculture, 7-8 February, Warsaw, Poland, 96. Czeczko R., Mikos-Bielak M. 2004: Efekty stosowania biostymulatora Asahi w uprawie ró nych gatunków warzyw. Ann. UMCS, Sec E, 59, 3, Djanaguiraman M., Devi D.D., Sheeba J.A., Bangarusamy U., Babu Ch. 2004: Effect of oxidative stress on abscission of tomato fruits and its regulation by nitrophenols. Trop. Agric. Res., Vol. 16, Djanaguiraman M., Sheeba J.A., Devi D.D., Bangarusamy U. 2005a: Effect of Atonik seed treatment on seedling physiology of cotton and tomato. J. Biol. Sci., 5, 2, Djanaguiraman M., Sheeba J.A., Devi D.D., Bangarusamy U. 2005b: Response of cotton to Atonik and TIBA for growth, enzymes and yield. J. Biol. Sci., 5, 2, Gawroñska H., Przybysz A., S³owiñski A. 2008a: Biological basis of the mode of action of the Asahi SL biostimulator. Book of abstracts of Conference: Biostimulators in modern agriculture, 7-8 February, Warsaw, Poland, 20. Gawroñska H., Przybysz A., Szalacha E., S³owiñski A. 2008b. Physiological and molecular mode of action of Asahi SL biostimulator under optimal and stress conditions. Biostimulators in modern agriculture general aspects (in press). Wyd. Wieœ Jutra. Warsaw. Gruszczyk M., Berbeæ S. 2004: Porównanie wp³ywu wybranych preparatów stosowanych dolistnie na plony i jakoœæ surowca z³ocienia maruny (Chrysanthemum parthenium L.). Ann. UMCS, Sec. E, 59,2, Grzyœ E., Demczuk A., Saca³a E. 2008: Effect of Ashai SL on the activity of nitrate reductase, chlorophyll content in the leaves and yield of maize under nitrogen deficiency in the soil. Book of abstracts of Conference: Biostimulators in modern agriculture, 7-8 February, Warsaw, Poland, 54. Harasimowicz-Herman G. 2008: Modelling of field structure elements of winter rape by introducing Asahi SL into cultivation technology. Book of abstracts of Conference: Biostimulators in modern agriculture, 7-8 February, Warsaw, Poland, 90. Harasimowicz-Herman G., Borowska M. 2006: Efekty dzia³ania biostymulatora Asahi SL w uprawie rzepaku ozimego w zale noœci od warunków pluwiotermicznych. Roœliny Oleiste/Roœliny Oleiste, 1, Jarosz A., S³owiñski A., Kositorna J., Smoliñski M. 2008: Including Asahi SL biostimulant into the technology

18 of sugar beet growing. Book of abstracts of Conference: Biostimulators in modern agriculture, 7-8 February, Warsaw, Poland, 122. Kositorna J., Smoliñski M. 2008: Biostimulators can protect sugar beet from stress caused by herbicides. Book of abstracts of Conference: Biostimulators in modern agriculture, 7-8 February, Warsaw, Poland, 26. Krajewska J., Latkowska M.J. 2008: Effects of biostimulants (Asahi SL and Siapton) on growth of Bergenia cordifolia ((Haw.) Sternb.) Rotblum and Hosta sp. (Tratt.) Sum and Substance and Minuteman. Book of abstracts of Conference: Biostimulators in modern agriculture, 7-8 February, Warsaw, Poland, 80. Malarz W., Kozak M., Kotecki A. 2008: The use of Asahi SL biostimulator in spring rape growing. Book of abstracts of Conference: Biostimulators in modern agriculture, 7-8 February, Warsaw, Poland, 100. Michalski T. 2008: Possibilities of increasing productivity of maize by use of non-conventional methods. Book of abstracts of Conference: Biostimulators in modern agriculture, 7-8 February, Warsaw, Poland, 28. Oosterhuis D. 2008: Atonik TM a biostimulators for increased nitrogen, protein and yield of cotton. Book of abstracts of Conference: Biostimulators in modern agriculture, 7-8 February, Warsaw, Poland, 18. Sas-Paszt L., urawicz E., Masny A., Filipczak J., Pluta S., Basak A. 2008: Biostymulators for small fruits. Book of abstracts of Conference: Biostimulators in modern agriculture, 7-8 February, Warsaw, Poland, 32. S³owiñski A. 2004: Biostymulatory w nowoczesnej uprawie roœlin. Wieœ Jutra, 3(68), S³owiñski A., Jarosz A. 2008: Including Asahi SL biostimulant into the technology of winter oilseed rape growing. Book of abstracts of Conference: Biostimulators in modern agriculture, 7-8 February, Warsaw, Poland, 98. Vavrina C.S. 1998a: Atonik plant growth stimulator: Effect on bell pepper under drip irrigation in SW Florida. Vegetable Horticulture. 23 Mar. [ Vavrina C.S. 1998b: Atonik plant growth stimulator: Effect on cucumber under seepage irrigation in SW Florida. Vegetable Horticulture. 30 Mar. [ Vavrina C.S. 1998c: Atonik plant growth stimulator: Effect on tomato under seepage irrigation in SW Florida. Vegetable Horticulture. 06 Apr. [ Wróbel J., WoŸniak A. 2008a: The effect of Atonik plant growth stimulator, applied by different methods, on the physiological activity and yield of common osier (Salix viminalis L.). Book of abstracts of Conference: Biostimulators in modern agriculture, 7-8 February, Warsaw, Poland, 86. Wróbel J., WoŸniak A. 2008b: The effect of Atonik plant growth stimulator on chemical composition of common osier Salix viminalis L., grown in different substrates. Book of abstracts of Conference: Biostimulators in modern agriculture, 7-8 February, Warsaw, Poland, 84. Zhao D., Oosterhuis D. 1997: Physiological response of growth chamber-grown cotton plants to the plant growth regulator PGR-IV under water-deficit stress. Environ. Exp. Botany, 38,

19 18 RRESPONSE OF WINTER OILSEED RAPE TO THE BIOSTIMULATOR ASAHI SL APPLIED IN SPRING Wojciech Budzyñski, Bogdan Dubis, Krzysztof Jankowski University of Warmia and Mazury in Olsztyn, Olsztyn Poland INTRODUCTION AND OBJECTIVE OF THE STUDY The presently grown varieties of winter oilseed rape have a high yield potential (~5.5 mg. ha -1 ) which, however, is difficult to utilize [Anonim 2007, Jankowski 2007]. The above limits are due not only to the low level of technological advancement of the production process but, above all, the crop s high sensitivity to abiotic and biotic stress factors. Abiotic stress is manifested by considerable frost damage in early spring due to high temperature fluctuations, and by limited branching and silique setting caused by precipitation shortage. The greatest biotic stressor is the occurrence of plant-feeding pests which seriously damage collar roots, stems, flowering branches and siliques. Under such growth and early spring developmental conditions, the effectiveness of the main yield-forming and yield-protection factors is low, relatively unstable over years and difficult to accurately forecast [Budzyñski, Ojczyk 1996, Muœnicki 2005, Jankowski 2007]. Active nitrophenol group compounds (Asahi SL and Atonik SL) may support plant regeneration after the occurrence of stress factors such as frost, drought or pest damage by the expression of defence mechanisms. This plant response was determined in studies on winter oilseed rape, sugar beets, potatoes and selected grain crops [Michalski, Horoszkiewicz-Janka 2005, Horoszkiewicz-Janka, Jajor 2006, Maciejewski et al. 2007, Jarosz et al. 2008, Sawicka, Mikos-Bielak 2008]. Biostimulators increase the plant s energy production, speed up cytoplasm flow in cells and tissues, stabilise the products of biochemical reactions and maximise the effectiveness of natural hormone synthesis [Gawroñska et al. 2008, Przybysz et al. 2008]. The application of Asahi SL stimulated the effectiveness of the photosynthetic apparatus and the activity of the antioxidant system [Gawroñska et al. 2008], and it increased the PI (performance index) which characterises the relative vitality of plants [Przybysz et al. 2008]. The objective of this study was to determine the effect of Asahi SL biostimulation used in various growth stage of plants on the stand architecture of winter oilseed rape, the yield-forming attributes of yielding plants and seed yield under experimental plots and large commecial fields. EXPERIMENTAL CONDITIONS AND METHODS The paper presents the results of five-year exact experiments and three-year largearea field experiments carried out on commercial fields to determine the effect of the biostimulator Asahi SL on the growth, development and yield of winter oilseed rape in the

20 farming production areas of the Warmia and Mazury province, which are characterised by regular oilseed rape freezing periods. The experiments were conducted on experimental and production fields at the University Research Station in Ba³cyny (N = , E = ). The exact experiments were carried out between The experiments were established in a randomized complete block design, in 4 replications with the following variables: A control (no biostimulation); B Asahi SL at stage BBCH 30; C Asahi SL at stage BBCH 50; D Asahi SL at stage BBCH 30 and 50. Regardless of season, the biostimulator Asahi SL was applied at a dose of 0.6 dm 3. ha -1 (quantity of spray liquid 300 dm 3. ha -1 ) in treatments combined with an insecticide program offering protection against Ceuthorrhynchus napi Gyll. and/or Meligethes aeneus F. pests. The experiments were set on grey-brown podsolic soil developed from on medium loam of soil suitability complex 2, quality class IIIa. The soil had a slightly acidic reaction, and it was characterised by a high content of phosphorus and an average content of potassium and magnesium. The forecrop was winter wheat (2002 and 2003) or a cereal legume mixture (2004, 2005, 2006). 35 kg P. ha -1 (triple superphosphate) and 100 kg K. ha -1 (60% potash salt) were applied prior to rape seed sowing. The nitrogen dose of 220 kg. ha -1 was applied in 3 parts: 40 kg. ha -1 (BBCH 00), 120 kg. ha -1 (BBCH 30) and 60 kg. ha -1 (BBCH 50). Dressed winter rape seeds were sown in the last ten days of August in the quantity of 80 germinating seeds per m 2 of a plot covering an area of 16 m 2, spacing of cm. Chemical weed control was introduced after sowing (BBCH 00), and in the spring the crops were protected against pests (BBCH 30 and 50) and diseases (BBCH 67). Rape plant were harvested in two phases. In , the large-area field experiments were also carried out on production fields with a total area of 70 ha. The following variables were applied: a control (no biostimulation); b Asahi SL at stage BBCH 30; c Asahi SL at stage BBCH 30 and 50. Crops were grown in accordance with an integrated technology based on a good agricultural practice. The results of yielding and biometric measurements of yielding plants were verified by an analysis of variance in accordance with the established experimental method. The mean values of the investigated attributes in all treatments were compared with the use of Duncan s test. LSD values were stated for 5% error. The economic profitability of applying the biostimulator Asahi SL in the production technology of oil-bearing raw material was evaluated based on the findings of Klepacki and Wa³kowski [2005]. RESULTS AND DISCUSSION The study was conducted in years characterized by different levels of rainfall, affecting water supply to rape plants (Tab. 1). Good humidity conditions for rape development and yielding were noted in the course of 4 years when total precipitation in the spring and summer season was higher than or approximated the water requirements of this species (Tab. 1). Seed yield was high. The yield of winter oilseed rape in 2005, a dry year, should also be regarded as satisfactory (Tab. 4). In comparison with the control treatment, the application of Asahi SL at the stage of inflorescence emergence and budding did not have a significant effect on stem elongation until processing maturity (Tab. 2). 19