Informative Model Of Biological Process Of Soybean Symbiotic Nitrogen Fixation

A.V. Kalinichenko

Dept of Agricultural Management, Poltava State Agricultural Institute, Poltava, Ukraine

The informative model of the biological process of soybean symbiotic nitrogen fixation was created on the basis of an informative-logical method of approach. It takes into account the presence of fortuitousness in natural phenomena. The usage of this model allows to improve the quality of a soybean seed and products of its processing. Received under this technology products of processing, extrudate and oilcake, contain all usually present amino acids and also the increased quantity (by 1.5% and more) of protein.

The model allows to solve such problems as: receipt of the prognosis of the expected values of a crop; of the quantity of the nitrogen and protein accumulated by a plant; of the nitrogen quantity that remained in soil for the given bacteria culture and soybean sort. It gives a solution of a direct goal (a short-term prediction of the expected values of informative parameters) as well as of an inverse task (the choice of the best culture of tuberous bacteria or soybean sort with the aim to receive the biggest values of the determined informative parameters). In addition, in case of need, it is possible to determine the probable interim values of informative parameters and to conduct a dynamic research of the process according to the determined moment of time or according to the periods of plants growth.

The research of the efficiency of the symbiotic nitrogen fixation was conducted on the crops of the soybean of the Crimean Scientific Industrial Society "Elite", Selection and Genetics Institute of the Ukrainian Academy of Agricultural Sciences, and of some farms in the Autonomous Republic of Crimea and Odesa region. These soybean seeds were processed with rhizotorfin produced on the basis of tuberous bacteria cultures 629a, 634b, 646. While studying the issues of influence of climatic factors and soybean genotype on nitrogen fixation efficiency, 122 collection soybean sorts both from home collection and produced in the USA, Canada, China and countries of Eastern and Western Europe, were taken. The study of the efficiency of the pre-sowing processing of soybeans was conducted on the harvests of the primary crops as well as post hay crops and reaping crops.

On the basis of the model, the process of selection of the perspective material for the symbiosis partners was improved, and culture B. japonicum 634b and soybean sorts of Krepysh, Odes'ka 124, Arkadia Odes'ka, Yug 40, Kharosoy, were recommended as the most effective.

Solution of numerous tasks and field researches were conducted on the large amount of soybean sorts and tuberous bacteria cultures. A short-term prediction of symbiosis system behavior was presented which allows us to determine the most perspective directions of the field research for realization and receipt of the high quality production for subsequent processing. Conclusions and recommendations on usage of the given model were made and offered according to the results of the research.

Application of the given research is proposed to determine the behavior of a biological system according to different factors (external as well as internal), to determine the most real final system conditions with interdependent output factors, and in addition, it is recommended to be used when choosing the most rational cropping strategy of soybean according to the practical needs of agricultural farms; in purposeful planning of soybean agricultural producing; in selection of the most effective cultures of nitrogen fixation bacteria and soybean plants in accordance with various external conditions when determining the conditions that allow to receive a plant crop of full value; and in selecting a complementary material among macro- and microsymbionts.

OPTIMIZATION OF INOCULATION OF CALLIANDRA CALOTHYRSUS, LEUCAENA LEUCOCEPHALA AND ACACIA MANGIUM WITH RHIZOBIA

D. Diouf12, S. Forestier23, M. Neyra2, D. Lesueur2,3

'Département de Biologie Végétale, UCAD, BP 5005 Dakar, Sénégal laboratoire de Microbiologie des Sols, IRD Bel Air, BP 1386 Dakar, Sénégal 3Programme Arbres et Plantations du CIRAD-Forêt, Dakar, Sénégal

1. Introduction

Several legume inoculation techniques are well known and used within the framework of many experiments. However, until now these techniques were often used without including several factors that can optimize inoculation. The purpose of our investigations was to study such factors as the physiological stage of the bacterial culture, the size of the inoculum and the mode of inoculation on the nodulation and biomass production for three agroforestry species: Calliandra calothyrsus, Leucaena leucocephala and Acacia mangium inoculated respectively with CCK13 (Lesueur et al. 1996), Ldk4 (Lesueur et al. 1998) and Aust. 13c (Galiana et al. 1990) strains.

2. Results and Discussion

The physiological stage of the bacterial culture had no significant effects on nodule biomass and seedling growth. However, inoculation with Ldk4 culture in the plate phase significantly improved nodulation of L. leucocephala. For all the three species, no significant differences in shoot biomass were noted.

Nodulation and growth of inoculated seedlings were less variable depending on the size of the inoculum. The greatest number of nodules was recorded on A. mangium for a dilution containing 1010 bacteria mL"1. Alternatively for C. calothyrsus and L. leucocephala, 109 bacteria mL"1 corresponds to the optimal dilution. Similar results were noted for C. calothyrsus (Lesueur et al. 1996) and fori, leucocephala (Lemkine, Lesueur 1998).

Inoculation method had significant effects on nodulation and seedling growth. For C. calothyrsus and A. mangium, inoculation with a liquid culture one week after sowing was more favorable for growth of the seedlings. On the other hand, inoculation of L. leucocephala with a bacterial culture mixed with arabic gum significantly improved seedling growth.

3. Conclusion

Our work aims to determine the types of inoculum and the best formulation that are favorable to ensure optimal growth of three agroforest species. Results showed that the improvement of the growth of C. calothyrsus, L. leucocephala and A. mangium by inoculation in nurseries with efficient rhizobium strains was dependent on the mode of inoculation. Our work could be used to help in the large-scale production of forest seedlings.

4. References

Galiana et al. (1990) Appl. Environ. Microbiol. 60, 3974-3980 Lemkine G, Lesueur D (1998) Aciar Proc. 86, 168-171 Lesueur D et al. (1996) Forest Farm Comm. Tree Research Reports, 62-76 Lesueur D et al. (1998) Aciar Proc. 86, 86-95

5. Acknowledgements

This work was supported by the European Commission (INCO Contract No. IC18-CT97-0194).

COMBINED EFFECTS OF RHIZOBIA INOCULATION AND HOST PLANT ORIGIN ON GROWTH AND NODULATION OF CALLIANDRA CALOTHYRSUS

'Programme Arbres et Plantations du CIRAD-Forêt, Dakar laboratoire de Microbiologie des Sols, IRD Bel Air, BP 1386 Dakar département de Biologie Végétale, UCAD, BP 5005 Dakar, Sénégal

1. Introduction

Several authors have described a significant variation in nodulation and nitrogen fixation between and within ecotypes of woody legumes such as Gliricidia sepium and Leucaena (Sanginga et al. 1991; Mureithi et al. 1994), but no data are available on growth and nodulation of Calliandra calothyrsus. C. calothyrsus is an important species in agroforestry because of its value as a forage. A greenhouse experiment was carried out in order to evaluate the performances of several ecotypes of C. calothyrsus inoculated with two types of rhizobia (Lesueur et al. 1996). Results obtained are useful for the identification of a standard inoculum for improving forage production for C. calothyrsus in the field.

2. Results and Discussion

Growth, nodulation and nitrogen fixation of C. calothyrsus trees were significantly stimulated by the inoculation with both rhizobium strains. These results confirmed those obtained by Lesueur et al. (1996). This positive effect of the inoculation is variable according to the C. calothyrsus ecotype. The occurrence of an interaction between both factors for the different parameters. Comparable interaction to those found in this study have been reported for Casuarina (Sanginga et al. 1990) and A. cyanophylla (Nasr et al. 1999).

3. Conclusion

The main objective of this work was to determine if the inoculation with one rhizobium strain had an effect on the growth and shoot total N content of several ecotypes. Results show that seed origin seemed to affect the growth, nodulation and nitrogen fixation of inoculated C. calothyrsus. For improving symbiotic nitrogen fixation the interaction between strain and C. calothyrsus seedlot will be taken into account.

4. References

Lesueur et al. (1996) Bois For. Trop. 248, 215-230

Sanginga et al. (1990) Soil Biol. Biochem. 22, 539-547

Sanginga et al. (1991) Biol. Fertil. Soils 11, 273-278

5. Acknowledgements

This work was supported by the European Commission (INCO Contract No. IC18-CT97-0194).

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