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IMPROVEMENT OF SYMBIOTIC NITROGEN FIXATION BY ALNUS SP.IN MONOCULTURE AND MIXED STANDS WITH POPLAR OR DOUGLAS IN THE NETHERLANDS.

Objective



RECENT INVESTIGATIONS POINTED OUT A SIGNIFICANT ECOTYPE DIFFERENTIATION FOR BLACK ALDER (ALNUS GLUTINOSA), BOTH WITH REGARD TO CULTIVATION SYSTEMS AS TO NODULATION WITH THE ROOT NODULE FORMING ACTINOMYCETE FRANKIA. GENETIC DIFFERENTIATIONS WITH REGARD TO HOST PLANT SPECIFITY AND NITROGEN FIXING ACTIVITY ALSO EXIST FOR FRANKIA-STRAINS. IT IS EXPECTED THAT THE RIGHT COMBINATION OF PLANTS (ECOTYPES, CLONES) AND FRANKIA-STRAINS CAN BE FOUND TO ACHIEVE A YIELD INCREMENT BOTH IN MONOCULTURE AS IN MIXED PLANTATIONS. SPECIAL ATTENTION WAS PAID TO THE FOREST ECOTYPE "BENTHEIM" OF ALNUS GLUTINOSA. THIS ECOTYPE IS CHARACTERIZED BY A RELATIVELY SLOW YOUTH GROWTH DURING THE FIRST 8 YEARS AND A DELAYED GENERATIVE PHASE. THIS ECOTYPE FORMS LARGE AND ERECT TRUNKS AND IS AN EXCELLENT COURSE OF WOOD. IT IS ABERRANT OF THE BETTER KNOWN PIONEER ECOTYPES (E.G. WEERRIBBEN) WHICH ARE CHARACTERIZED BY RAPID YOUTH GROWTH, EARLY EXTENSIVE FRUITING AND RELATIVELY SMALL SIZE. PLANT MATERIAL OF THE FOREST ECOTYPE "BENTHEIM" AND THE PIONEER ECOTYPE "WEERRIBBEN" HAVE BEEN CLONED WITH TISSUE CULTURE TECHNICS IN ORDER TO OBTAIN HOMOGENOUS PLANT MATERIAL FOR NODULATION STUDIES. THIS MATERIAL WAS PROPAGATED IN TISSUE CULTURE AND USED TO SET UP A STANDARDIZED SYSTEM TO MEASURE THE INFECTIVITY AND EFFECTIVITY OF ISOLATED FRANKIA-STRAINS UNDER AXENIC CONDITIONS. DIFFERENT ISOLATION TECHNICS WERE USED IN ORDER TO SELECT DIFFERENT TYPES OF FRANKIA-STRAINS. SPECIAL ATTENTION WAS PAID TO THE ISOLATION OF WIDELY OCCURING STRAINS WHICH PRODUCE SPORES WITHIN THE NODULES BUT WHICH HAVE NOT YET BEEN OBTAINED IN MASS CULTURE. THE INFECTIVITY OF ISOLATED STRAINS WAS DETERMINED BY INOCULATING THE PLANTS WITH FRANKIA-SUSPENSIONS UNDER STANDARDIZED CONDITIONS. NITROGEN-FIXING ACTIVITY OF FRANKIA CULTURES AND NODULATED PLANTS WERE MEASURED BY THE ACETYLENE REDUCTION METHOD.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

Rijksinstituut voor Onderzoek in de Bos- en Landschapsbouw 'De Dorschkamp'
Address
20,Bosrandweg
6700 AA Wageningen
Netherlands