Perembesan Senyawa Nitrogen dari Bintil Akar Kedelai (Glycine max (L) Merril)

Abstract

Nitrogen fixation resulting from the symbiosis between legumes and Rhyzobium sp. as well as being af value to the host plant is also of benefit to other plants growing alongside or after it. The benefit to other plants appears to arise from the release of nitrogen (N) from roots and from the availability of released by dead and decaying plant parts. The type and amount of released N is dependent on legume and Rhyzobium sp. and strains, plant growth condition, the growth medium and the stage of plant development. The purpose of the present research was to determine the effkts of plant age, Rhyzobium strains, level of N in the growth medium, and soybean variety on the release of N from roots and root nodules, including the effect of N release on other plants grown with soybean. To achieve this end, four consecutive experiments were conducted, namely, (1) Testing of methods of growing soybean in sterile and non-sterile sand medium free of N; (2) Pattern of N release from soybean roots; (3) Pattern of N release from soybean root nodules; and (4) Use of released N by maize interplanted with soybean. The results indicated that soybean releases some N from its roots. The amount of N released was influenced by, among other factors, variety, age. inoculum, and the level of N in the growth medium. Some N release was in the form of free amino acids, namely. aspartate, serine, glutamate, glycine, and alanine. Nitrogen release from root nodules of the soybean var. Clark 63 was 2.2.45 kg/ha., a level too low to be of value to another crop interplanted with soybean. It will be different if the soybean plants were cut and burried before the other crops were grown. Cutting and burrying of two weeks old soybean plants prior to maize planting will increase the N content of the maize to 19.7 mg N/2 plants.