Poster: Nutrient Biology

Abs # 404: Preferential utilization of organic nitrogen over inorganic nitrogen by some vegetable crops

Presenter:	Watanabe, Shuichi , nabeshu@affrc.go.jp
Authors	Watanabe, Shuichi  (A)   Yoshikawa, Hiroyasu  (A)   Yoshikawa, Seiko  (A)
Affiliations:	(A): National Agricultural Research Center for Western Region
Web Site:	http://nabeshu@affrc.go.jp

Yamagata et al. (2001) suggested the possibility that plants such as upland rice and chinese cabbage used organic nitrogen preferentially (1). They suggested that the ability to take up organic nitrogen was varied with plant species. Thus, the usability of organic nitrogen by some vegetable crops was examined. Every vegetable crop (chingensai, sunny lettuce, turnip and carrot) was cultivated in 1/5000a Wagner pots supplied with 0.8g nitrogen, enriched by ¹⁵N(2.57 Atom %) in the form of (NH₄)₂SO₄. A half of the nitrogen was supplied with two different forms. The one was supplied with a mixture of rice bran and straw (RBS: C/N=20) as organic fertilizer (ON plants). The other was supplied with (NH₄)₂SO₄ (IN plants). Growth amounts of all plants and total amounts of absorbed nitrogen were higher in ON plants than IN plants and nitrogen concentrations of ON and IN plants were nearly the equal. About 20% of absorbed nitrogen of ON plant was originated in ¹⁵N-NH₄ and 80% was in RBS. About 40% of absorbed nitrogen of IN plant was originated in ¹⁵N-NH₄. The ratios of ¹⁵N to total N in the plants were almost equal to the ratios of added ¹⁵N-NH₄ to total NH₄ in the pots. These results suggest that all plants tested in this examination absorb nitrogen compounds from organic fertilizers more from (NH₄)₂SO₄. under co-existence of inorganic and organic nitrogen sources. The effects of organic nitrogen on the uptake pattern of inorganic nitrogen are now under investigation by means of hydroponics using amino acid as organic nitrogen sources. (1) Yamagata M et al. (2001) Possibility of Direct Acquisition of Organic Nitrogen by Crops. In Plant Nutrient Acquisition New Perspectives, Springer, pp399-420