Responses Of Different Nitrogen Forms For Tomato Seedling By Either Homogenous Or Localized Culture

The materials of experimentation were the small orange tomato of Taiwan; In the present study, whole-and split-root experiments were together conducted to study the adapted situation of different nitrogen (N) forms on tomato (Lycopersicon esculentum Mill.) seedlings, that were root growth and morphology changing, and nitrate reductase (NR) activities and glutamine synthetase(GS) activities of the tomato seedlings roots and shoot leafs.Results showed that in whole-root system, tomato root and shoot gained the ultimate biomass with mixed culture of NO3--N and NH4+-N at the ratio of 75:25, while gained the least biomass with sole NH4+-N supply. With the increase of NH4+-N in solution, the total root length and root surface area decreased, while root volume and nitrate reductase activities with glutamine synthetase activities increased firstly and then decreased, and the root average diameter and nitrate reductase activities of the tomato seedlings'shoot leafs were largest at the ratio of NO3--N:NH4+-N as 75:25, whole the glutamine synthetase activities of the tomato seedlings'root and shoot leafs was largest at the ratio of NO3--N to NH4+-N as 50:50. In split-root system, however, tomato shoot gained the ultimate biomass in N+A (NO3--N+NH4+-N) treatment in which the ratio of NO3--N to NH4+-N is 50:50, and the shoot biomass treated by N+W (NO3--N+H2O) is the least. In split-root system, however, tomato seedlings'right roots and shoot leafs gained the ultimate nitrate reductase activities in N+AN treatment in which the right ratio of NO3--N to NH4+-N is 75:25, and nitrate reductase activities of the tomato seedlings'right roots and shoot leafs treated by N+A (NO--N+NH4+-N) is the least; Tomato seedlings'right roots and shoot leafs gained the ultimate glutamine synthetase activities in N+A (NO3--N+NH4+-N) treatment, and glutamine synthetase activities of the tomato seedlings'right roots and shoot leafs treated by N+N (NO3--N+NO3--N) is the least. Localized supply of NO3--N leads to a significant increase of the nitrate reductase activities of tomato seedlings roots and shoot leafs, but also controls the glutamine synthetase activities of tomato seedlings roots and shoot leafs in counter side (NO3--N supply). Localized supply of NH4+-N leads to not only a significant increase of the average root diameter itself, and also improves the root volume and surface area in counter side (NO3--N supply). Although localized supply of H20 could significantly decrease the total root length, the root surface area, root volume and the average of root diameter itself; But it promoted significantly the total root length, the surface area and root volume in the counter side (NO3--N supply). In conclusion, the change of root morphology and the effects of supersession enzyme activities of nitrogen, that are the nitrate reductase and the glutamine synthetase, might be the response for tomato seedlings to adapt to different N forms.