Response Of Growth And Absorption Characteristics Of Betula Platyphylla And Larix Spp. Seedlings From Different Origins To Organic Nitrogen Fertilization

The absorption of organic nitrogen has attracted increasing attention throughout the world in recent years.Some of the scholars consider that plant is directly absorbed and use organic nitrogen.However,the critical determinants of organic nitrogen absorption and deep-rooted mechanism remain unclear.Betula platyphylla and Larix spp.are widely distributed in north China.Seedlings and tissue culture seedlings of two species are used to determine the response and growth of seedlings under different provenances.Moreover,stable isotope tracer technique is used to study the change of nitrogen-absorbed under controlled environment and nitrogen treatments.The purpose of study is to verify the relation of absorbing organic nitrogen and latitude distribution.Further,we hve been analyzed the effects of habitat environment and nitrogen supply conditions on the absorption of organic nitrogen under different latitudes.The results are as follows:1.Plant seedling height,collar diameter,root volume,root length and biomass growth of two species seedlings were observed significantly increased in different nitrogen forms.The morphological indexes and biomass of Betula platyphylla were the highest in Gly-N and significantly higher than NH4+-N and CK(P<0.05),while those of Larix spp.seedlings were the highest in Gly-N,followed by Ni4+-N,and CK.There was significant difference between the growth and biomass of seedlings at different latitudes:seedlings hight,growth and biomass were recorded in Wu Zhai than Mo He and Wang Qing.The biomass of each part of Betula platyphylla and morphological indexes of Larix spp.Seedling.were negatively correlated with the latitude.2.Betula platyphylla and Larix spp.seedlings nitrogen content and nitrogen accumulation were significantly increased under different nitrogen levels or concentration.The nitrogen content of each organ of Betula platyphylla and Larix spp.seedlings was the highest in NH4+-N3 followed by Gly-N,and CK the lowest.Gly-N significantly increased the amount of nitrogen accumulation in the components of Betula platyphylla and Larix spp.,and aerial parts and root of Gly-N were increased by 101.3%,53.3%and 236.4%,109.6%,respectively.The habitat environment has significantly affect on nitrogen content and nitrogen accumulation of Betula platyphylla and Larix spp.In addition,the variation of nitrogen content and nitrogen accumulation has positively correlated with latitude.Nitrogen content was signifcant different in overground and root of birch and larch trees.3.Larix spp.seedlings organic nitrogen absorption was different under different nitrogen condition.The promotion of absorb molecular glycine was significant in the earlier stage after fertilization and control.The proportion of molecular glycine absorbed by Larix spp.was positively correlated with latitude under two kinds of nitrogen supply.4.There are obvious differences between the absorption of organic nitrogen under different culture conditions.The proportion of glycine that directly absorbed in the molecular state of Sterile seedlings was significantly higher than that of container seedlings.Results proved that the absorption of intact molecular glycine in Sterile seedlings was twice the rate as container seedlings.the proportion of molecular glycine absorbed by Betula platyphylla seedlings from three provenances was positively correlated with the latitude under two culture conditions.