| The experiments were carried using apple seedlings (Malus hupenensis Rehd). It was studied the characteristics of response of the seedlings growth to nitrogen forms under water culture condition.The main results were as follow:1. Rhizosphere supplied different nitrogen forms 3 to 7 days, the results indicated: In NO3—treatment, the seedlings growed better than NH4+ treatment.The photosynthesis rate,transpiration rate and stomata conductance by supplied NO3- were upper than NH4+ treatment.The levels of Z+ZR and iP+iPA were higher, ABA levels were lower, but the levels of IAA were similar between NO3- treatment and NH4+ treatment. After the leaves in NH4+ treatment were labeled NO3-, the growth of apple seedling were similar to the NO3- treatment, but better than NH4+ treatment. It indicated that the different effects of NO3- and NH4+ on the growth of Malus hupenensis Rehd seedlings related to the levels of ZR.2. The seedlings growed better in NH4NO3 treatment than fed solely with NO3- or NH4+. In NH4NO3 treatment, the photosynthesis rate,transpiration rate and stomata conductance were highest, and the levels of Z+ZR,iP+iPA and IAA were maximal, ABA level were lower.3. In order to disscuss the characteristic of Z-type cytokinins in response to NO3-, we determine the change of cytokinins concentration in different organs and leaf areas after NO3- application 0.5 to 24h. The results indicated: the concentration of zeatin and zeatin riboside (Z+ZR) both in roots and in leaves was increased quickly in 0.5 hour after nitrate supply,and the levels of Z+ZR were always higher than ammonium treatment and the control within 24 hour. In stems,the concentration of Z+ZR increased most in 1 hour after nitrate treatment,but then there was no significant difference between the... |
PDF Full Text Request