Maize Physiological Response Under Seawater Stress And Exploring In Mechanism Of Absorbing NO₃^- Of Maize

The study included two parts: First, 10 maize cultivars which were mainly cultivated in coastal area of province under seawater stress were studied. We studied the physiological and biochemical charge of the SOD and POD activity, soluble protein content, free proline contents , malondialdehyde(MDA)content and photosynthetic pigment content, photosynthetic rate of maize leaves, and the water concent of maize different apparatus , and we investigated the charge of ions of CI- concent, Na⁺ concent, K⁺ concent, Ca²⁺ concent and Ca²⁺/Na⁺, K⁺/Na⁺ et al in order to compare the changes of physiological indexes under seawater stress, and explored the salt tolerance of different maize varieties by membership function values, aims to provide theoretical foundation to guided by the maize production in coastal area in hebei. The results were as follows:(1) Under seawater stress, the photosynthetic pigment content, soluble protein content and photosynthetic rate of maize leaves were declined; water concent, K⁺ concent, Ca²⁺ concent and Ca²⁺/Na⁺, K⁺/Na⁺ were declined in maize different apparatus, and have difference of delice in different varietie.(2) Under seawater stress, POD, SOD activity of maize leaves have considerable difference in different varieties. The activity were increased in some varieties and were declined in other varietes.(3) Under seawater stress, the Na⁺ were increased in maize different apparatus and CI- concent, free proline content and malondialdehyde content of maize leaves were increased.(4) By evaluation of membership function value of 10 maize species on the salt tolerance results show: Jiyuan 1, Jingdan 28 and Dongdan 16 are the most tolerant species to salt stress; Liyu 16, Dongdan 13, Zhengdan 958, Lianyu 16 and Dongdan 8 are moderate tolerance to salt stress; Jundan 20 and Dongdan 60 are the weakest tolerance to salt stress. Second: The test uses non-invasive micro-test technique (NMT) in order to directly investigate the fluxes of NO₃^- at living maize root, while using routine method to investigate the nitrate content of maize. In order to study mechanism of absorbing NO₃^- of the root in maize, in order to provide theoretical foundation to research of nitrogen for the future. As well as provide technical method on the other ions in the absorption and velocity of maize root. The results were as follows:(1) The main areas of absorbing NO₃^- is elongation area in the root, and meristematic area and mature area is the main areas of the discharging, and concentrated in 1000-2500μm place.(2) With the NO₃^- concentration increasing, the root showed different trends of NO₃^-absorb, and in the 0.01-20mmol/L, maize root absorbed NO₃^-, and the uptake value is biggest at 15-20mmol/L ; But immediately shows discharging at 25mmol/L.(3) Maize seedlings root NO₃^- content reaches maximum at NO₃^- concentration for 5mmol/L, the change of NO₃^- content at shoot is not significant. We believe the main reasons causing difference of absorption rate and accumulation that flow differences of NO₃^- at different parts of root...