| In order to do some contrast studies to root growth, metabolism of hydrogen peroxide(H)2O2) and water regulation characteristics of winter wheat, we use spectrophotometer,fluorescent staining, scanning electron microscope and cell chemistry positioning methods atthe regreening and jointing stage of winter wheat growth. Such studies also had been done atdifferent nitrogen phosphate levels from low fertilizer level of N1P1(Nitrogen0.1g/kg, P2O50.05g/kg) to the high fertilizer level of N2P2(pure nitrogen0.3g/kg, P2O50.15g/kg) treatingwith winter wheat, and at different water deficit levels (the proportion of soil moisturecontent to field moisture is70%85%(CK),55%70%(LS), and40%55%(SS)).Theexperiment provides a theoretical basis for people to understand the root morphology and therelationship between physiological changes and cell functions of winter wheat and also give away to achieve an optimal control that promote the utilization of water and fertilizer whenwinter wheat grow at the water deficit conditions. The results were shown follows:(1) Effects of water-nitrate combination on root morphology indicate that under thesame N\P conditions, water stress in regreening and jointing stage inhibited the growth ofwinter wheat, which reduced the accumulation of dry matter. The relationship between thedegree of inhibition and the water stress were positively correlated. At the regreening stage,the root-top ratio was LS>CK>SS with N2P2> N1P1; At the jointing stage, the root-top ratiowas LS>SS>CK with N2P2<N1P1. When water stress at regreening and jointing stage, winterwheat can promote the growth and development of root hairs, enlarging the effective area toabsorb water and nutrients.(2) Effects of water-nitrate combination on root osmotic regulation show that under thesame N\P conditions, with water deficit intensified in regreening and jointing period, freepraline, soluble sugar and solubility protein were rising. At the same water defict level, thecontent of soil water performed to N2P2＞N1P1, which showed that after suffering from stressconditions, wheat can maintain its cell osmotic pressure through transmitting photosynthetic production to root for self-root synthesizing. Osmotic regulation matter finally improved itswater regulation features and this ability with higher nutrition more strength than that withlower nutrition. Osmotic regulation matter still maintain higher level in re-watering conditionafter root under water deficit conditions; especially after jointing stage, it can relieve hurtfrom earlier stage of cell.(3) Effects of water-nitrate combination on root H)2O2consumption indicate that underthe same N\P conditions, with water deficit intensified in returning green and jointing period,content of H)2O2was increased to the highest level in SS. The activity of SOD, POD and CATwere the highest level in LS to maintain the H)2O2dynamic balance. When the content ofMDA in cell was closed to CK, the level increased significantly in SS. After re-wateringtreaments, the activity of SOD, POD and CAT still keep intensified for eliminating excessH)2O2to restore the hurt in earlier water deficit stage. Under the same water level, althoughtreat wheat with high nutrition, its still grew vigorously, producing more H)2O2. But theenzyme to eliminate H)2O2active; therefore, after re-watering stage of growth, the MDAcontent of each treatment were lower than those with lower nutriments.(4) Effects of water-nitrate combination on H)2O2distribution of roots show thatfollowing the water deficit intensified in returning green and jointing period of wheat, H)2O2distribution area extended meristematic zone and elongation zone from root-shoot andmaturation region with fluorescence strength intensified slowly, which showed that underwater deficit condition, the root tip of winter wheat was the main area for producing H)2O2.Furthermore, H)2O2in the root-shoot cell of winter wheat with water deficit in jointing stagewere signed by CeCl3and the results told us that H)2O2mainly located on the cell membraneat the same water level; H)2O2content under higher fertilizer level higher than those withlower fertilizer treatments. With water stress intensified, there H)2O2mark appeared inintercellular space,cell wall,and vacuole membrane, which increased significantly.(5) Effects of water-nitrate combination on root anatomical structure illustrate that withwater deficit intensified in returning green and jointing period, the thin-wall cell of winterwheat root-tip cortex, whose shape changed from oval to no rules with new arrangement indisorder. Leading to increase the thickness of cortex and the ratio of cortex-root diameter. soit decreased the flow conductance of root, and enlarged the relative distant of watertransmitting to central-pillar. The order of central pillar was ruined and the ratio of drivingwater flowing air pressure decreased, improving the water dredge resistance. These changeswere helpfully to increase the resistance in root radial and axial flowing, which can improvethe ability for roots to keep water. Meanwhile, those changes of root anatomical structurewere regarded as a response to water stress. In conclusion, under the higher N\P nutrients treaments, applying fertilizer and watercontrol in re-watering stage after lighter water deficit in returning green period were usefulfor winter wheat growing and having higher yield, which can promote water efficience andincrease crop yield. |
