Effects Of Water Deficit On Microstructure And H₂O₂ Accumulation In Leaf And Root Of Maize

Maize is one of the largest water consumption crops, researching water deficit on the change of physiology and morphology and response to stress can provide essential theoretical foundation for the practical agriculture production. In a pot experiment with water treatments: 75%-85% of field capacity (control), 65%-75% of field capacity (light deficit), 55%-65% of field capacity (moderate deficit), and 45%-55% of field capacity (severe deficit). To research water deficit and rewatering on the change of morphology, anatomical structure and H₂O₂ accumulation in root and leave of maize, which is in seelding and jointing stage, with physiology experiment technology, green and the counterstain safranin stain , fluorescent dyes stain, SEM and cell chemistry labeling. The results were as follows:The effect of water deficit on root hair of maize:After water deficit treatment in seedling, maize root hair became thin, root hair density increased, distance from root point to root hair shortened, which was most denser in root hair and shortest distance from root point to root hair with severe treatment. Rewatering had no significant effect on root hair density and distance from root tip to root hair of maize root hair corn root has no evident change.It showed that decrease of codex parenchyma cells area and deformation shape with irregular arrangment resulted in width of codex in root hair zone of maize seedling and jointing getting thinner. With increasing water deficit, the endodermis in root hair zone of maize seedling decreased and deformated obviously, Comparatively, the endodermis of maize jointing changed unconspicuously, caused by mature casparian band enhenced mechanical strength of endodermis. Fluorescence observations showed that axial walls of endodermis thickened on seedling stage with light deficit. Both axial and inner tangential walls of casparian band of endodermis thickened more obviously on jointing stage with light and moderate deficit. Because of it developed into late growth, endodermis cell wall got more thickened after rewatering.The effect of water deficit on the stomata of maize: water deficit level is correlated positively with the density of stomata, and negative correlation with Stomata aperture, which get the highest level reduce in stomata aperture with severe disposal. After rewatering, the level of Stomata aperture were closed to control, the Stomata aperture of moderate deficit and severe deficit treatment recovered resume to a certain extent.The effect of water deficit on the H₂O₂ contents of roots and leaves: As the levels of water deficit aggravate, the H₂O₂ contents of roots and leaves rised up, which got to the highest content in the severe treatment. After rewatering, the H₂O₂ content in moderate deficit declines to the normal control. The H₂O₂ contents of moderate deficit and severe deficit was higher than the control, but the difference was not remarkable.The effect of water deficit on the distribution and accumulation of H₂O₂ in root: The result of water deficit on fluorescent stain showed maize root tip produce the most of H₂O₂. As the water deficit extend is aggravating, the accumulation of H₂O₂ increased and extented from root tip to meiosis zone. The result of CeCl3 labeling indicates that H₂O₂ mainly distributes on the cell membrane and the intercellular space of cells. The H₂O₂ accumulation of the treatments in jointing stage was higher than that in seedling period. In the moderate and severe deficit, the H₂O₂ accumulation was not only on the cell membrane and the intercellular space, but also on the tonoplast and mitochondria. In addition, the cell of root tip appears mitochondria swell and mitochondrialcristae reduce in the severe deficit. After rewatering, H₂O₂ have different degree of reduced in the treatments of jointing and seedling stage, there are still a few accumulation on the cell membrane and the intercellula space the moderate and severe.In sum, in order to influence the force of water deficit, maize promotes the root hair growth, changes the cortex thickness, increases the level of lignifications qualitative of endodermis., adjust Stomata aperture, increases the accumulation of H₂O₂ in root tip.