Effects Of Water Stress On Photosynthetic Characteristics And Morphological Indicators Of Maize

Using sweet maize as experimental materials.Water stress treatment was conducted to different maize verieties during different growing stage.The effect of photosynthetic characteristics and patterns features was discussed under water stress in the level of leaves. The studies provide scientific bases and technical guidance for drought resistance of maize.Based on the measurements of maize leaf photosynthetic.The light response curves of two different drought resistance maize variety and photosynthesis were fitted with rectangle hyperbolae.The result showed that the values of intrinsic quantum efficiency for CO₂ uptake(α),light-saturated net photosynthetic rate(Pn),dark respiration rat(Rd),light compensation point(LCP) and light saturation point(LSP) were decreased on water stress.The maize variety of high drought resistance decreased slowly and the maize variety of low drought resistance decreased rapid.Water stress decrease the use of high light and increase the use of low light of maize leaves under water stress.The decrease of the net photosynthetic rate were result from stomatal limit factor and nonstomatal limit factor under water stress.Through the measurement of chlorophyll fluorescence parameters under water stress,we defined the situation of the use of light and the dissipation of excess light in maize leaves. After water stress,photosynthetic rate was decreased.In order to reduce the injure from the excess light to Photosynthetic apparatus,non-photochemical quenching coefficient(NPQ) was increased,which can be transform the excess light to thermal energy to loss.It can reflect the ecological adaptation of maize to adverse conditions.The result showed the photosynthetic rate and transpiration rate of Jidan261 and Zhengdan958 were more influenced more heavily by water stress than Jingdan28.Thus,the chlorophyll fluorescence kinetic technique can quickly and precisely show the photosynthetic characteristics of maize under water stress.The change of photosynthetic indicators was different to different growing stage and different maize breed.Elongating stage is the photosynthesis sensitive stage under stress,and the change of photosynthetic indicators is comparatively large.The change of photosynthetic indicators of Jingdan28 was smaller under water stress.This breed was not sensitive to water stress,and keep high water use efficiency and light use efficiency.More light energy absorbed was converted into chemical energy and less light energy was dissipated through thermal energy.Zhengdan958's light use efficiency is in the middle level and Jidan261's light use efficiency is lowest.Maize dry matter accumulation rate was decreased under water stress.The decrease range was different to different breed and different growing stage.The leaf area,stomatal length and stomatal width were decreased,and the stomatal density was increased under water stress.So reduced the loss of water,and reflect the adaptability of maize under drought adversity.After water stress Seven days,irrigate to treatment.Leaf area increased rapidly, and emerge compensate grow phenomenon.The compensate effect is relevant to water stress stage.The decreased range of leaf area in elongating stare was biggest and the compensate effect was smallest after irrigated.Jidan261 is sensitive breed under water stress.The change range of leaf area is comparatively large,The change range of leaf area in Jingdan28 is smaller.The sensitive to water stress of Zhengdan958 is in middle level in three breed.To sum up,the photosynthetic characteristics and patterns features was changed under mild water stress.Different maize variety's sensitivity and adaptability in different growing stage is different under water stress.The high drought resistance variety was hold the high water use efficiency and light use efficiency.The change of indicators were smaller in moderate drought resistance variety,and the effect were biggest in low drought resistance variety under mild water stress.