Influence of Drought Stress on Plant Growth and Photosynthetic Traits in Maize Seedlings

The responses of plant growth,gas exchange,and chlorophyll fluorescence parameters were studied in two different maize hybrids Zhengdan 958(drought resistant)and Shaandan 902(drought-sensitive)under three different drought stresses(mild drought,moderate drought,severe drought)and normal irrigation in a pot experiment.The results showed that drought stress inhibited plant growth and relative growth rate in the two hybrids,resulting in a significant decline in biomass.With the increasing of drought stress,the maximum leaf net photosynthetic rate(Pnmax),apparent quantum efficiency(AQY),light saturation point(LSP),stomatal conductance(Gs),stomatal limitation(Ls),maximum electron transport rate(ETRm),photosynthetic efficiency(α),PSII actual quantum yield(ΦPSII)and photochemical quenching(qP)decreased,while the intercellular CO2 concentration(Ci),light compensation point(LCP)and non-photochemical quenching(qN)increased.But the change extents of all parameters were smaller in Zhengdan 958 than in Shaandan 902.This finding indicated that drought stress could significantly decrease the biomass of two maize hybrids,possibly caused by reduction in the photosynthetic efficiency of plants.The drought stress damaging effects on plant growth and photosynthesis were minimal on the Zhengdan 958 compared to Shaandan 902.Under drought stress the Zhengdan 958 maintained higher photosynthetic efficiency,stronger light energy transfer capacity and greater relative growth rate that may be the major physiological traits in the adaptive capacity to drought conditions.