Effect Of Plant Growth Regulators On Winter Wheat Growth Under Drought Stress

Wheat is one of the major food crops in China. Drought in the seedling stage leads to seriousdamage to wheat production, one of the mathods to solve this problem is the use of plant growthregulators (PGRs). In this experiment, effect of HA-K、NAA、SA and CSN on the morphologicalcharacteristic、hormone concentration and drought resistance of winter wheat (Aikang58) were studied.Based on the results above, the combination experiments of the regulators were conducted in order toachive the goal of promoting root growth and improving the drought resistance of wheat with shootunchanged. The experiment was conducted in the petri dish and PEG-6000solution was used tosimulate osmotic stress. The main conclusions are as follows:Concentration gradient tests of each regulator showed similar trend. With concentration increasedfrom low to high, the effect of the regulators turned form insignificant to significant, and then showednegative impact on AK58. Each regulator had a optimum concentration, HA-K at the concentration of50mg/kg could significantly improve plant height of AK58and NAA at the concentration of0.1mg/kghad the same effect, SA at the concentration of0.025mmol/L could improve plant height、shoot dryweight、root dry weight and biomass of AK58, while CSN at the concentration of50mg/kg couldimprove shoot dry weight and biomass but not as significant as SA. The concentration of four mainplant hormone was measured, the result showed that all the four regulators could improve theconcentration of IAA, which may be the reason of the promoting effect of these regulators. In addition,SA could also improve the concentration of ZR and GA and decrease the concentration of ABA. Underosmotic stress, none of the four regulators showed significant promoting effect on AK58.Under distilled water condition, The compound of HA-K、NAA and SA in the optimumconcentration showed no better promoting effect than each regulator alone. Then the combinationexperiment of NAA and SA were conducted with their concentration changed, seeds of AK58werefirstly cultured in distilled water for5days to accomplish germination and accumulate certain biomassand then in PEG solution (15%) for4days to simulate drought stress. The results showed that underdistilled water condition, SA (0.5mmol/L) could enhance seedling growth rate and NAA (20mg/kg)could increase root/shoot ratio of the wheat seedling. SA+NAA showed advantages as a compound.Under osmotic stress condition, NAA and SA+NAA could increase the biomass of the wheat seedling,SA and SA+NAA could improve plant water status and decrease the electrolyte leakage. The effect ofSA+NAA was better than SA or NAA separately. The combination experiment of HA-K and SAindicated that the promoting effect of HA-K+SA was weaker than HA-K or SA alone under distilledwater condition. Under osmotic stress, HA-K+SA showed no protecting effect and even had a negativeimpact on photosynthesis and chlorophyll fluorescence parameters of AK58, which indicated that thecombination of HA-K and SA may have induced adverse reaction.