Effects Of Plant Growth Regulators On Growth And Development Of Sorghum And Selection Of Regulators

ETH,CCC and Uniconazole are three common plant growth regulators which are widely used in agriculture production,but there are few studies on their regulat ion effects on sorghum growth and their mechanism.In this experiment,the sorghum variety ’Nongdahong 1’ was used as the material,which was cultivated by Hebei Agricultural University.Three different types of plant growth regulators,ETH,CCC and Uniconazole were sprayed uniformly at the sorghum jointing stage with three concentration gradients respectively,and the control group was treated with the same amount of water.The purpose was to study the effects of different types of plant growth reg,.ators at different concentrations on the growth,physiological,biochemical and yield its of sorghum,arid to screen out the appropriate plant growth regulators and spra,g concentrations in sorghum production.The main results are as follows:1.Sorghum plant height decreased(The plant heig.of each treatment was lower than that of the control:ETH:10.7%,11.7%,17.5%;CCC:6.1%,8.3%,11.5;Uniconazole:39.9%,44.7%,52.7%.),intemode length short(?)stem diameter increased,breaking-resistant strength enhanced after treated by(?).enous growth regulators,exogenous growth regulators effectively improved the lodging resistance of sorghum.Plant growth regulators could improve lodging resistance of sorghum by short ening leaf length.The effect of Uniconazole on stem and leaf of sorghum were significantly higher than that of ETH and CCC,and there were no significant difference between ETH and CCC.2.Leaf area,SPAD,Ci,Tr,Gs and Pn of each treatment were higher than those of CK at different growth stages,and increased with the increase of treatment concentration.Ci first increased and then decreased with the development process,reached the highest at the flowering stage,and then decreased.The effect of three plant growth regulators on Gs at low concentration was Uniconazole>CCC>ETH,and the difference was significant.However,the effects of three plant growth regulators on Pn were Uniconazole>ETH>CCC(Compared with the CK,Pn of sorghum at C3 concentration increased:Uniconazole:44.2%;ETH:22.9%;CCC:19.3.),Uniconazole and ETH and CCC were significantly different,ETH and CCC were not significantly different.3.SOD,POD,CAT activities,SP and SS contents of sorghum at different growth stages were higher than those of CK,while MDA content were lower than that of CK.The activities of SOD and POD decreased from jointing stage to bell mouth period,and increased from bell mouth period to filling stage.CAT activity first increased and then decreased with the development process,reaching the highest at the flowering stage,and then decreased.SP content increased from jointing stage to flowering stage,then decreased.Effects of three plant growth regulators on stress resistance of sorghum:Uniconazole>CCC>ETH.4.SOD,POD,CAT activities,SP and SS contents of sorghum at different growth stages were higher than those of CK,while MDA content was lower than that of control.GA content decreased with the development process;ZT and IAA content increased from jointing stage to trumpet stage,then decreased;ABA content inc reased from jointing stage to filling stage.The influence of three kinds of plant growth regulators on sorghum endogenous hormone content was Uniconazole>CCC>ETH,Uniconazole was significantly different from ETH and CCC,ETH and CCC no significant difference.5.After the analysis of sorghum yield index in the experiment,it was found that the GW of sorghum were significantly higher than that of the CK except that ETH had no significant difference with the CK at C1 concentration(GW were inc reased compared with the CK,respectively:Uniconazole:27.9%;CCC:11.3%;ETH:9.0%.),and increased with increasing concentration.After treatment with plant growth regulators,the TKW increased compared with the CK,except that there was significantly higher at C3 concentration of CCC than the CK,and there were no significant differences compared with the CK at other concentration.The KNE were significantly higher than that of the CK after treated with plant growth regulators,and increased with the increase of treatment concentration.Under different concentrat ions,the KNE of each treatment compared with the CK increased by:ETH:7.2%,13.5%,19.2%;CCC:10.2%,10.2%,18.6%;Uniconazole:22.7%,28.8%,36.0%.The results showed that plant growth regulators could increase sorghum yield by regulating sorghum yield coefficient.6.After treated with plant growth regulators,the content of protein,tannin,TP and TF in sorghum grain increased compared with the CK,and increased with the increase of treatment concentration.The content of starch and fat decreased compared with the CK,and decreased with the increase of treatment concentration.The re suits showed that plant growth regulators could regulate the accumulation of nutrients in sorghum and improve grain quality.7.The results showed that the regulation effects of plant growth regulators on sorghum growth weremainly through adjusting endogenous hormone content:(1)Plant height was significantly positively correlated with GA content,significantly negatively correlated with ABA content,and significantly negatively correlated with ZT content.Internode length was significantly positively correlated with GA and IAA content;It was significantly negatively correlated with ABA and ZT contents.Stem diameter was significantly negatively correlated with IAA content.Plant growth regulators reduced the content of GA and IAA in sorghum,increased the content of ABA and ZT,reduced plant height,increased stem diameter,improved stem folding resis tance,and enhanced lodging resistance.(2)The photosynthetic indexes of sorghum were positively correlated with ABA and ZT content,and negatively correlated with GA and IAA content.Plant growth regulators increased SPAD and photosynthetic index,improved photosynthetic capacity of sorghum andpromoted the accumulation of photosynthetic products by increasing ZT and ABA contents in sorghum.(3)Anti oxidant enzyme activity and osmotic adjustment substance content were positively correlated with ABA and ZT content,and negatively correlated with GA and IAA content.Plant growth regulators improved the stress resistance of sorghum by increasing the content of ZT and ABA,reducing the content of GA and IAA,promoted the activity of antioxidant enzymes and the content of osmotic regulators in sorghum,reduced the content of MDA.The results showed that the effect of uniconazole on sorghum was significantly greater than that of ETH and CCC.When the concentration of uniconazole was used at 1110 mg/L-1665mg/L,the plant height of sorghum were significantly reduced,the lodging resistance were effectively improved,and the yield of sorghum were significantly increased,and the effect on the growth period of sorghum was little,sorghum could harvest in time.