Effects Of Chitooligosaccharide On The Seedlings Drought Resistance And Yield Of Foxtail Millet

Foxtail millet is a drought tolerant and stable crop,which is mainly planted in the Loess Plateau of China.Drought is the key factor restricting agricultural production in the Loess Plateau.Chitooligosaccharides(COS)can be used not only as elicitors to induce plant disease resistance,but also as plant growth regulators and fertilizers.This paper studied the effects of COS on drought resistance and yield of Millet Seedlings,in order to provide theoretical basis for high and stable yield of millet.In this experiment,water culture method was used to study the effects of seed dressing with different concentrations of COS on seed activity and biomass of millet under PEG simulated drought stress.Pot experiment were employed to research the effects of different soil moisture contents on photosynthetic characteristics,protective enzyme activities and osmotic substance content of Millet Seedlings.Field experiment was used to study the effects of COS on Photosynthesis and yield of millet,the suitable concentration of COS was selected.The results are as follows.1.Under PEG simulated drought conditions(18%PEG-6000)chitooligosaccharide treatment could effectively promote the germination of millet seeds,which were improve the germination potential and germination rate,and promote the growth of radicels and plumules.COS treatment with 100 mg·L-1 has the best effect.compared with the control,the germination potential and germination rate of Jingu 45 and Jingu 42 increased by 15.38%,8.65%and 22.54%,6.80%respectively.2.With the increase of drought degree,the biomass of Millet Seedlings increased at first and then decreased.Slight and moderate drought(R 40%-60%)promoted foxtail millet seedlings growth by promoting root growth,reducing leaf transpiration,increasing antioxidant enzyme(SOD,POD,CAT)activities and osmotic adjustment substance content.Under extreme drought(R 20%-30%),millet seedlings suffered serious damage,including leaf wilting,destruction of antioxidant enzyme system and osmotic regulation system,increase of membrane lipid peroxidation.Foliar spraying 50-100 mg·L-1 COS increased Millet seedlings chlorophyll content and photosynthetic rate by 27.12%and 21.69%respectively under drought stress.chitooligosaccharide enhanced the activities of SOD,POD and CAT,increased the contents of Pro,SP and SS,decreased membrane lipid peroxidation and MDA content,alleviated the oxidative damage of Millet Seedlings under drought stress,and maintained growth.The seedling height,stem diameter,aboveground and underground dry weight of Jingu 45 and Jingu 42 increased by 23.95%,15.07%,26.33%,8.77%and 19.73%,10.10%,32.87%,29.27%respectively.3.In the fields experiment,spraying COS at Millet heading stage could increase the photosynthetic rate,dry biomass accumulation and yield,and increase the grain weight significantly.After spraying 100mg·L-1 COS,the yields of Jingu 45 and Jingu 42 were increased by 11.72%and 9.72%,respectively.