Preliminary Evaluation Of Drought Tolerance Of Gossypium Hirsutum Race

Cotton is an important commercial crop,which plays an irreplaceable role in daily life.There is a large cotton planting area in arid and semi-arid areas of China.Drought stress has a negative effect on whole growth stage of cotton,while the stages of seed germination,seedling and flowering were sensitive to drought stress.In order to reduce the damage caused by drought stress,it is an effective method to select cotton varieties with good drought tolerance.Gossypium hirsutum race is the wild type of upland cotton,also known as semi-wild cotton.Gossypium hirsutum race lives in the harsh natural environment,has drought resistance and salt tolerance characters.It is an excellent resource for genetic improvement of cotton resistance.In this study polyethylene glycol(PEG)was used as the medium of drought resistance selection in seed germination stage,used for hydroponics simulation to identification and screening drought resistance of Gossypium hirsutum races which provided the basis for drought tolerant cotton resource screening and breeding.In this study,PEG6000 was used to identify and evaluate the drought resistance of 69 Gossypium hirsutum racesaccetion.The main results are as follows:1.Screening test for identification of drought tolerance in germination stage of Gossypium hirsutum race accessions in upland cotton.With the increase of PEG6000 concentration,germination rate,germination potential and germination index of the tested seeds gradually decreased compared with the control group.When the treatment concentration exceeded 10%,germination indexes of all varieties of materials decreased sharply with the increase of PEG6000 concentration.When PEG6000 concentration reached 20%,seed germination significantly inhibited.The results showed that the PEG6000 treatment with a concentration of 5% was the key concentration affecting the germination of Gossypium hirsutum race seeds,and each germination index could be used as an effective evaluation index for the drought tolerance of Gossypium hirsutum race seeds during germination.2.Screening test for identification of drought tolerance of seedlings in Gossypium hirsutum race accessions Drought stress treatment was applied to Gossypium hirsutum race accessions with 10%,15%,17%,and 20% concentrations of PEG6000.According to the changes of phenotypic indicators of Gossypium hirsutum race accessions,the final concentration of 15% PEG6000 was used as the concentration of drought stress treatment in the Gossypium hirsutum race accessions.The drought tolerance of 69 Gossypium hirsutum race accessions were graded at seedling stage.The seedlings of Gossypium hirsutum race accessions were treated with PEG6000,and the phenotypic changes of each material were observed every 8 hours.It was found that 24 hours after drought stress was the critical period for drought tolerance.3.The drought tolerance of 69 Gossypium hirsutum race accessions in the germination and seedling stages was identified.It was preliminarily determined that Morrilli 134,Palmeri 51,and Yucatanense 1039 A were drought-tolerant materials for seedling stage,Latifolium 16 B,Yucatanense 2094 B,and Latifolium 40 TX were drought-tolerant materials during the germination period.