A Study Of Screening Low Phosphorus Tolerance Cotton Varieties With Fusarium And Verticillium Wilts Resistance At Seedling Stage

A vermiculite culture experiment and solution irrigating were carried outsimultaneously to approach the screening index for low P tolerant cotton varieties inpreliminary experiment. 6 genotypes cottons had been adopted in present research workfor investigating dry weight, fresh weight, the total proportion of leaves, chlorophyllcontent, P utilization efficiency, plant height and root-shoot ratio of cotton seedlingsunder different phosphorus supply in the nutrients solution. The differences of each indexwere compared in different genotypes so that the screening indexes for low P tolerantcotton varieties were confirmed and a method was founded to screen low P tolerantcotton varieties at seedling stage. 88 cotton varieties with Fusarium and Verticillium wiltsresistance were screened in this method for low P tolerant. The results were as followed:(1) The differences of cotton varieties in phosphorus nutrition were significant. Theseedling dry weight, fresh weight, the total proportion of leaves, chlorophyll contentand P utilization efficiency were close related with P nutrition, the differences ofthem among different P concentrations and cotton varieties were significant so thatthese indexes were confirmed to screen cotton varieties with Fusarium andVerticillium wilts resistance at seedling stage; but differences of plant height androot-shoot ratio were not significant.(2) The variations of cotton varieties in phosphorus nutrition were significant. The Pconcentration has obvious effect on the total proportion of leaves, dry weight, shootdry weight, and no significant effect on fresh weight and chlorophyll content.(3) The correlation analysis showed that a significant relationship existed betweenrelative total dry weight and fresh weight, total leaf areas, shoot dry weight, PUE atseedling stage. The relative shoot dry weight was regarded as a selection index of theresponse to P stress.(4) The differences of fresh weight, chlorophyll content, the total proportion ofleaves, shoot dry weight, root dry weight, shoot and root P utilization efficiencyamong different P concentrations and 88 cotton varieties with Fusarium andVerticillium wilts resistance were significant. These varieties had been divided intotwo groups by cluster analysis. The cotton varieties Zhongmiansuo21,Zhong99,Shanmian11 were high P using efficiency genotypes; Nongda94-7,Jinmian14,Chuan243,GK2,Tashiganl were low P using efficiency genotypes.