Research and Identification of the Morphological Indices of Topping-free Cotton's Germplasm Resources

【 Objective 】 To study the phenotypic traits of the germplasm resources of the cotton with particular features. The results might provide references for future plant shaping, non manual chemical control topping and cotton varieties that are suitable for machine harvesting.【 Method 】Through field cultivation and fixed point observation, the research studied the plant morphology of sicot75 throughout its growth duration under the condition of no chemical control topping. The collected data were then analyzed and compared.【 Result 】Without chemical control the differences were not significant between the height of first fruiting branch, node of first fruiting branch, number of sympodials and number of nodes to the indices after the treatment. For the chemical control group, a significant difference was shown between the initial plant height and the plant height after the treatment. The difference, however, met the requirements of machine harvesting.【 Conclusion 】Partial morphological indices of sicot75 are not sensitive to mepiquat chloride, and the plant height is stable under the condition of no chemical control. This feature, used as an important germplasm resource, provides an effective resource reserved for cultivating topping-free cotton varieties with suitable plant type and high stability in terms of plant height.