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Acta Prataculturae Sinica ›› 2022, Vol. 31 ›› Issue (10): 135-144.DOI: 10.11686/cyxb2021390

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Identification and physiological study of variation in reproductive fertility in clonal lines of Medicago sativa cultivar ‘Qingshui’

Zi-li LI(), Shang-li SHI(), Yun A, Hui-hui ZHANG, Xiao-long LI   

  1. Pratacultural College,Gansu Agricultural University,Key Laboratory of Grassland Ecosystem of Ministry of Education,Sino-U. S. Centers for Grazing Land Ecosystem Sustainability,Lanzhou 730070,China
  • Received:2021-10-28 Revised:2021-12-01 Online:2022-10-20 Published:2022-09-14
  • Contact: Shang-li SHI

Abstract:

A fertility analysis and identification and physiological characteristics of sterile material was undertaken in Medicagosativa cultivar ‘Qingshui’ to provide support for breeding sterile lines. Six clonal propagation lines (GN-A1, GN-A2, GN-A3, GN-A4, GN-A5 and GN-A6) with fertility variations were studied together with plants of normal fertility (CK). At the full flowering growth stage, pollen grains were collected for I2-KI staining to determine fertility and flower buds were analyzed for nutrient metabolism indexes (soluble sugar, SS; soluble protein, SP; starch, Sta and proline, Pro) and for indicators of membrane lipid peroxidation (catalase, CAT; peroxidase, POD; superoxide dismutase, SOD and malondialdehyde, MDA) at different development stages. It was found that the pollen vital staining rate of fertile CK plants was up to 98.37%, and pollen grains were full and spherical. The pollen staining rates of GN-A1, GN-A2, GN-A3 and GN-A6 plants were all lower than 5%, and the pollen grains were dried up and mostly had elliptical or irregular shapes, and these were preliminarily identified as sterile plants. The pollen staining rate of GN-A4 and GN-A5 plants were 54.80% and 63.60%, respectively with the majority of pollen grains elliptical, and relatively few dried grains. These were classified as typical semi-sterile plants. The supply of SS, SP, Sta and Pro of sterile plants (GN-A1, GN-A2, GN-A3 and GN-A6) was insufficient as the floral development period progressed. Indicators of membrane lipid peroxidation, POD and SOD activities in sterile plants were higher than those in the fertile plants for the whole floral development period, while CAT activity of sterile plants was higher than that of fertile plants at floral development stage Ⅰ and Ⅱ, and then decreased gradually. The content of MDA in the fertile plants was significantly higher (P<0.05) than that in the sterile plants at floral development stages Ⅰ, Ⅱ and Ⅳ. CAT, POD and SOD activities, and SS and SP levels showed variation in the flower buds of sterile plants, but were comparatively stable during the development of fertile plants, indicating that the changes of the measured physiological indexes were closely linked to reproductive fertility.

Key words: Medicago sativa cultivar ‘Qingshui’, fertility identification, physiology, coefficient of variation