1Key Laboratory of Grassland Resources, Ministry of Education, College of Grassland Science, Inner Mongolia Agricultural University, Hohhot010018, China.
2Institute of Forest and Grassland Genetics and Breeding, Inner Mongolia Academy of Forestry Science, Hohhot010018, China.
*Corresponding Author: Fengling Shi, Key Laboratory of Grassland Resources, Ministry of Education, College of Grassland Science, Inner Mongolia Agricultural University, Hohhot010018, China. Email: shifengling@imau.edu.cn
Medicago sativa subsp.falcata (yellow-flowered alfalfa), a perennial leguminous forage crop, has inherent agronomic limitations, including slow growth, low biomass yield and difficulties in cultivation. The development of polyploid germplasm is a promising strategy for varietal improvement, requiring systematic optimization of colchicine induction protocols.
Using imbibed seeds of diploid Medicago sativa subsp. falcata (2n=16), we performed colchicine soak treatments and systematically characterized mutagenized plants via stomatal morphology analysis and chromosome counting. Our quantitative assessment revealed concentration and exposure time-dependent effects on seed germination, seedling development and polyploidization efficiency.
The results showed that increasing colchicine concentrations led to a progressive inhibition of seed germination and seedling growth. This was evidenced by a delay in germination initiation, a reduction in germination rates, an increase in hypocotyl diameter and a shortening of radicle length. After treatment with 0.15% colchicine for 6 hours, chromosome doubling was observed at a frequency of 10%, with a seedling survival rate of 39%. Simultaneously, the stomatal density of the treated polyploid plants reached the lowest. These results indicate that this method represents a feasible approach for polyploid breeding in this germplasm.
Chromosome number, Colchicine, Imbibed seeds, Medicago sativa subsp falcata, Mutagenic dosage, Stomatal density
