Polymorphism of fertility and self-fertility of alfalfa varieties ‘Jõgeva 118’ and ‘Ellerslie I’ and the opportunities for use the plants selected from these populations as initial material for plant breeding to breed partially self-pollinative varieties and hybrid varieties.
Fertilization of the flowers on free pollination and self-pollination has been investigated with 135 varieties of Medicago sativa L., M. varia Martyn., M. falcata L.
and M. borealis Grossh.
in the open field trials at Jõgeva during 1983…1990. Obtained experimental data enable to clarify the polymorphism of these characters in the populations and to find initial material for different breeding aims.
Among the investigated varieties the most notable by seed yield, level of fertility and self-fertility of the flowers were the varieties of M. varia ‘Jõgeva 118’ (Estonia) and ‘Ellerslie I’ (Canada).
On the free pollination of the flowers (experimental variant K) the populations of both varieties mainly consisted of partially fertile (Fk=0.1…29.9 %) and sterile (Fk=0 %) plants. These two groups of plants accounted for 70.9 % from the population variety ‘Jõgeva 118’ and 84.9 % from the population of variety ‘Ellerslie I’. The plants with intermediate (Fk=30.0…49.9 %) and above intermediate (Fk=50.0…79.9 %) fertility occurred considerably less in the populations (Table 2, Figure 1). Generally the following regularity was valid: the higher the class of fertility (or self-fertility), the less plants belonged to that class.
On the base of the figures of self-fertility (experimental variant ATI) even more plants belonged to the class of partially self-fertile (IFk=0.1…29.9 %) and self-sterile (IFk=0 %) plants – 88.1 % on the variety ‘Ellerslie I’ and 93.0 % on the variety ‘Jõgeva 118’. It was still possible to find the plants with intermediate (IFk=30.0…49.9 %), above intermediate (IFk=50.0…79.9 %) and even high self-fertility (IFk=80.0…100 %) from both populations (Table 3, Figure 2). Hence the plants with very different level of self-fertility were found in the populations of these varieties. The clones of these plants can be used as initial material in breeding process, conducted on different methods, to create partially self-pollinative varieties.
Artificial tripping of the flowers (experimental variants KT and KTI) promoted the fertili-zation of the flowers of investigated varieties. Effect of this treatment was significantly superior with variety ‘Jõgeva 118’ (Tables 2 and 3, Figures 1 and 2).
From both populations the plants were found which formed the pods only with free pollina-tion. In the population of variety ‘Ellerslie I’ 7 such plants occurred (with fertility in the control variant Fk=1.3…25.0 %) and in the population of variety ‘Jõgeva 118’ 5 plants (with fertility in the control variant Fk=2.2…36.3 %). These plants could be completely sterile, hence interesting material in the breeding of hybrid varieties. As F1 hybrid varieties based on the heterosis effect are not bred at Jõgeva, the reasons and stability of self-sterility of these plants were not clarified in further research.