Breeding of tetraploid red clover at Jogeva
1990
Kotkas, H. (Estonian Scientific Research Institute of Agriculture and Land Reclamation, Saku (Estonia))
In 1972 two diploid red clover varieties - "Jogeva 205" (late flowering) and "Jogeva 433" (early-flowering) were polyploidized at the Jogeva Plant Breeding Station. 1-2 mm long germinated seeds, which were in the 0,2% colchicine solution, were kept during 5 minutes in the vacuum, 4 months later the survived plants were planted into field and by indirect estimation 31% (J 205) and 24% ("J 433") of them were polyploid or chimaera. Tetraploid successors were obtained from 363 late and 176 early clover co-plants. Also the ploidy of the morphological differences and number of chloroplasts in the guard cells of stomata before planting and on the shape of dry pollengrains after planting. About half of the co-plants gave only tetraploid successors, the other half was microploid, the last 21 plants gave only diploid successors. The selection began with both clovers in the C1-generation and has been going on up to now, i.e. to the C6...C7-generations, the attention being mostly paid to the seed yield. The strain numbers obtained with mass selection have up to now exceeded the diploid initial varieties in green matter and hay yields. The seed yield of tetraploid clover depends on the same way on the wheather as that of diploid clover, and therefore the seed yield is unstable, but it does not seem to be lower than the yield of the diploid initial variety
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