Abstract
To facilitate efficient breeding of triploid loquats (Eriobotrya japonica Lindle.) by crossing diploid loquats with tetraploid loquats, we investigated differences of morphological and fruit bearing characteristics among diploid ‘Tanaka’, a tetraploid produced from the diploid ‘Tanaka’ and a triploid produced by crossing between the diploid ‘Tanaka’ and the tetraploid. In addition, we investigated the ratio of triploid seedlings produced by reciprocal crossing between diploid loquats and tetraploid loquats.
Leaf width and thickness, stomata length, maximal diameter of calyx, petal length and width, and pollen grain diameter in the di-, tri- and tetraploid plants significantly increased with increasing polyploidy level in loquats. The ratios of shoots bearing flower clusters were about 70% in all di-, tri- and tetraploid plants. The pollen germination ratios were high at 95% in both the diploid ‘Tanaka’ and the tetraploid. However, it was markedly low at 8% in the triploid, and the fructification was also extremely low at 0.1%. The ratios of triploid seedlings produced by reciprocal crossing between tetraploids and diploids ranged from 92% to 100%. There were no great differences among the reciprocal crosses.
