Ploidy and virus reaction in Physalis floridana RYDB.

Abstract

Diploid Physalis floridana has 24, and the induced autotetraploid 48 somatic chromosomes. The increased ploidy resulted in the usual increases in size of stomates, pollen, and seed, but in a decreased nitrogen content of the leaves. Dry matter production of the leaves and stems was 28.3 per cent, greater in the tetraploid than in the diploid. The percentage moisture content was not increased by tetraploidy. The increased ploidy did not affect the reaction to several mesophyll viruses, but resulted in a marked increase in the sensitivity to the phloem virus, leaf roll. Inoculation with leaf roll at the third true-leaf stage reduced the mean fresh weight per plant by 26.5 per cent. in the diploid, and 57.3 per cent. in the tetraploid. The greater sensitivity of the tetraploid followed inoculations at other growth stages, but, with both diploid and tetraploid P. floridana, the closer the plants were to the flowering stage at inoculation the less obvious the reaction.