Triploidy and Seedlessness in Guava (Psidium guajava L.)

The cytological behaviour and morphological characteristics of diploid and triploid forms of guava are presented. Meiosis is regular in the diploids with the formation of 11 bivalents. The triploids in general could be distinguished by their greater vigour, large leaves and thicker petals. Meiosis is characterised by a maximum association of chromosomes as 11 trivalents. The differential development of tissues (ovary wall and placenta) can be attributed to a difference in female sterility. The placenta development is greater in diploids which are fertile or where only partial (genic) female sterility is operative. In case of triploids which are highly seedless, genic sterility is superimposed on chromosomal sterility; the stimulation in placenta development is thereby retarded as fertilisation fails and there appears to result a greaster development of the ovary wall.