Pattern of diversity for morphological and alkaloid yield related traits among the periwinkle Catharanthus roseus accessions collected from in and around Indian subcontinent

Thirty two accessions of periwinkle Catharanthus roseus collected from diff erent semitemperate to tropical geographical areas of Indian subcontinent, Madagascar, Singapore and Malaysia were characterized under field condition s for 53 growth, development, morphogenesis and alkaloid yield related char acters over a few seasons at Lucknow, India. Large differences were observe d among the accessions for each of the characters examined. The differences among the accessions ranged 3, 80 and 15 fold for the alkaloid yield relat ed traits - leaf dry matter yield and leaf vincristine and vinblastine conc entration, respectively. Strong correlations were observed between leaf are a and leaf yield with leaf alkaloid, root and root alkaloid yields, content s of dimeric alkaloid in leaves with yields of respective alkaloids, leaf n umber and root alkaloid content with leaf vinblastine yield and leaf vinbla stine content with leaf vincristine and vinblastine yields. Multi-variate a nalyses allowed classification of the accessions into 5 to 7 morphologicall y and presumably genetically distinct groups. Generally, the accessions com ing from tropical agro-climates tended to get separated from those having o rigins in subtropical to semi-temperate environments. Three clusters were o bserved to bear complementary characters for possibly cross-parenting high alkaloid yielding transgressive segregants. One of the accessions of C. ros eus in which the leaf vincristine content was 5 fold and vinblastine conten t one and a half fold of the respective all accession means appeared suitab le for the domesticated cultivation. It was proposed that accumulation of h igh amounts of total alkaloids and one or more dimeric alkaloids in leaves of certain accessions may be a reflection of reproductive fitness achieved under the biotic and abiotic stresses imposed on their parent populations, sometime in their evolutionary pathway.