Seed quality diversity, trait associations and grouping of accessions in Jatropha curcas L.

Jatropha curcas L. (jatropha) has recently received great attention for its utilization in biofuel production, rehabilitation of wasteland and rural development. Improvement of seed quality is an important breeding goal but jatropha seed quality has been investigated with sample sets comprising a small number of traits, accessions and environments. Our main goal was to investigate a large number of traits in a wide and geographical diverse collection of seed samples to have a comprehensive view on the phenotypic variation of seed quality in jatropha. Our objectives were to (i) assess phenotypic variation of jatropha seed quality traits, (ii) investigate the association among those traits (iii) group germplasm and (iv) examine the partition of the trait variation attributed to factors of geographical origin (world regions and countries) and sampling procedures (single seeds vs. seed samples). Phenotypic variation was larger than reported previously. We detected a strong positive association between seed weight and the contents of oil in seed and kernel. Oil content in seed was negatively associated with the ratio of shell weight to seed weight. Contents of oil and protein in kernel were also associated negatively. Accessions from Africa and Central and North America grouped together and separated of accessions from Asia and South America. Countries and accessions within countries contributed most to the total variance of seed quality traits. Determination of seed quality among accessions using seed samples is more efficient than using single seeds.