Pisum sativum L. is one of the plant species where infraspecific genome size variation, up to 1.29-fold between cultivars, has been reported. The present investigation deals with a Feulgen cytophotometric analysis of this phenomenon in 25 wild accessions, landraces, and cultivars of widely different geographic origin. Differences between accessions were maximally 1.054-fold in single experiments but proved to be nonreproducible upon repeated measurements. Seedlings of the same accession often differed significantly, up to 1.056-fold, but values from root and shoot tips in one individual were not significantly correlated, indicating the absence of true genome size variation between plants. Upon calibration against Allium cepa a 1C value of 4.42 pg is estimated for Pisum sativum. Altogether the data suggest that, contrary to the divergence in the literature data and recent reports on DNA content variation, the pea has a stable genome size.

Flow cytometric measurements of nuclear DNA content were performed using ethidium bromide as the DNA stain (internal standard, Hordeum vulgare 'Ditta', 1C = 5.063 pg) in 25 samples belonging to nine diploid species and four varieties of Capsicum: C. chacoense, C. parvifolium, C. frutescens, C. chinense, C. annuum var. annuum, C. baccatum var. baccatum, C. baccatum var. pendulum, C. baccatum var. umbilicatum, C. eximium and C. pubescens, all with 2n = 24, and C. campylopodium with 2n = 26. In addition, one sample each of C. annuum var. annuum and C. pubescens were also analysed using Feulgen densitometry (standard, Allium cepa 'Stuttgarter Riesen', 1C = 16.75 pg). Both staining methods resulted in very similar relative values. Genome size displays significant variation between but not within species (except in C. campylopodium), and contributes to their taxonomic grouping. 1C-values range from 3.34-3.43 pg (3273-3361 Mbp) in C. chacoense and the C. annuum complex to 4.53-5.77 pg (4439-5655 Mbp) in C. campylopodium and C. parvifolium. The data obtained support conclusions on phylogenetic relationships in the genus derived from karyotype analyses using chromosome banding approaches. In Capsicum, constitutive heterochromatin amount is correlated with genome size, except in C. parvifolium, and is regarded as an additive genomic component.

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