ANATOMICAL VARIATION IN FIRST LEAVES OF NINE <i>TRITUCUM</i> GENOTYPES, AND ITS RELATIONSHIP TO PHOTOSYNTHETIC CAPACITY

Abstract

S ummary The variation in over 20 leaf characters including morphological, anatomical and cellular features have been examined in nine Triticum genotypes at three levels of ploidy. The characters included transectional leaf area, leaf width, distance between vascular bundles, volume occupied by each cell type, cell size and number, and chloroplast size and number. Analysis of these characters showed that the major components of the variation were related to the ploidy level and the genotype of the species and cultivars examined. The measured characters most strongly influenced by ploidy level were cell size, chloroplast number and leaf thickness. Genetic variation accounted for the variation in all other measured characters. The interaction of genetic variation with the major effects attributable to ploidy level creates a characteristic anatomical ‘fingerprint’ for each genotype. The observation that photosynthetic capacity is negatively correlated with the ratio of mesophyll cell size to nuclear genome size, and with no other character, is discussed.