Leaf Morphology, Pigment Complex, and Productivity in Wild-Type and afila Pea Genotypes

The effects of genetically determined changes in leaf morphology on the characteristics of growth, pigment complex, and productivity were studied in pea plants (Pisum sativum L.). The homeotic afila(af ) mutation, which transformed leaflets into tendrils, decreased the leaf area and the chlorophyll (Chl) content per plant (CCP) in the af/af plants 1.5-fold as compared to the wild type (Af/Af). The loss of leaflets in the af/af plants was partly recompensed by expansion of the tendrils and stipules and by extra accumulation of Chl (a + b). The mutation did not affect Chl (a + b) that fell to the share of light-harvesting complexes (LHC) and the ratio of Chl a/b (representing the relative distribution of chlorophylls between LHC and the reaction centers); neither it affected the quantum efficiency of the primary charge separation (Fv/Fm). The diminished assimilating area (AA) in the af/af plants at the preflowering period did not reduce the final biomass and grain yield. The measurement of the area shaded by plants in the glasshouse experiments and the direct assessment of the vertical profile of solar radiation in the field stand canopies demonstrated that this phenomenon was in particular related to the fact that, in the af/af plants, the solar radiation was available to the apical and subapical leaves (as in the wild-type plants) and also to the lower metamers. As a result, the actively functioning AA expanded, and the photoassimilating potential of the af/af plants was enhanced. Our data presume the direct relationship between plant production and CCP.