Roles of Stipules Include Determination of Flowering Time and Pod Harvest Index in Garden Pea Grain Legume Pisum sativum

Abstract

Stipules are known to photosynthesize and provide protection to the organs differentiating at the apex, associated leaf and branch-bud and inflorescence in the axil of leaf. Stipules are expected to affect the bearer plant in multiple ways. To reveal the relative roles of stipules and leaves in Pisum sativum, the growth and development properties of leaf⁺ stipule⁻ (L⁺S⁻), leaf⁻ stipule⁺ (L⁻S⁺) and leaf⁺ stipule⁺ (L⁺S⁺) plants were compared. The L⁻S⁺ and L⁺S⁻ plants were respectively obtained by surgically removing the leaves and stipules as soon as formed from the post-embryonic nodes of the genetically wild type stipule and leaf bearing plants. The three sets of plants were arranged in a completely randomized design and sampled at the near harvest time for the phenotypic quantitation of ten primary and six secondary traits. The L⁻S⁺ and L⁺S⁻ plants were later in flowering, scarce in branching and total number of nodes, lower in biomass and bore pods in lesser numbers than L⁺S⁺ plants. The biomass allocation to leaves and/or stems was higher in L⁺S⁻and L⁻S⁺ plants as compared to L⁺S⁺ plants in which pods were the principal organs of biomass deposition. The observations allowed the conclusions that both stipules and leaves determine the flowering time and presence of stipules maximizes biomass allocation to pods and in turn the harvest index.