Initiation and morphogenesis of groundnut (Arachis hypogaea L.) pods in solution culture

Abstract

A recently-developed solution culture technique was used to study the effects of aeration and calcium (Ca) on groundnut (Arachis hypogaea L.) pod development. Two experiments were conducted with seven groundnut lines, TMV-2, Chico and A116L4 (Spanish), CBRR4 (Valencia), A125L25 (Valencia x Spanish), and Shulamit Strain 1 (SH-1) and Virginia Brunch Strain 1 (VB-1) (Virginia). Plants were grown in a potting mix, and the attached gynophores cultured in darkened polycarbonate jars containing nutrient solution. Non-aeration of solution prevented pod development, but pods and seeds of all lines developed in aerated, darkened nutrient solutions (ionic strength approx. 9 mM). Normal pods and seeds were produced by TMV-2, Chico and CBRR4, but constricted pods developed in SH-1 and VB-1. A secondary gynophore developed between the basal and apical seed compartments in A116L4 and A125L25, and in VB-1 at high Ca (500-2500 μM) in solution. The secondary gynophores were similar to those produced in other Arachis spp. but not usually found in cultivated forms of A. hypogaea. Septate and non-septate hairs developed on submerged gynophores and pods, but were sparse on those of SH-1 and VB-1. The magnitude of the effects of aeration and Ca concentration on pod initiation and morphogenesis differed in experiments conducted in summer and winter and among the lines tested.