Initiation and Morphogenesis of Groundnut (Arachis hypogaeaL.) Pods in Solution Culture

A recently-developed solution culture technique was used to study the effects of aeration and calcium (Ca) on groundnut(Arachis hypogaeaL.) pod development. Two experiments were conducted with seven groundnut lines, TMV-2, Chico and A116L4 (Spanish), CBRR4 (Valencia), A125L25 (Valencia×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 otherArachisspp. but not usually found in cultivated forms ofA. 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.