Department of Plant Sciences

Low soil pH and calcium (Ca) deficiency in both the root and pod-zone are important problems for groundnut (Arachis hypogaea L.) production world over on account of the light-textured nature of the soils suitable for its production. An experiment was conducted to examine the interaction of pH and Ca supply in the pod-zone on reproductive growth of groundnut. Attached gynophores were cultured singly in solutions at three pH levels (3.5, 5.0 and 6.5) in factorial combination with three solution Ca concentration levels (500, 1000 and 2000 µM). Generally, low pH had an adverse effect on the reproductive growth of groundnut. Approximately 58% of the gynophores cultured in treatment combinations with pH 3.5 produced normal pods, compared to 94% in combinations with pH 5.0 and 6.5. Both pod mass and seed mass were also severely depressed in treatment combinations with pH 3.5 compared to combinations with pH 5.0 and pH 6.5. Increasing Ca from 500 to 2000 µM Ca at low pH had limited ameliorative effect on pod-set, pod and seed mass whereas positive responses were higher at the intermediate pH of 5.0. A combination of high Ca and pH appeared to be detrimental to pod and seed growth. Pods formed at higher pH and Ca levels generally had dense cover of hairs.