Influence of Sweet Potato Plant Residue on Growth of Sweet Potato Vine Cuttings and Cowpea Plants

Abstract

Abstract Possible allelopathic effects of decaying sweet potato plant residue on sweet potato [Ipomoea batatas (L.) Lam.] and cowpea [Vigna unquiculata (L.) Walp.] growth were assessed. Residue treatments consisted of factorial combinations of 2 sweet potato cultivars (‘Jewel’ or ‘Centennial’), 2 plant parts (vines or storage roots), and 2 methods of tissue preparation–dried, or frozen and then dried. Ground sweet potato residues were mixed with sand [2.7% residue (w/w)] and placed in pots. Dry weights of ‘Jewel’ sweet potato plant shoots 57 days after planting were reduced 32% and 74% by vine and storage root residues, respectively, while dry weights of ‘Centennial’ sweet potato plant shoots were reduced 18% and 73%, respectively. Dried vine tissue had no apparent inhibitory effect, but vines frozen prior to drying reduced fresh and dry weights of ‘Centennial’ shoots. Dry weights of ‘Brown crowder’ cowpea plant shoots were reduced 79% and 91% by sweet potato vine and storage root residues, respectively. Nodulation of cowpeas grown in residue-amended pots was negligible compared to plants grown in pure sand. Leachate pH from pots containing sweet potato root residue was 1.4 and 2 pH units lower than that from nonamended pots with both sweet potato cultivars and cowpeas, respectively.