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Cover Crops Affect Sorghum Seedling Growth
Author(s) -
Dabney Seth M.,
Schreiber Jonathon D.,
Rothrock Craig S.,
Johnson Joseph R.
Publication year - 1996
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1996.00021962003600060020x
Subject(s) - seedling , agronomy , sorghum , sowing , cover crop , biology , shoot , germination , legume , rhizoctonia solani , horticulture
Recently killed cover crops often interfere with crop seedling growth. Controlled‐environment and field studies were conducted to characterize the nature and persistence of cover crop interference with sorghum [ Sorghum bicolor (L.) Moench] seedling growth and to test several seed‐zone management practices that might alleviate detrimental effects. Germination, root and shoot length, and disease incidence of sorghum germinated at 25°C for 5 d in soil collected 2, 4, 7, 14, 23, and 32 d after killing cover crops indicated legume cover crops were more detrimental to seedling growth than were nonlegumes. Surface residues, subsurface residues, and residue leachates contributed to the deleterious effects. Seedling shoot disease incidence of 50% persisted through 32 d when legume residues were mixed into soil or placed on top of soil at planting, but disappeared by 7 to 14 d if residues were removed. Pathogenic organisms isolated from lesions on seedlings indicated legume cover crops increased damage due to Rhizoctonia solani Kühn. In a no‐till field study, stand density was reduced 15% and aboveground seedling dry weight was reduced 45%, from 85 to 45 mg plant −1 28 d after planting, when sorghum was planted 1 d after killing crimson clover ( Trifolium incarnatum L.) compared with planting 21 d or longer after killing. Insecticide, activated charcoal, or CaO 2 seed coating improved sorghum stand density 15%, but did not affect seedling size. In‐furrow fungicide drench had no effect on stand density, but phytotoxic effects of the fungicide reduced shoot and root growth rates in both field and controlled‐environment studies. Residue removal combined with selected in‐furrow treatments may allow the interval between cover‐crop killing and successful no‐till planting to be reduced to less than 7 d.