Allelopathic Effects of Wheat Straw on Cotton Germination, Emergence, and Yield

Abstract

Because of recently enacted conservation compliance legislation, reduced and no‐till farming systems in which crop residues are left on the soil surface are becoming more important in areas where soils are highly erodible. On the southern high plains of Texas, many producers are planting cotton (Gossypium hirsutum L.) into wheat straw (Triticum aestivum L.). This study was conducted to determine the allelopathic potential of wheat residues on cotton germination, emergence, seedling growth, and lint yield. Laboratory bioassays revealed that cotton seedling development was inhibited by aqueous extracts of wheat straw. Cotton cultivars were screened for the ability to tolerate the inhibitive effects of wheat straw in laboratory bioassays and greenhouse pot studies. Tolerant ‘Paymaster 404’ and intolerant ‘Acala A246’ were identified and used in field experiments that were conducted in 1986 and 1987 to determine the influence of wheat stubble residues on their emergence and yield. Major reductions in emergence only occurred when above ground residues were present in the seedbed. Emergence was reduced by an average of 9% for Paymaster 404 and 21% for Acala A246 when wheat stubble residues were present in the seedbed. The allelopathic effect of wheat stubble indirectly influenced lint yield by affecting population densities. The negative effect of wheat stubble on cotton stand establishment can apparently be overcome by; limiting the amount of above ground residues that are incorporated into the seedbed during planting, increasing the seeding rates, and planting tolerant cultivars.

Autotoxicity of wheat (Triticum aestivum L.) as determined by laboratory bioassays

“…Wheat autotoxicity can be largely ameliorated by an effective management package, including a proper crop rotation to reduce the accumulation of autotoxins (Opoku et al 1997;Putnam and Duke 1978), selection of crops and varieties tolerant to autotoxins due to the considerable variation in sensitivity among different crops and varieties (Hicks et al 1989;Protic et al 1980), and avoidance of the inhibitory period of decomposing residues by the delay in sowing (Tesar 1993). It appears that autotoxicity can be overcome by reducing the quantity of straw retained, increasing sowing rates (Hicks et al 1989;Purvis and Jones 1990) and supplementing with nitrogen fertilizer (Rice 1984;Hairston et al 1987).…”

“…Merr.] (Hicks et al 1989) and soybean (Glycine max L. Merr) (Protic 1977). Wheat straw was also allelopathic to a number of forage crops including sorghum (Sorghum bicolor L. Moench), pearl millet (Pennisetum glaucum L.), clusterbean (Cyamopsis tetragonoloba L.) and cowpeas (Vigna unguiculata L.…”

Zero-tillage establishment of alfalfa and meadow bromegrass as influenced by previous annual grain crop

“…Allelopathic effecrs from phytotoxic substances produced from decaying residues have been shown to inhibit germination and establishment of subsequent crops (Hicks et al 1989). Wolf and White (1992) (Smoliak 1990).…”

Allelopathic Effects of Cereal Rye on Weed Suppression and Forage Yield in Alfalfa

“…In addition to producing allelochemicals, allelopathic crops and their residues also produce microbial toxins at the time of decomposition, which jointly create a phytotoxic environment [23]. Allelochemicals are released from plant roots, leaves, and stems [24] and affect other crops within the same area [25].…”