Double-cropping and crop rotation effects on diseases and grain yield of pearl millet.

摘要

The effects of double-cropping and crop rotation sequences on grain yield and diseases of pearl millet (Pennisetum glaucum) were evaluated to determine the compatibility of pearl millet in southeastern agricultural cropping systems. Pearl millet hybrid HGM 100 was sown with minimum tillage, double-cropped with canola [rape] or wheat (Triticum aestivum). Soyabeans were used as an alternative summer annual to pearl millet in rotation sequences. Treatment effects on seedling stand density, panicle number, grain yield, leaf blight (caused by Exserohilum rostratum), stalk and neck rot (associated with a number of fungi), and smut (caused by Moesziomyces penicillariae) severity were determined. Seedling stands 3 weeks after sowing were lower following canola than wheat in 1995 and 1997, and panicle number was lower in 1997. No other yield-associated variables were affected by the previous winter crop. In comparison of crop rotations, inconsistent effects were observed in stand density in 1997, and panicle number in 1996 and 1997. Seedling stand density and panicle number were lower with 2 years of pearl millet compared with 1 year, but were highest for the 3 sequential years of cultivation in 1997. A trend toward increased smut severity in plots continuously growing pearl millet was observed in 1997. Within subplots, stand density was highly correlated with panicle number in 1996 and 1997 (r>=0.51, P<0.01), with leaf blight severity in 1995 and 1996 (r>=0.33, P<0.01) and with stalk and neck rot in 1996(r=0.60, P<0.01). Yield was negatively correlated (r<=-0.31, P<0.01) with leaf blight severity in 1995 and 1996, and stalk and neck rot in 1996 (r=-0.46, P<0.01). Stalk and neck rot in 1996 was probably caused by Fusarium graminearum [Gibberella zeae], which was more commonly isolated from pearl millet following canola than wheat. Neither the previous winter annual crop nor the number of sequential years of pearl millet cultivation had detrimental, limiting effects on pearl millet grain yield or diseases.