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Rate and Timing of Potassium Fertilization and Fungicide Influence Rice Yield and Stem Rot
Author(s) -
Maschmann Elliot T.,
Slaton Nathan A.,
Cartwright Richard D.,
Norman Richard J.
Publication year - 2010
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/agronj2009.0245
Subject(s) - azoxystrobin , stem rot , fungicide , agronomy , potash , panicle , human fertilization , oryza sativa , yield (engineering) , sclerotium , biology , potassium , horticulture , fertilizer , chemistry , materials science , biochemistry , organic chemistry , metallurgy , gene
Potassium deficient rice ( Oryza sativa L.) is susceptible to diseases including stem rot ( Sclerotium oryzae Catt.). Knowledge of how to manage K deficiency and the increased disease susceptibility is necessary to reduce rice yield losses. Our objectives were to determine the influence of K rate, application time, and azoxystrobin fungicide on grain yield and stem rot index (SRI) of rice grown on soils with low K availability. Muriate of potash was applied at 0, 56, and 112 kg K ha −1 to rice preflood (PF), panicle differentiation (PD), or the late boot (LB) stage. Azoxystrobin fungicide was applied at 0 and 0.23 kg a.i. ha −1 following the PD K application. Stem rot was assessed at maturity and expressed as SRI on a 1‐to‐5 scale, with 1 indicating no disease symptoms (healthy) and 5 being a dead culm. Potassium fertilization increased grain yield by 8 to 11% above rice receiving no K. Within each K application time, grain yield of rice receiving 0.23 kg ha −1 azoxystrobin was 6 to 12% greater than rice receiving no azoxystrobin. Within each azoxystrobin rate, rice yields were lowest when no K was applied, intermediate for K applied at LB, and greatest for K applied PF or PD. The average SRI was reduced significantly by K fertilization and azoxystrobin application. Potassium fertilizer applied between PD and LB can reduce yield losses from K deficiency. Sufficient K fertilizer should be applied PF to prevent potential yield losses from K deficiency and minimize stem rot incidence and severity.