Relationship between potassium fertilization and panicle blast severity in upland rice

Abstract

-The influence of K 2 O (0, 40, 80, 120 kg ha -1 ) at varying rates of N application (0, 30, 60 kg ha -1 ) at planting, on panicle blast (Pyricularia grisea (Cooke) Sacc.) was studied in a field experiment conducted during three consecutive years with the upland rice cultivar Douradão. Panicle blast severity decreased with increasing rates of potassium in the absence of nitrogen (N0). The relationship between panicle blast and K rates was quadratic at 30 kg ha -1 of nitrogen. Significant response to K fertilization was not obtained at 60 kg ha -1 of nitrogen in relation to panicle blast severity. RELAÇÃO ENTRE ADUBAÇÃO POTÁSSICA E SEVERIDADE DE BRUSONE NAS PANÍCULAS EM ARROZ DE SEQUEIRORESUMO -Estudou-se a influência da adubação potássica (0, 40, 80, 120 kg ha Rice blast caused by Pyricularia grisea (Cooke) Sacc. is a major yield constraint in upland rice in Brazil. The pathosystem is divided into leaf and panicle blast subsystems (Teng et al., 1991). Although both leaf and panicle blast affect grain yield, losses are greater due to panicle blast during grain formation in susceptible rice cultivars (Prabhu et al., 1986).The success of blast disease management program depends upon the availability of accurate and precise information on quantitative relationships between major nutrients and disease severity and grain yield.

Interactive Effect of Different Nitrogen and Potash Levels on the Incidence of Bacterial Leaf Blight of Rice (<i>Oryza sativa L.</i>)

“…So for better management of disease a balanced combination of N and K should be applied. It is suggested that K:N ratio is more important than the effect of each individual nutrient in blast development [18].…”

“…Sufficient K nutrition increases cell cuticle thickness, cell wall strength and production of phenols that ultimately implant resistance in crops [17]. Potassium fertilization greatly affected panicle blast development, the response being significantly linear and negative with increasing levels of potash [18]. Thus, disease incidence can be lowered by high K levels [19] [20].…”

N and K interactions in cucumber plants artificially inoculated with P. cubensis

“…Downy mildew severity was reduced significantly under low N as K rates increased while high infection was noticed under elevated doses of N and K. Interaction between N and K application relative to plant response against pathogens has also been ascertained for other fungal infections. Prabhu et al concluded that fertilization with increased K had significantly linear negative response on rice blast only in the absence of additional N [23]. It is well documented that plant reaction against attack of pathogens is influenced by nutrients availability and balanced nutrition [24,25].…”

The impact of potassium on downy mildew of cucumber and its leaf/soil nutritional status.

“…The significant increase of the downy mildew disease at the higher K doses (500 to 700 mg L -1 ) could be explained by possible alterations in nutrient balance or the N: K ratio, as N and P were given to cucumber plants at fixed concentrations of 250 and 50 mg L -1 respectively. The N: K ratio was implicated in severity of many diseases caused by various plant pathogens [20,21]. Moreover, the importance of the K fertilizer type used on plant disease development has been discussed [20].…”