Effect of micronutrient fertilizer on severity and incidence of rice blast disease

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Rice is the most important food crop and a major food grain for more than a third of the world’s population. Rice blast caused by Magnaporthe oryzae continues to be the most destructive disease of rice, affects more than 50% of the cultivated rice area on average and ranked as the most important disease encountered. The objectives of this study field were; i) To compare the effect of different micronutrient fertilizer combinations on the incidence and severity of rice blast disease in lowland rice production system and ii) To compare the efficiency of method of application (soil versus foliar) of micronutrients on lowering the incidence and severity of rice blast disease in low land rice The experiment was carried out in Doho Rice Irrigation scheme, in Butaleja district, Uganda. The experiment was carried out in a Randomized Complete Block Design with four replicates and 12 different combinations of micronutrients fertilizer and one variety (K98), hence a total of 48 plots. The plots were treated with different fertilizer combination and NP was applied in splits at tillering, booting and panicle filling to all the plots except control plots. Data on the severity of rice blast disease on the leaves, sheath and panicles and the incidence of blast on leaves and sheath on the different plots were collected one month after transplanting and the thereafter every two weeks using Systematic sampling. The rice blast incidence on the leaf and panicle was generally high (90% to 100%) compared to sheath. There were no significant differences detected between treatments for the rice blast incidence on leaf (p= 0.716), sheath blast (p=0.995) and panicle (p=0.828). There was a highly significant difference (p<0.01) on panicle and leaf blast disease between the fertilizer treatments. Plots that received no treatment had a higher disease severity than those that received treatments. Application of NPK + Mn + B+ S + Zn, NP + Mn +B + S +Zn, NPK + Mn +B + S, NPK + Mn +B +Zn (foliar applied) or Effect foliar applied significantly reduces leaf blast disease severity compared to the control. The least panicle blast severity (2.24) was recorded in plot treated with NPK + Mn + S + Zn (T5) so absence of boron greatly reduces grain blast while the highest severity was recorded on plot treated with NPK alone (T1). I recommend that farmers should apply NPK in combination with micronutrients especially Elfert commercial fertilizer. Farmers should use the recommended nitrogen fertilizer rates which varies according to the already available nitrogen content in their soils. The recommended nitrogen fertilizer rate is 173.5 kgha-1 of urea, for phosphorous is 86.95 kgha-1 of TSP applied after transplanting the rice, potassium is 66.65 kgha-1 of MoP then Elfert is 10 kgha-1. (2.839Mb)
Author
Ajam, Angella Lowra
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http://hdl.handle.net/20.500.12281/4564
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